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"\u6b64\u6e90\u7801\u8bb0\u5f55\u7684\u6587\u672c\u540d\u79f0\uff1aBitmapOr.", "\u5e76\u884c\u611f\u77e5\u4e0e\u5e76\u884c\u5b89\u5168\u662f\u4e0d\u540c\u7684\u8ba1\u5212\u5c5e\u6027\u3002\u5728\u5e76\u884c\u5de5\u4f5c\u8fdb\u7a0b\u5185\u8fd0\u884c\u7684\u8282\u70b9\u4e0d\u4e00\u5b9a\u662f\u5e76\u884c\u611f\u77e5\u8282\u70b9\u3002"]}, {"title": "\u5185\u5b58\u4e0e\u4e34\u65f6\u5b58\u50a8", "paragraphs": ["\u6b64\u8282\u70b9\u6309\u57fa\u4e8e work_mem \u7684\u9884\u7b97\u5206\u914d\u5143\u7ec4\u4f4d\u7f6e\u4f4d\u56fe\u3002\u4f4d\u56fe\u53ef\u4ee5\u4fdd\u7559\u9875\u7ea7\u6709\u635f\u6761\u76ee\uff0c\u800c\u4e0d\u8bb0\u5f55\u6bcf\u4e2a\u5143\u7ec4\u4f4d\u7f6e\uff0c\u56e0\u6b64\u4ecd\u53ef\u80fd\u9700\u8981\u5806\u91cd\u68c0\u3002"]}, {"title": "\u5e76\u884c\u6267\u884c\u4e0e\u8fd0\u884c\u4fe1\u606f\u91c7\u96c6", "paragraphs": ["\u4ee5\u4e0b\u6e90\u7801\u56de\u8c03\u53ef\u4ee5\u534f\u8c03\u6267\u884c\u6216\u6536\u96c6\u5de5\u4f5c\u8fdb\u7a0b\u7684\u6d4b\u91cf\u6570\u636e\u3002\u56de\u8c03\u5b58\u5728\u4e0d\u4ee3\u8868\u8be5\u8282\u70b9\u666e\u904d\u652f\u6301\u5171\u4eab\u5e76\u884c\u626b\u63cf\u6216\u5171\u4eab\u72b6\u6001\u3002", "\u6b64\u6784\u5efa\u7684\u56de\u8c03\uff1anone extracted from this node implementation."]}, {"title": "\u540c\u7248\u672c\u624b\u518c\u8bf4\u660e", "paragraphs": ["\u7531\u4e8e\u5b9e\u73b0\u4e0a\u7684\u9650\u5236\uff0cBitmapAnd \u548c BitmapOr \u8282\u70b9\u62a5\u544a\u7684\u5b9e\u9645\u884c\u6570\u59cb\u7ec8\u4e3a\u96f6\u3002"]}, {"title": "\u6267\u884c\u5668\u5b9e\u73b0\u8bf4\u660e", "paragraphs": ["\u8bf4\u660e\uff1aBitmapOr \u4e0d\u4f7f\u7528\u5de6\u53f3\u5b50\u6811\uff0c\u800c\u50cf Append \u4e00\u6837\u7ef4\u62a4\u5b50\u8ba1\u5212\u5217\u8868\u3002\u4e0d\u8fc7\u5176\u903b\u8f91\u6bd4 Append \u7b80\u5355\u5f97\u591a\uff0c\u56e0\u4e3a\u65e0\u9700\u5904\u7406\u6b63\u5411\u6216\u53cd\u5411\u6267\u884c\u3002", "BitmapOr \u8ba1\u5212\u6ca1\u6709\u8868\u8fbe\u5f0f\u4e0a\u4e0b\u6587\uff0c\u56e0\u4e3a\u5b83\u4eec\u4ece\u4e0d\u8c03\u7528 ExecQual \u6216 ExecProject\uff0c\u4e5f\u4e0d\u9700\u8981\u5143\u7ec4\u69fd\u3002", "\u5bf9\u6bcf\u4e2a\u5f85\u6267\u884c\u8ba1\u5212\u8c03\u7528 ExecInitNode\uff0c\u5e76\u5c06\u7ed3\u679c\u4fdd\u5b58\u5230 bitmapplanstates \u6570\u7ec4\u3002", "\u53ef\u5bf9 BitmapIndexScan \u5b50\u8282\u70b9\u4f5c\u7279\u6b8a\u5904\u7406\uff0c\u907f\u514d\u4e3a\u6bcf\u4e2a\u5b50\u8282\u70b9\u663e\u5f0f\u8c03\u7528 tbm_union\uff1a\u76f4\u63a5\u4e0b\u4f20\u5f53\u524d\u7ed3\u679c\u4f4d\u56fe\uff0c\u8ba9\u5b50\u8282\u70b9\u5c06\u7ed3\u679c\u6309\u4f4d OR \u5408\u5e76\u8fdb\u53bb\u3002", "ExecReScan \u4e0d\u77e5\u9053\u5f53\u524d\u8282\u70b9\u7684\u5b50\u8ba1\u5212\uff0c\u56e0\u6b64\u5fc5\u987b\u81ea\u884c\u901a\u77e5\u5b50\u8ba1\u5212\u54ea\u4e9b\u53c2\u6570\u53d1\u751f\u4e86\u53d8\u5316\u3002"]}, {"code": "case T_BitmapOr:\n\t\t\tpname = sname = \"BitmapOr\";\n\t\t\tbreak;", "title": "\u6838\u5fc3\u6e90\u7801\u4e2d\u7684 EXPLAIN \u6807\u8bc6"}], "description_zh": "\u5bf9\u5404\u5b50\u8ba1\u5212\u751f\u6210\u7684\u4f4d\u56fe\u6c42\u5e76\u96c6\u3002", "description_zh_html": "<p>\u5bf9\u5404\u5b50\u8ba1\u5212\u751f\u6210\u7684\u4f4d\u56fe\u6c42\u5e76\u96c6\u3002</p><p>\u6838\u5fc3\u8282\u70b9\u6807\u8bc6\uff1a<code>T_BitmapOr</code>\uff1bEXPLAIN \u540d\u79f0\uff1a<code>BitmapOr</code>\u3002</p><p>\u672c\u7248\u672c\u6e90\u7801\u4e2d\u7684\u5e76\u884c\u6267\u884c\u6216\u89c2\u6d4b\u56de\u8c03\uff1a\u8be5\u8282\u70b9\u5b9e\u73b0\u4e2d\u672a\u63d0\u53d6\u5230\u6b64\u7c7b\u56de\u8c03\u3002\u56de\u8c03\u7684\u5b58\u5728\u4e0d\u8868\u793a\u8be5\u8282\u70b9\u5fc5\u7136\u652f\u6301\u5171\u4eab\u5e76\u884c\u626b\u63cf\uff1b\u5728\u5e76\u884c\u5de5\u4f5c\u8fdb\u7a0b\u4e2d\u6267\u884c\u4e5f\u4e0d\u7b49\u4e8e\u5177\u6709\u5e76\u884c\u611f\u77e5\u80fd\u529b\u3002</p><h3>\u540c\u7248\u672c\u4e2d\u6587\u624b\u518c\u8282\u9009</h3><p> <code class=\"command\">EXPLAIN ANALYZE</code> \u6d4b\u5f97\u7684\u8fd0\u884c\u65f6\u95f4\uff0c\u53ef\u80fd\u4ee5\u4e24\u79cd\u91cd\u8981\u65b9\u5f0f\u504f\u79bb\u540c\u4e00\u67e5\u8be2\u7684\u6b63\u5e38\u6267\u884c\u65f6\u95f4\u3002\u7b2c\u4e00\uff0c\u7531\u4e8e\u4e0d\u4f1a\u5411\u5ba2\u6237\u7aef\u4f20\u9012\u4efb\u4f55\u8f93\u51fa\u884c\uff0c\u56e0\u6b64\u7f51\u7edc\u4f20\u8f93\u5f00\u9500\u548c I/O \u8f6c\u6362\u5f00\u9500\u5747\u4e0d\u4f1a\u88ab\u8ba1\u5165\u3002\u7b2c\u4e8c\uff0c<code class=\"command\">EXPLAIN ANALYZE</code> \u9644\u52a0\u7684\u6d4b\u91cf\u5f00\u9500\u672c\u8eab\u53ef\u80fd\u76f8\u5f53\u53ef\u89c2\uff0c\u5c24\u5176\u662f\u5728\u64cd\u4f5c\u7cfb\u7edf\u8c03\u7528 <code class=\"function\">gettimeofday()</code> \u8f83\u6162\u7684\u673a\u5668\u4e0a\u3002\u53ef\u4ee5\u4f7f\u7528 <a class=\"xref\" href=\"/zh/docs/10/pgtesttiming.html\"><span class=\"refentrytitle\"><span class=\"application\">pg_test_timing</span></span></a> \u5de5\u5177\u6765\u6d4b\u91cf\u7cfb\u7edf\u4e0a\u7684\u8ba1\u65f6\u5f00\u9500\u3002\n   </p><p>    \u4e0d\u5e94\u5c06 <code class=\"command\">EXPLAIN</code> \u7ed3\u679c\u5916\u63a8\u5230\u4e0e\u5b9e\u9645\u6d4b\u8bd5\u573a\u666f\u5dee\u5f02\u5f88\u5927\u7684\u60c5\u51b5\u3002\u4f8b\u5982\uff0c\u5728\u4e00\u4e2a\u5f88\u5c0f\u7684\u8868\u4e0a\u5f97\u5230\u7684\u7ed3\u679c\uff0c\u4e0d\u80fd\u5047\u5b9a\u4e5f\u9002\u7528\u4e8e\u5927\u578b\u8868\u3002\u89c4\u5212\u5668\u7684\u4ee3\u4ef7\u4f30\u8ba1\u4e0d\u662f\u7ebf\u6027\u7684\uff0c\u56e0\u6b64\u5b83\u53ef\u80fd\u4f1a\u4e3a\u66f4\u5927\u6216\u66f4\u5c0f\u7684\u8868\u9009\u62e9\u4e0d\u540c\u7684\u8ba1\u5212\u3002\u4e00\u4e2a\u6781\u7aef\u793a\u4f8b\u662f\uff1a\u5bf9\u4e8e\u53ea\u5360\u7528\u4e00\u4e2a\u78c1\u76d8\u9875\u7684\u8868\uff0c\u65e0\u8bba\u7d22\u5f15\u662f\u5426\u53ef\u7528\uff0c\u51e0\u4e4e\u603b\u4f1a\u5f97\u5230\u987a\u5e8f\u626b\u63cf\u8ba1\u5212\u3002\u89c4\u5212\u5668\u8ba4\u8bc6\u5230\uff0c\u65e0\u8bba\u5982\u4f55\u5904\u7406\u8be5\u8868\u90fd\u9700\u8981\u4e00\u6b21\u78c1\u76d8\u9875\u8bfb\u53d6\uff0c\u56e0\u6b64\u518d\u989d\u5916\u8bfb\u53d6\u9875\u9762\u53bb\u67e5\u770b\u7d22\u5f15\u5e76\u6ca1\u6709\u4ef7\u503c\u3002\uff08\u524d\u9762\u7684 <code class=\"literal\">polygon_tbl</code> \u793a\u4f8b\u5df2\u7ecf\u5c55\u793a\u8fc7\u8fd9\u79cd\u60c5\u51b5\u3002\uff09\n   </p><p>\u6709\u65f6\u5b9e\u9645\u503c\u4e0e\u4f30\u8ba1\u503c\u4e0d\u592a\u4e00\u81f4\uff0c\u4f46\u5b9e\u9645\u4e0a\u5e76\u6ca1\u6709\u95ee\u9898\u3002\u5176\u4e2d\u4e00\u79cd\u60c5\u51b5\u662f\uff0c\u8ba1\u5212\u8282\u70b9\u7684\u6267\u884c\u56e0 <code class=\"literal\">LIMIT</code> \u6216\u7c7b\u4f3c\u6548\u679c\u800c\u63d0\u524d\u505c\u6b62\u3002\u4f8b\u5982\uff0c\u5728\u524d\u9762\u4f7f\u7528\u7684 <code class=\"literal\">LIMIT</code> \u67e5\u8be2\u4e2d\uff1a</p><p>Index Scan \u8282\u70b9\u7684\u4f30\u8ba1\u4ee3\u4ef7\u548c\u884c\u6570\u6309\u8be5\u8282\u70b9\u6267\u884c\u5230\u5b8c\u6210\u7684\u60c5\u51b5\u663e\u793a\u3002\u4f46\u5b9e\u9645\u4e0a\uff0cLimit \u8282\u70b9\u53d6\u5f97\u4e24\u884c\u540e\u5c31\u505c\u6b62\u8bf7\u6c42\u884c\uff0c\u56e0\u6b64\u5b9e\u9645\u884c\u6570\u53ea\u6709 2\uff0c\u8fd0\u884c\u65f6\u95f4\u4e5f\u5c0f\u4e8e\u4f30\u8ba1\u4ee3\u4ef7\u6240\u6697\u793a\u7684\u65f6\u95f4\u3002\u8fd9\u4e0d\u662f\u4f30\u8ba1\u9519\u8bef\uff0c\u53ea\u662f\u4f30\u8ba1\u503c\u4e0e\u5b9e\u9645\u503c\u7684\u663e\u793a\u65b9\u5f0f\u5b58\u5728\u5dee\u522b\u3002</p><p><a href=\"/zh/docs/10/performance-tips.html#USING-EXPLAIN-CAVEATS\">\u67e5\u770b\u5b8c\u6574\u4e2d\u6587\u624b\u518c\u4e0e\u4e0a\u4e0b\u6587</a>\u3002</p><p>\u672c\u9875\u5f00\u5934\u7684\u4e2d\u6587\u8bf4\u660e\u4e3a PG.CENTER \u5bf9\u7f16\u8f91\u8bf4\u660e\u7684\u7ffb\u8bd1\uff1b\u624b\u518c\u8282\u9009\u4fdd\u7559\u5bf9\u5e94\u7248\u672c\u4e2d\u6587\u6587\u6863\u539f\u6587\u3002\u6e90\u7801\u4fe1\u606f\u53ca\u624b\u518c\u793a\u4f8b\u4e0d\u4ee3\u8868\u91cd\u65b0\u8fdb\u884c\u8fc7\u8fd0\u884c\u6d4b\u8bd5\u3002</p>"}, "summary": "\u5bf9\u5404\u5b50\u8ba1\u5212\u751f\u6210\u7684\u4f4d\u56fe\u6c42\u5e76\u96c6\u3002", "version": "10", "link_map": {"/zh/docs/10/pgtesttiming.html": "/docs/10/pgtesttiming.html", "/zh/docs/10/performance-tips.html#USING-EXPLAIN-CAVEATS": "/docs/10/performance-tips.html#USING-EXPLAIN-CAVEATS"}, "body_html": "<p>\u5bf9\u5404\u5b50\u8ba1\u5212\u751f\u6210\u7684\u4f4d\u56fe\u6c42\u5e76\u96c6\u3002</p><p>\u6838\u5fc3\u8282\u70b9\u6807\u8bc6\uff1a<code>T_BitmapOr</code>\uff1bEXPLAIN \u540d\u79f0\uff1a<code>BitmapOr</code>\u3002</p><p>\u672c\u7248\u672c\u6e90\u7801\u4e2d\u7684\u5e76\u884c\u6267\u884c\u6216\u89c2\u6d4b\u56de\u8c03\uff1a\u8be5\u8282\u70b9\u5b9e\u73b0\u4e2d\u672a\u63d0\u53d6\u5230\u6b64\u7c7b\u56de\u8c03\u3002\u56de\u8c03\u7684\u5b58\u5728\u4e0d\u8868\u793a\u8be5\u8282\u70b9\u5fc5\u7136\u652f\u6301\u5171\u4eab\u5e76\u884c\u626b\u63cf\uff1b\u5728\u5e76\u884c\u5de5\u4f5c\u8fdb\u7a0b\u4e2d\u6267\u884c\u4e5f\u4e0d\u7b49\u4e8e\u5177\u6709\u5e76\u884c\u611f\u77e5\u80fd\u529b\u3002</p><h3>\u540c\u7248\u672c\u4e2d\u6587\u624b\u518c\u8282\u9009</h3><p> <code>EXPLAIN ANALYZE</code> \u6d4b\u5f97\u7684\u8fd0\u884c\u65f6\u95f4\uff0c\u53ef\u80fd\u4ee5\u4e24\u79cd\u91cd\u8981\u65b9\u5f0f\u504f\u79bb\u540c\u4e00\u67e5\u8be2\u7684\u6b63\u5e38\u6267\u884c\u65f6\u95f4\u3002\u7b2c\u4e00\uff0c\u7531\u4e8e\u4e0d\u4f1a\u5411\u5ba2\u6237\u7aef\u4f20\u9012\u4efb\u4f55\u8f93\u51fa\u884c\uff0c\u56e0\u6b64\u7f51\u7edc\u4f20\u8f93\u5f00\u9500\u548c I/O \u8f6c\u6362\u5f00\u9500\u5747\u4e0d\u4f1a\u88ab\u8ba1\u5165\u3002\u7b2c\u4e8c\uff0c<code>EXPLAIN ANALYZE</code> \u9644\u52a0\u7684\u6d4b\u91cf\u5f00\u9500\u672c\u8eab\u53ef\u80fd\u76f8\u5f53\u53ef\u89c2\uff0c\u5c24\u5176\u662f\u5728\u64cd\u4f5c\u7cfb\u7edf\u8c03\u7528 <code>gettimeofday()</code> \u8f83\u6162\u7684\u673a\u5668\u4e0a\u3002\u53ef\u4ee5\u4f7f\u7528 <a href=\"/zh/docs/10/pgtesttiming.html\" rel=\"nofollow\"><span><span>pg_test_timing</span></span></a> \u5de5\u5177\u6765\u6d4b\u91cf\u7cfb\u7edf\u4e0a\u7684\u8ba1\u65f6\u5f00\u9500\u3002\n   </p><p>    \u4e0d\u5e94\u5c06 <code>EXPLAIN</code> \u7ed3\u679c\u5916\u63a8\u5230\u4e0e\u5b9e\u9645\u6d4b\u8bd5\u573a\u666f\u5dee\u5f02\u5f88\u5927\u7684\u60c5\u51b5\u3002\u4f8b\u5982\uff0c\u5728\u4e00\u4e2a\u5f88\u5c0f\u7684\u8868\u4e0a\u5f97\u5230\u7684\u7ed3\u679c\uff0c\u4e0d\u80fd\u5047\u5b9a\u4e5f\u9002\u7528\u4e8e\u5927\u578b\u8868\u3002\u89c4\u5212\u5668\u7684\u4ee3\u4ef7\u4f30\u8ba1\u4e0d\u662f\u7ebf\u6027\u7684\uff0c\u56e0\u6b64\u5b83\u53ef\u80fd\u4f1a\u4e3a\u66f4\u5927\u6216\u66f4\u5c0f\u7684\u8868\u9009\u62e9\u4e0d\u540c\u7684\u8ba1\u5212\u3002\u4e00\u4e2a\u6781\u7aef\u793a\u4f8b\u662f\uff1a\u5bf9\u4e8e\u53ea\u5360\u7528\u4e00\u4e2a\u78c1\u76d8\u9875\u7684\u8868\uff0c\u65e0\u8bba\u7d22\u5f15\u662f\u5426\u53ef\u7528\uff0c\u51e0\u4e4e\u603b\u4f1a\u5f97\u5230\u987a\u5e8f\u626b\u63cf\u8ba1\u5212\u3002\u89c4\u5212\u5668\u8ba4\u8bc6\u5230\uff0c\u65e0\u8bba\u5982\u4f55\u5904\u7406\u8be5\u8868\u90fd\u9700\u8981\u4e00\u6b21\u78c1\u76d8\u9875\u8bfb\u53d6\uff0c\u56e0\u6b64\u518d\u989d\u5916\u8bfb\u53d6\u9875\u9762\u53bb\u67e5\u770b\u7d22\u5f15\u5e76\u6ca1\u6709\u4ef7\u503c\u3002\uff08\u524d\u9762\u7684 <code>polygon_tbl</code> \u793a\u4f8b\u5df2\u7ecf\u5c55\u793a\u8fc7\u8fd9\u79cd\u60c5\u51b5\u3002\uff09\n   </p><p>\u6709\u65f6\u5b9e\u9645\u503c\u4e0e\u4f30\u8ba1\u503c\u4e0d\u592a\u4e00\u81f4\uff0c\u4f46\u5b9e\u9645\u4e0a\u5e76\u6ca1\u6709\u95ee\u9898\u3002\u5176\u4e2d\u4e00\u79cd\u60c5\u51b5\u662f\uff0c\u8ba1\u5212\u8282\u70b9\u7684\u6267\u884c\u56e0 <code>LIMIT</code> \u6216\u7c7b\u4f3c\u6548\u679c\u800c\u63d0\u524d\u505c\u6b62\u3002\u4f8b\u5982\uff0c\u5728\u524d\u9762\u4f7f\u7528\u7684 <code>LIMIT</code> \u67e5\u8be2\u4e2d\uff1a</p><p>Index Scan \u8282\u70b9\u7684\u4f30\u8ba1\u4ee3\u4ef7\u548c\u884c\u6570\u6309\u8be5\u8282\u70b9\u6267\u884c\u5230\u5b8c\u6210\u7684\u60c5\u51b5\u663e\u793a\u3002\u4f46\u5b9e\u9645\u4e0a\uff0cLimit \u8282\u70b9\u53d6\u5f97\u4e24\u884c\u540e\u5c31\u505c\u6b62\u8bf7\u6c42\u884c\uff0c\u56e0\u6b64\u5b9e\u9645\u884c\u6570\u53ea\u6709 2\uff0c\u8fd0\u884c\u65f6\u95f4\u4e5f\u5c0f\u4e8e\u4f30\u8ba1\u4ee3\u4ef7\u6240\u6697\u793a\u7684\u65f6\u95f4\u3002\u8fd9\u4e0d\u662f\u4f30\u8ba1\u9519\u8bef\uff0c\u53ea\u662f\u4f30\u8ba1\u503c\u4e0e\u5b9e\u9645\u503c\u7684\u663e\u793a\u65b9\u5f0f\u5b58\u5728\u5dee\u522b\u3002</p><p><a href=\"/zh/docs/10/performance-tips.html#USING-EXPLAIN-CAVEATS\" rel=\"nofollow\">\u67e5\u770b\u5b8c\u6574\u4e2d\u6587\u624b\u518c\u4e0e\u4e0a\u4e0b\u6587</a>\u3002</p><p>\u672c\u9875\u5f00\u5934\u7684\u4e2d\u6587\u8bf4\u660e\u4e3a PG.CENTER \u5bf9\u7f16\u8f91\u8bf4\u660e\u7684\u7ffb\u8bd1\uff1b\u624b\u518c\u8282\u9009\u4fdd\u7559\u5bf9\u5e94\u7248\u672c\u4e2d\u6587\u6587\u6863\u539f\u6587\u3002\u6e90\u7801\u4fe1\u606f\u53ca\u624b\u518c\u793a\u4f8b\u4e0d\u4ee3\u8868\u91cd\u65b0\u8fdb\u884c\u8fc7\u8fd0\u884c\u6d4b\u8bd5\u3002</p>", "body_sha256": "00ad604a4056e81b947a4e0c3eb1663f6f052baf57e8e8e461ae2e7a0ee85f47", "content_hash": "739f21af9671893574b7bee52e27823436ed3f7c5ac6ed291e6cab6794edbd5d", "source_database": "center", "source_revision": "94a4b2528372458e5662c18d406629266667c437198160a18cdfd2c4a4d6eee9"}, "tables_zh": [{"key": "explain-labels", "rows": [{"label": "BitmapOr", "identity": "BitmapOr"}], "title": "\u672c\u6784\u5efa\u4e2d\u7684 EXPLAIN \u6807\u7b7e", "columns": [{"key": "label", "label": "\u6587\u672c\u683c\u5f0f\u6807\u7b7e"}, {"key": "identity", "label": "\u7ed3\u6784\u5316\u8282\u70b9\u6807\u8bc6"}]}], "strategies": [], "description": ["\u5bf9\u5404\u5b50\u8ba1\u5212\u751f\u6210\u7684\u4f4d\u56fe\u6c42\u5e76\u96c6\u3002"], "sections_zh": [{"title": "EXPLAIN \u540d\u79f0\u4e0e\u5c5e\u6027", "paragraphs": ["\u7ed3\u6784\u5316\u683c\u5f0f\u4f7f\u7528\u4e0a\u8ff0 Node Type\u3002\u6587\u672c\u683c\u5f0f\u540d\u79f0\u8fd8\u53ef\u80fd\u5305\u542b\u64cd\u4f5c\u3001\u7b56\u7565\u3001\u8fde\u63a5\u7c7b\u578b\u3001\u626b\u63cf\u65b9\u5411\u6216\u805a\u5408\u9636\u6bb5\u5c5e\u6027\u3002", "\u6b64\u6e90\u7801\u8bb0\u5f55\u7684\u6587\u672c\u540d\u79f0\uff1aBitmapOr.", "\u5e76\u884c\u611f\u77e5\u4e0e\u5e76\u884c\u5b89\u5168\u662f\u4e0d\u540c\u7684\u8ba1\u5212\u5c5e\u6027\u3002\u5728\u5e76\u884c\u5de5\u4f5c\u8fdb\u7a0b\u5185\u8fd0\u884c\u7684\u8282\u70b9\u4e0d\u4e00\u5b9a\u662f\u5e76\u884c\u611f\u77e5\u8282\u70b9\u3002"]}, {"title": "\u5185\u5b58\u4e0e\u4e34\u65f6\u5b58\u50a8", "paragraphs": ["\u6b64\u8282\u70b9\u6309\u57fa\u4e8e work_mem \u7684\u9884\u7b97\u5206\u914d\u5143\u7ec4\u4f4d\u7f6e\u4f4d\u56fe\u3002\u4f4d\u56fe\u53ef\u4ee5\u4fdd\u7559\u9875\u7ea7\u6709\u635f\u6761\u76ee\uff0c\u800c\u4e0d\u8bb0\u5f55\u6bcf\u4e2a\u5143\u7ec4\u4f4d\u7f6e\uff0c\u56e0\u6b64\u4ecd\u53ef\u80fd\u9700\u8981\u5806\u91cd\u68c0\u3002"]}, {"title": "\u5e76\u884c\u6267\u884c\u4e0e\u8fd0\u884c\u4fe1\u606f\u91c7\u96c6", "paragraphs": ["\u4ee5\u4e0b\u6e90\u7801\u56de\u8c03\u53ef\u4ee5\u534f\u8c03\u6267\u884c\u6216\u6536\u96c6\u5de5\u4f5c\u8fdb\u7a0b\u7684\u6d4b\u91cf\u6570\u636e\u3002\u56de\u8c03\u5b58\u5728\u4e0d\u4ee3\u8868\u8be5\u8282\u70b9\u666e\u904d\u652f\u6301\u5171\u4eab\u5e76\u884c\u626b\u63cf\u6216\u5171\u4eab\u72b6\u6001\u3002", "\u6b64\u6784\u5efa\u7684\u56de\u8c03\uff1anone extracted from this node implementation."]}, {"title": "\u540c\u7248\u672c\u624b\u518c\u8bf4\u660e", "paragraphs": ["\u7531\u4e8e\u5b9e\u73b0\u4e0a\u7684\u9650\u5236\uff0cBitmapAnd \u548c BitmapOr \u8282\u70b9\u62a5\u544a\u7684\u5b9e\u9645\u884c\u6570\u59cb\u7ec8\u4e3a\u96f6\u3002"]}, {"title": "\u6267\u884c\u5668\u5b9e\u73b0\u8bf4\u660e", "paragraphs": ["\u8bf4\u660e\uff1aBitmapOr \u4e0d\u4f7f\u7528\u5de6\u53f3\u5b50\u6811\uff0c\u800c\u50cf Append \u4e00\u6837\u7ef4\u62a4\u5b50\u8ba1\u5212\u5217\u8868\u3002\u4e0d\u8fc7\u5176\u903b\u8f91\u6bd4 Append \u7b80\u5355\u5f97\u591a\uff0c\u56e0\u4e3a\u65e0\u9700\u5904\u7406\u6b63\u5411\u6216\u53cd\u5411\u6267\u884c\u3002", "BitmapOr \u8ba1\u5212\u6ca1\u6709\u8868\u8fbe\u5f0f\u4e0a\u4e0b\u6587\uff0c\u56e0\u4e3a\u5b83\u4eec\u4ece\u4e0d\u8c03\u7528 ExecQual \u6216 ExecProject\uff0c\u4e5f\u4e0d\u9700\u8981\u5143\u7ec4\u69fd\u3002", "\u5bf9\u6bcf\u4e2a\u5f85\u6267\u884c\u8ba1\u5212\u8c03\u7528 ExecInitNode\uff0c\u5e76\u5c06\u7ed3\u679c\u4fdd\u5b58\u5230 bitmapplanstates \u6570\u7ec4\u3002", "\u53ef\u5bf9 BitmapIndexScan \u5b50\u8282\u70b9\u4f5c\u7279\u6b8a\u5904\u7406\uff0c\u907f\u514d\u4e3a\u6bcf\u4e2a\u5b50\u8282\u70b9\u663e\u5f0f\u8c03\u7528 tbm_union\uff1a\u76f4\u63a5\u4e0b\u4f20\u5f53\u524d\u7ed3\u679c\u4f4d\u56fe\uff0c\u8ba9\u5b50\u8282\u70b9\u5c06\u7ed3\u679c\u6309\u4f4d OR \u5408\u5e76\u8fdb\u53bb\u3002", "ExecReScan \u4e0d\u77e5\u9053\u5f53\u524d\u8282\u70b9\u7684\u5b50\u8ba1\u5212\uff0c\u56e0\u6b64\u5fc5\u987b\u81ea\u884c\u901a\u77e5\u5b50\u8ba1\u5212\u54ea\u4e9b\u53c2\u6570\u53d1\u751f\u4e86\u53d8\u5316\u3002"]}, {"code": "case T_BitmapOr:\n\t\t\tpname = sname = \"BitmapOr\";\n\t\t\tbreak;", "title": "\u6838\u5fc3\u6e90\u7801\u4e2d\u7684 EXPLAIN \u6807\u8bc6"}], "localization": {"status": "complete", "sources": [], "language": "zh", "original_text": {"/versions/10/description/0": "Unions bitmaps produced by its child plans.", "/versions/10/facts/0/label": "Core node tag", "/versions/10/facts/1/label": "Structured EXPLAIN Node Type", "/versions/10/facts/2/label": "Inputs", "/versions/10/facts/2/value": "Bitmap-producing child plans", "/versions/10/facts/3/label": "Output", "/versions/10/facts/3/value": "Tuple-location bitmap, not a tuple stream", "/versions/10/facts/4/label": "Executor initializer", "/versions/10/facts/5/label": "Memory mechanism", "/versions/10/tables/0/title": "EXPLAIN labels in this source build", "/versions/10/related/1/label": "Using EXPLAIN", "/versions/10/related/2/label": "Parallel plans", "/versions/10/sections/0/title": "EXPLAIN names and attributes", "/versions/10/sections/1/title": "Memory and temporary storage", "/versions/10/sections/2/title": "Parallel execution and instrumentation", "/versions/10/sections/3/title": "Same-version manual discussion", "/versions/10/sections/4/title": "Executor implementation notes", "/versions/10/sections/5/title": "EXPLAIN identity in core source", "/versions/10/memory/description": "The node allocates a tuple-location bitmap using a work_mem-derived budget. A bitmap can retain page-level lossy entries instead of every tuple location; heap rechecks then remain necessary.", "/versions/10/sections/0/paragraphs/0": "Structured formats use the Node Type above. Text-format spellings can also include operation, strategy, join type, scan direction or aggregation-stage attributes.", "/versions/10/sections/0/paragraphs/1": "Text names recorded by this source: BitmapOr.", "/versions/10/sections/0/paragraphs/2": "Parallel-aware and parallel-safe are different plan properties. A node running inside a parallel worker is not necessarily a parallel-aware node.", "/versions/10/sections/1/paragraphs/0": "The node allocates a tuple-location bitmap using a work_mem-derived budget. A bitmap can retain page-level lossy entries instead of every tuple location; heap rechecks then remain necessary.", "/versions/10/sections/2/paragraphs/0": "The source callbacks below can coordinate execution or collect worker instrumentation. Their presence is not a blanket claim that this node supports a shared parallel scan or shared state.", "/versions/10/sections/2/paragraphs/1": "Callbacks in this build: none extracted from this node implementation.", "/versions/10/sections/3/paragraphs/0": "BitmapAnd and BitmapOr nodes always report their actual row counts as zero, due to implementation limitations.", "/versions/10/sections/4/paragraphs/0": "NOTES BitmapOr nodes don't make use of their left and right subtrees, rather they maintain a list of subplans, much like Append nodes. The logic is much simpler than Append, however, since we needn't cope with forward/backward execution.", "/versions/10/sections/4/paragraphs/1": "BitmapOr plans don't have expression contexts because they never call ExecQual or ExecProject. They don't need any tuple slots either.", "/versions/10/sections/4/paragraphs/2": "call ExecInitNode on each of the plans to be executed and save the results into the array \"bitmapplanstates\".", "/versions/10/sections/4/paragraphs/3": "We can special-case BitmapIndexScan children to avoid an explicit tbm_union step for each child: just pass down the current result bitmap and let the child OR directly into it.", "/versions/10/sections/4/paragraphs/4": "ExecReScan doesn't know about my subplans, so I have to do changed-parameter signaling myself.", "/versions/10/tables/0/columns/0/label": "Text-format label", "/versions/10/tables/0/columns/1/label": "Structured node identity"}, "fallback_fields": [], "source_language": "en", "original_snapshot_sha256": "00707544822ea37b2daa98f0f642e99cedf861a9785ea0f12f3c6ce394b84431", "canonical_center_text_hash": "739f21af9671893574b7bee52e27823436ed3f7c5ac6ed291e6cab6794edbd5d"}, "evidence_kind": "source and documentation", "explain_names": ["BitmapOr"], "partial_modes": [], "description_zh": "\u5bf9\u5404\u5b50\u8ba1\u5212\u751f\u6210\u7684\u4f4d\u56fe\u6c42\u5e76\u96c6\u3002", "comparison_data": {"node_tag": "T_BitmapOr", "strategies": [], "text_names": ["BitmapOr"], "initializer": "ExecInitBitmapOr", "partial_modes": [], "memory_mechanism": "bitmap-lossification", "parallel_callbacks": []}, "comparison_hash": "c0ca503a6029c37ec720213dcdc3094997eb194d4920da68f94a7420d3e8f1d2", "manual_language": "zh", "explain_prefixes": ["Parallel"], "runtime_verified": false, "source_inventory": {"explain": "src/backend/commands/explain.c", "executor": "src/backend/executor/execProcnode.c", "implementation": "src/backend/executor/nodeBitmapOr.c"}, "parallel_callbacks": [], "description_zh_html": "<p>\u5bf9\u5404\u5b50\u8ba1\u5212\u751f\u6210\u7684\u4f4d\u56fe\u6c42\u5e76\u96c6\u3002</p><p>\u6838\u5fc3\u8282\u70b9\u6807\u8bc6\uff1a<code>T_BitmapOr</code>\uff1bEXPLAIN \u540d\u79f0\uff1a<code>BitmapOr</code>\u3002</p><p>\u672c\u7248\u672c\u6e90\u7801\u4e2d\u7684\u5e76\u884c\u6267\u884c\u6216\u89c2\u6d4b\u56de\u8c03\uff1a\u8be5\u8282\u70b9\u5b9e\u73b0\u4e2d\u672a\u63d0\u53d6\u5230\u6b64\u7c7b\u56de\u8c03\u3002\u56de\u8c03\u7684\u5b58\u5728\u4e0d\u8868\u793a\u8be5\u8282\u70b9\u5fc5\u7136\u652f\u6301\u5171\u4eab\u5e76\u884c\u626b\u63cf\uff1b\u5728\u5e76\u884c\u5de5\u4f5c\u8fdb\u7a0b\u4e2d\u6267\u884c\u4e5f\u4e0d\u7b49\u4e8e\u5177\u6709\u5e76\u884c\u611f\u77e5\u80fd\u529b\u3002</p><h3>\u540c\u7248\u672c\u4e2d\u6587\u624b\u518c\u8282\u9009</h3><p> <code>EXPLAIN ANALYZE</code> \u6d4b\u5f97\u7684\u8fd0\u884c\u65f6\u95f4\uff0c\u53ef\u80fd\u4ee5\u4e24\u79cd\u91cd\u8981\u65b9\u5f0f\u504f\u79bb\u540c\u4e00\u67e5\u8be2\u7684\u6b63\u5e38\u6267\u884c\u65f6\u95f4\u3002\u7b2c\u4e00\uff0c\u7531\u4e8e\u4e0d\u4f1a\u5411\u5ba2\u6237\u7aef\u4f20\u9012\u4efb\u4f55\u8f93\u51fa\u884c\uff0c\u56e0\u6b64\u7f51\u7edc\u4f20\u8f93\u5f00\u9500\u548c I/O \u8f6c\u6362\u5f00\u9500\u5747\u4e0d\u4f1a\u88ab\u8ba1\u5165\u3002\u7b2c\u4e8c\uff0c<code>EXPLAIN ANALYZE</code> \u9644\u52a0\u7684\u6d4b\u91cf\u5f00\u9500\u672c\u8eab\u53ef\u80fd\u76f8\u5f53\u53ef\u89c2\uff0c\u5c24\u5176\u662f\u5728\u64cd\u4f5c\u7cfb\u7edf\u8c03\u7528 <code>gettimeofday()</code> \u8f83\u6162\u7684\u673a\u5668\u4e0a\u3002\u53ef\u4ee5\u4f7f\u7528 <a href=\"/zh/docs/10/pgtesttiming.html\" rel=\"nofollow\"><span><span>pg_test_timing</span></span></a> \u5de5\u5177\u6765\u6d4b\u91cf\u7cfb\u7edf\u4e0a\u7684\u8ba1\u65f6\u5f00\u9500\u3002\n   </p><p>    \u4e0d\u5e94\u5c06 <code>EXPLAIN</code> \u7ed3\u679c\u5916\u63a8\u5230\u4e0e\u5b9e\u9645\u6d4b\u8bd5\u573a\u666f\u5dee\u5f02\u5f88\u5927\u7684\u60c5\u51b5\u3002\u4f8b\u5982\uff0c\u5728\u4e00\u4e2a\u5f88\u5c0f\u7684\u8868\u4e0a\u5f97\u5230\u7684\u7ed3\u679c\uff0c\u4e0d\u80fd\u5047\u5b9a\u4e5f\u9002\u7528\u4e8e\u5927\u578b\u8868\u3002\u89c4\u5212\u5668\u7684\u4ee3\u4ef7\u4f30\u8ba1\u4e0d\u662f\u7ebf\u6027\u7684\uff0c\u56e0\u6b64\u5b83\u53ef\u80fd\u4f1a\u4e3a\u66f4\u5927\u6216\u66f4\u5c0f\u7684\u8868\u9009\u62e9\u4e0d\u540c\u7684\u8ba1\u5212\u3002\u4e00\u4e2a\u6781\u7aef\u793a\u4f8b\u662f\uff1a\u5bf9\u4e8e\u53ea\u5360\u7528\u4e00\u4e2a\u78c1\u76d8\u9875\u7684\u8868\uff0c\u65e0\u8bba\u7d22\u5f15\u662f\u5426\u53ef\u7528\uff0c\u51e0\u4e4e\u603b\u4f1a\u5f97\u5230\u987a\u5e8f\u626b\u63cf\u8ba1\u5212\u3002\u89c4\u5212\u5668\u8ba4\u8bc6\u5230\uff0c\u65e0\u8bba\u5982\u4f55\u5904\u7406\u8be5\u8868\u90fd\u9700\u8981\u4e00\u6b21\u78c1\u76d8\u9875\u8bfb\u53d6\uff0c\u56e0\u6b64\u518d\u989d\u5916\u8bfb\u53d6\u9875\u9762\u53bb\u67e5\u770b\u7d22\u5f15\u5e76\u6ca1\u6709\u4ef7\u503c\u3002\uff08\u524d\u9762\u7684 <code>polygon_tbl</code> \u793a\u4f8b\u5df2\u7ecf\u5c55\u793a\u8fc7\u8fd9\u79cd\u60c5\u51b5\u3002\uff09\n   </p><p>\u6709\u65f6\u5b9e\u9645\u503c\u4e0e\u4f30\u8ba1\u503c\u4e0d\u592a\u4e00\u81f4\uff0c\u4f46\u5b9e\u9645\u4e0a\u5e76\u6ca1\u6709\u95ee\u9898\u3002\u5176\u4e2d\u4e00\u79cd\u60c5\u51b5\u662f\uff0c\u8ba1\u5212\u8282\u70b9\u7684\u6267\u884c\u56e0 <code>LIMIT</code> \u6216\u7c7b\u4f3c\u6548\u679c\u800c\u63d0\u524d\u505c\u6b62\u3002\u4f8b\u5982\uff0c\u5728\u524d\u9762\u4f7f\u7528\u7684 <code>LIMIT</code> \u67e5\u8be2\u4e2d\uff1a</p><p>Index Scan \u8282\u70b9\u7684\u4f30\u8ba1\u4ee3\u4ef7\u548c\u884c\u6570\u6309\u8be5\u8282\u70b9\u6267\u884c\u5230\u5b8c\u6210\u7684\u60c5\u51b5\u663e\u793a\u3002\u4f46\u5b9e\u9645\u4e0a\uff0cLimit \u8282\u70b9\u53d6\u5f97\u4e24\u884c\u540e\u5c31\u505c\u6b62\u8bf7\u6c42\u884c\uff0c\u56e0\u6b64\u5b9e\u9645\u884c\u6570\u53ea\u6709 2\uff0c\u8fd0\u884c\u65f6\u95f4\u4e5f\u5c0f\u4e8e\u4f30\u8ba1\u4ee3\u4ef7\u6240\u6697\u793a\u7684\u65f6\u95f4\u3002\u8fd9\u4e0d\u662f\u4f30\u8ba1\u9519\u8bef\uff0c\u53ea\u662f\u4f30\u8ba1\u503c\u4e0e\u5b9e\u9645\u503c\u7684\u663e\u793a\u65b9\u5f0f\u5b58\u5728\u5dee\u522b\u3002</p><p><a href=\"/zh/docs/10/performance-tips.html#USING-EXPLAIN-CAVEATS\" rel=\"nofollow\">\u67e5\u770b\u5b8c\u6574\u4e2d\u6587\u624b\u518c\u4e0e\u4e0a\u4e0b\u6587</a>\u3002</p><p>\u672c\u9875\u5f00\u5934\u7684\u4e2d\u6587\u8bf4\u660e\u4e3a PG.CENTER \u5bf9\u7f16\u8f91\u8bf4\u660e\u7684\u7ffb\u8bd1\uff1b\u624b\u518c\u8282\u9009\u4fdd\u7559\u5bf9\u5e94\u7248\u672c\u4e2d\u6587\u6587\u6863\u539f\u6587\u3002\u6e90\u7801\u4fe1\u606f\u53ca\u624b\u518c\u793a\u4f8b\u4e0d\u4ee3\u8868\u91cd\u65b0\u8fdb\u884c\u8fc7\u8fd0\u884c\u6d4b\u8bd5\u3002</p>"}, "11": {"facts": [{"label": "\u6838\u5fc3\u8282\u70b9\u6807\u7b7e", "value": "T_BitmapOr"}, {"label": "\u7ed3\u6784\u5316 EXPLAIN \u8282\u70b9\u7c7b\u578b", "value": "BitmapOr"}, {"label": "\u8f93\u5165", "value": "\u4ea7\u751f\u4f4d\u56fe\u7684\u5b50\u8ba1\u5212"}, {"label": "\u8f93\u51fa", "value": "\u5143\u7ec4\u4f4d\u7f6e\u4f4d\u56fe\uff0c\u4e0d\u662f\u5143\u7ec4\u6d41"}, {"label": "\u6267\u884c\u5668\u521d\u59cb\u5316\u51fd\u6570", "value": "ExecInitBitmapOr"}, {"label": "\u5185\u5b58\u673a\u5236", "value": "bitmap-lossification"}], "memory": {"evidence": [{"url": "https://ftp.postgresql.org/pub/source/v11.22/postgresql-11.22.tar.bz2", "path": "src/backend/executor/nodeBitmapOr.c", "label": "src/backend/executor/nodeBitmapOr.c", "sha256": "fe542bc106cc764b0fca94e021870478945c29fafb5d08e8f2e99eeb3762a632", "archive_sha256": "2cb7c97d7a0d7278851bbc9c61f467b69c094c72b81740b751108e7892ebe1f0"}, {"url": "https://ftp.postgresql.org/pub/source/v11.22/postgresql-11.22.tar.bz2", "path": "src/backend/nodes/tidbitmap.c", "label": "src/backend/nodes/tidbitmap.c", "sha256": "a47e915ced1ae75d21b8d7b7b67ae09c4bf230069208aa5d9f5b6c2ca6ae85d1", 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"https://ftp.postgresql.org/pub/source/v11.22/postgresql-11.22.tar.bz2", "source_snapshot_utc": ""}, "sources": [{"url": "https://ftp.postgresql.org/pub/source/v11.22/postgresql-11.22.tar.bz2", "line": 1043, "path": "src/backend/commands/explain.c", "label": "src/backend/commands/explain.c:1043", "sha256": "9df8400c1a4377179572ceb916d6020fca4e2760f74bf416d77ed97476523bbd", "archive_sha256": "2cb7c97d7a0d7278851bbc9c61f467b69c094c72b81740b751108e7892ebe1f0"}, {"url": "https://ftp.postgresql.org/pub/source/v11.22/postgresql-11.22.tar.bz2", "line": 199, "path": "src/backend/executor/execProcnode.c", "label": "src/backend/executor/execProcnode.c:199", "sha256": "95ef4d4a5df4c29f14af9763fae2c530449bdacdf3853d9ff297adf1fed6153b", "archive_sha256": "2cb7c97d7a0d7278851bbc9c61f467b69c094c72b81740b751108e7892ebe1f0"}, {"url": "https://ftp.postgresql.org/pub/source/v11.22/postgresql-11.22.tar.bz2", "path": "src/backend/executor/nodeBitmapOr.c", "label": "src/backend/executor/nodeBitmapOr.c", 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"2cb7c97d7a0d7278851bbc9c61f467b69c094c72b81740b751108e7892ebe1f0"}, "facts_zh": [{"label": "\u6838\u5fc3\u8282\u70b9\u6807\u7b7e", "value": "T_BitmapOr"}, {"label": "\u7ed3\u6784\u5316 EXPLAIN \u8282\u70b9\u7c7b\u578b", "value": "BitmapOr"}, {"label": "\u8f93\u5165", "value": "\u4ea7\u751f\u4f4d\u56fe\u7684\u5b50\u8ba1\u5212"}, {"label": "\u8f93\u51fa", "value": "\u5143\u7ec4\u4f4d\u7f6e\u4f4d\u56fe\uff0c\u4e0d\u662f\u5143\u7ec4\u6d41"}, {"label": "\u6267\u884c\u5668\u521d\u59cb\u5316\u51fd\u6570", "value": "ExecInitBitmapOr"}, {"label": "\u5185\u5b58\u673a\u5236", "value": "bitmap-lossification"}], "node_tag": "T_BitmapOr", "sections": [{"title": "EXPLAIN \u540d\u79f0\u4e0e\u5c5e\u6027", "paragraphs": ["\u7ed3\u6784\u5316\u683c\u5f0f\u4f7f\u7528\u4e0a\u8ff0 Node Type\u3002\u6587\u672c\u683c\u5f0f\u540d\u79f0\u8fd8\u53ef\u80fd\u5305\u542b\u64cd\u4f5c\u3001\u7b56\u7565\u3001\u8fde\u63a5\u7c7b\u578b\u3001\u626b\u63cf\u65b9\u5411\u6216\u805a\u5408\u9636\u6bb5\u5c5e\u6027\u3002", "\u6b64\u6e90\u7801\u8bb0\u5f55\u7684\u6587\u672c\u540d\u79f0\uff1aBitmapOr.", "\u5e76\u884c\u611f\u77e5\u4e0e\u5e76\u884c\u5b89\u5168\u662f\u4e0d\u540c\u7684\u8ba1\u5212\u5c5e\u6027\u3002\u5728\u5e76\u884c\u5de5\u4f5c\u8fdb\u7a0b\u5185\u8fd0\u884c\u7684\u8282\u70b9\u4e0d\u4e00\u5b9a\u662f\u5e76\u884c\u611f\u77e5\u8282\u70b9\u3002"]}, {"title": "\u5185\u5b58\u4e0e\u4e34\u65f6\u5b58\u50a8", "paragraphs": ["\u6b64\u8282\u70b9\u6309\u57fa\u4e8e work_mem \u7684\u9884\u7b97\u5206\u914d\u5143\u7ec4\u4f4d\u7f6e\u4f4d\u56fe\u3002\u4f4d\u56fe\u53ef\u4ee5\u4fdd\u7559\u9875\u7ea7\u6709\u635f\u6761\u76ee\uff0c\u800c\u4e0d\u8bb0\u5f55\u6bcf\u4e2a\u5143\u7ec4\u4f4d\u7f6e\uff0c\u56e0\u6b64\u4ecd\u53ef\u80fd\u9700\u8981\u5806\u91cd\u68c0\u3002"]}, {"title": "\u5e76\u884c\u6267\u884c\u4e0e\u8fd0\u884c\u4fe1\u606f\u91c7\u96c6", "paragraphs": ["\u4ee5\u4e0b\u6e90\u7801\u56de\u8c03\u53ef\u4ee5\u534f\u8c03\u6267\u884c\u6216\u6536\u96c6\u5de5\u4f5c\u8fdb\u7a0b\u7684\u6d4b\u91cf\u6570\u636e\u3002\u56de\u8c03\u5b58\u5728\u4e0d\u4ee3\u8868\u8be5\u8282\u70b9\u666e\u904d\u652f\u6301\u5171\u4eab\u5e76\u884c\u626b\u63cf\u6216\u5171\u4eab\u72b6\u6001\u3002", "\u6b64\u6784\u5efa\u7684\u56de\u8c03\uff1anone extracted from this node implementation."]}, {"title": "\u540c\u7248\u672c\u624b\u518c\u8bf4\u660e", "paragraphs": ["\u7531\u4e8e\u5b9e\u73b0\u4e0a\u7684\u9650\u5236\uff0cBitmapAnd \u548c BitmapOr \u8282\u70b9\u62a5\u544a\u7684\u5b9e\u9645\u884c\u6570\u59cb\u7ec8\u4e3a\u96f6\u3002"]}, {"title": "\u6267\u884c\u5668\u5b9e\u73b0\u8bf4\u660e", "paragraphs": ["\u8bf4\u660e\uff1aBitmapOr \u4e0d\u4f7f\u7528\u5de6\u53f3\u5b50\u6811\uff0c\u800c\u50cf Append \u4e00\u6837\u7ef4\u62a4\u5b50\u8ba1\u5212\u5217\u8868\u3002\u4e0d\u8fc7\u5176\u903b\u8f91\u6bd4 Append \u7b80\u5355\u5f97\u591a\uff0c\u56e0\u4e3a\u65e0\u9700\u5904\u7406\u6b63\u5411\u6216\u53cd\u5411\u6267\u884c\u3002", "\u5bf9\u6bcf\u4e2a\u5f85\u6267\u884c\u8ba1\u5212\u8c03\u7528 ExecInitNode\uff0c\u5e76\u5c06\u7ed3\u679c\u4fdd\u5b58\u5230 bitmapplanstates \u6570\u7ec4\u3002", "BitmapOr \u8ba1\u5212\u6ca1\u6709\u8868\u8fbe\u5f0f\u4e0a\u4e0b\u6587\uff0c\u56e0\u4e3a\u5b83\u4eec\u4ece\u4e0d\u8c03\u7528 ExecQual \u6216 ExecProject\uff0c\u4e5f\u4e0d\u9700\u8981\u5143\u7ec4\u69fd\u3002", "\u53ef\u5bf9 BitmapIndexScan \u5b50\u8282\u70b9\u4f5c\u7279\u6b8a\u5904\u7406\uff0c\u907f\u514d\u4e3a\u6bcf\u4e2a\u5b50\u8282\u70b9\u663e\u5f0f\u8c03\u7528 tbm_union\uff1a\u76f4\u63a5\u4e0b\u4f20\u5f53\u524d\u7ed3\u679c\u4f4d\u56fe\uff0c\u8ba9\u5b50\u8282\u70b9\u5c06\u7ed3\u679c\u6309\u4f4d OR \u5408\u5e76\u8fdb\u53bb\u3002", "ExecReScan \u4e0d\u77e5\u9053\u5f53\u524d\u8282\u70b9\u7684\u5b50\u8ba1\u5212\uff0c\u56e0\u6b64\u5fc5\u987b\u81ea\u884c\u901a\u77e5\u5b50\u8ba1\u5212\u54ea\u4e9b\u53c2\u6570\u53d1\u751f\u4e86\u53d8\u5316\u3002"]}, {"code": "case T_BitmapOr:\n\t\t\tpname = sname = \"BitmapOr\";\n\t\t\tbreak;", "title": "\u6838\u5fc3\u6e90\u7801\u4e2d\u7684 EXPLAIN \u6807\u8bc6"}], "center_zh": {"title": "BitmapOr", "locale": "zh-Hans", "source": {"key": "bitmapor", "locale": "zh-Hans", "version": "11", "text_hash": "4c124e4e2a4d4ff8315844911a4cab3b4c756e7c18a652cbfc93eef1fc66dc2f", "collection": "plan", "dataset_hash": "7c31b524dfe136022d39a6ae8dcfac6b3bbd5f8fdaf422536599981252aff0c9", "source_database": "center", "source_revision": "2cb7c97d7a0d7278851bbc9c61f467b69c094c72b81740b751108e7892ebe1f0"}, "payload": {"facts": [{"label": "\u6838\u5fc3\u8282\u70b9\u6807\u7b7e", "value": "T_BitmapOr"}, {"label": "\u7ed3\u6784\u5316 EXPLAIN \u8282\u70b9\u7c7b\u578b", "value": "BitmapOr"}, {"label": "\u8f93\u5165", "value": "\u4ea7\u751f\u4f4d\u56fe\u7684\u5b50\u8ba1\u5212"}, {"label": "\u8f93\u51fa", "value": "\u5143\u7ec4\u4f4d\u7f6e\u4f4d\u56fe\uff0c\u4e0d\u662f\u5143\u7ec4\u6d41"}, {"label": "\u6267\u884c\u5668\u521d\u59cb\u5316\u51fd\u6570", "value": "ExecInitBitmapOr"}, {"label": "\u5185\u5b58\u673a\u5236", "value": "bitmap-lossification"}], "tables": [{"key": "explain-labels", "rows": [{"label": "BitmapOr", "identity": "BitmapOr"}], "title": "\u672c\u6784\u5efa\u4e2d\u7684 EXPLAIN \u6807\u7b7e", "columns": [{"key": "label", "label": "\u6587\u672c\u683c\u5f0f\u6807\u7b7e"}, {"key": "identity", "label": "\u7ed3\u6784\u5316\u8282\u70b9\u6807\u8bc6"}]}], "zh_from": {"kind": "same-version-chinese-manual-with-authored-translation-of-reviewed-guidance", "manual": {"url": "/zh/docs/11/performance-tips.html#USING-EXPLAIN-CAVEATS", "anchor": "USING-EXPLAIN-CAVEATS", "locale": "zh-Hans", "version": "11", "build_id": 64, "page_key": "performance-tips.html", "extraction": "concept-introduction", "source_hash": "617a30102327f61276ba77fb034f4bf1bbb677d91d4eb5507dc14d740e6394c9", "fragment_sha256": "c79e3525362a785384e6a35086117497c1887ce348ed76ca79aa11f88e1165af", "source_revision": "unknown:rendered-translation-baseline", "translation_revision": "snapshot:sha256:ef5c7bc074acae9795db16e6b7482aea3b222bd4bcce0f76831332b97a21e8a1", "translated_from_revision": null}, "body_sha256": "e368c4cdd86af2a3b857466e53196dc5fd84abe58f9103f0605078ef91be8fb9", "runtime_rerun": false, "authored_translation": "authored-translation-of-reviewed-guidance", "source_facts_revision": "2cb7c97d7a0d7278851bbc9c61f467b69c094c72b81740b751108e7892ebe1f0"}, "sections": [{"title": "EXPLAIN \u540d\u79f0\u4e0e\u5c5e\u6027", "paragraphs": ["\u7ed3\u6784\u5316\u683c\u5f0f\u4f7f\u7528\u4e0a\u8ff0 Node Type\u3002\u6587\u672c\u683c\u5f0f\u540d\u79f0\u8fd8\u53ef\u80fd\u5305\u542b\u64cd\u4f5c\u3001\u7b56\u7565\u3001\u8fde\u63a5\u7c7b\u578b\u3001\u626b\u63cf\u65b9\u5411\u6216\u805a\u5408\u9636\u6bb5\u5c5e\u6027\u3002", "\u6b64\u6e90\u7801\u8bb0\u5f55\u7684\u6587\u672c\u540d\u79f0\uff1aBitmapOr.", "\u5e76\u884c\u611f\u77e5\u4e0e\u5e76\u884c\u5b89\u5168\u662f\u4e0d\u540c\u7684\u8ba1\u5212\u5c5e\u6027\u3002\u5728\u5e76\u884c\u5de5\u4f5c\u8fdb\u7a0b\u5185\u8fd0\u884c\u7684\u8282\u70b9\u4e0d\u4e00\u5b9a\u662f\u5e76\u884c\u611f\u77e5\u8282\u70b9\u3002"]}, {"title": "\u5185\u5b58\u4e0e\u4e34\u65f6\u5b58\u50a8", "paragraphs": ["\u6b64\u8282\u70b9\u6309\u57fa\u4e8e work_mem \u7684\u9884\u7b97\u5206\u914d\u5143\u7ec4\u4f4d\u7f6e\u4f4d\u56fe\u3002\u4f4d\u56fe\u53ef\u4ee5\u4fdd\u7559\u9875\u7ea7\u6709\u635f\u6761\u76ee\uff0c\u800c\u4e0d\u8bb0\u5f55\u6bcf\u4e2a\u5143\u7ec4\u4f4d\u7f6e\uff0c\u56e0\u6b64\u4ecd\u53ef\u80fd\u9700\u8981\u5806\u91cd\u68c0\u3002"]}, {"title": "\u5e76\u884c\u6267\u884c\u4e0e\u8fd0\u884c\u4fe1\u606f\u91c7\u96c6", "paragraphs": ["\u4ee5\u4e0b\u6e90\u7801\u56de\u8c03\u53ef\u4ee5\u534f\u8c03\u6267\u884c\u6216\u6536\u96c6\u5de5\u4f5c\u8fdb\u7a0b\u7684\u6d4b\u91cf\u6570\u636e\u3002\u56de\u8c03\u5b58\u5728\u4e0d\u4ee3\u8868\u8be5\u8282\u70b9\u666e\u904d\u652f\u6301\u5171\u4eab\u5e76\u884c\u626b\u63cf\u6216\u5171\u4eab\u72b6\u6001\u3002", "\u6b64\u6784\u5efa\u7684\u56de\u8c03\uff1anone extracted from this node implementation."]}, {"title": "\u540c\u7248\u672c\u624b\u518c\u8bf4\u660e", "paragraphs": ["\u7531\u4e8e\u5b9e\u73b0\u4e0a\u7684\u9650\u5236\uff0cBitmapAnd \u548c BitmapOr \u8282\u70b9\u62a5\u544a\u7684\u5b9e\u9645\u884c\u6570\u59cb\u7ec8\u4e3a\u96f6\u3002"]}, {"title": "\u6267\u884c\u5668\u5b9e\u73b0\u8bf4\u660e", "paragraphs": ["\u8bf4\u660e\uff1aBitmapOr \u4e0d\u4f7f\u7528\u5de6\u53f3\u5b50\u6811\uff0c\u800c\u50cf Append \u4e00\u6837\u7ef4\u62a4\u5b50\u8ba1\u5212\u5217\u8868\u3002\u4e0d\u8fc7\u5176\u903b\u8f91\u6bd4 Append \u7b80\u5355\u5f97\u591a\uff0c\u56e0\u4e3a\u65e0\u9700\u5904\u7406\u6b63\u5411\u6216\u53cd\u5411\u6267\u884c\u3002", "\u5bf9\u6bcf\u4e2a\u5f85\u6267\u884c\u8ba1\u5212\u8c03\u7528 ExecInitNode\uff0c\u5e76\u5c06\u7ed3\u679c\u4fdd\u5b58\u5230 bitmapplanstates \u6570\u7ec4\u3002", "BitmapOr \u8ba1\u5212\u6ca1\u6709\u8868\u8fbe\u5f0f\u4e0a\u4e0b\u6587\uff0c\u56e0\u4e3a\u5b83\u4eec\u4ece\u4e0d\u8c03\u7528 ExecQual \u6216 ExecProject\uff0c\u4e5f\u4e0d\u9700\u8981\u5143\u7ec4\u69fd\u3002", "\u53ef\u5bf9 BitmapIndexScan \u5b50\u8282\u70b9\u4f5c\u7279\u6b8a\u5904\u7406\uff0c\u907f\u514d\u4e3a\u6bcf\u4e2a\u5b50\u8282\u70b9\u663e\u5f0f\u8c03\u7528 tbm_union\uff1a\u76f4\u63a5\u4e0b\u4f20\u5f53\u524d\u7ed3\u679c\u4f4d\u56fe\uff0c\u8ba9\u5b50\u8282\u70b9\u5c06\u7ed3\u679c\u6309\u4f4d OR \u5408\u5e76\u8fdb\u53bb\u3002", "ExecReScan \u4e0d\u77e5\u9053\u5f53\u524d\u8282\u70b9\u7684\u5b50\u8ba1\u5212\uff0c\u56e0\u6b64\u5fc5\u987b\u81ea\u884c\u901a\u77e5\u5b50\u8ba1\u5212\u54ea\u4e9b\u53c2\u6570\u53d1\u751f\u4e86\u53d8\u5316\u3002"]}, {"code": "case T_BitmapOr:\n\t\t\tpname = sname = \"BitmapOr\";\n\t\t\tbreak;", "title": "\u6838\u5fc3\u6e90\u7801\u4e2d\u7684 EXPLAIN \u6807\u8bc6"}], "description_zh": "\u5bf9\u5404\u5b50\u8ba1\u5212\u751f\u6210\u7684\u4f4d\u56fe\u6c42\u5e76\u96c6\u3002", "description_zh_html": "<p>\u5bf9\u5404\u5b50\u8ba1\u5212\u751f\u6210\u7684\u4f4d\u56fe\u6c42\u5e76\u96c6\u3002</p><p>\u6838\u5fc3\u8282\u70b9\u6807\u8bc6\uff1a<code>T_BitmapOr</code>\uff1bEXPLAIN \u540d\u79f0\uff1a<code>BitmapOr</code>\u3002</p><p>\u672c\u7248\u672c\u6e90\u7801\u4e2d\u7684\u5e76\u884c\u6267\u884c\u6216\u89c2\u6d4b\u56de\u8c03\uff1a\u8be5\u8282\u70b9\u5b9e\u73b0\u4e2d\u672a\u63d0\u53d6\u5230\u6b64\u7c7b\u56de\u8c03\u3002\u56de\u8c03\u7684\u5b58\u5728\u4e0d\u8868\u793a\u8be5\u8282\u70b9\u5fc5\u7136\u652f\u6301\u5171\u4eab\u5e76\u884c\u626b\u63cf\uff1b\u5728\u5e76\u884c\u5de5\u4f5c\u8fdb\u7a0b\u4e2d\u6267\u884c\u4e5f\u4e0d\u7b49\u4e8e\u5177\u6709\u5e76\u884c\u611f\u77e5\u80fd\u529b\u3002</p><h3>\u540c\u7248\u672c\u4e2d\u6587\u624b\u518c\u8282\u9009</h3><p>\n<code class=\"command\">EXPLAIN ANALYZE</code> \u6d4b\u5f97\u7684\u8fd0\u884c\u65f6\u95f4\uff0c\u53ef\u80fd\u4ee5\u4e24\u79cd\u91cd\u8981\u65b9\u5f0f\u504f\u79bb\u540c\u4e00\u67e5\u8be2\u7684\u6b63\u5e38\u6267\u884c\u65f6\u95f4\u3002\u7b2c\u4e00\uff0c\u7531\u4e8e\u4e0d\u4f1a\u5411\u5ba2\u6237\u7aef\u4f20\u9012\u4efb\u4f55\u8f93\u51fa\u884c\uff0c\u56e0\u6b64\u7f51\u7edc\u4f20\u8f93\u5f00\u9500\u548c I/O \u8f6c\u6362\u5f00\u9500\u5747\u4e0d\u4f1a\u88ab\u8ba1\u5165\u3002\u7b2c\u4e8c\uff0c<code class=\"command\">EXPLAIN ANALYZE</code> \u9644\u52a0\u7684\u6d4b\u91cf\u5f00\u9500\u672c\u8eab\u53ef\u80fd\u76f8\u5f53\u53ef\u89c2\uff0c\u5c24\u5176\u662f\u5728\u64cd\u4f5c\u7cfb\u7edf\u8c03\u7528 <code class=\"function\">gettimeofday()</code> \u8f83\u6162\u7684\u673a\u5668\u4e0a\u3002\u53ef\u4ee5\u4f7f\u7528 <a class=\"xref\" href=\"/zh/docs/11/pgtesttiming.html\"><span class=\"refentrytitle\"><span class=\"application\">pg_test_timing</span></span></a> \u5de5\u5177\u6765\u6d4b\u91cf\u7cfb\u7edf\u4e0a\u7684\u8ba1\u65f6\u5f00\u9500\u3002\n   </p><p>\n    \u4e0d\u5e94\u5c06 <code class=\"command\">EXPLAIN</code> \u7ed3\u679c\u5916\u63a8\u5230\u4e0e\u5b9e\u9645\u6d4b\u8bd5\u573a\u666f\u5dee\u5f02\u5f88\u5927\u7684\u60c5\u51b5\u3002\u4f8b\u5982\uff0c\u5728\u4e00\u4e2a\u5f88\u5c0f\u7684\u8868\u4e0a\u5f97\u5230\u7684\u7ed3\u679c\uff0c\u4e0d\u80fd\u5047\u5b9a\u4e5f\u9002\u7528\u4e8e\u5927\u578b\u8868\u3002\u89c4\u5212\u5668\u7684\u4ee3\u4ef7\u4f30\u8ba1\u4e0d\u662f\u7ebf\u6027\u7684\uff0c\u56e0\u6b64\u5b83\u53ef\u80fd\u4f1a\u4e3a\u66f4\u5927\u6216\u66f4\u5c0f\u7684\u8868\u9009\u62e9\u4e0d\u540c\u7684\u8ba1\u5212\u3002\u4e00\u4e2a\u6781\u7aef\u793a\u4f8b\u662f\uff1a\u5bf9\u4e8e\u53ea\u5360\u7528\u4e00\u4e2a\u78c1\u76d8\u9875\u7684\u8868\uff0c\u65e0\u8bba\u7d22\u5f15\u662f\u5426\u53ef\u7528\uff0c\u51e0\u4e4e\u603b\u4f1a\u5f97\u5230\u987a\u5e8f\u626b\u63cf\u8ba1\u5212\u3002\u89c4\u5212\u5668\u8ba4\u8bc6\u5230\uff0c\u65e0\u8bba\u5982\u4f55\u5904\u7406\u8be5\u8868\u90fd\u9700\u8981\u4e00\u6b21\u78c1\u76d8\u9875\u8bfb\u53d6\uff0c\u56e0\u6b64\u518d\u989d\u5916\u8bfb\u53d6\u9875\u9762\u53bb\u67e5\u770b\u7d22\u5f15\u5e76\u6ca1\u6709\u4ef7\u503c\u3002\uff08\u524d\u9762\u7684 <code class=\"literal\">polygon_tbl</code> \u793a\u4f8b\u5df2\u7ecf\u5c55\u793a\u8fc7\u8fd9\u79cd\u60c5\u51b5\u3002\uff09\n   </p><p>\n    \u5728\u67d0\u4e9b\u60c5\u51b5\u4e0b\uff0c\u5b9e\u9645\u503c\u548c\u4f30\u8ba1\u503c\u4e0d\u4f1a\u5f88\u597d\u5730\u5bf9\u5e94\uff0c\u4f46\u8fd9\u5e76\u4e0d\u8868\u793a\u51fa\u73b0\u4e86\u95ee\u9898\u3002\u5176\u4e2d\u4e00\u79cd\u60c5\u51b5\u662f\uff0c\u8ba1\u5212\u8282\u70b9\u7684\u6267\u884c\u4f1a\u88ab <code class=\"literal\">LIMIT</code> \u6216\u7c7b\u4f3c\u6548\u679c\u63d0\u524d\u622a\u65ad\u3002\u4f8b\u5982\uff0c\u5728\u524d\u9762\u7528\u8fc7\u7684 <code class=\"literal\">LIMIT</code> \u67e5\u8be2\u4e2d\uff1a\n\n</p><p>\n\n    Index Scan \u8282\u70b9\u7684\u4f30\u8ba1\u4ee3\u4ef7\u548c\u884c\u8ba1\u6570\u663e\u793a\u5f97\u50cf\u662f\u5b83\u4f1a\u8fd0\u884c\u5230\u7ed3\u675f\u4e00\u6837\u3002\u4f46\u5b9e\u9645\u4e0a\uff0cLimit \u8282\u70b9\u5728\u62ff\u5230\u4e24\u884c\u4e4b\u540e\u5c31\u505c\u6b62\u8bf7\u6c42\u66f4\u591a\u884c\uff0c\u56e0\u6b64\u5b9e\u9645\u884c\u8ba1\u6570\u53ea\u6709 2\uff0c\u8fd0\u884c\u65f6\u95f4\u4e5f\u4f4e\u4e8e\u4ee3\u4ef7\u4f30\u8ba1\u6240\u6697\u793a\u7684\u6c34\u5e73\u3002\u8fd9\u5e76\u4e0d\u662f\u4f30\u8ba1\u9519\u8bef\uff0c\u53ea\u662f\u4f30\u8ba1\u503c\u4e0e\u771f\u5b9e\u503c\u7684\u663e\u793a\u65b9\u5f0f\u4e0d\u540c\u800c\u5df2\u3002\n   </p><p><a href=\"/zh/docs/11/performance-tips.html#USING-EXPLAIN-CAVEATS\">\u67e5\u770b\u5b8c\u6574\u4e2d\u6587\u624b\u518c\u4e0e\u4e0a\u4e0b\u6587</a>\u3002</p><p>\u672c\u9875\u5f00\u5934\u7684\u4e2d\u6587\u8bf4\u660e\u4e3a PG.CENTER \u5bf9\u7f16\u8f91\u8bf4\u660e\u7684\u7ffb\u8bd1\uff1b\u624b\u518c\u8282\u9009\u4fdd\u7559\u5bf9\u5e94\u7248\u672c\u4e2d\u6587\u6587\u6863\u539f\u6587\u3002\u6e90\u7801\u4fe1\u606f\u53ca\u624b\u518c\u793a\u4f8b\u4e0d\u4ee3\u8868\u91cd\u65b0\u8fdb\u884c\u8fc7\u8fd0\u884c\u6d4b\u8bd5\u3002</p>"}, "summary": "\u5bf9\u5404\u5b50\u8ba1\u5212\u751f\u6210\u7684\u4f4d\u56fe\u6c42\u5e76\u96c6\u3002", "version": "11", "link_map": {"/zh/docs/11/pgtesttiming.html": "/docs/11/pgtesttiming.html", "/zh/docs/11/performance-tips.html#USING-EXPLAIN-CAVEATS": "/docs/11/performance-tips.html#USING-EXPLAIN-CAVEATS"}, "body_html": "<p>\u5bf9\u5404\u5b50\u8ba1\u5212\u751f\u6210\u7684\u4f4d\u56fe\u6c42\u5e76\u96c6\u3002</p><p>\u6838\u5fc3\u8282\u70b9\u6807\u8bc6\uff1a<code>T_BitmapOr</code>\uff1bEXPLAIN \u540d\u79f0\uff1a<code>BitmapOr</code>\u3002</p><p>\u672c\u7248\u672c\u6e90\u7801\u4e2d\u7684\u5e76\u884c\u6267\u884c\u6216\u89c2\u6d4b\u56de\u8c03\uff1a\u8be5\u8282\u70b9\u5b9e\u73b0\u4e2d\u672a\u63d0\u53d6\u5230\u6b64\u7c7b\u56de\u8c03\u3002\u56de\u8c03\u7684\u5b58\u5728\u4e0d\u8868\u793a\u8be5\u8282\u70b9\u5fc5\u7136\u652f\u6301\u5171\u4eab\u5e76\u884c\u626b\u63cf\uff1b\u5728\u5e76\u884c\u5de5\u4f5c\u8fdb\u7a0b\u4e2d\u6267\u884c\u4e5f\u4e0d\u7b49\u4e8e\u5177\u6709\u5e76\u884c\u611f\u77e5\u80fd\u529b\u3002</p><h3>\u540c\u7248\u672c\u4e2d\u6587\u624b\u518c\u8282\u9009</h3><p>\n<code>EXPLAIN ANALYZE</code> \u6d4b\u5f97\u7684\u8fd0\u884c\u65f6\u95f4\uff0c\u53ef\u80fd\u4ee5\u4e24\u79cd\u91cd\u8981\u65b9\u5f0f\u504f\u79bb\u540c\u4e00\u67e5\u8be2\u7684\u6b63\u5e38\u6267\u884c\u65f6\u95f4\u3002\u7b2c\u4e00\uff0c\u7531\u4e8e\u4e0d\u4f1a\u5411\u5ba2\u6237\u7aef\u4f20\u9012\u4efb\u4f55\u8f93\u51fa\u884c\uff0c\u56e0\u6b64\u7f51\u7edc\u4f20\u8f93\u5f00\u9500\u548c I/O \u8f6c\u6362\u5f00\u9500\u5747\u4e0d\u4f1a\u88ab\u8ba1\u5165\u3002\u7b2c\u4e8c\uff0c<code>EXPLAIN ANALYZE</code> \u9644\u52a0\u7684\u6d4b\u91cf\u5f00\u9500\u672c\u8eab\u53ef\u80fd\u76f8\u5f53\u53ef\u89c2\uff0c\u5c24\u5176\u662f\u5728\u64cd\u4f5c\u7cfb\u7edf\u8c03\u7528 <code>gettimeofday()</code> \u8f83\u6162\u7684\u673a\u5668\u4e0a\u3002\u53ef\u4ee5\u4f7f\u7528 <a href=\"/zh/docs/11/pgtesttiming.html\" rel=\"nofollow\"><span><span>pg_test_timing</span></span></a> \u5de5\u5177\u6765\u6d4b\u91cf\u7cfb\u7edf\u4e0a\u7684\u8ba1\u65f6\u5f00\u9500\u3002\n   </p><p>\n    \u4e0d\u5e94\u5c06 <code>EXPLAIN</code> \u7ed3\u679c\u5916\u63a8\u5230\u4e0e\u5b9e\u9645\u6d4b\u8bd5\u573a\u666f\u5dee\u5f02\u5f88\u5927\u7684\u60c5\u51b5\u3002\u4f8b\u5982\uff0c\u5728\u4e00\u4e2a\u5f88\u5c0f\u7684\u8868\u4e0a\u5f97\u5230\u7684\u7ed3\u679c\uff0c\u4e0d\u80fd\u5047\u5b9a\u4e5f\u9002\u7528\u4e8e\u5927\u578b\u8868\u3002\u89c4\u5212\u5668\u7684\u4ee3\u4ef7\u4f30\u8ba1\u4e0d\u662f\u7ebf\u6027\u7684\uff0c\u56e0\u6b64\u5b83\u53ef\u80fd\u4f1a\u4e3a\u66f4\u5927\u6216\u66f4\u5c0f\u7684\u8868\u9009\u62e9\u4e0d\u540c\u7684\u8ba1\u5212\u3002\u4e00\u4e2a\u6781\u7aef\u793a\u4f8b\u662f\uff1a\u5bf9\u4e8e\u53ea\u5360\u7528\u4e00\u4e2a\u78c1\u76d8\u9875\u7684\u8868\uff0c\u65e0\u8bba\u7d22\u5f15\u662f\u5426\u53ef\u7528\uff0c\u51e0\u4e4e\u603b\u4f1a\u5f97\u5230\u987a\u5e8f\u626b\u63cf\u8ba1\u5212\u3002\u89c4\u5212\u5668\u8ba4\u8bc6\u5230\uff0c\u65e0\u8bba\u5982\u4f55\u5904\u7406\u8be5\u8868\u90fd\u9700\u8981\u4e00\u6b21\u78c1\u76d8\u9875\u8bfb\u53d6\uff0c\u56e0\u6b64\u518d\u989d\u5916\u8bfb\u53d6\u9875\u9762\u53bb\u67e5\u770b\u7d22\u5f15\u5e76\u6ca1\u6709\u4ef7\u503c\u3002\uff08\u524d\u9762\u7684 <code>polygon_tbl</code> \u793a\u4f8b\u5df2\u7ecf\u5c55\u793a\u8fc7\u8fd9\u79cd\u60c5\u51b5\u3002\uff09\n   </p><p>\n    \u5728\u67d0\u4e9b\u60c5\u51b5\u4e0b\uff0c\u5b9e\u9645\u503c\u548c\u4f30\u8ba1\u503c\u4e0d\u4f1a\u5f88\u597d\u5730\u5bf9\u5e94\uff0c\u4f46\u8fd9\u5e76\u4e0d\u8868\u793a\u51fa\u73b0\u4e86\u95ee\u9898\u3002\u5176\u4e2d\u4e00\u79cd\u60c5\u51b5\u662f\uff0c\u8ba1\u5212\u8282\u70b9\u7684\u6267\u884c\u4f1a\u88ab <code>LIMIT</code> \u6216\u7c7b\u4f3c\u6548\u679c\u63d0\u524d\u622a\u65ad\u3002\u4f8b\u5982\uff0c\u5728\u524d\u9762\u7528\u8fc7\u7684 <code>LIMIT</code> \u67e5\u8be2\u4e2d\uff1a\n\n</p><p>\n\n    Index Scan \u8282\u70b9\u7684\u4f30\u8ba1\u4ee3\u4ef7\u548c\u884c\u8ba1\u6570\u663e\u793a\u5f97\u50cf\u662f\u5b83\u4f1a\u8fd0\u884c\u5230\u7ed3\u675f\u4e00\u6837\u3002\u4f46\u5b9e\u9645\u4e0a\uff0cLimit \u8282\u70b9\u5728\u62ff\u5230\u4e24\u884c\u4e4b\u540e\u5c31\u505c\u6b62\u8bf7\u6c42\u66f4\u591a\u884c\uff0c\u56e0\u6b64\u5b9e\u9645\u884c\u8ba1\u6570\u53ea\u6709 2\uff0c\u8fd0\u884c\u65f6\u95f4\u4e5f\u4f4e\u4e8e\u4ee3\u4ef7\u4f30\u8ba1\u6240\u6697\u793a\u7684\u6c34\u5e73\u3002\u8fd9\u5e76\u4e0d\u662f\u4f30\u8ba1\u9519\u8bef\uff0c\u53ea\u662f\u4f30\u8ba1\u503c\u4e0e\u771f\u5b9e\u503c\u7684\u663e\u793a\u65b9\u5f0f\u4e0d\u540c\u800c\u5df2\u3002\n   </p><p><a href=\"/zh/docs/11/performance-tips.html#USING-EXPLAIN-CAVEATS\" rel=\"nofollow\">\u67e5\u770b\u5b8c\u6574\u4e2d\u6587\u624b\u518c\u4e0e\u4e0a\u4e0b\u6587</a>\u3002</p><p>\u672c\u9875\u5f00\u5934\u7684\u4e2d\u6587\u8bf4\u660e\u4e3a PG.CENTER \u5bf9\u7f16\u8f91\u8bf4\u660e\u7684\u7ffb\u8bd1\uff1b\u624b\u518c\u8282\u9009\u4fdd\u7559\u5bf9\u5e94\u7248\u672c\u4e2d\u6587\u6587\u6863\u539f\u6587\u3002\u6e90\u7801\u4fe1\u606f\u53ca\u624b\u518c\u793a\u4f8b\u4e0d\u4ee3\u8868\u91cd\u65b0\u8fdb\u884c\u8fc7\u8fd0\u884c\u6d4b\u8bd5\u3002</p>", "body_sha256": "81ae184e25c558fe503d442492f93894a0feca7398a7bed189457a3479f5d065", "content_hash": "4c124e4e2a4d4ff8315844911a4cab3b4c756e7c18a652cbfc93eef1fc66dc2f", "source_database": "center", "source_revision": "2cb7c97d7a0d7278851bbc9c61f467b69c094c72b81740b751108e7892ebe1f0"}, "tables_zh": [{"key": "explain-labels", "rows": [{"label": "BitmapOr", "identity": "BitmapOr"}], "title": "\u672c\u6784\u5efa\u4e2d\u7684 EXPLAIN \u6807\u7b7e", "columns": [{"key": "label", "label": "\u6587\u672c\u683c\u5f0f\u6807\u7b7e"}, {"key": "identity", "label": "\u7ed3\u6784\u5316\u8282\u70b9\u6807\u8bc6"}]}], "strategies": [], "description": ["\u5bf9\u5404\u5b50\u8ba1\u5212\u751f\u6210\u7684\u4f4d\u56fe\u6c42\u5e76\u96c6\u3002"], "sections_zh": [{"title": "EXPLAIN \u540d\u79f0\u4e0e\u5c5e\u6027", "paragraphs": ["\u7ed3\u6784\u5316\u683c\u5f0f\u4f7f\u7528\u4e0a\u8ff0 Node Type\u3002\u6587\u672c\u683c\u5f0f\u540d\u79f0\u8fd8\u53ef\u80fd\u5305\u542b\u64cd\u4f5c\u3001\u7b56\u7565\u3001\u8fde\u63a5\u7c7b\u578b\u3001\u626b\u63cf\u65b9\u5411\u6216\u805a\u5408\u9636\u6bb5\u5c5e\u6027\u3002", "\u6b64\u6e90\u7801\u8bb0\u5f55\u7684\u6587\u672c\u540d\u79f0\uff1aBitmapOr.", "\u5e76\u884c\u611f\u77e5\u4e0e\u5e76\u884c\u5b89\u5168\u662f\u4e0d\u540c\u7684\u8ba1\u5212\u5c5e\u6027\u3002\u5728\u5e76\u884c\u5de5\u4f5c\u8fdb\u7a0b\u5185\u8fd0\u884c\u7684\u8282\u70b9\u4e0d\u4e00\u5b9a\u662f\u5e76\u884c\u611f\u77e5\u8282\u70b9\u3002"]}, {"title": "\u5185\u5b58\u4e0e\u4e34\u65f6\u5b58\u50a8", "paragraphs": ["\u6b64\u8282\u70b9\u6309\u57fa\u4e8e work_mem \u7684\u9884\u7b97\u5206\u914d\u5143\u7ec4\u4f4d\u7f6e\u4f4d\u56fe\u3002\u4f4d\u56fe\u53ef\u4ee5\u4fdd\u7559\u9875\u7ea7\u6709\u635f\u6761\u76ee\uff0c\u800c\u4e0d\u8bb0\u5f55\u6bcf\u4e2a\u5143\u7ec4\u4f4d\u7f6e\uff0c\u56e0\u6b64\u4ecd\u53ef\u80fd\u9700\u8981\u5806\u91cd\u68c0\u3002"]}, {"title": "\u5e76\u884c\u6267\u884c\u4e0e\u8fd0\u884c\u4fe1\u606f\u91c7\u96c6", "paragraphs": ["\u4ee5\u4e0b\u6e90\u7801\u56de\u8c03\u53ef\u4ee5\u534f\u8c03\u6267\u884c\u6216\u6536\u96c6\u5de5\u4f5c\u8fdb\u7a0b\u7684\u6d4b\u91cf\u6570\u636e\u3002\u56de\u8c03\u5b58\u5728\u4e0d\u4ee3\u8868\u8be5\u8282\u70b9\u666e\u904d\u652f\u6301\u5171\u4eab\u5e76\u884c\u626b\u63cf\u6216\u5171\u4eab\u72b6\u6001\u3002", "\u6b64\u6784\u5efa\u7684\u56de\u8c03\uff1anone extracted from this node implementation."]}, {"title": "\u540c\u7248\u672c\u624b\u518c\u8bf4\u660e", "paragraphs": ["\u7531\u4e8e\u5b9e\u73b0\u4e0a\u7684\u9650\u5236\uff0cBitmapAnd \u548c BitmapOr \u8282\u70b9\u62a5\u544a\u7684\u5b9e\u9645\u884c\u6570\u59cb\u7ec8\u4e3a\u96f6\u3002"]}, {"title": "\u6267\u884c\u5668\u5b9e\u73b0\u8bf4\u660e", "paragraphs": ["\u8bf4\u660e\uff1aBitmapOr \u4e0d\u4f7f\u7528\u5de6\u53f3\u5b50\u6811\uff0c\u800c\u50cf Append \u4e00\u6837\u7ef4\u62a4\u5b50\u8ba1\u5212\u5217\u8868\u3002\u4e0d\u8fc7\u5176\u903b\u8f91\u6bd4 Append \u7b80\u5355\u5f97\u591a\uff0c\u56e0\u4e3a\u65e0\u9700\u5904\u7406\u6b63\u5411\u6216\u53cd\u5411\u6267\u884c\u3002", "\u5bf9\u6bcf\u4e2a\u5f85\u6267\u884c\u8ba1\u5212\u8c03\u7528 ExecInitNode\uff0c\u5e76\u5c06\u7ed3\u679c\u4fdd\u5b58\u5230 bitmapplanstates \u6570\u7ec4\u3002", "BitmapOr \u8ba1\u5212\u6ca1\u6709\u8868\u8fbe\u5f0f\u4e0a\u4e0b\u6587\uff0c\u56e0\u4e3a\u5b83\u4eec\u4ece\u4e0d\u8c03\u7528 ExecQual \u6216 ExecProject\uff0c\u4e5f\u4e0d\u9700\u8981\u5143\u7ec4\u69fd\u3002", "\u53ef\u5bf9 BitmapIndexScan \u5b50\u8282\u70b9\u4f5c\u7279\u6b8a\u5904\u7406\uff0c\u907f\u514d\u4e3a\u6bcf\u4e2a\u5b50\u8282\u70b9\u663e\u5f0f\u8c03\u7528 tbm_union\uff1a\u76f4\u63a5\u4e0b\u4f20\u5f53\u524d\u7ed3\u679c\u4f4d\u56fe\uff0c\u8ba9\u5b50\u8282\u70b9\u5c06\u7ed3\u679c\u6309\u4f4d OR \u5408\u5e76\u8fdb\u53bb\u3002", "ExecReScan \u4e0d\u77e5\u9053\u5f53\u524d\u8282\u70b9\u7684\u5b50\u8ba1\u5212\uff0c\u56e0\u6b64\u5fc5\u987b\u81ea\u884c\u901a\u77e5\u5b50\u8ba1\u5212\u54ea\u4e9b\u53c2\u6570\u53d1\u751f\u4e86\u53d8\u5316\u3002"]}, {"code": "case T_BitmapOr:\n\t\t\tpname = sname = \"BitmapOr\";\n\t\t\tbreak;", "title": "\u6838\u5fc3\u6e90\u7801\u4e2d\u7684 EXPLAIN \u6807\u8bc6"}], "localization": {"status": "complete", "sources": [], "language": "zh", "original_text": {"/versions/11/description/0": "Unions bitmaps produced by its child plans.", "/versions/11/facts/0/label": "Core node tag", "/versions/11/facts/1/label": "Structured EXPLAIN Node Type", "/versions/11/facts/2/label": "Inputs", "/versions/11/facts/2/value": "Bitmap-producing child plans", "/versions/11/facts/3/label": "Output", "/versions/11/facts/3/value": "Tuple-location bitmap, not a tuple stream", "/versions/11/facts/4/label": "Executor initializer", "/versions/11/facts/5/label": "Memory mechanism", "/versions/11/tables/0/title": "EXPLAIN labels in this source build", "/versions/11/related/1/label": "Using EXPLAIN", "/versions/11/related/2/label": "Parallel plans", "/versions/11/sections/0/title": "EXPLAIN names and attributes", "/versions/11/sections/1/title": "Memory and temporary storage", "/versions/11/sections/2/title": "Parallel execution and instrumentation", "/versions/11/sections/3/title": "Same-version manual discussion", "/versions/11/sections/4/title": "Executor implementation notes", "/versions/11/sections/5/title": "EXPLAIN identity in core source", "/versions/11/memory/description": "The node allocates a tuple-location bitmap using a work_mem-derived budget. A bitmap can retain page-level lossy entries instead of every tuple location; heap rechecks then remain necessary.", "/versions/11/sections/0/paragraphs/0": "Structured formats use the Node Type above. Text-format spellings can also include operation, strategy, join type, scan direction or aggregation-stage attributes.", "/versions/11/sections/0/paragraphs/1": "Text names recorded by this source: BitmapOr.", "/versions/11/sections/0/paragraphs/2": "Parallel-aware and parallel-safe are different plan properties. A node running inside a parallel worker is not necessarily a parallel-aware node.", "/versions/11/sections/1/paragraphs/0": "The node allocates a tuple-location bitmap using a work_mem-derived budget. A bitmap can retain page-level lossy entries instead of every tuple location; heap rechecks then remain necessary.", "/versions/11/sections/2/paragraphs/0": "The source callbacks below can coordinate execution or collect worker instrumentation. Their presence is not a blanket claim that this node supports a shared parallel scan or shared state.", "/versions/11/sections/2/paragraphs/1": "Callbacks in this build: none extracted from this node implementation.", "/versions/11/sections/3/paragraphs/0": "BitmapAnd and BitmapOr nodes always report their actual row counts as zero, due to implementation limitations.", "/versions/11/sections/4/paragraphs/0": "NOTES BitmapOr nodes don't make use of their left and right subtrees, rather they maintain a list of subplans, much like Append nodes. The logic is much simpler than Append, however, since we needn't cope with forward/backward execution.", "/versions/11/sections/4/paragraphs/1": "call ExecInitNode on each of the plans to be executed and save the results into the array \"bitmapplanstates\".", "/versions/11/sections/4/paragraphs/2": "BitmapOr plans don't have expression contexts because they never call ExecQual or ExecProject. They don't need any tuple slots either.", "/versions/11/sections/4/paragraphs/3": "We can special-case BitmapIndexScan children to avoid an explicit tbm_union step for each child: just pass down the current result bitmap and let the child OR directly into it.", "/versions/11/sections/4/paragraphs/4": "ExecReScan doesn't know about my subplans, so I have to do changed-parameter signaling myself.", "/versions/11/tables/0/columns/0/label": "Text-format label", "/versions/11/tables/0/columns/1/label": "Structured node identity"}, "fallback_fields": [], "source_language": "en", "original_snapshot_sha256": "2984fbc92eca3f5d9571ec130a4265caca80a7c61e3a43e0205828d8cd658b13", "canonical_center_text_hash": "4c124e4e2a4d4ff8315844911a4cab3b4c756e7c18a652cbfc93eef1fc66dc2f"}, "evidence_kind": "source and documentation", "explain_names": ["BitmapOr"], "partial_modes": [], "description_zh": "\u5bf9\u5404\u5b50\u8ba1\u5212\u751f\u6210\u7684\u4f4d\u56fe\u6c42\u5e76\u96c6\u3002", "comparison_data": {"node_tag": "T_BitmapOr", "strategies": [], "text_names": ["BitmapOr"], "initializer": "ExecInitBitmapOr", "partial_modes": [], "memory_mechanism": "bitmap-lossification", "parallel_callbacks": []}, "comparison_hash": "c0ca503a6029c37ec720213dcdc3094997eb194d4920da68f94a7420d3e8f1d2", "manual_language": "zh", "explain_prefixes": ["Parallel"], "runtime_verified": false, "source_inventory": {"explain": "src/backend/commands/explain.c", "executor": "src/backend/executor/execProcnode.c", "implementation": "src/backend/executor/nodeBitmapOr.c"}, "parallel_callbacks": [], "description_zh_html": "<p>\u5bf9\u5404\u5b50\u8ba1\u5212\u751f\u6210\u7684\u4f4d\u56fe\u6c42\u5e76\u96c6\u3002</p><p>\u6838\u5fc3\u8282\u70b9\u6807\u8bc6\uff1a<code>T_BitmapOr</code>\uff1bEXPLAIN \u540d\u79f0\uff1a<code>BitmapOr</code>\u3002</p><p>\u672c\u7248\u672c\u6e90\u7801\u4e2d\u7684\u5e76\u884c\u6267\u884c\u6216\u89c2\u6d4b\u56de\u8c03\uff1a\u8be5\u8282\u70b9\u5b9e\u73b0\u4e2d\u672a\u63d0\u53d6\u5230\u6b64\u7c7b\u56de\u8c03\u3002\u56de\u8c03\u7684\u5b58\u5728\u4e0d\u8868\u793a\u8be5\u8282\u70b9\u5fc5\u7136\u652f\u6301\u5171\u4eab\u5e76\u884c\u626b\u63cf\uff1b\u5728\u5e76\u884c\u5de5\u4f5c\u8fdb\u7a0b\u4e2d\u6267\u884c\u4e5f\u4e0d\u7b49\u4e8e\u5177\u6709\u5e76\u884c\u611f\u77e5\u80fd\u529b\u3002</p><h3>\u540c\u7248\u672c\u4e2d\u6587\u624b\u518c\u8282\u9009</h3><p>\n<code>EXPLAIN ANALYZE</code> \u6d4b\u5f97\u7684\u8fd0\u884c\u65f6\u95f4\uff0c\u53ef\u80fd\u4ee5\u4e24\u79cd\u91cd\u8981\u65b9\u5f0f\u504f\u79bb\u540c\u4e00\u67e5\u8be2\u7684\u6b63\u5e38\u6267\u884c\u65f6\u95f4\u3002\u7b2c\u4e00\uff0c\u7531\u4e8e\u4e0d\u4f1a\u5411\u5ba2\u6237\u7aef\u4f20\u9012\u4efb\u4f55\u8f93\u51fa\u884c\uff0c\u56e0\u6b64\u7f51\u7edc\u4f20\u8f93\u5f00\u9500\u548c I/O \u8f6c\u6362\u5f00\u9500\u5747\u4e0d\u4f1a\u88ab\u8ba1\u5165\u3002\u7b2c\u4e8c\uff0c<code>EXPLAIN ANALYZE</code> \u9644\u52a0\u7684\u6d4b\u91cf\u5f00\u9500\u672c\u8eab\u53ef\u80fd\u76f8\u5f53\u53ef\u89c2\uff0c\u5c24\u5176\u662f\u5728\u64cd\u4f5c\u7cfb\u7edf\u8c03\u7528 <code>gettimeofday()</code> \u8f83\u6162\u7684\u673a\u5668\u4e0a\u3002\u53ef\u4ee5\u4f7f\u7528 <a href=\"/zh/docs/11/pgtesttiming.html\" rel=\"nofollow\"><span><span>pg_test_timing</span></span></a> \u5de5\u5177\u6765\u6d4b\u91cf\u7cfb\u7edf\u4e0a\u7684\u8ba1\u65f6\u5f00\u9500\u3002\n   </p><p>\n    \u4e0d\u5e94\u5c06 <code>EXPLAIN</code> \u7ed3\u679c\u5916\u63a8\u5230\u4e0e\u5b9e\u9645\u6d4b\u8bd5\u573a\u666f\u5dee\u5f02\u5f88\u5927\u7684\u60c5\u51b5\u3002\u4f8b\u5982\uff0c\u5728\u4e00\u4e2a\u5f88\u5c0f\u7684\u8868\u4e0a\u5f97\u5230\u7684\u7ed3\u679c\uff0c\u4e0d\u80fd\u5047\u5b9a\u4e5f\u9002\u7528\u4e8e\u5927\u578b\u8868\u3002\u89c4\u5212\u5668\u7684\u4ee3\u4ef7\u4f30\u8ba1\u4e0d\u662f\u7ebf\u6027\u7684\uff0c\u56e0\u6b64\u5b83\u53ef\u80fd\u4f1a\u4e3a\u66f4\u5927\u6216\u66f4\u5c0f\u7684\u8868\u9009\u62e9\u4e0d\u540c\u7684\u8ba1\u5212\u3002\u4e00\u4e2a\u6781\u7aef\u793a\u4f8b\u662f\uff1a\u5bf9\u4e8e\u53ea\u5360\u7528\u4e00\u4e2a\u78c1\u76d8\u9875\u7684\u8868\uff0c\u65e0\u8bba\u7d22\u5f15\u662f\u5426\u53ef\u7528\uff0c\u51e0\u4e4e\u603b\u4f1a\u5f97\u5230\u987a\u5e8f\u626b\u63cf\u8ba1\u5212\u3002\u89c4\u5212\u5668\u8ba4\u8bc6\u5230\uff0c\u65e0\u8bba\u5982\u4f55\u5904\u7406\u8be5\u8868\u90fd\u9700\u8981\u4e00\u6b21\u78c1\u76d8\u9875\u8bfb\u53d6\uff0c\u56e0\u6b64\u518d\u989d\u5916\u8bfb\u53d6\u9875\u9762\u53bb\u67e5\u770b\u7d22\u5f15\u5e76\u6ca1\u6709\u4ef7\u503c\u3002\uff08\u524d\u9762\u7684 <code>polygon_tbl</code> \u793a\u4f8b\u5df2\u7ecf\u5c55\u793a\u8fc7\u8fd9\u79cd\u60c5\u51b5\u3002\uff09\n   </p><p>\n    \u5728\u67d0\u4e9b\u60c5\u51b5\u4e0b\uff0c\u5b9e\u9645\u503c\u548c\u4f30\u8ba1\u503c\u4e0d\u4f1a\u5f88\u597d\u5730\u5bf9\u5e94\uff0c\u4f46\u8fd9\u5e76\u4e0d\u8868\u793a\u51fa\u73b0\u4e86\u95ee\u9898\u3002\u5176\u4e2d\u4e00\u79cd\u60c5\u51b5\u662f\uff0c\u8ba1\u5212\u8282\u70b9\u7684\u6267\u884c\u4f1a\u88ab <code>LIMIT</code> \u6216\u7c7b\u4f3c\u6548\u679c\u63d0\u524d\u622a\u65ad\u3002\u4f8b\u5982\uff0c\u5728\u524d\u9762\u7528\u8fc7\u7684 <code>LIMIT</code> \u67e5\u8be2\u4e2d\uff1a\n\n</p><p>\n\n    Index Scan \u8282\u70b9\u7684\u4f30\u8ba1\u4ee3\u4ef7\u548c\u884c\u8ba1\u6570\u663e\u793a\u5f97\u50cf\u662f\u5b83\u4f1a\u8fd0\u884c\u5230\u7ed3\u675f\u4e00\u6837\u3002\u4f46\u5b9e\u9645\u4e0a\uff0cLimit \u8282\u70b9\u5728\u62ff\u5230\u4e24\u884c\u4e4b\u540e\u5c31\u505c\u6b62\u8bf7\u6c42\u66f4\u591a\u884c\uff0c\u56e0\u6b64\u5b9e\u9645\u884c\u8ba1\u6570\u53ea\u6709 2\uff0c\u8fd0\u884c\u65f6\u95f4\u4e5f\u4f4e\u4e8e\u4ee3\u4ef7\u4f30\u8ba1\u6240\u6697\u793a\u7684\u6c34\u5e73\u3002\u8fd9\u5e76\u4e0d\u662f\u4f30\u8ba1\u9519\u8bef\uff0c\u53ea\u662f\u4f30\u8ba1\u503c\u4e0e\u771f\u5b9e\u503c\u7684\u663e\u793a\u65b9\u5f0f\u4e0d\u540c\u800c\u5df2\u3002\n   </p><p><a href=\"/zh/docs/11/performance-tips.html#USING-EXPLAIN-CAVEATS\" rel=\"nofollow\">\u67e5\u770b\u5b8c\u6574\u4e2d\u6587\u624b\u518c\u4e0e\u4e0a\u4e0b\u6587</a>\u3002</p><p>\u672c\u9875\u5f00\u5934\u7684\u4e2d\u6587\u8bf4\u660e\u4e3a PG.CENTER \u5bf9\u7f16\u8f91\u8bf4\u660e\u7684\u7ffb\u8bd1\uff1b\u624b\u518c\u8282\u9009\u4fdd\u7559\u5bf9\u5e94\u7248\u672c\u4e2d\u6587\u6587\u6863\u539f\u6587\u3002\u6e90\u7801\u4fe1\u606f\u53ca\u624b\u518c\u793a\u4f8b\u4e0d\u4ee3\u8868\u91cd\u65b0\u8fdb\u884c\u8fc7\u8fd0\u884c\u6d4b\u8bd5\u3002</p>"}, "12": {"facts": [{"label": "\u6838\u5fc3\u8282\u70b9\u6807\u7b7e", "value": "T_BitmapOr"}, {"label": "\u7ed3\u6784\u5316 EXPLAIN \u8282\u70b9\u7c7b\u578b", "value": "BitmapOr"}, {"label": "\u8f93\u5165", "value": "\u4ea7\u751f\u4f4d\u56fe\u7684\u5b50\u8ba1\u5212"}, {"label": "\u8f93\u51fa", "value": "\u5143\u7ec4\u4f4d\u7f6e\u4f4d\u56fe\uff0c\u4e0d\u662f\u5143\u7ec4\u6d41"}, {"label": "\u6267\u884c\u5668\u521d\u59cb\u5316\u51fd\u6570", "value": "ExecInitBitmapOr"}, {"label": "\u5185\u5b58\u673a\u5236", "value": "bitmap-lossification"}], "memory": {"evidence": [{"url": "https://ftp.postgresql.org/pub/source/v12.22/postgresql-12.22.tar.bz2", "path": "src/backend/executor/nodeBitmapOr.c", "label": "src/backend/executor/nodeBitmapOr.c", "sha256": "00f6348b2dd4ed868e6f2f8dae8662651547db206664e4682c3557c6a798f19b", "archive_sha256": "8df3c0474782589d3c6f374b5133b1bd14d168086edbc13c6e72e67dd4527a3b"}, {"url": "https://ftp.postgresql.org/pub/source/v12.22/postgresql-12.22.tar.bz2", "path": "src/backend/nodes/tidbitmap.c", "label": "src/backend/nodes/tidbitmap.c", "sha256": "8a18d2e770adab40a9172ebc6895501ec22f650b479c4e9ce44ca010c57ad24d", "archive_sha256": "8df3c0474782589d3c6f374b5133b1bd14d168086edbc13c6e72e67dd4527a3b"}], "mechanism": "bitmap-lossification", "description": "The node allocates a tuple-location bitmap using a work_mem-derived budget. A bitmap can retain page-level lossy entries instead of every tuple location; heap rechecks then remain necessary.", "source_notes": []}, "tables": [{"key": "explain-labels", "rows": [{"label": "BitmapOr", "identity": "BitmapOr"}], "title": "\u672c\u6784\u5efa\u4e2d\u7684 EXPLAIN \u6807\u7b7e", "columns": [{"key": "label", "label": "\u6587\u672c\u683c\u5f0f\u6807\u7b7e"}, {"key": "identity", "label": "\u7ed3\u6784\u5316\u8282\u70b9\u6807\u8bc6"}]}], "related": [{"url": "/wiki/sql/explain/?v=12", "label": "EXPLAIN"}, {"url": "/docs/12/using-explain.html", "label": "\u4f7f\u7528 EXPLAIN"}, {"url": "/docs/12/parallel-plans.html", "label": "\u5e76\u884c\u8ba1\u5212"}, {"url": "/wiki/guc/work_mem/?v=12", "label": "work_mem"}], "release": {"ref": "PostgreSQL 12.22 source archive", "label": "12.22", "major": "12", "channel": "historical", "revision": "8df3c0474782589d3c6f374b5133b1bd14d168086edbc13c6e72e67dd4527a3b", "source_url": "https://ftp.postgresql.org/pub/source/v12.22/postgresql-12.22.tar.bz2", "source_snapshot_utc": ""}, "sources": [{"url": "https://ftp.postgresql.org/pub/source/v12.22/postgresql-12.22.tar.bz2", "line": 1114, "path": "src/backend/commands/explain.c", "label": "src/backend/commands/explain.c:1114", "sha256": "d02ea84fdaa201de5d9360645a9f24bfbd2c31f7d45a639e09560ac0e6b6471d", "archive_sha256": "8df3c0474782589d3c6f374b5133b1bd14d168086edbc13c6e72e67dd4527a3b"}, {"url": "https://ftp.postgresql.org/pub/source/v12.22/postgresql-12.22.tar.bz2", "line": 199, "path": "src/backend/executor/execProcnode.c", "label": "src/backend/executor/execProcnode.c:199", "sha256": "311b17379fe54e3f342fe5ad41c43afbdfa1b844978db2bb2eb22b82520d3256", "archive_sha256": "8df3c0474782589d3c6f374b5133b1bd14d168086edbc13c6e72e67dd4527a3b"}, {"url": "https://ftp.postgresql.org/pub/source/v12.22/postgresql-12.22.tar.bz2", "path": "src/backend/executor/nodeBitmapOr.c", "label": "src/backend/executor/nodeBitmapOr.c", 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"06297525f2180b07e752837a3351be9c871b56559f535bcd0a67dec9baac10c0"}], "zh_from": {"kind": "same-version-chinese-manual-with-authored-translation-of-reviewed-guidance", "manual": {"url": "/zh/docs/12/performance-tips.html#USING-EXPLAIN-CAVEATS", "anchor": "USING-EXPLAIN-CAVEATS", "locale": "zh-Hans", "version": "12", "build_id": 65, "page_key": "performance-tips.html", "extraction": "concept-introduction", "source_hash": "773efea8d76bcea57eb449ceb506a51025a4125ceaa9b765a1039e558f5cfe98", "fragment_sha256": "0b01646082e88a38811f27eea6c54c2c678a259321350208ec7e457f0821d2ca", "source_revision": "unknown:rendered-translation-baseline", "translation_revision": "snapshot:sha256:86d2ff781f93e1de17122ebc514d5e64fcb63fed15941f496d7e146c6dcc7a49", "translated_from_revision": null}, "body_sha256": "7267b37c30d6450a2ecfff019900fc9faf4bb1f7cf5d5a34a2e2b2391881937b", "runtime_rerun": false, "authored_translation": "authored-translation-of-reviewed-guidance", "source_facts_revision": "8df3c0474782589d3c6f374b5133b1bd14d168086edbc13c6e72e67dd4527a3b"}, "facts_zh": [{"label": "\u6838\u5fc3\u8282\u70b9\u6807\u7b7e", "value": "T_BitmapOr"}, {"label": "\u7ed3\u6784\u5316 EXPLAIN \u8282\u70b9\u7c7b\u578b", "value": "BitmapOr"}, {"label": "\u8f93\u5165", "value": "\u4ea7\u751f\u4f4d\u56fe\u7684\u5b50\u8ba1\u5212"}, {"label": "\u8f93\u51fa", "value": "\u5143\u7ec4\u4f4d\u7f6e\u4f4d\u56fe\uff0c\u4e0d\u662f\u5143\u7ec4\u6d41"}, {"label": "\u6267\u884c\u5668\u521d\u59cb\u5316\u51fd\u6570", "value": "ExecInitBitmapOr"}, {"label": "\u5185\u5b58\u673a\u5236", "value": "bitmap-lossification"}], "node_tag": "T_BitmapOr", "sections": [{"title": "EXPLAIN \u540d\u79f0\u4e0e\u5c5e\u6027", "paragraphs": ["\u7ed3\u6784\u5316\u683c\u5f0f\u4f7f\u7528\u4e0a\u8ff0 Node Type\u3002\u6587\u672c\u683c\u5f0f\u540d\u79f0\u8fd8\u53ef\u80fd\u5305\u542b\u64cd\u4f5c\u3001\u7b56\u7565\u3001\u8fde\u63a5\u7c7b\u578b\u3001\u626b\u63cf\u65b9\u5411\u6216\u805a\u5408\u9636\u6bb5\u5c5e\u6027\u3002", "\u6b64\u6e90\u7801\u8bb0\u5f55\u7684\u6587\u672c\u540d\u79f0\uff1aBitmapOr.", "\u5e76\u884c\u611f\u77e5\u4e0e\u5e76\u884c\u5b89\u5168\u662f\u4e0d\u540c\u7684\u8ba1\u5212\u5c5e\u6027\u3002\u5728\u5e76\u884c\u5de5\u4f5c\u8fdb\u7a0b\u5185\u8fd0\u884c\u7684\u8282\u70b9\u4e0d\u4e00\u5b9a\u662f\u5e76\u884c\u611f\u77e5\u8282\u70b9\u3002"]}, {"title": "\u5185\u5b58\u4e0e\u4e34\u65f6\u5b58\u50a8", "paragraphs": ["\u6b64\u8282\u70b9\u6309\u57fa\u4e8e work_mem \u7684\u9884\u7b97\u5206\u914d\u5143\u7ec4\u4f4d\u7f6e\u4f4d\u56fe\u3002\u4f4d\u56fe\u53ef\u4ee5\u4fdd\u7559\u9875\u7ea7\u6709\u635f\u6761\u76ee\uff0c\u800c\u4e0d\u8bb0\u5f55\u6bcf\u4e2a\u5143\u7ec4\u4f4d\u7f6e\uff0c\u56e0\u6b64\u4ecd\u53ef\u80fd\u9700\u8981\u5806\u91cd\u68c0\u3002"]}, {"title": "\u5e76\u884c\u6267\u884c\u4e0e\u8fd0\u884c\u4fe1\u606f\u91c7\u96c6", "paragraphs": ["\u4ee5\u4e0b\u6e90\u7801\u56de\u8c03\u53ef\u4ee5\u534f\u8c03\u6267\u884c\u6216\u6536\u96c6\u5de5\u4f5c\u8fdb\u7a0b\u7684\u6d4b\u91cf\u6570\u636e\u3002\u56de\u8c03\u5b58\u5728\u4e0d\u4ee3\u8868\u8be5\u8282\u70b9\u666e\u904d\u652f\u6301\u5171\u4eab\u5e76\u884c\u626b\u63cf\u6216\u5171\u4eab\u72b6\u6001\u3002", "\u6b64\u6784\u5efa\u7684\u56de\u8c03\uff1anone extracted from this node implementation."]}, {"title": "\u540c\u7248\u672c\u624b\u518c\u8bf4\u660e", "paragraphs": ["\u7531\u4e8e\u5b9e\u73b0\u4e0a\u7684\u9650\u5236\uff0cBitmapAnd \u548c BitmapOr \u8282\u70b9\u62a5\u544a\u7684\u5b9e\u9645\u884c\u6570\u59cb\u7ec8\u4e3a\u96f6\u3002"]}, {"title": "\u6267\u884c\u5668\u5b9e\u73b0\u8bf4\u660e", "paragraphs": ["\u8bf4\u660e\uff1aBitmapOr \u4e0d\u4f7f\u7528\u5de6\u53f3\u5b50\u6811\uff0c\u800c\u50cf Append \u4e00\u6837\u7ef4\u62a4\u5b50\u8ba1\u5212\u5217\u8868\u3002\u4e0d\u8fc7\u5176\u903b\u8f91\u6bd4 Append \u7b80\u5355\u5f97\u591a\uff0c\u56e0\u4e3a\u65e0\u9700\u5904\u7406\u6b63\u5411\u6216\u53cd\u5411\u6267\u884c\u3002", "\u5bf9\u6bcf\u4e2a\u5f85\u6267\u884c\u8ba1\u5212\u8c03\u7528 ExecInitNode\uff0c\u5e76\u5c06\u7ed3\u679c\u4fdd\u5b58\u5230 bitmapplanstates \u6570\u7ec4\u3002", "BitmapOr \u8ba1\u5212\u6ca1\u6709\u8868\u8fbe\u5f0f\u4e0a\u4e0b\u6587\uff0c\u56e0\u4e3a\u5b83\u4eec\u4ece\u4e0d\u8c03\u7528 ExecQual \u6216 ExecProject\uff0c\u4e5f\u4e0d\u9700\u8981\u5143\u7ec4\u69fd\u3002", "\u53ef\u5bf9 BitmapIndexScan \u5b50\u8282\u70b9\u4f5c\u7279\u6b8a\u5904\u7406\uff0c\u907f\u514d\u4e3a\u6bcf\u4e2a\u5b50\u8282\u70b9\u663e\u5f0f\u8c03\u7528 tbm_union\uff1a\u76f4\u63a5\u4e0b\u4f20\u5f53\u524d\u7ed3\u679c\u4f4d\u56fe\uff0c\u8ba9\u5b50\u8282\u70b9\u5c06\u7ed3\u679c\u6309\u4f4d OR \u5408\u5e76\u8fdb\u53bb\u3002", "ExecReScan \u4e0d\u77e5\u9053\u5f53\u524d\u8282\u70b9\u7684\u5b50\u8ba1\u5212\uff0c\u56e0\u6b64\u5fc5\u987b\u81ea\u884c\u901a\u77e5\u5b50\u8ba1\u5212\u54ea\u4e9b\u53c2\u6570\u53d1\u751f\u4e86\u53d8\u5316\u3002"]}, {"code": "case T_BitmapOr:\n\t\t\tpname = sname = \"BitmapOr\";\n\t\t\tbreak;", "title": "\u6838\u5fc3\u6e90\u7801\u4e2d\u7684 EXPLAIN \u6807\u8bc6"}], "center_zh": {"title": "BitmapOr", "locale": "zh-Hans", "source": {"key": "bitmapor", "locale": "zh-Hans", "version": "12", "text_hash": "ba91b44499d5ee942f03991bb4c54a49a297e0cfc9b7dab70c52417992a16da7", "collection": "plan", "dataset_hash": "7c31b524dfe136022d39a6ae8dcfac6b3bbd5f8fdaf422536599981252aff0c9", "source_database": "center", "source_revision": "8df3c0474782589d3c6f374b5133b1bd14d168086edbc13c6e72e67dd4527a3b"}, "payload": {"facts": [{"label": "\u6838\u5fc3\u8282\u70b9\u6807\u7b7e", "value": "T_BitmapOr"}, {"label": "\u7ed3\u6784\u5316 EXPLAIN \u8282\u70b9\u7c7b\u578b", "value": "BitmapOr"}, {"label": "\u8f93\u5165", "value": "\u4ea7\u751f\u4f4d\u56fe\u7684\u5b50\u8ba1\u5212"}, {"label": "\u8f93\u51fa", "value": "\u5143\u7ec4\u4f4d\u7f6e\u4f4d\u56fe\uff0c\u4e0d\u662f\u5143\u7ec4\u6d41"}, {"label": "\u6267\u884c\u5668\u521d\u59cb\u5316\u51fd\u6570", "value": "ExecInitBitmapOr"}, {"label": "\u5185\u5b58\u673a\u5236", "value": "bitmap-lossification"}], "tables": [{"key": "explain-labels", "rows": [{"label": "BitmapOr", "identity": "BitmapOr"}], "title": "\u672c\u6784\u5efa\u4e2d\u7684 EXPLAIN \u6807\u7b7e", "columns": [{"key": "label", "label": "\u6587\u672c\u683c\u5f0f\u6807\u7b7e"}, {"key": "identity", "label": "\u7ed3\u6784\u5316\u8282\u70b9\u6807\u8bc6"}]}], "zh_from": {"kind": "same-version-chinese-manual-with-authored-translation-of-reviewed-guidance", "manual": {"url": "/zh/docs/12/performance-tips.html#USING-EXPLAIN-CAVEATS", "anchor": "USING-EXPLAIN-CAVEATS", "locale": "zh-Hans", "version": "12", "build_id": 65, "page_key": "performance-tips.html", "extraction": "concept-introduction", "source_hash": "773efea8d76bcea57eb449ceb506a51025a4125ceaa9b765a1039e558f5cfe98", "fragment_sha256": "0b01646082e88a38811f27eea6c54c2c678a259321350208ec7e457f0821d2ca", "source_revision": "unknown:rendered-translation-baseline", "translation_revision": "snapshot:sha256:86d2ff781f93e1de17122ebc514d5e64fcb63fed15941f496d7e146c6dcc7a49", "translated_from_revision": null}, "body_sha256": "7267b37c30d6450a2ecfff019900fc9faf4bb1f7cf5d5a34a2e2b2391881937b", "runtime_rerun": false, "authored_translation": "authored-translation-of-reviewed-guidance", "source_facts_revision": "8df3c0474782589d3c6f374b5133b1bd14d168086edbc13c6e72e67dd4527a3b"}, "sections": [{"title": "EXPLAIN \u540d\u79f0\u4e0e\u5c5e\u6027", "paragraphs": ["\u7ed3\u6784\u5316\u683c\u5f0f\u4f7f\u7528\u4e0a\u8ff0 Node Type\u3002\u6587\u672c\u683c\u5f0f\u540d\u79f0\u8fd8\u53ef\u80fd\u5305\u542b\u64cd\u4f5c\u3001\u7b56\u7565\u3001\u8fde\u63a5\u7c7b\u578b\u3001\u626b\u63cf\u65b9\u5411\u6216\u805a\u5408\u9636\u6bb5\u5c5e\u6027\u3002", "\u6b64\u6e90\u7801\u8bb0\u5f55\u7684\u6587\u672c\u540d\u79f0\uff1aBitmapOr.", "\u5e76\u884c\u611f\u77e5\u4e0e\u5e76\u884c\u5b89\u5168\u662f\u4e0d\u540c\u7684\u8ba1\u5212\u5c5e\u6027\u3002\u5728\u5e76\u884c\u5de5\u4f5c\u8fdb\u7a0b\u5185\u8fd0\u884c\u7684\u8282\u70b9\u4e0d\u4e00\u5b9a\u662f\u5e76\u884c\u611f\u77e5\u8282\u70b9\u3002"]}, {"title": "\u5185\u5b58\u4e0e\u4e34\u65f6\u5b58\u50a8", "paragraphs": ["\u6b64\u8282\u70b9\u6309\u57fa\u4e8e work_mem \u7684\u9884\u7b97\u5206\u914d\u5143\u7ec4\u4f4d\u7f6e\u4f4d\u56fe\u3002\u4f4d\u56fe\u53ef\u4ee5\u4fdd\u7559\u9875\u7ea7\u6709\u635f\u6761\u76ee\uff0c\u800c\u4e0d\u8bb0\u5f55\u6bcf\u4e2a\u5143\u7ec4\u4f4d\u7f6e\uff0c\u56e0\u6b64\u4ecd\u53ef\u80fd\u9700\u8981\u5806\u91cd\u68c0\u3002"]}, {"title": "\u5e76\u884c\u6267\u884c\u4e0e\u8fd0\u884c\u4fe1\u606f\u91c7\u96c6", "paragraphs": ["\u4ee5\u4e0b\u6e90\u7801\u56de\u8c03\u53ef\u4ee5\u534f\u8c03\u6267\u884c\u6216\u6536\u96c6\u5de5\u4f5c\u8fdb\u7a0b\u7684\u6d4b\u91cf\u6570\u636e\u3002\u56de\u8c03\u5b58\u5728\u4e0d\u4ee3\u8868\u8be5\u8282\u70b9\u666e\u904d\u652f\u6301\u5171\u4eab\u5e76\u884c\u626b\u63cf\u6216\u5171\u4eab\u72b6\u6001\u3002", "\u6b64\u6784\u5efa\u7684\u56de\u8c03\uff1anone extracted from this node implementation."]}, {"title": "\u540c\u7248\u672c\u624b\u518c\u8bf4\u660e", "paragraphs": ["\u7531\u4e8e\u5b9e\u73b0\u4e0a\u7684\u9650\u5236\uff0cBitmapAnd \u548c BitmapOr \u8282\u70b9\u62a5\u544a\u7684\u5b9e\u9645\u884c\u6570\u59cb\u7ec8\u4e3a\u96f6\u3002"]}, {"title": "\u6267\u884c\u5668\u5b9e\u73b0\u8bf4\u660e", "paragraphs": ["\u8bf4\u660e\uff1aBitmapOr \u4e0d\u4f7f\u7528\u5de6\u53f3\u5b50\u6811\uff0c\u800c\u50cf Append \u4e00\u6837\u7ef4\u62a4\u5b50\u8ba1\u5212\u5217\u8868\u3002\u4e0d\u8fc7\u5176\u903b\u8f91\u6bd4 Append \u7b80\u5355\u5f97\u591a\uff0c\u56e0\u4e3a\u65e0\u9700\u5904\u7406\u6b63\u5411\u6216\u53cd\u5411\u6267\u884c\u3002", "\u5bf9\u6bcf\u4e2a\u5f85\u6267\u884c\u8ba1\u5212\u8c03\u7528 ExecInitNode\uff0c\u5e76\u5c06\u7ed3\u679c\u4fdd\u5b58\u5230 bitmapplanstates \u6570\u7ec4\u3002", "BitmapOr \u8ba1\u5212\u6ca1\u6709\u8868\u8fbe\u5f0f\u4e0a\u4e0b\u6587\uff0c\u56e0\u4e3a\u5b83\u4eec\u4ece\u4e0d\u8c03\u7528 ExecQual \u6216 ExecProject\uff0c\u4e5f\u4e0d\u9700\u8981\u5143\u7ec4\u69fd\u3002", "\u53ef\u5bf9 BitmapIndexScan \u5b50\u8282\u70b9\u4f5c\u7279\u6b8a\u5904\u7406\uff0c\u907f\u514d\u4e3a\u6bcf\u4e2a\u5b50\u8282\u70b9\u663e\u5f0f\u8c03\u7528 tbm_union\uff1a\u76f4\u63a5\u4e0b\u4f20\u5f53\u524d\u7ed3\u679c\u4f4d\u56fe\uff0c\u8ba9\u5b50\u8282\u70b9\u5c06\u7ed3\u679c\u6309\u4f4d OR \u5408\u5e76\u8fdb\u53bb\u3002", "ExecReScan \u4e0d\u77e5\u9053\u5f53\u524d\u8282\u70b9\u7684\u5b50\u8ba1\u5212\uff0c\u56e0\u6b64\u5fc5\u987b\u81ea\u884c\u901a\u77e5\u5b50\u8ba1\u5212\u54ea\u4e9b\u53c2\u6570\u53d1\u751f\u4e86\u53d8\u5316\u3002"]}, {"code": "case T_BitmapOr:\n\t\t\tpname = sname = \"BitmapOr\";\n\t\t\tbreak;", "title": "\u6838\u5fc3\u6e90\u7801\u4e2d\u7684 EXPLAIN \u6807\u8bc6"}], "description_zh": "\u5bf9\u5404\u5b50\u8ba1\u5212\u751f\u6210\u7684\u4f4d\u56fe\u6c42\u5e76\u96c6\u3002", "description_zh_html": "<p>\u5bf9\u5404\u5b50\u8ba1\u5212\u751f\u6210\u7684\u4f4d\u56fe\u6c42\u5e76\u96c6\u3002</p><p>\u6838\u5fc3\u8282\u70b9\u6807\u8bc6\uff1a<code>T_BitmapOr</code>\uff1bEXPLAIN \u540d\u79f0\uff1a<code>BitmapOr</code>\u3002</p><p>\u672c\u7248\u672c\u6e90\u7801\u4e2d\u7684\u5e76\u884c\u6267\u884c\u6216\u89c2\u6d4b\u56de\u8c03\uff1a\u8be5\u8282\u70b9\u5b9e\u73b0\u4e2d\u672a\u63d0\u53d6\u5230\u6b64\u7c7b\u56de\u8c03\u3002\u56de\u8c03\u7684\u5b58\u5728\u4e0d\u8868\u793a\u8be5\u8282\u70b9\u5fc5\u7136\u652f\u6301\u5171\u4eab\u5e76\u884c\u626b\u63cf\uff1b\u5728\u5e76\u884c\u5de5\u4f5c\u8fdb\u7a0b\u4e2d\u6267\u884c\u4e5f\u4e0d\u7b49\u4e8e\u5177\u6709\u5e76\u884c\u611f\u77e5\u80fd\u529b\u3002</p><h3>\u540c\u7248\u672c\u4e2d\u6587\u624b\u518c\u8282\u9009</h3><p>\n<code class=\"command\">EXPLAIN ANALYZE</code> \u6d4b\u5f97\u7684\u8fd0\u884c\u65f6\u95f4\uff0c\u53ef\u80fd\u4ee5\u4e24\u79cd\u91cd\u8981\u65b9\u5f0f\u504f\u79bb\u540c\u4e00\u67e5\u8be2\u7684\u6b63\u5e38\u6267\u884c\u65f6\u95f4\u3002\u7b2c\u4e00\uff0c\u7531\u4e8e\u4e0d\u4f1a\u5411\u5ba2\u6237\u7aef\u4f20\u9012\u4efb\u4f55\u8f93\u51fa\u884c\uff0c\u56e0\u6b64\u7f51\u7edc\u4f20\u8f93\u5f00\u9500\u548c I/O \u8f6c\u6362\u5f00\u9500\u5747\u4e0d\u4f1a\u88ab\u8ba1\u5165\u3002\u7b2c\u4e8c\uff0c<code class=\"command\">EXPLAIN ANALYZE</code> \u9644\u52a0\u7684\u6d4b\u91cf\u5f00\u9500\u672c\u8eab\u53ef\u80fd\u76f8\u5f53\u53ef\u89c2\uff0c\u5c24\u5176\u662f\u5728\u64cd\u4f5c\u7cfb\u7edf\u8c03\u7528 <code class=\"function\">gettimeofday()</code> \u8f83\u6162\u7684\u673a\u5668\u4e0a\u3002\u53ef\u4ee5\u4f7f\u7528 <a class=\"xref\" href=\"/zh/docs/12/pgtesttiming.html\"><span class=\"refentrytitle\"><span class=\"application\">pg_test_timing</span></span></a> \u5de5\u5177\u6765\u6d4b\u91cf\u7cfb\u7edf\u4e0a\u7684\u8ba1\u65f6\u5f00\u9500\u3002\n   </p><p>\n    \u4e0d\u5e94\u5c06 <code class=\"command\">EXPLAIN</code> \u7ed3\u679c\u5916\u63a8\u5230\u4e0e\u5b9e\u9645\u6d4b\u8bd5\u573a\u666f\u5dee\u5f02\u5f88\u5927\u7684\u60c5\u51b5\u3002\u4f8b\u5982\uff0c\u5728\u4e00\u4e2a\u5f88\u5c0f\u7684\u8868\u4e0a\u5f97\u5230\u7684\u7ed3\u679c\uff0c\u4e0d\u80fd\u5047\u5b9a\u4e5f\u9002\u7528\u4e8e\u5927\u578b\u8868\u3002\u89c4\u5212\u5668\u7684\u4ee3\u4ef7\u4f30\u8ba1\u4e0d\u662f\u7ebf\u6027\u7684\uff0c\u56e0\u6b64\u5b83\u53ef\u80fd\u4f1a\u4e3a\u66f4\u5927\u6216\u66f4\u5c0f\u7684\u8868\u9009\u62e9\u4e0d\u540c\u7684\u8ba1\u5212\u3002\u4e00\u4e2a\u6781\u7aef\u793a\u4f8b\u662f\uff1a\u5bf9\u4e8e\u53ea\u5360\u7528\u4e00\u4e2a\u78c1\u76d8\u9875\u7684\u8868\uff0c\u65e0\u8bba\u7d22\u5f15\u662f\u5426\u53ef\u7528\uff0c\u51e0\u4e4e\u603b\u4f1a\u5f97\u5230\u987a\u5e8f\u626b\u63cf\u8ba1\u5212\u3002\u89c4\u5212\u5668\u8ba4\u8bc6\u5230\uff0c\u65e0\u8bba\u5982\u4f55\u5904\u7406\u8be5\u8868\u90fd\u9700\u8981\u4e00\u6b21\u78c1\u76d8\u9875\u8bfb\u53d6\uff0c\u56e0\u6b64\u518d\u989d\u5916\u8bfb\u53d6\u9875\u9762\u53bb\u67e5\u770b\u7d22\u5f15\u5e76\u6ca1\u6709\u4ef7\u503c\u3002\uff08\u524d\u9762\u7684 <code class=\"literal\">polygon_tbl</code> \u793a\u4f8b\u5df2\u7ecf\u5c55\u793a\u8fc7\u8fd9\u79cd\u60c5\u51b5\u3002\uff09\n   </p><p>\n    \u5728\u67d0\u4e9b\u60c5\u51b5\u4e0b\uff0c\u5b9e\u9645\u503c\u548c\u4f30\u8ba1\u503c\u4e0d\u4f1a\u5f88\u597d\u5730\u5bf9\u5e94\uff0c\u4f46\u8fd9\u5e76\u4e0d\u8868\u793a\u51fa\u73b0\u4e86\u95ee\u9898\u3002\u5176\u4e2d\u4e00\u79cd\u60c5\u51b5\u662f\uff0c\u8ba1\u5212\u8282\u70b9\u7684\u6267\u884c\u4f1a\u88ab <code class=\"literal\">LIMIT</code> \u6216\u7c7b\u4f3c\u6548\u679c\u63d0\u524d\u622a\u65ad\u3002\u4f8b\u5982\uff0c\u5728\u524d\u9762\u7528\u8fc7\u7684 <code class=\"literal\">LIMIT</code> \u67e5\u8be2\u4e2d\uff1a\n\n</p><p>\n\n    Index Scan \u8282\u70b9\u7684\u4f30\u8ba1\u4ee3\u4ef7\u548c\u884c\u8ba1\u6570\u663e\u793a\u5f97\u50cf\u662f\u5b83\u4f1a\u8fd0\u884c\u5230\u7ed3\u675f\u4e00\u6837\u3002\u4f46\u5b9e\u9645\u4e0a\uff0cLimit \u8282\u70b9\u5728\u62ff\u5230\u4e24\u884c\u4e4b\u540e\u5c31\u505c\u6b62\u8bf7\u6c42\u66f4\u591a\u884c\uff0c\u56e0\u6b64\u5b9e\u9645\u884c\u8ba1\u6570\u53ea\u6709 2\uff0c\u8fd0\u884c\u65f6\u95f4\u4e5f\u4f4e\u4e8e\u4ee3\u4ef7\u4f30\u8ba1\u6240\u6697\u793a\u7684\u6c34\u5e73\u3002\u8fd9\u5e76\u4e0d\u662f\u4f30\u8ba1\u9519\u8bef\uff0c\u53ea\u662f\u4f30\u8ba1\u503c\u4e0e\u771f\u5b9e\u503c\u7684\u663e\u793a\u65b9\u5f0f\u4e0d\u540c\u800c\u5df2\u3002\n   </p><p><a href=\"/zh/docs/12/performance-tips.html#USING-EXPLAIN-CAVEATS\">\u67e5\u770b\u5b8c\u6574\u4e2d\u6587\u624b\u518c\u4e0e\u4e0a\u4e0b\u6587</a>\u3002</p><p>\u672c\u9875\u5f00\u5934\u7684\u4e2d\u6587\u8bf4\u660e\u4e3a PG.CENTER \u5bf9\u7f16\u8f91\u8bf4\u660e\u7684\u7ffb\u8bd1\uff1b\u624b\u518c\u8282\u9009\u4fdd\u7559\u5bf9\u5e94\u7248\u672c\u4e2d\u6587\u6587\u6863\u539f\u6587\u3002\u6e90\u7801\u4fe1\u606f\u53ca\u624b\u518c\u793a\u4f8b\u4e0d\u4ee3\u8868\u91cd\u65b0\u8fdb\u884c\u8fc7\u8fd0\u884c\u6d4b\u8bd5\u3002</p>"}, "summary": "\u5bf9\u5404\u5b50\u8ba1\u5212\u751f\u6210\u7684\u4f4d\u56fe\u6c42\u5e76\u96c6\u3002", "version": "12", "link_map": {"/zh/docs/12/pgtesttiming.html": "/docs/12/pgtesttiming.html", "/zh/docs/12/performance-tips.html#USING-EXPLAIN-CAVEATS": "/docs/12/performance-tips.html#USING-EXPLAIN-CAVEATS"}, "body_html": "<p>\u5bf9\u5404\u5b50\u8ba1\u5212\u751f\u6210\u7684\u4f4d\u56fe\u6c42\u5e76\u96c6\u3002</p><p>\u6838\u5fc3\u8282\u70b9\u6807\u8bc6\uff1a<code>T_BitmapOr</code>\uff1bEXPLAIN \u540d\u79f0\uff1a<code>BitmapOr</code>\u3002</p><p>\u672c\u7248\u672c\u6e90\u7801\u4e2d\u7684\u5e76\u884c\u6267\u884c\u6216\u89c2\u6d4b\u56de\u8c03\uff1a\u8be5\u8282\u70b9\u5b9e\u73b0\u4e2d\u672a\u63d0\u53d6\u5230\u6b64\u7c7b\u56de\u8c03\u3002\u56de\u8c03\u7684\u5b58\u5728\u4e0d\u8868\u793a\u8be5\u8282\u70b9\u5fc5\u7136\u652f\u6301\u5171\u4eab\u5e76\u884c\u626b\u63cf\uff1b\u5728\u5e76\u884c\u5de5\u4f5c\u8fdb\u7a0b\u4e2d\u6267\u884c\u4e5f\u4e0d\u7b49\u4e8e\u5177\u6709\u5e76\u884c\u611f\u77e5\u80fd\u529b\u3002</p><h3>\u540c\u7248\u672c\u4e2d\u6587\u624b\u518c\u8282\u9009</h3><p>\n<code>EXPLAIN ANALYZE</code> \u6d4b\u5f97\u7684\u8fd0\u884c\u65f6\u95f4\uff0c\u53ef\u80fd\u4ee5\u4e24\u79cd\u91cd\u8981\u65b9\u5f0f\u504f\u79bb\u540c\u4e00\u67e5\u8be2\u7684\u6b63\u5e38\u6267\u884c\u65f6\u95f4\u3002\u7b2c\u4e00\uff0c\u7531\u4e8e\u4e0d\u4f1a\u5411\u5ba2\u6237\u7aef\u4f20\u9012\u4efb\u4f55\u8f93\u51fa\u884c\uff0c\u56e0\u6b64\u7f51\u7edc\u4f20\u8f93\u5f00\u9500\u548c I/O \u8f6c\u6362\u5f00\u9500\u5747\u4e0d\u4f1a\u88ab\u8ba1\u5165\u3002\u7b2c\u4e8c\uff0c<code>EXPLAIN ANALYZE</code> \u9644\u52a0\u7684\u6d4b\u91cf\u5f00\u9500\u672c\u8eab\u53ef\u80fd\u76f8\u5f53\u53ef\u89c2\uff0c\u5c24\u5176\u662f\u5728\u64cd\u4f5c\u7cfb\u7edf\u8c03\u7528 <code>gettimeofday()</code> \u8f83\u6162\u7684\u673a\u5668\u4e0a\u3002\u53ef\u4ee5\u4f7f\u7528 <a href=\"/zh/docs/12/pgtesttiming.html\" rel=\"nofollow\"><span><span>pg_test_timing</span></span></a> \u5de5\u5177\u6765\u6d4b\u91cf\u7cfb\u7edf\u4e0a\u7684\u8ba1\u65f6\u5f00\u9500\u3002\n   </p><p>\n    \u4e0d\u5e94\u5c06 <code>EXPLAIN</code> \u7ed3\u679c\u5916\u63a8\u5230\u4e0e\u5b9e\u9645\u6d4b\u8bd5\u573a\u666f\u5dee\u5f02\u5f88\u5927\u7684\u60c5\u51b5\u3002\u4f8b\u5982\uff0c\u5728\u4e00\u4e2a\u5f88\u5c0f\u7684\u8868\u4e0a\u5f97\u5230\u7684\u7ed3\u679c\uff0c\u4e0d\u80fd\u5047\u5b9a\u4e5f\u9002\u7528\u4e8e\u5927\u578b\u8868\u3002\u89c4\u5212\u5668\u7684\u4ee3\u4ef7\u4f30\u8ba1\u4e0d\u662f\u7ebf\u6027\u7684\uff0c\u56e0\u6b64\u5b83\u53ef\u80fd\u4f1a\u4e3a\u66f4\u5927\u6216\u66f4\u5c0f\u7684\u8868\u9009\u62e9\u4e0d\u540c\u7684\u8ba1\u5212\u3002\u4e00\u4e2a\u6781\u7aef\u793a\u4f8b\u662f\uff1a\u5bf9\u4e8e\u53ea\u5360\u7528\u4e00\u4e2a\u78c1\u76d8\u9875\u7684\u8868\uff0c\u65e0\u8bba\u7d22\u5f15\u662f\u5426\u53ef\u7528\uff0c\u51e0\u4e4e\u603b\u4f1a\u5f97\u5230\u987a\u5e8f\u626b\u63cf\u8ba1\u5212\u3002\u89c4\u5212\u5668\u8ba4\u8bc6\u5230\uff0c\u65e0\u8bba\u5982\u4f55\u5904\u7406\u8be5\u8868\u90fd\u9700\u8981\u4e00\u6b21\u78c1\u76d8\u9875\u8bfb\u53d6\uff0c\u56e0\u6b64\u518d\u989d\u5916\u8bfb\u53d6\u9875\u9762\u53bb\u67e5\u770b\u7d22\u5f15\u5e76\u6ca1\u6709\u4ef7\u503c\u3002\uff08\u524d\u9762\u7684 <code>polygon_tbl</code> \u793a\u4f8b\u5df2\u7ecf\u5c55\u793a\u8fc7\u8fd9\u79cd\u60c5\u51b5\u3002\uff09\n   </p><p>\n    \u5728\u67d0\u4e9b\u60c5\u51b5\u4e0b\uff0c\u5b9e\u9645\u503c\u548c\u4f30\u8ba1\u503c\u4e0d\u4f1a\u5f88\u597d\u5730\u5bf9\u5e94\uff0c\u4f46\u8fd9\u5e76\u4e0d\u8868\u793a\u51fa\u73b0\u4e86\u95ee\u9898\u3002\u5176\u4e2d\u4e00\u79cd\u60c5\u51b5\u662f\uff0c\u8ba1\u5212\u8282\u70b9\u7684\u6267\u884c\u4f1a\u88ab <code>LIMIT</code> \u6216\u7c7b\u4f3c\u6548\u679c\u63d0\u524d\u622a\u65ad\u3002\u4f8b\u5982\uff0c\u5728\u524d\u9762\u7528\u8fc7\u7684 <code>LIMIT</code> \u67e5\u8be2\u4e2d\uff1a\n\n</p><p>\n\n    Index Scan \u8282\u70b9\u7684\u4f30\u8ba1\u4ee3\u4ef7\u548c\u884c\u8ba1\u6570\u663e\u793a\u5f97\u50cf\u662f\u5b83\u4f1a\u8fd0\u884c\u5230\u7ed3\u675f\u4e00\u6837\u3002\u4f46\u5b9e\u9645\u4e0a\uff0cLimit \u8282\u70b9\u5728\u62ff\u5230\u4e24\u884c\u4e4b\u540e\u5c31\u505c\u6b62\u8bf7\u6c42\u66f4\u591a\u884c\uff0c\u56e0\u6b64\u5b9e\u9645\u884c\u8ba1\u6570\u53ea\u6709 2\uff0c\u8fd0\u884c\u65f6\u95f4\u4e5f\u4f4e\u4e8e\u4ee3\u4ef7\u4f30\u8ba1\u6240\u6697\u793a\u7684\u6c34\u5e73\u3002\u8fd9\u5e76\u4e0d\u662f\u4f30\u8ba1\u9519\u8bef\uff0c\u53ea\u662f\u4f30\u8ba1\u503c\u4e0e\u771f\u5b9e\u503c\u7684\u663e\u793a\u65b9\u5f0f\u4e0d\u540c\u800c\u5df2\u3002\n   </p><p><a href=\"/zh/docs/12/performance-tips.html#USING-EXPLAIN-CAVEATS\" rel=\"nofollow\">\u67e5\u770b\u5b8c\u6574\u4e2d\u6587\u624b\u518c\u4e0e\u4e0a\u4e0b\u6587</a>\u3002</p><p>\u672c\u9875\u5f00\u5934\u7684\u4e2d\u6587\u8bf4\u660e\u4e3a PG.CENTER \u5bf9\u7f16\u8f91\u8bf4\u660e\u7684\u7ffb\u8bd1\uff1b\u624b\u518c\u8282\u9009\u4fdd\u7559\u5bf9\u5e94\u7248\u672c\u4e2d\u6587\u6587\u6863\u539f\u6587\u3002\u6e90\u7801\u4fe1\u606f\u53ca\u624b\u518c\u793a\u4f8b\u4e0d\u4ee3\u8868\u91cd\u65b0\u8fdb\u884c\u8fc7\u8fd0\u884c\u6d4b\u8bd5\u3002</p>", "body_sha256": "a31fe3f5279cbfe3b49c16c2f47852fff0091cb35124fcb716995af034561d37", "content_hash": "ba91b44499d5ee942f03991bb4c54a49a297e0cfc9b7dab70c52417992a16da7", "source_database": "center", "source_revision": "8df3c0474782589d3c6f374b5133b1bd14d168086edbc13c6e72e67dd4527a3b"}, "tables_zh": [{"key": "explain-labels", "rows": [{"label": "BitmapOr", "identity": "BitmapOr"}], "title": "\u672c\u6784\u5efa\u4e2d\u7684 EXPLAIN \u6807\u7b7e", "columns": [{"key": "label", "label": "\u6587\u672c\u683c\u5f0f\u6807\u7b7e"}, {"key": "identity", "label": "\u7ed3\u6784\u5316\u8282\u70b9\u6807\u8bc6"}]}], "strategies": [], "description": ["\u5bf9\u5404\u5b50\u8ba1\u5212\u751f\u6210\u7684\u4f4d\u56fe\u6c42\u5e76\u96c6\u3002"], "sections_zh": [{"title": "EXPLAIN \u540d\u79f0\u4e0e\u5c5e\u6027", "paragraphs": ["\u7ed3\u6784\u5316\u683c\u5f0f\u4f7f\u7528\u4e0a\u8ff0 Node Type\u3002\u6587\u672c\u683c\u5f0f\u540d\u79f0\u8fd8\u53ef\u80fd\u5305\u542b\u64cd\u4f5c\u3001\u7b56\u7565\u3001\u8fde\u63a5\u7c7b\u578b\u3001\u626b\u63cf\u65b9\u5411\u6216\u805a\u5408\u9636\u6bb5\u5c5e\u6027\u3002", "\u6b64\u6e90\u7801\u8bb0\u5f55\u7684\u6587\u672c\u540d\u79f0\uff1aBitmapOr.", "\u5e76\u884c\u611f\u77e5\u4e0e\u5e76\u884c\u5b89\u5168\u662f\u4e0d\u540c\u7684\u8ba1\u5212\u5c5e\u6027\u3002\u5728\u5e76\u884c\u5de5\u4f5c\u8fdb\u7a0b\u5185\u8fd0\u884c\u7684\u8282\u70b9\u4e0d\u4e00\u5b9a\u662f\u5e76\u884c\u611f\u77e5\u8282\u70b9\u3002"]}, {"title": "\u5185\u5b58\u4e0e\u4e34\u65f6\u5b58\u50a8", "paragraphs": ["\u6b64\u8282\u70b9\u6309\u57fa\u4e8e work_mem \u7684\u9884\u7b97\u5206\u914d\u5143\u7ec4\u4f4d\u7f6e\u4f4d\u56fe\u3002\u4f4d\u56fe\u53ef\u4ee5\u4fdd\u7559\u9875\u7ea7\u6709\u635f\u6761\u76ee\uff0c\u800c\u4e0d\u8bb0\u5f55\u6bcf\u4e2a\u5143\u7ec4\u4f4d\u7f6e\uff0c\u56e0\u6b64\u4ecd\u53ef\u80fd\u9700\u8981\u5806\u91cd\u68c0\u3002"]}, {"title": "\u5e76\u884c\u6267\u884c\u4e0e\u8fd0\u884c\u4fe1\u606f\u91c7\u96c6", "paragraphs": ["\u4ee5\u4e0b\u6e90\u7801\u56de\u8c03\u53ef\u4ee5\u534f\u8c03\u6267\u884c\u6216\u6536\u96c6\u5de5\u4f5c\u8fdb\u7a0b\u7684\u6d4b\u91cf\u6570\u636e\u3002\u56de\u8c03\u5b58\u5728\u4e0d\u4ee3\u8868\u8be5\u8282\u70b9\u666e\u904d\u652f\u6301\u5171\u4eab\u5e76\u884c\u626b\u63cf\u6216\u5171\u4eab\u72b6\u6001\u3002", "\u6b64\u6784\u5efa\u7684\u56de\u8c03\uff1anone extracted from this node implementation."]}, {"title": "\u540c\u7248\u672c\u624b\u518c\u8bf4\u660e", "paragraphs": ["\u7531\u4e8e\u5b9e\u73b0\u4e0a\u7684\u9650\u5236\uff0cBitmapAnd \u548c BitmapOr \u8282\u70b9\u62a5\u544a\u7684\u5b9e\u9645\u884c\u6570\u59cb\u7ec8\u4e3a\u96f6\u3002"]}, {"title": "\u6267\u884c\u5668\u5b9e\u73b0\u8bf4\u660e", "paragraphs": ["\u8bf4\u660e\uff1aBitmapOr \u4e0d\u4f7f\u7528\u5de6\u53f3\u5b50\u6811\uff0c\u800c\u50cf Append \u4e00\u6837\u7ef4\u62a4\u5b50\u8ba1\u5212\u5217\u8868\u3002\u4e0d\u8fc7\u5176\u903b\u8f91\u6bd4 Append \u7b80\u5355\u5f97\u591a\uff0c\u56e0\u4e3a\u65e0\u9700\u5904\u7406\u6b63\u5411\u6216\u53cd\u5411\u6267\u884c\u3002", "\u5bf9\u6bcf\u4e2a\u5f85\u6267\u884c\u8ba1\u5212\u8c03\u7528 ExecInitNode\uff0c\u5e76\u5c06\u7ed3\u679c\u4fdd\u5b58\u5230 bitmapplanstates \u6570\u7ec4\u3002", "BitmapOr \u8ba1\u5212\u6ca1\u6709\u8868\u8fbe\u5f0f\u4e0a\u4e0b\u6587\uff0c\u56e0\u4e3a\u5b83\u4eec\u4ece\u4e0d\u8c03\u7528 ExecQual \u6216 ExecProject\uff0c\u4e5f\u4e0d\u9700\u8981\u5143\u7ec4\u69fd\u3002", "\u53ef\u5bf9 BitmapIndexScan \u5b50\u8282\u70b9\u4f5c\u7279\u6b8a\u5904\u7406\uff0c\u907f\u514d\u4e3a\u6bcf\u4e2a\u5b50\u8282\u70b9\u663e\u5f0f\u8c03\u7528 tbm_union\uff1a\u76f4\u63a5\u4e0b\u4f20\u5f53\u524d\u7ed3\u679c\u4f4d\u56fe\uff0c\u8ba9\u5b50\u8282\u70b9\u5c06\u7ed3\u679c\u6309\u4f4d OR \u5408\u5e76\u8fdb\u53bb\u3002", "ExecReScan \u4e0d\u77e5\u9053\u5f53\u524d\u8282\u70b9\u7684\u5b50\u8ba1\u5212\uff0c\u56e0\u6b64\u5fc5\u987b\u81ea\u884c\u901a\u77e5\u5b50\u8ba1\u5212\u54ea\u4e9b\u53c2\u6570\u53d1\u751f\u4e86\u53d8\u5316\u3002"]}, {"code": "case T_BitmapOr:\n\t\t\tpname = sname = \"BitmapOr\";\n\t\t\tbreak;", "title": "\u6838\u5fc3\u6e90\u7801\u4e2d\u7684 EXPLAIN \u6807\u8bc6"}], "localization": {"status": "complete", "sources": [], "language": "zh", "original_text": {"/versions/12/description/0": "Unions bitmaps produced by its child plans.", "/versions/12/facts/0/label": "Core node tag", "/versions/12/facts/1/label": "Structured EXPLAIN Node Type", "/versions/12/facts/2/label": "Inputs", "/versions/12/facts/2/value": "Bitmap-producing child plans", "/versions/12/facts/3/label": "Output", "/versions/12/facts/3/value": "Tuple-location bitmap, not a tuple stream", "/versions/12/facts/4/label": "Executor initializer", "/versions/12/facts/5/label": "Memory mechanism", "/versions/12/tables/0/title": "EXPLAIN labels in this source build", "/versions/12/related/1/label": "Using EXPLAIN", "/versions/12/related/2/label": "Parallel plans", "/versions/12/sections/0/title": "EXPLAIN names and attributes", "/versions/12/sections/1/title": "Memory and temporary storage", "/versions/12/sections/2/title": "Parallel execution and instrumentation", "/versions/12/sections/3/title": "Same-version manual discussion", "/versions/12/sections/4/title": "Executor implementation notes", "/versions/12/sections/5/title": "EXPLAIN identity in core source", "/versions/12/memory/description": "The node allocates a tuple-location bitmap using a work_mem-derived budget. A bitmap can retain page-level lossy entries instead of every tuple location; heap rechecks then remain necessary.", "/versions/12/sections/0/paragraphs/0": "Structured formats use the Node Type above. Text-format spellings can also include operation, strategy, join type, scan direction or aggregation-stage attributes.", "/versions/12/sections/0/paragraphs/1": "Text names recorded by this source: BitmapOr.", "/versions/12/sections/0/paragraphs/2": "Parallel-aware and parallel-safe are different plan properties. A node running inside a parallel worker is not necessarily a parallel-aware node.", "/versions/12/sections/1/paragraphs/0": "The node allocates a tuple-location bitmap using a work_mem-derived budget. A bitmap can retain page-level lossy entries instead of every tuple location; heap rechecks then remain necessary.", "/versions/12/sections/2/paragraphs/0": "The source callbacks below can coordinate execution or collect worker instrumentation. Their presence is not a blanket claim that this node supports a shared parallel scan or shared state.", "/versions/12/sections/2/paragraphs/1": "Callbacks in this build: none extracted from this node implementation.", "/versions/12/sections/3/paragraphs/0": "BitmapAnd and BitmapOr nodes always report their actual row counts as zero, due to implementation limitations.", "/versions/12/sections/4/paragraphs/0": "NOTES BitmapOr nodes don't make use of their left and right subtrees, rather they maintain a list of subplans, much like Append nodes. The logic is much simpler than Append, however, since we needn't cope with forward/backward execution.", "/versions/12/sections/4/paragraphs/1": "call ExecInitNode on each of the plans to be executed and save the results into the array \"bitmapplanstates\".", "/versions/12/sections/4/paragraphs/2": "BitmapOr plans don't have expression contexts because they never call ExecQual or ExecProject. They don't need any tuple slots either.", "/versions/12/sections/4/paragraphs/3": "We can special-case BitmapIndexScan children to avoid an explicit tbm_union step for each child: just pass down the current result bitmap and let the child OR directly into it.", "/versions/12/sections/4/paragraphs/4": "ExecReScan doesn't know about my subplans, so I have to do changed-parameter signaling myself.", "/versions/12/tables/0/columns/0/label": "Text-format label", "/versions/12/tables/0/columns/1/label": "Structured node identity"}, "fallback_fields": [], "source_language": "en", "original_snapshot_sha256": "c47c6279baa93a4403b00303c1c2f1799a062b3781835c9be4a92c307c84c908", "canonical_center_text_hash": "ba91b44499d5ee942f03991bb4c54a49a297e0cfc9b7dab70c52417992a16da7"}, "evidence_kind": "source and documentation", "explain_names": ["BitmapOr"], "partial_modes": [], "description_zh": "\u5bf9\u5404\u5b50\u8ba1\u5212\u751f\u6210\u7684\u4f4d\u56fe\u6c42\u5e76\u96c6\u3002", "comparison_data": {"node_tag": "T_BitmapOr", "strategies": [], "text_names": ["BitmapOr"], "initializer": "ExecInitBitmapOr", "partial_modes": [], "memory_mechanism": "bitmap-lossification", "parallel_callbacks": []}, "comparison_hash": "c0ca503a6029c37ec720213dcdc3094997eb194d4920da68f94a7420d3e8f1d2", "manual_language": "zh", "explain_prefixes": ["Parallel"], "runtime_verified": false, "source_inventory": {"explain": "src/backend/commands/explain.c", "executor": "src/backend/executor/execProcnode.c", "implementation": "src/backend/executor/nodeBitmapOr.c"}, "parallel_callbacks": [], "description_zh_html": "<p>\u5bf9\u5404\u5b50\u8ba1\u5212\u751f\u6210\u7684\u4f4d\u56fe\u6c42\u5e76\u96c6\u3002</p><p>\u6838\u5fc3\u8282\u70b9\u6807\u8bc6\uff1a<code>T_BitmapOr</code>\uff1bEXPLAIN \u540d\u79f0\uff1a<code>BitmapOr</code>\u3002</p><p>\u672c\u7248\u672c\u6e90\u7801\u4e2d\u7684\u5e76\u884c\u6267\u884c\u6216\u89c2\u6d4b\u56de\u8c03\uff1a\u8be5\u8282\u70b9\u5b9e\u73b0\u4e2d\u672a\u63d0\u53d6\u5230\u6b64\u7c7b\u56de\u8c03\u3002\u56de\u8c03\u7684\u5b58\u5728\u4e0d\u8868\u793a\u8be5\u8282\u70b9\u5fc5\u7136\u652f\u6301\u5171\u4eab\u5e76\u884c\u626b\u63cf\uff1b\u5728\u5e76\u884c\u5de5\u4f5c\u8fdb\u7a0b\u4e2d\u6267\u884c\u4e5f\u4e0d\u7b49\u4e8e\u5177\u6709\u5e76\u884c\u611f\u77e5\u80fd\u529b\u3002</p><h3>\u540c\u7248\u672c\u4e2d\u6587\u624b\u518c\u8282\u9009</h3><p>\n<code>EXPLAIN ANALYZE</code> \u6d4b\u5f97\u7684\u8fd0\u884c\u65f6\u95f4\uff0c\u53ef\u80fd\u4ee5\u4e24\u79cd\u91cd\u8981\u65b9\u5f0f\u504f\u79bb\u540c\u4e00\u67e5\u8be2\u7684\u6b63\u5e38\u6267\u884c\u65f6\u95f4\u3002\u7b2c\u4e00\uff0c\u7531\u4e8e\u4e0d\u4f1a\u5411\u5ba2\u6237\u7aef\u4f20\u9012\u4efb\u4f55\u8f93\u51fa\u884c\uff0c\u56e0\u6b64\u7f51\u7edc\u4f20\u8f93\u5f00\u9500\u548c I/O \u8f6c\u6362\u5f00\u9500\u5747\u4e0d\u4f1a\u88ab\u8ba1\u5165\u3002\u7b2c\u4e8c\uff0c<code>EXPLAIN ANALYZE</code> \u9644\u52a0\u7684\u6d4b\u91cf\u5f00\u9500\u672c\u8eab\u53ef\u80fd\u76f8\u5f53\u53ef\u89c2\uff0c\u5c24\u5176\u662f\u5728\u64cd\u4f5c\u7cfb\u7edf\u8c03\u7528 <code>gettimeofday()</code> \u8f83\u6162\u7684\u673a\u5668\u4e0a\u3002\u53ef\u4ee5\u4f7f\u7528 <a href=\"/zh/docs/12/pgtesttiming.html\" rel=\"nofollow\"><span><span>pg_test_timing</span></span></a> \u5de5\u5177\u6765\u6d4b\u91cf\u7cfb\u7edf\u4e0a\u7684\u8ba1\u65f6\u5f00\u9500\u3002\n   </p><p>\n    \u4e0d\u5e94\u5c06 <code>EXPLAIN</code> \u7ed3\u679c\u5916\u63a8\u5230\u4e0e\u5b9e\u9645\u6d4b\u8bd5\u573a\u666f\u5dee\u5f02\u5f88\u5927\u7684\u60c5\u51b5\u3002\u4f8b\u5982\uff0c\u5728\u4e00\u4e2a\u5f88\u5c0f\u7684\u8868\u4e0a\u5f97\u5230\u7684\u7ed3\u679c\uff0c\u4e0d\u80fd\u5047\u5b9a\u4e5f\u9002\u7528\u4e8e\u5927\u578b\u8868\u3002\u89c4\u5212\u5668\u7684\u4ee3\u4ef7\u4f30\u8ba1\u4e0d\u662f\u7ebf\u6027\u7684\uff0c\u56e0\u6b64\u5b83\u53ef\u80fd\u4f1a\u4e3a\u66f4\u5927\u6216\u66f4\u5c0f\u7684\u8868\u9009\u62e9\u4e0d\u540c\u7684\u8ba1\u5212\u3002\u4e00\u4e2a\u6781\u7aef\u793a\u4f8b\u662f\uff1a\u5bf9\u4e8e\u53ea\u5360\u7528\u4e00\u4e2a\u78c1\u76d8\u9875\u7684\u8868\uff0c\u65e0\u8bba\u7d22\u5f15\u662f\u5426\u53ef\u7528\uff0c\u51e0\u4e4e\u603b\u4f1a\u5f97\u5230\u987a\u5e8f\u626b\u63cf\u8ba1\u5212\u3002\u89c4\u5212\u5668\u8ba4\u8bc6\u5230\uff0c\u65e0\u8bba\u5982\u4f55\u5904\u7406\u8be5\u8868\u90fd\u9700\u8981\u4e00\u6b21\u78c1\u76d8\u9875\u8bfb\u53d6\uff0c\u56e0\u6b64\u518d\u989d\u5916\u8bfb\u53d6\u9875\u9762\u53bb\u67e5\u770b\u7d22\u5f15\u5e76\u6ca1\u6709\u4ef7\u503c\u3002\uff08\u524d\u9762\u7684 <code>polygon_tbl</code> \u793a\u4f8b\u5df2\u7ecf\u5c55\u793a\u8fc7\u8fd9\u79cd\u60c5\u51b5\u3002\uff09\n   </p><p>\n    \u5728\u67d0\u4e9b\u60c5\u51b5\u4e0b\uff0c\u5b9e\u9645\u503c\u548c\u4f30\u8ba1\u503c\u4e0d\u4f1a\u5f88\u597d\u5730\u5bf9\u5e94\uff0c\u4f46\u8fd9\u5e76\u4e0d\u8868\u793a\u51fa\u73b0\u4e86\u95ee\u9898\u3002\u5176\u4e2d\u4e00\u79cd\u60c5\u51b5\u662f\uff0c\u8ba1\u5212\u8282\u70b9\u7684\u6267\u884c\u4f1a\u88ab <code>LIMIT</code> \u6216\u7c7b\u4f3c\u6548\u679c\u63d0\u524d\u622a\u65ad\u3002\u4f8b\u5982\uff0c\u5728\u524d\u9762\u7528\u8fc7\u7684 <code>LIMIT</code> \u67e5\u8be2\u4e2d\uff1a\n\n</p><p>\n\n    Index Scan \u8282\u70b9\u7684\u4f30\u8ba1\u4ee3\u4ef7\u548c\u884c\u8ba1\u6570\u663e\u793a\u5f97\u50cf\u662f\u5b83\u4f1a\u8fd0\u884c\u5230\u7ed3\u675f\u4e00\u6837\u3002\u4f46\u5b9e\u9645\u4e0a\uff0cLimit \u8282\u70b9\u5728\u62ff\u5230\u4e24\u884c\u4e4b\u540e\u5c31\u505c\u6b62\u8bf7\u6c42\u66f4\u591a\u884c\uff0c\u56e0\u6b64\u5b9e\u9645\u884c\u8ba1\u6570\u53ea\u6709 2\uff0c\u8fd0\u884c\u65f6\u95f4\u4e5f\u4f4e\u4e8e\u4ee3\u4ef7\u4f30\u8ba1\u6240\u6697\u793a\u7684\u6c34\u5e73\u3002\u8fd9\u5e76\u4e0d\u662f\u4f30\u8ba1\u9519\u8bef\uff0c\u53ea\u662f\u4f30\u8ba1\u503c\u4e0e\u771f\u5b9e\u503c\u7684\u663e\u793a\u65b9\u5f0f\u4e0d\u540c\u800c\u5df2\u3002\n   </p><p><a href=\"/zh/docs/12/performance-tips.html#USING-EXPLAIN-CAVEATS\" rel=\"nofollow\">\u67e5\u770b\u5b8c\u6574\u4e2d\u6587\u624b\u518c\u4e0e\u4e0a\u4e0b\u6587</a>\u3002</p><p>\u672c\u9875\u5f00\u5934\u7684\u4e2d\u6587\u8bf4\u660e\u4e3a PG.CENTER \u5bf9\u7f16\u8f91\u8bf4\u660e\u7684\u7ffb\u8bd1\uff1b\u624b\u518c\u8282\u9009\u4fdd\u7559\u5bf9\u5e94\u7248\u672c\u4e2d\u6587\u6587\u6863\u539f\u6587\u3002\u6e90\u7801\u4fe1\u606f\u53ca\u624b\u518c\u793a\u4f8b\u4e0d\u4ee3\u8868\u91cd\u65b0\u8fdb\u884c\u8fc7\u8fd0\u884c\u6d4b\u8bd5\u3002</p>"}, "13": {"facts": [{"label": "\u6838\u5fc3\u8282\u70b9\u6807\u7b7e", "value": "T_BitmapOr"}, {"label": "\u7ed3\u6784\u5316 EXPLAIN \u8282\u70b9\u7c7b\u578b", "value": "BitmapOr"}, {"label": "\u8f93\u5165", "value": "\u4ea7\u751f\u4f4d\u56fe\u7684\u5b50\u8ba1\u5212"}, {"label": "\u8f93\u51fa", "value": "\u5143\u7ec4\u4f4d\u7f6e\u4f4d\u56fe\uff0c\u4e0d\u662f\u5143\u7ec4\u6d41"}, {"label": "\u6267\u884c\u5668\u521d\u59cb\u5316\u51fd\u6570", "value": "ExecInitBitmapOr"}, {"label": "\u5185\u5b58\u673a\u5236", "value": "bitmap-lossification"}], "memory": {"evidence": [{"url": "https://ftp.postgresql.org/pub/source/v13.23/postgresql-13.23.tar.bz2", "path": "src/backend/executor/nodeBitmapOr.c", "label": "src/backend/executor/nodeBitmapOr.c", "sha256": "96e6d1ff7286faf41be8aaac14215f63475484da8c54f8aca1ca91500e0c01d1", "archive_sha256": "6ec3c82726af92b7dec873fa1cdf881eca92a4219787dfad05acb6b10e041fd6"}, {"url": "https://ftp.postgresql.org/pub/source/v13.23/postgresql-13.23.tar.bz2", "path": "src/backend/nodes/tidbitmap.c", "label": "src/backend/nodes/tidbitmap.c", "sha256": "a0823f106dd0af7415c44a788a8b258dc13afc6dab320d0dec0a2d17f418fdb8", "archive_sha256": "6ec3c82726af92b7dec873fa1cdf881eca92a4219787dfad05acb6b10e041fd6"}], "mechanism": "bitmap-lossification", "description": "The node allocates a tuple-location bitmap using a work_mem-derived budget. 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"6ec3c82726af92b7dec873fa1cdf881eca92a4219787dfad05acb6b10e041fd6"}, "facts_zh": [{"label": "\u6838\u5fc3\u8282\u70b9\u6807\u7b7e", "value": "T_BitmapOr"}, {"label": "\u7ed3\u6784\u5316 EXPLAIN \u8282\u70b9\u7c7b\u578b", "value": "BitmapOr"}, {"label": "\u8f93\u5165", "value": "\u4ea7\u751f\u4f4d\u56fe\u7684\u5b50\u8ba1\u5212"}, {"label": "\u8f93\u51fa", "value": "\u5143\u7ec4\u4f4d\u7f6e\u4f4d\u56fe\uff0c\u4e0d\u662f\u5143\u7ec4\u6d41"}, {"label": "\u6267\u884c\u5668\u521d\u59cb\u5316\u51fd\u6570", "value": "ExecInitBitmapOr"}, {"label": "\u5185\u5b58\u673a\u5236", "value": "bitmap-lossification"}], "node_tag": "T_BitmapOr", "sections": [{"title": "EXPLAIN \u540d\u79f0\u4e0e\u5c5e\u6027", "paragraphs": ["\u7ed3\u6784\u5316\u683c\u5f0f\u4f7f\u7528\u4e0a\u8ff0 Node Type\u3002\u6587\u672c\u683c\u5f0f\u540d\u79f0\u8fd8\u53ef\u80fd\u5305\u542b\u64cd\u4f5c\u3001\u7b56\u7565\u3001\u8fde\u63a5\u7c7b\u578b\u3001\u626b\u63cf\u65b9\u5411\u6216\u805a\u5408\u9636\u6bb5\u5c5e\u6027\u3002", 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["\u4ee5\u4e0b\u6e90\u7801\u56de\u8c03\u53ef\u4ee5\u534f\u8c03\u6267\u884c\u6216\u6536\u96c6\u5de5\u4f5c\u8fdb\u7a0b\u7684\u6d4b\u91cf\u6570\u636e\u3002\u56de\u8c03\u5b58\u5728\u4e0d\u4ee3\u8868\u8be5\u8282\u70b9\u666e\u904d\u652f\u6301\u5171\u4eab\u5e76\u884c\u626b\u63cf\u6216\u5171\u4eab\u72b6\u6001\u3002", "\u6b64\u6784\u5efa\u7684\u56de\u8c03\uff1anone extracted from this node implementation."]}, {"title": "\u540c\u7248\u672c\u624b\u518c\u8bf4\u660e", "paragraphs": ["\u7531\u4e8e\u5b9e\u73b0\u4e0a\u7684\u9650\u5236\uff0cBitmapAnd \u548c BitmapOr \u8282\u70b9\u62a5\u544a\u7684\u5b9e\u9645\u884c\u6570\u59cb\u7ec8\u4e3a\u96f6\u3002"]}, {"title": "\u6267\u884c\u5668\u5b9e\u73b0\u8bf4\u660e", "paragraphs": ["\u8bf4\u660e\uff1aBitmapOr \u4e0d\u4f7f\u7528\u5de6\u53f3\u5b50\u6811\uff0c\u800c\u50cf Append \u4e00\u6837\u7ef4\u62a4\u5b50\u8ba1\u5212\u5217\u8868\u3002\u4e0d\u8fc7\u5176\u903b\u8f91\u6bd4 Append \u7b80\u5355\u5f97\u591a\uff0c\u56e0\u4e3a\u65e0\u9700\u5904\u7406\u6b63\u5411\u6216\u53cd\u5411\u6267\u884c\u3002", "\u5bf9\u6bcf\u4e2a\u5f85\u6267\u884c\u8ba1\u5212\u8c03\u7528 ExecInitNode\uff0c\u5e76\u5c06\u7ed3\u679c\u4fdd\u5b58\u5230 bitmapplanstates \u6570\u7ec4\u3002", "BitmapOr \u8ba1\u5212\u6ca1\u6709\u8868\u8fbe\u5f0f\u4e0a\u4e0b\u6587\uff0c\u56e0\u4e3a\u5b83\u4eec\u4ece\u4e0d\u8c03\u7528 ExecQual \u6216 ExecProject\uff0c\u4e5f\u4e0d\u9700\u8981\u5143\u7ec4\u69fd\u3002", "\u53ef\u5bf9 BitmapIndexScan \u5b50\u8282\u70b9\u4f5c\u7279\u6b8a\u5904\u7406\uff0c\u907f\u514d\u4e3a\u6bcf\u4e2a\u5b50\u8282\u70b9\u663e\u5f0f\u8c03\u7528 tbm_union\uff1a\u76f4\u63a5\u4e0b\u4f20\u5f53\u524d\u7ed3\u679c\u4f4d\u56fe\uff0c\u8ba9\u5b50\u8282\u70b9\u5c06\u7ed3\u679c\u6309\u4f4d OR \u5408\u5e76\u8fdb\u53bb\u3002", "ExecReScan \u4e0d\u77e5\u9053\u5f53\u524d\u8282\u70b9\u7684\u5b50\u8ba1\u5212\uff0c\u56e0\u6b64\u5fc5\u987b\u81ea\u884c\u901a\u77e5\u5b50\u8ba1\u5212\u54ea\u4e9b\u53c2\u6570\u53d1\u751f\u4e86\u53d8\u5316\u3002"]}, {"code": "case T_BitmapOr:\n\t\t\tpname = sname = \"BitmapOr\";\n\t\t\tbreak;", "title": "\u6838\u5fc3\u6e90\u7801\u4e2d\u7684 EXPLAIN \u6807\u8bc6"}], "center_zh": {"title": "BitmapOr", "locale": "zh-Hans", "source": {"key": "bitmapor", "locale": "zh-Hans", "version": "13", "text_hash": "61975fc8a857795f0e78772f09107271e2e74beba42346602dcc6ff71bfef398", "collection": "plan", "dataset_hash": "7c31b524dfe136022d39a6ae8dcfac6b3bbd5f8fdaf422536599981252aff0c9", "source_database": "center", "source_revision": "6ec3c82726af92b7dec873fa1cdf881eca92a4219787dfad05acb6b10e041fd6"}, "payload": {"facts": [{"label": "\u6838\u5fc3\u8282\u70b9\u6807\u7b7e", "value": "T_BitmapOr"}, {"label": "\u7ed3\u6784\u5316 EXPLAIN \u8282\u70b9\u7c7b\u578b", "value": "BitmapOr"}, {"label": "\u8f93\u5165", "value": "\u4ea7\u751f\u4f4d\u56fe\u7684\u5b50\u8ba1\u5212"}, {"label": "\u8f93\u51fa", "value": "\u5143\u7ec4\u4f4d\u7f6e\u4f4d\u56fe\uff0c\u4e0d\u662f\u5143\u7ec4\u6d41"}, {"label": "\u6267\u884c\u5668\u521d\u59cb\u5316\u51fd\u6570", "value": "ExecInitBitmapOr"}, {"label": "\u5185\u5b58\u673a\u5236", "value": "bitmap-lossification"}], "tables": [{"key": "explain-labels", "rows": [{"label": "BitmapOr", "identity": "BitmapOr"}], "title": "\u672c\u6784\u5efa\u4e2d\u7684 EXPLAIN \u6807\u7b7e", "columns": [{"key": "label", "label": "\u6587\u672c\u683c\u5f0f\u6807\u7b7e"}, {"key": "identity", "label": "\u7ed3\u6784\u5316\u8282\u70b9\u6807\u8bc6"}]}], "zh_from": {"kind": "same-version-chinese-manual-with-authored-translation-of-reviewed-guidance", "manual": {"url": "/zh/docs/13/performance-tips.html#USING-EXPLAIN-CAVEATS", "anchor": "USING-EXPLAIN-CAVEATS", "locale": "zh-Hans", "version": "13", "build_id": 66, "page_key": "performance-tips.html", "extraction": "concept-introduction", "source_hash": "d7400476f3cf658423dd2d2f64b6b6b0e53d8fdc8692b9e93a05587095d469e1", "fragment_sha256": "21218c0f0d772e94c4033e57f3569c5dabc01f5665466716c58bcc4e7a364e8e", "source_revision": "unknown:rendered-translation-baseline", "translation_revision": "snapshot:sha256:a13a825c39f0268ef1cfe9137e283e38d0da73b2d7894f0733c7b26372a4f6a4", "translated_from_revision": null}, "body_sha256": "bb690c5c241684576c7646ff19ac92f10c1c11c2cc6e8ba3d75e138fe2f5ce6e", "runtime_rerun": false, "authored_translation": "authored-translation-of-reviewed-guidance", "source_facts_revision": "6ec3c82726af92b7dec873fa1cdf881eca92a4219787dfad05acb6b10e041fd6"}, "sections": [{"title": "EXPLAIN \u540d\u79f0\u4e0e\u5c5e\u6027", "paragraphs": ["\u7ed3\u6784\u5316\u683c\u5f0f\u4f7f\u7528\u4e0a\u8ff0 Node Type\u3002\u6587\u672c\u683c\u5f0f\u540d\u79f0\u8fd8\u53ef\u80fd\u5305\u542b\u64cd\u4f5c\u3001\u7b56\u7565\u3001\u8fde\u63a5\u7c7b\u578b\u3001\u626b\u63cf\u65b9\u5411\u6216\u805a\u5408\u9636\u6bb5\u5c5e\u6027\u3002", "\u6b64\u6e90\u7801\u8bb0\u5f55\u7684\u6587\u672c\u540d\u79f0\uff1aBitmapOr.", "\u5e76\u884c\u611f\u77e5\u4e0e\u5e76\u884c\u5b89\u5168\u662f\u4e0d\u540c\u7684\u8ba1\u5212\u5c5e\u6027\u3002\u5728\u5e76\u884c\u5de5\u4f5c\u8fdb\u7a0b\u5185\u8fd0\u884c\u7684\u8282\u70b9\u4e0d\u4e00\u5b9a\u662f\u5e76\u884c\u611f\u77e5\u8282\u70b9\u3002"]}, {"title": "\u5185\u5b58\u4e0e\u4e34\u65f6\u5b58\u50a8", "paragraphs": ["\u6b64\u8282\u70b9\u6309\u57fa\u4e8e work_mem \u7684\u9884\u7b97\u5206\u914d\u5143\u7ec4\u4f4d\u7f6e\u4f4d\u56fe\u3002\u4f4d\u56fe\u53ef\u4ee5\u4fdd\u7559\u9875\u7ea7\u6709\u635f\u6761\u76ee\uff0c\u800c\u4e0d\u8bb0\u5f55\u6bcf\u4e2a\u5143\u7ec4\u4f4d\u7f6e\uff0c\u56e0\u6b64\u4ecd\u53ef\u80fd\u9700\u8981\u5806\u91cd\u68c0\u3002"]}, {"title": "\u5e76\u884c\u6267\u884c\u4e0e\u8fd0\u884c\u4fe1\u606f\u91c7\u96c6", "paragraphs": ["\u4ee5\u4e0b\u6e90\u7801\u56de\u8c03\u53ef\u4ee5\u534f\u8c03\u6267\u884c\u6216\u6536\u96c6\u5de5\u4f5c\u8fdb\u7a0b\u7684\u6d4b\u91cf\u6570\u636e\u3002\u56de\u8c03\u5b58\u5728\u4e0d\u4ee3\u8868\u8be5\u8282\u70b9\u666e\u904d\u652f\u6301\u5171\u4eab\u5e76\u884c\u626b\u63cf\u6216\u5171\u4eab\u72b6\u6001\u3002", "\u6b64\u6784\u5efa\u7684\u56de\u8c03\uff1anone extracted from this node implementation."]}, {"title": "\u540c\u7248\u672c\u624b\u518c\u8bf4\u660e", "paragraphs": ["\u7531\u4e8e\u5b9e\u73b0\u4e0a\u7684\u9650\u5236\uff0cBitmapAnd \u548c BitmapOr \u8282\u70b9\u62a5\u544a\u7684\u5b9e\u9645\u884c\u6570\u59cb\u7ec8\u4e3a\u96f6\u3002"]}, {"title": "\u6267\u884c\u5668\u5b9e\u73b0\u8bf4\u660e", "paragraphs": ["\u8bf4\u660e\uff1aBitmapOr \u4e0d\u4f7f\u7528\u5de6\u53f3\u5b50\u6811\uff0c\u800c\u50cf Append \u4e00\u6837\u7ef4\u62a4\u5b50\u8ba1\u5212\u5217\u8868\u3002\u4e0d\u8fc7\u5176\u903b\u8f91\u6bd4 Append \u7b80\u5355\u5f97\u591a\uff0c\u56e0\u4e3a\u65e0\u9700\u5904\u7406\u6b63\u5411\u6216\u53cd\u5411\u6267\u884c\u3002", "\u5bf9\u6bcf\u4e2a\u5f85\u6267\u884c\u8ba1\u5212\u8c03\u7528 ExecInitNode\uff0c\u5e76\u5c06\u7ed3\u679c\u4fdd\u5b58\u5230 bitmapplanstates \u6570\u7ec4\u3002", "BitmapOr \u8ba1\u5212\u6ca1\u6709\u8868\u8fbe\u5f0f\u4e0a\u4e0b\u6587\uff0c\u56e0\u4e3a\u5b83\u4eec\u4ece\u4e0d\u8c03\u7528 ExecQual \u6216 ExecProject\uff0c\u4e5f\u4e0d\u9700\u8981\u5143\u7ec4\u69fd\u3002", "\u53ef\u5bf9 BitmapIndexScan \u5b50\u8282\u70b9\u4f5c\u7279\u6b8a\u5904\u7406\uff0c\u907f\u514d\u4e3a\u6bcf\u4e2a\u5b50\u8282\u70b9\u663e\u5f0f\u8c03\u7528 tbm_union\uff1a\u76f4\u63a5\u4e0b\u4f20\u5f53\u524d\u7ed3\u679c\u4f4d\u56fe\uff0c\u8ba9\u5b50\u8282\u70b9\u5c06\u7ed3\u679c\u6309\u4f4d OR \u5408\u5e76\u8fdb\u53bb\u3002", "ExecReScan \u4e0d\u77e5\u9053\u5f53\u524d\u8282\u70b9\u7684\u5b50\u8ba1\u5212\uff0c\u56e0\u6b64\u5fc5\u987b\u81ea\u884c\u901a\u77e5\u5b50\u8ba1\u5212\u54ea\u4e9b\u53c2\u6570\u53d1\u751f\u4e86\u53d8\u5316\u3002"]}, {"code": "case T_BitmapOr:\n\t\t\tpname = sname = \"BitmapOr\";\n\t\t\tbreak;", "title": "\u6838\u5fc3\u6e90\u7801\u4e2d\u7684 EXPLAIN \u6807\u8bc6"}], "description_zh": "\u5bf9\u5404\u5b50\u8ba1\u5212\u751f\u6210\u7684\u4f4d\u56fe\u6c42\u5e76\u96c6\u3002", "description_zh_html": "<p>\u5bf9\u5404\u5b50\u8ba1\u5212\u751f\u6210\u7684\u4f4d\u56fe\u6c42\u5e76\u96c6\u3002</p><p>\u6838\u5fc3\u8282\u70b9\u6807\u8bc6\uff1a<code>T_BitmapOr</code>\uff1bEXPLAIN \u540d\u79f0\uff1a<code>BitmapOr</code>\u3002</p><p>\u672c\u7248\u672c\u6e90\u7801\u4e2d\u7684\u5e76\u884c\u6267\u884c\u6216\u89c2\u6d4b\u56de\u8c03\uff1a\u8be5\u8282\u70b9\u5b9e\u73b0\u4e2d\u672a\u63d0\u53d6\u5230\u6b64\u7c7b\u56de\u8c03\u3002\u56de\u8c03\u7684\u5b58\u5728\u4e0d\u8868\u793a\u8be5\u8282\u70b9\u5fc5\u7136\u652f\u6301\u5171\u4eab\u5e76\u884c\u626b\u63cf\uff1b\u5728\u5e76\u884c\u5de5\u4f5c\u8fdb\u7a0b\u4e2d\u6267\u884c\u4e5f\u4e0d\u7b49\u4e8e\u5177\u6709\u5e76\u884c\u611f\u77e5\u80fd\u529b\u3002</p><h3>\u540c\u7248\u672c\u4e2d\u6587\u624b\u518c\u8282\u9009</h3><p>\n<code class=\"command\">EXPLAIN ANALYZE</code> \u6d4b\u5f97\u7684\u8fd0\u884c\u65f6\u95f4\uff0c\u53ef\u80fd\u4ee5\u4e24\u79cd\u91cd\u8981\u65b9\u5f0f\u504f\u79bb\u540c\u4e00\u67e5\u8be2\u7684\u6b63\u5e38\u6267\u884c\u65f6\u95f4\u3002\u7b2c\u4e00\uff0c\u7531\u4e8e\u4e0d\u4f1a\u5411\u5ba2\u6237\u7aef\u4f20\u9012\u4efb\u4f55\u8f93\u51fa\u884c\uff0c\u56e0\u6b64\u7f51\u7edc\u4f20\u8f93\u5f00\u9500\u548c I/O \u8f6c\u6362\u5f00\u9500\u5747\u4e0d\u4f1a\u88ab\u8ba1\u5165\u3002\u7b2c\u4e8c\uff0c<code class=\"command\">EXPLAIN ANALYZE</code> \u9644\u52a0\u7684\u6d4b\u91cf\u5f00\u9500\u672c\u8eab\u53ef\u80fd\u76f8\u5f53\u53ef\u89c2\uff0c\u5c24\u5176\u662f\u5728\u64cd\u4f5c\u7cfb\u7edf\u8c03\u7528 <code class=\"function\">gettimeofday()</code> \u8f83\u6162\u7684\u673a\u5668\u4e0a\u3002\u53ef\u4ee5\u4f7f\u7528 <a class=\"xref\" href=\"/zh/docs/13/pgtesttiming.html\"><span class=\"refentrytitle\"><span class=\"application\">pg_test_timing</span></span></a> \u5de5\u5177\u6765\u6d4b\u91cf\u7cfb\u7edf\u4e0a\u7684\u8ba1\u65f6\u5f00\u9500\u3002\n   </p><p>\n    \u4e0d\u5e94\u5c06 <code class=\"command\">EXPLAIN</code> \u7ed3\u679c\u5916\u63a8\u5230\u4e0e\u5b9e\u9645\u6d4b\u8bd5\u573a\u666f\u5dee\u5f02\u5f88\u5927\u7684\u60c5\u51b5\u3002\u4f8b\u5982\uff0c\u5728\u4e00\u4e2a\u5f88\u5c0f\u7684\u8868\u4e0a\u5f97\u5230\u7684\u7ed3\u679c\uff0c\u4e0d\u80fd\u5047\u5b9a\u4e5f\u9002\u7528\u4e8e\u5927\u578b\u8868\u3002\u89c4\u5212\u5668\u7684\u4ee3\u4ef7\u4f30\u8ba1\u4e0d\u662f\u7ebf\u6027\u7684\uff0c\u56e0\u6b64\u5b83\u53ef\u80fd\u4f1a\u4e3a\u66f4\u5927\u6216\u66f4\u5c0f\u7684\u8868\u9009\u62e9\u4e0d\u540c\u7684\u8ba1\u5212\u3002\u4e00\u4e2a\u6781\u7aef\u793a\u4f8b\u662f\uff1a\u5bf9\u4e8e\u53ea\u5360\u7528\u4e00\u4e2a\u78c1\u76d8\u9875\u7684\u8868\uff0c\u65e0\u8bba\u7d22\u5f15\u662f\u5426\u53ef\u7528\uff0c\u51e0\u4e4e\u603b\u4f1a\u5f97\u5230\u987a\u5e8f\u626b\u63cf\u8ba1\u5212\u3002\u89c4\u5212\u5668\u8ba4\u8bc6\u5230\uff0c\u65e0\u8bba\u5982\u4f55\u5904\u7406\u8be5\u8868\u90fd\u9700\u8981\u4e00\u6b21\u78c1\u76d8\u9875\u8bfb\u53d6\uff0c\u56e0\u6b64\u518d\u989d\u5916\u8bfb\u53d6\u9875\u9762\u53bb\u67e5\u770b\u7d22\u5f15\u5e76\u6ca1\u6709\u4ef7\u503c\u3002\uff08\u524d\u9762\u7684 <code class=\"literal\">polygon_tbl</code> \u793a\u4f8b\u5df2\u7ecf\u5c55\u793a\u8fc7\u8fd9\u79cd\u60c5\u51b5\u3002\uff09\n   </p><p>\n    \u5728\u67d0\u4e9b\u60c5\u51b5\u4e0b\uff0c\u5b9e\u9645\u503c\u548c\u4f30\u8ba1\u503c\u4e0d\u4f1a\u5f88\u597d\u5730\u5bf9\u5e94\uff0c\u4f46\u8fd9\u5e76\u4e0d\u8868\u793a\u51fa\u73b0\u4e86\u95ee\u9898\u3002\u5176\u4e2d\u4e00\u79cd\u60c5\u51b5\u662f\uff0c\u8ba1\u5212\u8282\u70b9\u7684\u6267\u884c\u4f1a\u88ab <code class=\"literal\">LIMIT</code> \u6216\u7c7b\u4f3c\u6548\u679c\u63d0\u524d\u622a\u65ad\u3002\u4f8b\u5982\uff0c\u5728\u524d\u9762\u7528\u8fc7\u7684 <code class=\"literal\">LIMIT</code> \u67e5\u8be2\u4e2d\uff1a\n\n</p><p>\n\n    Index Scan \u8282\u70b9\u7684\u4f30\u8ba1\u4ee3\u4ef7\u548c\u884c\u8ba1\u6570\u663e\u793a\u5f97\u50cf\u662f\u5b83\u4f1a\u8fd0\u884c\u5230\u7ed3\u675f\u4e00\u6837\u3002\u4f46\u5b9e\u9645\u4e0a\uff0cLimit \u8282\u70b9\u5728\u62ff\u5230\u4e24\u884c\u4e4b\u540e\u5c31\u505c\u6b62\u8bf7\u6c42\u66f4\u591a\u884c\uff0c\u56e0\u6b64\u5b9e\u9645\u884c\u8ba1\u6570\u53ea\u6709 2\uff0c\u8fd0\u884c\u65f6\u95f4\u4e5f\u4f4e\u4e8e\u4ee3\u4ef7\u4f30\u8ba1\u6240\u6697\u793a\u7684\u6c34\u5e73\u3002\u8fd9\u5e76\u4e0d\u662f\u4f30\u8ba1\u9519\u8bef\uff0c\u53ea\u662f\u4f30\u8ba1\u503c\u4e0e\u771f\u5b9e\u503c\u7684\u663e\u793a\u65b9\u5f0f\u4e0d\u540c\u800c\u5df2\u3002\n   </p><p><a href=\"/zh/docs/13/performance-tips.html#USING-EXPLAIN-CAVEATS\">\u67e5\u770b\u5b8c\u6574\u4e2d\u6587\u624b\u518c\u4e0e\u4e0a\u4e0b\u6587</a>\u3002</p><p>\u672c\u9875\u5f00\u5934\u7684\u4e2d\u6587\u8bf4\u660e\u4e3a PG.CENTER \u5bf9\u7f16\u8f91\u8bf4\u660e\u7684\u7ffb\u8bd1\uff1b\u624b\u518c\u8282\u9009\u4fdd\u7559\u5bf9\u5e94\u7248\u672c\u4e2d\u6587\u6587\u6863\u539f\u6587\u3002\u6e90\u7801\u4fe1\u606f\u53ca\u624b\u518c\u793a\u4f8b\u4e0d\u4ee3\u8868\u91cd\u65b0\u8fdb\u884c\u8fc7\u8fd0\u884c\u6d4b\u8bd5\u3002</p>"}, "summary": "\u5bf9\u5404\u5b50\u8ba1\u5212\u751f\u6210\u7684\u4f4d\u56fe\u6c42\u5e76\u96c6\u3002", "version": "13", "link_map": {"/zh/docs/13/pgtesttiming.html": "/docs/13/pgtesttiming.html", "/zh/docs/13/performance-tips.html#USING-EXPLAIN-CAVEATS": "/docs/13/performance-tips.html#USING-EXPLAIN-CAVEATS"}, "body_html": "<p>\u5bf9\u5404\u5b50\u8ba1\u5212\u751f\u6210\u7684\u4f4d\u56fe\u6c42\u5e76\u96c6\u3002</p><p>\u6838\u5fc3\u8282\u70b9\u6807\u8bc6\uff1a<code>T_BitmapOr</code>\uff1bEXPLAIN \u540d\u79f0\uff1a<code>BitmapOr</code>\u3002</p><p>\u672c\u7248\u672c\u6e90\u7801\u4e2d\u7684\u5e76\u884c\u6267\u884c\u6216\u89c2\u6d4b\u56de\u8c03\uff1a\u8be5\u8282\u70b9\u5b9e\u73b0\u4e2d\u672a\u63d0\u53d6\u5230\u6b64\u7c7b\u56de\u8c03\u3002\u56de\u8c03\u7684\u5b58\u5728\u4e0d\u8868\u793a\u8be5\u8282\u70b9\u5fc5\u7136\u652f\u6301\u5171\u4eab\u5e76\u884c\u626b\u63cf\uff1b\u5728\u5e76\u884c\u5de5\u4f5c\u8fdb\u7a0b\u4e2d\u6267\u884c\u4e5f\u4e0d\u7b49\u4e8e\u5177\u6709\u5e76\u884c\u611f\u77e5\u80fd\u529b\u3002</p><h3>\u540c\u7248\u672c\u4e2d\u6587\u624b\u518c\u8282\u9009</h3><p>\n<code>EXPLAIN ANALYZE</code> \u6d4b\u5f97\u7684\u8fd0\u884c\u65f6\u95f4\uff0c\u53ef\u80fd\u4ee5\u4e24\u79cd\u91cd\u8981\u65b9\u5f0f\u504f\u79bb\u540c\u4e00\u67e5\u8be2\u7684\u6b63\u5e38\u6267\u884c\u65f6\u95f4\u3002\u7b2c\u4e00\uff0c\u7531\u4e8e\u4e0d\u4f1a\u5411\u5ba2\u6237\u7aef\u4f20\u9012\u4efb\u4f55\u8f93\u51fa\u884c\uff0c\u56e0\u6b64\u7f51\u7edc\u4f20\u8f93\u5f00\u9500\u548c I/O \u8f6c\u6362\u5f00\u9500\u5747\u4e0d\u4f1a\u88ab\u8ba1\u5165\u3002\u7b2c\u4e8c\uff0c<code>EXPLAIN ANALYZE</code> \u9644\u52a0\u7684\u6d4b\u91cf\u5f00\u9500\u672c\u8eab\u53ef\u80fd\u76f8\u5f53\u53ef\u89c2\uff0c\u5c24\u5176\u662f\u5728\u64cd\u4f5c\u7cfb\u7edf\u8c03\u7528 <code>gettimeofday()</code> \u8f83\u6162\u7684\u673a\u5668\u4e0a\u3002\u53ef\u4ee5\u4f7f\u7528 <a href=\"/zh/docs/13/pgtesttiming.html\" rel=\"nofollow\"><span><span>pg_test_timing</span></span></a> \u5de5\u5177\u6765\u6d4b\u91cf\u7cfb\u7edf\u4e0a\u7684\u8ba1\u65f6\u5f00\u9500\u3002\n   </p><p>\n    \u4e0d\u5e94\u5c06 <code>EXPLAIN</code> \u7ed3\u679c\u5916\u63a8\u5230\u4e0e\u5b9e\u9645\u6d4b\u8bd5\u573a\u666f\u5dee\u5f02\u5f88\u5927\u7684\u60c5\u51b5\u3002\u4f8b\u5982\uff0c\u5728\u4e00\u4e2a\u5f88\u5c0f\u7684\u8868\u4e0a\u5f97\u5230\u7684\u7ed3\u679c\uff0c\u4e0d\u80fd\u5047\u5b9a\u4e5f\u9002\u7528\u4e8e\u5927\u578b\u8868\u3002\u89c4\u5212\u5668\u7684\u4ee3\u4ef7\u4f30\u8ba1\u4e0d\u662f\u7ebf\u6027\u7684\uff0c\u56e0\u6b64\u5b83\u53ef\u80fd\u4f1a\u4e3a\u66f4\u5927\u6216\u66f4\u5c0f\u7684\u8868\u9009\u62e9\u4e0d\u540c\u7684\u8ba1\u5212\u3002\u4e00\u4e2a\u6781\u7aef\u793a\u4f8b\u662f\uff1a\u5bf9\u4e8e\u53ea\u5360\u7528\u4e00\u4e2a\u78c1\u76d8\u9875\u7684\u8868\uff0c\u65e0\u8bba\u7d22\u5f15\u662f\u5426\u53ef\u7528\uff0c\u51e0\u4e4e\u603b\u4f1a\u5f97\u5230\u987a\u5e8f\u626b\u63cf\u8ba1\u5212\u3002\u89c4\u5212\u5668\u8ba4\u8bc6\u5230\uff0c\u65e0\u8bba\u5982\u4f55\u5904\u7406\u8be5\u8868\u90fd\u9700\u8981\u4e00\u6b21\u78c1\u76d8\u9875\u8bfb\u53d6\uff0c\u56e0\u6b64\u518d\u989d\u5916\u8bfb\u53d6\u9875\u9762\u53bb\u67e5\u770b\u7d22\u5f15\u5e76\u6ca1\u6709\u4ef7\u503c\u3002\uff08\u524d\u9762\u7684 <code>polygon_tbl</code> \u793a\u4f8b\u5df2\u7ecf\u5c55\u793a\u8fc7\u8fd9\u79cd\u60c5\u51b5\u3002\uff09\n   </p><p>\n    \u5728\u67d0\u4e9b\u60c5\u51b5\u4e0b\uff0c\u5b9e\u9645\u503c\u548c\u4f30\u8ba1\u503c\u4e0d\u4f1a\u5f88\u597d\u5730\u5bf9\u5e94\uff0c\u4f46\u8fd9\u5e76\u4e0d\u8868\u793a\u51fa\u73b0\u4e86\u95ee\u9898\u3002\u5176\u4e2d\u4e00\u79cd\u60c5\u51b5\u662f\uff0c\u8ba1\u5212\u8282\u70b9\u7684\u6267\u884c\u4f1a\u88ab <code>LIMIT</code> \u6216\u7c7b\u4f3c\u6548\u679c\u63d0\u524d\u622a\u65ad\u3002\u4f8b\u5982\uff0c\u5728\u524d\u9762\u7528\u8fc7\u7684 <code>LIMIT</code> \u67e5\u8be2\u4e2d\uff1a\n\n</p><p>\n\n    Index Scan \u8282\u70b9\u7684\u4f30\u8ba1\u4ee3\u4ef7\u548c\u884c\u8ba1\u6570\u663e\u793a\u5f97\u50cf\u662f\u5b83\u4f1a\u8fd0\u884c\u5230\u7ed3\u675f\u4e00\u6837\u3002\u4f46\u5b9e\u9645\u4e0a\uff0cLimit \u8282\u70b9\u5728\u62ff\u5230\u4e24\u884c\u4e4b\u540e\u5c31\u505c\u6b62\u8bf7\u6c42\u66f4\u591a\u884c\uff0c\u56e0\u6b64\u5b9e\u9645\u884c\u8ba1\u6570\u53ea\u6709 2\uff0c\u8fd0\u884c\u65f6\u95f4\u4e5f\u4f4e\u4e8e\u4ee3\u4ef7\u4f30\u8ba1\u6240\u6697\u793a\u7684\u6c34\u5e73\u3002\u8fd9\u5e76\u4e0d\u662f\u4f30\u8ba1\u9519\u8bef\uff0c\u53ea\u662f\u4f30\u8ba1\u503c\u4e0e\u771f\u5b9e\u503c\u7684\u663e\u793a\u65b9\u5f0f\u4e0d\u540c\u800c\u5df2\u3002\n   </p><p><a href=\"/zh/docs/13/performance-tips.html#USING-EXPLAIN-CAVEATS\" rel=\"nofollow\">\u67e5\u770b\u5b8c\u6574\u4e2d\u6587\u624b\u518c\u4e0e\u4e0a\u4e0b\u6587</a>\u3002</p><p>\u672c\u9875\u5f00\u5934\u7684\u4e2d\u6587\u8bf4\u660e\u4e3a PG.CENTER \u5bf9\u7f16\u8f91\u8bf4\u660e\u7684\u7ffb\u8bd1\uff1b\u624b\u518c\u8282\u9009\u4fdd\u7559\u5bf9\u5e94\u7248\u672c\u4e2d\u6587\u6587\u6863\u539f\u6587\u3002\u6e90\u7801\u4fe1\u606f\u53ca\u624b\u518c\u793a\u4f8b\u4e0d\u4ee3\u8868\u91cd\u65b0\u8fdb\u884c\u8fc7\u8fd0\u884c\u6d4b\u8bd5\u3002</p>", "body_sha256": "5ae90484cc7d7efa6d49ec62eb8726d97f423ae691d12e6fa1750a05c9dc8e02", "content_hash": "61975fc8a857795f0e78772f09107271e2e74beba42346602dcc6ff71bfef398", "source_database": "center", "source_revision": "6ec3c82726af92b7dec873fa1cdf881eca92a4219787dfad05acb6b10e041fd6"}, "tables_zh": [{"key": "explain-labels", "rows": [{"label": "BitmapOr", "identity": "BitmapOr"}], "title": "\u672c\u6784\u5efa\u4e2d\u7684 EXPLAIN \u6807\u7b7e", "columns": [{"key": "label", "label": "\u6587\u672c\u683c\u5f0f\u6807\u7b7e"}, {"key": "identity", "label": "\u7ed3\u6784\u5316\u8282\u70b9\u6807\u8bc6"}]}], "strategies": [], "description": ["\u5bf9\u5404\u5b50\u8ba1\u5212\u751f\u6210\u7684\u4f4d\u56fe\u6c42\u5e76\u96c6\u3002"], "sections_zh": [{"title": "EXPLAIN \u540d\u79f0\u4e0e\u5c5e\u6027", "paragraphs": ["\u7ed3\u6784\u5316\u683c\u5f0f\u4f7f\u7528\u4e0a\u8ff0 Node Type\u3002\u6587\u672c\u683c\u5f0f\u540d\u79f0\u8fd8\u53ef\u80fd\u5305\u542b\u64cd\u4f5c\u3001\u7b56\u7565\u3001\u8fde\u63a5\u7c7b\u578b\u3001\u626b\u63cf\u65b9\u5411\u6216\u805a\u5408\u9636\u6bb5\u5c5e\u6027\u3002", "\u6b64\u6e90\u7801\u8bb0\u5f55\u7684\u6587\u672c\u540d\u79f0\uff1aBitmapOr.", "\u5e76\u884c\u611f\u77e5\u4e0e\u5e76\u884c\u5b89\u5168\u662f\u4e0d\u540c\u7684\u8ba1\u5212\u5c5e\u6027\u3002\u5728\u5e76\u884c\u5de5\u4f5c\u8fdb\u7a0b\u5185\u8fd0\u884c\u7684\u8282\u70b9\u4e0d\u4e00\u5b9a\u662f\u5e76\u884c\u611f\u77e5\u8282\u70b9\u3002"]}, {"title": "\u5185\u5b58\u4e0e\u4e34\u65f6\u5b58\u50a8", "paragraphs": ["\u6b64\u8282\u70b9\u6309\u57fa\u4e8e work_mem \u7684\u9884\u7b97\u5206\u914d\u5143\u7ec4\u4f4d\u7f6e\u4f4d\u56fe\u3002\u4f4d\u56fe\u53ef\u4ee5\u4fdd\u7559\u9875\u7ea7\u6709\u635f\u6761\u76ee\uff0c\u800c\u4e0d\u8bb0\u5f55\u6bcf\u4e2a\u5143\u7ec4\u4f4d\u7f6e\uff0c\u56e0\u6b64\u4ecd\u53ef\u80fd\u9700\u8981\u5806\u91cd\u68c0\u3002"]}, {"title": "\u5e76\u884c\u6267\u884c\u4e0e\u8fd0\u884c\u4fe1\u606f\u91c7\u96c6", "paragraphs": ["\u4ee5\u4e0b\u6e90\u7801\u56de\u8c03\u53ef\u4ee5\u534f\u8c03\u6267\u884c\u6216\u6536\u96c6\u5de5\u4f5c\u8fdb\u7a0b\u7684\u6d4b\u91cf\u6570\u636e\u3002\u56de\u8c03\u5b58\u5728\u4e0d\u4ee3\u8868\u8be5\u8282\u70b9\u666e\u904d\u652f\u6301\u5171\u4eab\u5e76\u884c\u626b\u63cf\u6216\u5171\u4eab\u72b6\u6001\u3002", "\u6b64\u6784\u5efa\u7684\u56de\u8c03\uff1anone extracted from this node implementation."]}, {"title": "\u540c\u7248\u672c\u624b\u518c\u8bf4\u660e", "paragraphs": ["\u7531\u4e8e\u5b9e\u73b0\u4e0a\u7684\u9650\u5236\uff0cBitmapAnd \u548c BitmapOr \u8282\u70b9\u62a5\u544a\u7684\u5b9e\u9645\u884c\u6570\u59cb\u7ec8\u4e3a\u96f6\u3002"]}, {"title": "\u6267\u884c\u5668\u5b9e\u73b0\u8bf4\u660e", "paragraphs": ["\u8bf4\u660e\uff1aBitmapOr \u4e0d\u4f7f\u7528\u5de6\u53f3\u5b50\u6811\uff0c\u800c\u50cf Append \u4e00\u6837\u7ef4\u62a4\u5b50\u8ba1\u5212\u5217\u8868\u3002\u4e0d\u8fc7\u5176\u903b\u8f91\u6bd4 Append \u7b80\u5355\u5f97\u591a\uff0c\u56e0\u4e3a\u65e0\u9700\u5904\u7406\u6b63\u5411\u6216\u53cd\u5411\u6267\u884c\u3002", "\u5bf9\u6bcf\u4e2a\u5f85\u6267\u884c\u8ba1\u5212\u8c03\u7528 ExecInitNode\uff0c\u5e76\u5c06\u7ed3\u679c\u4fdd\u5b58\u5230 bitmapplanstates \u6570\u7ec4\u3002", "BitmapOr \u8ba1\u5212\u6ca1\u6709\u8868\u8fbe\u5f0f\u4e0a\u4e0b\u6587\uff0c\u56e0\u4e3a\u5b83\u4eec\u4ece\u4e0d\u8c03\u7528 ExecQual \u6216 ExecProject\uff0c\u4e5f\u4e0d\u9700\u8981\u5143\u7ec4\u69fd\u3002", "\u53ef\u5bf9 BitmapIndexScan \u5b50\u8282\u70b9\u4f5c\u7279\u6b8a\u5904\u7406\uff0c\u907f\u514d\u4e3a\u6bcf\u4e2a\u5b50\u8282\u70b9\u663e\u5f0f\u8c03\u7528 tbm_union\uff1a\u76f4\u63a5\u4e0b\u4f20\u5f53\u524d\u7ed3\u679c\u4f4d\u56fe\uff0c\u8ba9\u5b50\u8282\u70b9\u5c06\u7ed3\u679c\u6309\u4f4d OR \u5408\u5e76\u8fdb\u53bb\u3002", "ExecReScan \u4e0d\u77e5\u9053\u5f53\u524d\u8282\u70b9\u7684\u5b50\u8ba1\u5212\uff0c\u56e0\u6b64\u5fc5\u987b\u81ea\u884c\u901a\u77e5\u5b50\u8ba1\u5212\u54ea\u4e9b\u53c2\u6570\u53d1\u751f\u4e86\u53d8\u5316\u3002"]}, {"code": "case T_BitmapOr:\n\t\t\tpname = sname = \"BitmapOr\";\n\t\t\tbreak;", "title": "\u6838\u5fc3\u6e90\u7801\u4e2d\u7684 EXPLAIN \u6807\u8bc6"}], "localization": {"status": "complete", "sources": [], "language": "zh", "original_text": {"/versions/13/description/0": "Unions bitmaps produced by its child plans.", "/versions/13/facts/0/label": "Core node tag", "/versions/13/facts/1/label": "Structured EXPLAIN Node Type", "/versions/13/facts/2/label": "Inputs", "/versions/13/facts/2/value": "Bitmap-producing child plans", "/versions/13/facts/3/label": "Output", "/versions/13/facts/3/value": "Tuple-location bitmap, not a tuple stream", "/versions/13/facts/4/label": "Executor initializer", "/versions/13/facts/5/label": "Memory mechanism", "/versions/13/tables/0/title": "EXPLAIN labels in this source build", "/versions/13/related/1/label": "Using EXPLAIN", "/versions/13/related/2/label": "Parallel plans", "/versions/13/sections/0/title": "EXPLAIN names and attributes", "/versions/13/sections/1/title": "Memory and temporary storage", "/versions/13/sections/2/title": "Parallel execution and instrumentation", "/versions/13/sections/3/title": "Same-version manual discussion", "/versions/13/sections/4/title": "Executor implementation notes", "/versions/13/sections/5/title": "EXPLAIN identity in core source", "/versions/13/memory/description": "The node allocates a tuple-location bitmap using a work_mem-derived budget. A bitmap can retain page-level lossy entries instead of every tuple location; heap rechecks then remain necessary.", "/versions/13/sections/0/paragraphs/0": "Structured formats use the Node Type above. Text-format spellings can also include operation, strategy, join type, scan direction or aggregation-stage attributes.", "/versions/13/sections/0/paragraphs/1": "Text names recorded by this source: BitmapOr.", "/versions/13/sections/0/paragraphs/2": "Parallel-aware and parallel-safe are different plan properties. A node running inside a parallel worker is not necessarily a parallel-aware node.", "/versions/13/sections/1/paragraphs/0": "The node allocates a tuple-location bitmap using a work_mem-derived budget. A bitmap can retain page-level lossy entries instead of every tuple location; heap rechecks then remain necessary.", "/versions/13/sections/2/paragraphs/0": "The source callbacks below can coordinate execution or collect worker instrumentation. Their presence is not a blanket claim that this node supports a shared parallel scan or shared state.", "/versions/13/sections/2/paragraphs/1": "Callbacks in this build: none extracted from this node implementation.", "/versions/13/sections/3/paragraphs/0": "BitmapAnd and BitmapOr nodes always report their actual row counts as zero, due to implementation limitations.", "/versions/13/sections/4/paragraphs/0": "NOTES BitmapOr nodes don't make use of their left and right subtrees, rather they maintain a list of subplans, much like Append nodes. The logic is much simpler than Append, however, since we needn't cope with forward/backward execution.", "/versions/13/sections/4/paragraphs/1": "call ExecInitNode on each of the plans to be executed and save the results into the array \"bitmapplanstates\".", "/versions/13/sections/4/paragraphs/2": "BitmapOr plans don't have expression contexts because they never call ExecQual or ExecProject. They don't need any tuple slots either.", "/versions/13/sections/4/paragraphs/3": "We can special-case BitmapIndexScan children to avoid an explicit tbm_union step for each child: just pass down the current result bitmap and let the child OR directly into it.", "/versions/13/sections/4/paragraphs/4": "ExecReScan doesn't know about my subplans, so I have to do changed-parameter signaling myself.", "/versions/13/tables/0/columns/0/label": "Text-format label", "/versions/13/tables/0/columns/1/label": "Structured node identity"}, "fallback_fields": [], "source_language": "en", "original_snapshot_sha256": "346186fbdb88c919ce836127aedceb86ec2dcce8494ce7aeda9bcd4244f72e38", "canonical_center_text_hash": "61975fc8a857795f0e78772f09107271e2e74beba42346602dcc6ff71bfef398"}, "evidence_kind": "source and documentation", "explain_names": ["BitmapOr"], "partial_modes": [], "description_zh": "\u5bf9\u5404\u5b50\u8ba1\u5212\u751f\u6210\u7684\u4f4d\u56fe\u6c42\u5e76\u96c6\u3002", "comparison_data": {"node_tag": "T_BitmapOr", "strategies": [], "text_names": ["BitmapOr"], "initializer": "ExecInitBitmapOr", "partial_modes": [], "memory_mechanism": "bitmap-lossification", "parallel_callbacks": []}, "comparison_hash": "c0ca503a6029c37ec720213dcdc3094997eb194d4920da68f94a7420d3e8f1d2", "manual_language": "zh", "explain_prefixes": ["Parallel"], "runtime_verified": false, "source_inventory": {"explain": "src/backend/commands/explain.c", "executor": "src/backend/executor/execProcnode.c", "implementation": "src/backend/executor/nodeBitmapOr.c"}, "parallel_callbacks": [], "description_zh_html": "<p>\u5bf9\u5404\u5b50\u8ba1\u5212\u751f\u6210\u7684\u4f4d\u56fe\u6c42\u5e76\u96c6\u3002</p><p>\u6838\u5fc3\u8282\u70b9\u6807\u8bc6\uff1a<code>T_BitmapOr</code>\uff1bEXPLAIN \u540d\u79f0\uff1a<code>BitmapOr</code>\u3002</p><p>\u672c\u7248\u672c\u6e90\u7801\u4e2d\u7684\u5e76\u884c\u6267\u884c\u6216\u89c2\u6d4b\u56de\u8c03\uff1a\u8be5\u8282\u70b9\u5b9e\u73b0\u4e2d\u672a\u63d0\u53d6\u5230\u6b64\u7c7b\u56de\u8c03\u3002\u56de\u8c03\u7684\u5b58\u5728\u4e0d\u8868\u793a\u8be5\u8282\u70b9\u5fc5\u7136\u652f\u6301\u5171\u4eab\u5e76\u884c\u626b\u63cf\uff1b\u5728\u5e76\u884c\u5de5\u4f5c\u8fdb\u7a0b\u4e2d\u6267\u884c\u4e5f\u4e0d\u7b49\u4e8e\u5177\u6709\u5e76\u884c\u611f\u77e5\u80fd\u529b\u3002</p><h3>\u540c\u7248\u672c\u4e2d\u6587\u624b\u518c\u8282\u9009</h3><p>\n<code>EXPLAIN ANALYZE</code> \u6d4b\u5f97\u7684\u8fd0\u884c\u65f6\u95f4\uff0c\u53ef\u80fd\u4ee5\u4e24\u79cd\u91cd\u8981\u65b9\u5f0f\u504f\u79bb\u540c\u4e00\u67e5\u8be2\u7684\u6b63\u5e38\u6267\u884c\u65f6\u95f4\u3002\u7b2c\u4e00\uff0c\u7531\u4e8e\u4e0d\u4f1a\u5411\u5ba2\u6237\u7aef\u4f20\u9012\u4efb\u4f55\u8f93\u51fa\u884c\uff0c\u56e0\u6b64\u7f51\u7edc\u4f20\u8f93\u5f00\u9500\u548c I/O \u8f6c\u6362\u5f00\u9500\u5747\u4e0d\u4f1a\u88ab\u8ba1\u5165\u3002\u7b2c\u4e8c\uff0c<code>EXPLAIN ANALYZE</code> \u9644\u52a0\u7684\u6d4b\u91cf\u5f00\u9500\u672c\u8eab\u53ef\u80fd\u76f8\u5f53\u53ef\u89c2\uff0c\u5c24\u5176\u662f\u5728\u64cd\u4f5c\u7cfb\u7edf\u8c03\u7528 <code>gettimeofday()</code> \u8f83\u6162\u7684\u673a\u5668\u4e0a\u3002\u53ef\u4ee5\u4f7f\u7528 <a href=\"/zh/docs/13/pgtesttiming.html\" rel=\"nofollow\"><span><span>pg_test_timing</span></span></a> \u5de5\u5177\u6765\u6d4b\u91cf\u7cfb\u7edf\u4e0a\u7684\u8ba1\u65f6\u5f00\u9500\u3002\n   </p><p>\n    \u4e0d\u5e94\u5c06 <code>EXPLAIN</code> \u7ed3\u679c\u5916\u63a8\u5230\u4e0e\u5b9e\u9645\u6d4b\u8bd5\u573a\u666f\u5dee\u5f02\u5f88\u5927\u7684\u60c5\u51b5\u3002\u4f8b\u5982\uff0c\u5728\u4e00\u4e2a\u5f88\u5c0f\u7684\u8868\u4e0a\u5f97\u5230\u7684\u7ed3\u679c\uff0c\u4e0d\u80fd\u5047\u5b9a\u4e5f\u9002\u7528\u4e8e\u5927\u578b\u8868\u3002\u89c4\u5212\u5668\u7684\u4ee3\u4ef7\u4f30\u8ba1\u4e0d\u662f\u7ebf\u6027\u7684\uff0c\u56e0\u6b64\u5b83\u53ef\u80fd\u4f1a\u4e3a\u66f4\u5927\u6216\u66f4\u5c0f\u7684\u8868\u9009\u62e9\u4e0d\u540c\u7684\u8ba1\u5212\u3002\u4e00\u4e2a\u6781\u7aef\u793a\u4f8b\u662f\uff1a\u5bf9\u4e8e\u53ea\u5360\u7528\u4e00\u4e2a\u78c1\u76d8\u9875\u7684\u8868\uff0c\u65e0\u8bba\u7d22\u5f15\u662f\u5426\u53ef\u7528\uff0c\u51e0\u4e4e\u603b\u4f1a\u5f97\u5230\u987a\u5e8f\u626b\u63cf\u8ba1\u5212\u3002\u89c4\u5212\u5668\u8ba4\u8bc6\u5230\uff0c\u65e0\u8bba\u5982\u4f55\u5904\u7406\u8be5\u8868\u90fd\u9700\u8981\u4e00\u6b21\u78c1\u76d8\u9875\u8bfb\u53d6\uff0c\u56e0\u6b64\u518d\u989d\u5916\u8bfb\u53d6\u9875\u9762\u53bb\u67e5\u770b\u7d22\u5f15\u5e76\u6ca1\u6709\u4ef7\u503c\u3002\uff08\u524d\u9762\u7684 <code>polygon_tbl</code> \u793a\u4f8b\u5df2\u7ecf\u5c55\u793a\u8fc7\u8fd9\u79cd\u60c5\u51b5\u3002\uff09\n   </p><p>\n    \u5728\u67d0\u4e9b\u60c5\u51b5\u4e0b\uff0c\u5b9e\u9645\u503c\u548c\u4f30\u8ba1\u503c\u4e0d\u4f1a\u5f88\u597d\u5730\u5bf9\u5e94\uff0c\u4f46\u8fd9\u5e76\u4e0d\u8868\u793a\u51fa\u73b0\u4e86\u95ee\u9898\u3002\u5176\u4e2d\u4e00\u79cd\u60c5\u51b5\u662f\uff0c\u8ba1\u5212\u8282\u70b9\u7684\u6267\u884c\u4f1a\u88ab <code>LIMIT</code> \u6216\u7c7b\u4f3c\u6548\u679c\u63d0\u524d\u622a\u65ad\u3002\u4f8b\u5982\uff0c\u5728\u524d\u9762\u7528\u8fc7\u7684 <code>LIMIT</code> \u67e5\u8be2\u4e2d\uff1a\n\n</p><p>\n\n    Index Scan \u8282\u70b9\u7684\u4f30\u8ba1\u4ee3\u4ef7\u548c\u884c\u8ba1\u6570\u663e\u793a\u5f97\u50cf\u662f\u5b83\u4f1a\u8fd0\u884c\u5230\u7ed3\u675f\u4e00\u6837\u3002\u4f46\u5b9e\u9645\u4e0a\uff0cLimit \u8282\u70b9\u5728\u62ff\u5230\u4e24\u884c\u4e4b\u540e\u5c31\u505c\u6b62\u8bf7\u6c42\u66f4\u591a\u884c\uff0c\u56e0\u6b64\u5b9e\u9645\u884c\u8ba1\u6570\u53ea\u6709 2\uff0c\u8fd0\u884c\u65f6\u95f4\u4e5f\u4f4e\u4e8e\u4ee3\u4ef7\u4f30\u8ba1\u6240\u6697\u793a\u7684\u6c34\u5e73\u3002\u8fd9\u5e76\u4e0d\u662f\u4f30\u8ba1\u9519\u8bef\uff0c\u53ea\u662f\u4f30\u8ba1\u503c\u4e0e\u771f\u5b9e\u503c\u7684\u663e\u793a\u65b9\u5f0f\u4e0d\u540c\u800c\u5df2\u3002\n   </p><p><a href=\"/zh/docs/13/performance-tips.html#USING-EXPLAIN-CAVEATS\" rel=\"nofollow\">\u67e5\u770b\u5b8c\u6574\u4e2d\u6587\u624b\u518c\u4e0e\u4e0a\u4e0b\u6587</a>\u3002</p><p>\u672c\u9875\u5f00\u5934\u7684\u4e2d\u6587\u8bf4\u660e\u4e3a PG.CENTER \u5bf9\u7f16\u8f91\u8bf4\u660e\u7684\u7ffb\u8bd1\uff1b\u624b\u518c\u8282\u9009\u4fdd\u7559\u5bf9\u5e94\u7248\u672c\u4e2d\u6587\u6587\u6863\u539f\u6587\u3002\u6e90\u7801\u4fe1\u606f\u53ca\u624b\u518c\u793a\u4f8b\u4e0d\u4ee3\u8868\u91cd\u65b0\u8fdb\u884c\u8fc7\u8fd0\u884c\u6d4b\u8bd5\u3002</p>"}, "14": {"facts": [{"label": "\u6838\u5fc3\u8282\u70b9\u6807\u7b7e", "value": "T_BitmapOr"}, {"label": "\u7ed3\u6784\u5316 EXPLAIN \u8282\u70b9\u7c7b\u578b", "value": 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Type\u3002\u6587\u672c\u683c\u5f0f\u540d\u79f0\u8fd8\u53ef\u80fd\u5305\u542b\u64cd\u4f5c\u3001\u7b56\u7565\u3001\u8fde\u63a5\u7c7b\u578b\u3001\u626b\u63cf\u65b9\u5411\u6216\u805a\u5408\u9636\u6bb5\u5c5e\u6027\u3002", "\u6b64\u6e90\u7801\u8bb0\u5f55\u7684\u6587\u672c\u540d\u79f0\uff1aBitmapOr.", "\u5e76\u884c\u611f\u77e5\u4e0e\u5e76\u884c\u5b89\u5168\u662f\u4e0d\u540c\u7684\u8ba1\u5212\u5c5e\u6027\u3002\u5728\u5e76\u884c\u5de5\u4f5c\u8fdb\u7a0b\u5185\u8fd0\u884c\u7684\u8282\u70b9\u4e0d\u4e00\u5b9a\u662f\u5e76\u884c\u611f\u77e5\u8282\u70b9\u3002"]}, {"title": "\u5185\u5b58\u4e0e\u4e34\u65f6\u5b58\u50a8", "paragraphs": ["\u6b64\u8282\u70b9\u6309\u57fa\u4e8e work_mem \u7684\u9884\u7b97\u5206\u914d\u5143\u7ec4\u4f4d\u7f6e\u4f4d\u56fe\u3002\u4f4d\u56fe\u53ef\u4ee5\u4fdd\u7559\u9875\u7ea7\u6709\u635f\u6761\u76ee\uff0c\u800c\u4e0d\u8bb0\u5f55\u6bcf\u4e2a\u5143\u7ec4\u4f4d\u7f6e\uff0c\u56e0\u6b64\u4ecd\u53ef\u80fd\u9700\u8981\u5806\u91cd\u68c0\u3002"]}, {"title": "\u5e76\u884c\u6267\u884c\u4e0e\u8fd0\u884c\u4fe1\u606f\u91c7\u96c6", "paragraphs": ["\u4ee5\u4e0b\u6e90\u7801\u56de\u8c03\u53ef\u4ee5\u534f\u8c03\u6267\u884c\u6216\u6536\u96c6\u5de5\u4f5c\u8fdb\u7a0b\u7684\u6d4b\u91cf\u6570\u636e\u3002\u56de\u8c03\u5b58\u5728\u4e0d\u4ee3\u8868\u8be5\u8282\u70b9\u666e\u904d\u652f\u6301\u5171\u4eab\u5e76\u884c\u626b\u63cf\u6216\u5171\u4eab\u72b6\u6001\u3002", "\u6b64\u6784\u5efa\u7684\u56de\u8c03\uff1anone extracted from this node implementation."]}, {"title": "\u540c\u7248\u672c\u624b\u518c\u8bf4\u660e", "paragraphs": ["\u7531\u4e8e\u5b9e\u73b0\u4e0a\u7684\u9650\u5236\uff0cBitmapAnd \u548c BitmapOr \u8282\u70b9\u62a5\u544a\u7684\u5b9e\u9645\u884c\u6570\u59cb\u7ec8\u4e3a\u96f6\u3002"]}, {"title": "\u6267\u884c\u5668\u5b9e\u73b0\u8bf4\u660e", "paragraphs": ["\u8bf4\u660e\uff1aBitmapOr \u4e0d\u4f7f\u7528\u5de6\u53f3\u5b50\u6811\uff0c\u800c\u50cf Append \u4e00\u6837\u7ef4\u62a4\u5b50\u8ba1\u5212\u5217\u8868\u3002\u4e0d\u8fc7\u5176\u903b\u8f91\u6bd4 Append \u7b80\u5355\u5f97\u591a\uff0c\u56e0\u4e3a\u65e0\u9700\u5904\u7406\u6b63\u5411\u6216\u53cd\u5411\u6267\u884c\u3002", "\u5bf9\u6bcf\u4e2a\u5f85\u6267\u884c\u8ba1\u5212\u8c03\u7528 ExecInitNode\uff0c\u5e76\u5c06\u7ed3\u679c\u4fdd\u5b58\u5230 bitmapplanstates \u6570\u7ec4\u3002", "BitmapOr \u8ba1\u5212\u6ca1\u6709\u8868\u8fbe\u5f0f\u4e0a\u4e0b\u6587\uff0c\u56e0\u4e3a\u5b83\u4eec\u4ece\u4e0d\u8c03\u7528 ExecQual \u6216 ExecProject\uff0c\u4e5f\u4e0d\u9700\u8981\u5143\u7ec4\u69fd\u3002", "\u53ef\u5bf9 BitmapIndexScan \u5b50\u8282\u70b9\u4f5c\u7279\u6b8a\u5904\u7406\uff0c\u907f\u514d\u4e3a\u6bcf\u4e2a\u5b50\u8282\u70b9\u663e\u5f0f\u8c03\u7528 tbm_union\uff1a\u76f4\u63a5\u4e0b\u4f20\u5f53\u524d\u7ed3\u679c\u4f4d\u56fe\uff0c\u8ba9\u5b50\u8282\u70b9\u5c06\u7ed3\u679c\u6309\u4f4d OR \u5408\u5e76\u8fdb\u53bb\u3002", "ExecReScan \u4e0d\u77e5\u9053\u5f53\u524d\u8282\u70b9\u7684\u5b50\u8ba1\u5212\uff0c\u56e0\u6b64\u5fc5\u987b\u81ea\u884c\u901a\u77e5\u5b50\u8ba1\u5212\u54ea\u4e9b\u53c2\u6570\u53d1\u751f\u4e86\u53d8\u5316\u3002"]}, {"code": "case T_BitmapOr:\n\t\t\tpname = sname = \"BitmapOr\";\n\t\t\tbreak;", "title": "\u6838\u5fc3\u6e90\u7801\u4e2d\u7684 EXPLAIN \u6807\u8bc6"}], "center_zh": {"title": "BitmapOr", "locale": "zh-Hans", "source": {"key": "bitmapor", "locale": "zh-Hans", "version": "14", "text_hash": "eac3f8c761e925970a44a2fd898f775385c537364bf884640c15befc10b7df9d", "collection": "plan", "dataset_hash": "7c31b524dfe136022d39a6ae8dcfac6b3bbd5f8fdaf422536599981252aff0c9", "source_database": "center", "source_revision": "a7fa7ed3d558172355f51406097a7bd4f6b473be80f311ef7cda96bf383d8897"}, "payload": {"facts": [{"label": "\u6838\u5fc3\u8282\u70b9\u6807\u7b7e", "value": "T_BitmapOr"}, {"label": "\u7ed3\u6784\u5316 EXPLAIN \u8282\u70b9\u7c7b\u578b", "value": "BitmapOr"}, {"label": "\u8f93\u5165", "value": "\u4ea7\u751f\u4f4d\u56fe\u7684\u5b50\u8ba1\u5212"}, {"label": "\u8f93\u51fa", "value": "\u5143\u7ec4\u4f4d\u7f6e\u4f4d\u56fe\uff0c\u4e0d\u662f\u5143\u7ec4\u6d41"}, {"label": "\u6267\u884c\u5668\u521d\u59cb\u5316\u51fd\u6570", "value": "ExecInitBitmapOr"}, {"label": "\u5185\u5b58\u673a\u5236", "value": "bitmap-lossification"}], "tables": [{"key": "explain-labels", "rows": [{"label": "BitmapOr", "identity": "BitmapOr"}], "title": "\u672c\u6784\u5efa\u4e2d\u7684 EXPLAIN \u6807\u7b7e", "columns": [{"key": "label", "label": "\u6587\u672c\u683c\u5f0f\u6807\u7b7e"}, {"key": "identity", "label": "\u7ed3\u6784\u5316\u8282\u70b9\u6807\u8bc6"}]}], "zh_from": {"kind": "same-version-chinese-manual-with-authored-translation-of-reviewed-guidance", "manual": {"url": "/zh/docs/14/performance-tips.html#USING-EXPLAIN-CAVEATS", "anchor": "USING-EXPLAIN-CAVEATS", "locale": "zh-Hans", "version": "14", "build_id": 99, "page_key": "performance-tips.html", "extraction": "concept-introduction", "source_hash": "62cadce9a200c7891b3bbf04fc22c8dc17b4525aec0d020a074310592666f6d4", "fragment_sha256": "51a5b2eb623e5ace0e116b6e0e4784914d01a1d3aed1987d7035645b7b35bf2b", "source_revision": "unknown:rendered-translation-baseline", "translation_revision": "git:b1b500221dbe5437cfca004d6b04d3f6e422765d;html-sha256:87e6aa4fd6e1ec85c5f4a6de4f5647cfd9e5de734ca2c266d32b6d6192c662ef", "translated_from_revision": null}, "body_sha256": "20109caf6fdfa1b95dd0e516b9d0969b7cee5c7632bba471fa9d4b8219d49147", "runtime_rerun": false, "authored_translation": "authored-translation-of-reviewed-guidance", "source_facts_revision": "a7fa7ed3d558172355f51406097a7bd4f6b473be80f311ef7cda96bf383d8897"}, "sections": [{"title": "EXPLAIN \u540d\u79f0\u4e0e\u5c5e\u6027", "paragraphs": ["\u7ed3\u6784\u5316\u683c\u5f0f\u4f7f\u7528\u4e0a\u8ff0 Node Type\u3002\u6587\u672c\u683c\u5f0f\u540d\u79f0\u8fd8\u53ef\u80fd\u5305\u542b\u64cd\u4f5c\u3001\u7b56\u7565\u3001\u8fde\u63a5\u7c7b\u578b\u3001\u626b\u63cf\u65b9\u5411\u6216\u805a\u5408\u9636\u6bb5\u5c5e\u6027\u3002", "\u6b64\u6e90\u7801\u8bb0\u5f55\u7684\u6587\u672c\u540d\u79f0\uff1aBitmapOr.", "\u5e76\u884c\u611f\u77e5\u4e0e\u5e76\u884c\u5b89\u5168\u662f\u4e0d\u540c\u7684\u8ba1\u5212\u5c5e\u6027\u3002\u5728\u5e76\u884c\u5de5\u4f5c\u8fdb\u7a0b\u5185\u8fd0\u884c\u7684\u8282\u70b9\u4e0d\u4e00\u5b9a\u662f\u5e76\u884c\u611f\u77e5\u8282\u70b9\u3002"]}, {"title": "\u5185\u5b58\u4e0e\u4e34\u65f6\u5b58\u50a8", "paragraphs": ["\u6b64\u8282\u70b9\u6309\u57fa\u4e8e work_mem \u7684\u9884\u7b97\u5206\u914d\u5143\u7ec4\u4f4d\u7f6e\u4f4d\u56fe\u3002\u4f4d\u56fe\u53ef\u4ee5\u4fdd\u7559\u9875\u7ea7\u6709\u635f\u6761\u76ee\uff0c\u800c\u4e0d\u8bb0\u5f55\u6bcf\u4e2a\u5143\u7ec4\u4f4d\u7f6e\uff0c\u56e0\u6b64\u4ecd\u53ef\u80fd\u9700\u8981\u5806\u91cd\u68c0\u3002"]}, {"title": "\u5e76\u884c\u6267\u884c\u4e0e\u8fd0\u884c\u4fe1\u606f\u91c7\u96c6", "paragraphs": ["\u4ee5\u4e0b\u6e90\u7801\u56de\u8c03\u53ef\u4ee5\u534f\u8c03\u6267\u884c\u6216\u6536\u96c6\u5de5\u4f5c\u8fdb\u7a0b\u7684\u6d4b\u91cf\u6570\u636e\u3002\u56de\u8c03\u5b58\u5728\u4e0d\u4ee3\u8868\u8be5\u8282\u70b9\u666e\u904d\u652f\u6301\u5171\u4eab\u5e76\u884c\u626b\u63cf\u6216\u5171\u4eab\u72b6\u6001\u3002", "\u6b64\u6784\u5efa\u7684\u56de\u8c03\uff1anone extracted from this node implementation."]}, {"title": "\u540c\u7248\u672c\u624b\u518c\u8bf4\u660e", "paragraphs": ["\u7531\u4e8e\u5b9e\u73b0\u4e0a\u7684\u9650\u5236\uff0cBitmapAnd \u548c BitmapOr \u8282\u70b9\u62a5\u544a\u7684\u5b9e\u9645\u884c\u6570\u59cb\u7ec8\u4e3a\u96f6\u3002"]}, {"title": "\u6267\u884c\u5668\u5b9e\u73b0\u8bf4\u660e", "paragraphs": ["\u8bf4\u660e\uff1aBitmapOr \u4e0d\u4f7f\u7528\u5de6\u53f3\u5b50\u6811\uff0c\u800c\u50cf Append \u4e00\u6837\u7ef4\u62a4\u5b50\u8ba1\u5212\u5217\u8868\u3002\u4e0d\u8fc7\u5176\u903b\u8f91\u6bd4 Append \u7b80\u5355\u5f97\u591a\uff0c\u56e0\u4e3a\u65e0\u9700\u5904\u7406\u6b63\u5411\u6216\u53cd\u5411\u6267\u884c\u3002", "\u5bf9\u6bcf\u4e2a\u5f85\u6267\u884c\u8ba1\u5212\u8c03\u7528 ExecInitNode\uff0c\u5e76\u5c06\u7ed3\u679c\u4fdd\u5b58\u5230 bitmapplanstates \u6570\u7ec4\u3002", "BitmapOr \u8ba1\u5212\u6ca1\u6709\u8868\u8fbe\u5f0f\u4e0a\u4e0b\u6587\uff0c\u56e0\u4e3a\u5b83\u4eec\u4ece\u4e0d\u8c03\u7528 ExecQual \u6216 ExecProject\uff0c\u4e5f\u4e0d\u9700\u8981\u5143\u7ec4\u69fd\u3002", "\u53ef\u5bf9 BitmapIndexScan \u5b50\u8282\u70b9\u4f5c\u7279\u6b8a\u5904\u7406\uff0c\u907f\u514d\u4e3a\u6bcf\u4e2a\u5b50\u8282\u70b9\u663e\u5f0f\u8c03\u7528 tbm_union\uff1a\u76f4\u63a5\u4e0b\u4f20\u5f53\u524d\u7ed3\u679c\u4f4d\u56fe\uff0c\u8ba9\u5b50\u8282\u70b9\u5c06\u7ed3\u679c\u6309\u4f4d OR \u5408\u5e76\u8fdb\u53bb\u3002", "ExecReScan \u4e0d\u77e5\u9053\u5f53\u524d\u8282\u70b9\u7684\u5b50\u8ba1\u5212\uff0c\u56e0\u6b64\u5fc5\u987b\u81ea\u884c\u901a\u77e5\u5b50\u8ba1\u5212\u54ea\u4e9b\u53c2\u6570\u53d1\u751f\u4e86\u53d8\u5316\u3002"]}, {"code": "case T_BitmapOr:\n\t\t\tpname = sname = \"BitmapOr\";\n\t\t\tbreak;", "title": "\u6838\u5fc3\u6e90\u7801\u4e2d\u7684 EXPLAIN \u6807\u8bc6"}], "description_zh": "\u5bf9\u5404\u5b50\u8ba1\u5212\u751f\u6210\u7684\u4f4d\u56fe\u6c42\u5e76\u96c6\u3002", "description_zh_html": "<p>\u5bf9\u5404\u5b50\u8ba1\u5212\u751f\u6210\u7684\u4f4d\u56fe\u6c42\u5e76\u96c6\u3002</p><p>\u6838\u5fc3\u8282\u70b9\u6807\u8bc6\uff1a<code>T_BitmapOr</code>\uff1bEXPLAIN \u540d\u79f0\uff1a<code>BitmapOr</code>\u3002</p><p>\u672c\u7248\u672c\u6e90\u7801\u4e2d\u7684\u5e76\u884c\u6267\u884c\u6216\u89c2\u6d4b\u56de\u8c03\uff1a\u8be5\u8282\u70b9\u5b9e\u73b0\u4e2d\u672a\u63d0\u53d6\u5230\u6b64\u7c7b\u56de\u8c03\u3002\u56de\u8c03\u7684\u5b58\u5728\u4e0d\u8868\u793a\u8be5\u8282\u70b9\u5fc5\u7136\u652f\u6301\u5171\u4eab\u5e76\u884c\u626b\u63cf\uff1b\u5728\u5e76\u884c\u5de5\u4f5c\u8fdb\u7a0b\u4e2d\u6267\u884c\u4e5f\u4e0d\u7b49\u4e8e\u5177\u6709\u5e76\u884c\u611f\u77e5\u80fd\u529b\u3002</p><h3>\u540c\u7248\u672c\u4e2d\u6587\u624b\u518c\u8282\u9009</h3><p>\n<code class=\"command\">EXPLAIN ANALYZE</code> \u6d4b\u5f97\u7684\u8fd0\u884c\u65f6\u95f4\uff0c\u53ef\u80fd\u4ee5\u4e24\u79cd\u91cd\u8981\u65b9\u5f0f\u504f\u79bb\u540c\u4e00\u67e5\u8be2\u7684\u6b63\u5e38\u6267\u884c\u65f6\u95f4\u3002\u7b2c\u4e00\uff0c\u7531\u4e8e\u4e0d\u4f1a\u5411\u5ba2\u6237\u7aef\u4f20\u9012\u4efb\u4f55\u8f93\u51fa\u884c\uff0c\u56e0\u6b64\u7f51\u7edc\u4f20\u8f93\u5f00\u9500\u548c I/O \u8f6c\u6362\u5f00\u9500\u5747\u4e0d\u4f1a\u88ab\u8ba1\u5165\u3002\u7b2c\u4e8c\uff0c<code class=\"command\">EXPLAIN ANALYZE</code> \u9644\u52a0\u7684\u6d4b\u91cf\u5f00\u9500\u672c\u8eab\u53ef\u80fd\u76f8\u5f53\u53ef\u89c2\uff0c\u5c24\u5176\u662f\u5728\u64cd\u4f5c\u7cfb\u7edf\u8c03\u7528 <code class=\"function\">gettimeofday()</code> \u8f83\u6162\u7684\u673a\u5668\u4e0a\u3002\u53ef\u4ee5\u4f7f\u7528 <a class=\"xref\" href=\"/zh/docs/14/pgtesttiming.html\"><span class=\"refentrytitle\"><span class=\"application\">pg_test_timing</span></span></a> \u5de5\u5177\u6765\u6d4b\u91cf\u7cfb\u7edf\u4e0a\u7684\u8ba1\u65f6\u5f00\u9500\u3002\n   </p><p>\n    \u4e0d\u5e94\u5c06 <code class=\"command\">EXPLAIN</code> \u7ed3\u679c\u5916\u63a8\u5230\u4e0e\u5b9e\u9645\u6d4b\u8bd5\u573a\u666f\u5dee\u5f02\u5f88\u5927\u7684\u60c5\u51b5\u3002\u4f8b\u5982\uff0c\u5728\u4e00\u4e2a\u5f88\u5c0f\u7684\u8868\u4e0a\u5f97\u5230\u7684\u7ed3\u679c\uff0c\u4e0d\u80fd\u5047\u5b9a\u4e5f\u9002\u7528\u4e8e\u5927\u578b\u8868\u3002\u89c4\u5212\u5668\u7684\u4ee3\u4ef7\u4f30\u8ba1\u4e0d\u662f\u7ebf\u6027\u7684\uff0c\u56e0\u6b64\u5b83\u53ef\u80fd\u4f1a\u4e3a\u66f4\u5927\u6216\u66f4\u5c0f\u7684\u8868\u9009\u62e9\u4e0d\u540c\u7684\u8ba1\u5212\u3002\u4e00\u4e2a\u6781\u7aef\u793a\u4f8b\u662f\uff1a\u5bf9\u4e8e\u53ea\u5360\u7528\u4e00\u4e2a\u78c1\u76d8\u9875\u7684\u8868\uff0c\u65e0\u8bba\u7d22\u5f15\u662f\u5426\u53ef\u7528\uff0c\u51e0\u4e4e\u603b\u4f1a\u5f97\u5230\u987a\u5e8f\u626b\u63cf\u8ba1\u5212\u3002\u89c4\u5212\u5668\u8ba4\u8bc6\u5230\uff0c\u65e0\u8bba\u5982\u4f55\u5904\u7406\u8be5\u8868\u90fd\u9700\u8981\u4e00\u6b21\u78c1\u76d8\u9875\u8bfb\u53d6\uff0c\u56e0\u6b64\u518d\u989d\u5916\u8bfb\u53d6\u9875\u9762\u53bb\u67e5\u770b\u7d22\u5f15\u5e76\u6ca1\u6709\u4ef7\u503c\u3002\uff08\u524d\u9762\u7684 <code class=\"literal\">polygon_tbl</code> \u793a\u4f8b\u5df2\u7ecf\u5c55\u793a\u8fc7\u8fd9\u79cd\u60c5\u51b5\u3002\uff09\n   </p><p>\u6709\u65f6\u5b9e\u9645\u503c\u4e0e\u4f30\u8ba1\u503c\u4e0d\u592a\u4e00\u81f4\uff0c\u4f46\u5b9e\u9645\u4e0a\u5e76\u6ca1\u6709\u95ee\u9898\u3002\u5176\u4e2d\u4e00\u79cd\u60c5\u51b5\u662f\uff0c\u8ba1\u5212\u8282\u70b9\u7684\u6267\u884c\u56e0 <code class=\"literal\">LIMIT</code> \u6216\u7c7b\u4f3c\u6548\u679c\u800c\u63d0\u524d\u505c\u6b62\u3002\u4f8b\u5982\uff0c\u5728\u524d\u9762\u4f7f\u7528\u7684 <code class=\"literal\">LIMIT</code> \u67e5\u8be2\u4e2d\uff1a</p><p>Index Scan \u8282\u70b9\u7684\u4f30\u8ba1\u4ee3\u4ef7\u548c\u884c\u6570\u6309\u8be5\u8282\u70b9\u6267\u884c\u5230\u5b8c\u6210\u7684\u60c5\u51b5\u663e\u793a\u3002\u4f46\u5b9e\u9645\u4e0a\uff0cLimit \u8282\u70b9\u53d6\u5f97\u4e24\u884c\u540e\u5c31\u505c\u6b62\u8bf7\u6c42\u884c\uff0c\u56e0\u6b64\u5b9e\u9645\u884c\u6570\u53ea\u6709 2\uff0c\u8fd0\u884c\u65f6\u95f4\u4e5f\u5c0f\u4e8e\u4f30\u8ba1\u4ee3\u4ef7\u6240\u6697\u793a\u7684\u65f6\u95f4\u3002\u8fd9\u4e0d\u662f\u4f30\u8ba1\u9519\u8bef\uff0c\u53ea\u662f\u4f30\u8ba1\u503c\u4e0e\u5b9e\u9645\u503c\u7684\u663e\u793a\u65b9\u5f0f\u5b58\u5728\u5dee\u522b\u3002</p><p><a href=\"/zh/docs/14/performance-tips.html#USING-EXPLAIN-CAVEATS\">\u67e5\u770b\u5b8c\u6574\u4e2d\u6587\u624b\u518c\u4e0e\u4e0a\u4e0b\u6587</a>\u3002</p><p>\u672c\u9875\u5f00\u5934\u7684\u4e2d\u6587\u8bf4\u660e\u4e3a PG.CENTER \u5bf9\u7f16\u8f91\u8bf4\u660e\u7684\u7ffb\u8bd1\uff1b\u624b\u518c\u8282\u9009\u4fdd\u7559\u5bf9\u5e94\u7248\u672c\u4e2d\u6587\u6587\u6863\u539f\u6587\u3002\u6e90\u7801\u4fe1\u606f\u53ca\u624b\u518c\u793a\u4f8b\u4e0d\u4ee3\u8868\u91cd\u65b0\u8fdb\u884c\u8fc7\u8fd0\u884c\u6d4b\u8bd5\u3002</p>"}, "summary": "\u5bf9\u5404\u5b50\u8ba1\u5212\u751f\u6210\u7684\u4f4d\u56fe\u6c42\u5e76\u96c6\u3002", "version": "14", "link_map": {"/zh/docs/14/pgtesttiming.html": "/docs/14/pgtesttiming.html", "/zh/docs/14/performance-tips.html#USING-EXPLAIN-CAVEATS": "/docs/14/performance-tips.html#USING-EXPLAIN-CAVEATS"}, "body_html": "<p>\u5bf9\u5404\u5b50\u8ba1\u5212\u751f\u6210\u7684\u4f4d\u56fe\u6c42\u5e76\u96c6\u3002</p><p>\u6838\u5fc3\u8282\u70b9\u6807\u8bc6\uff1a<code>T_BitmapOr</code>\uff1bEXPLAIN \u540d\u79f0\uff1a<code>BitmapOr</code>\u3002</p><p>\u672c\u7248\u672c\u6e90\u7801\u4e2d\u7684\u5e76\u884c\u6267\u884c\u6216\u89c2\u6d4b\u56de\u8c03\uff1a\u8be5\u8282\u70b9\u5b9e\u73b0\u4e2d\u672a\u63d0\u53d6\u5230\u6b64\u7c7b\u56de\u8c03\u3002\u56de\u8c03\u7684\u5b58\u5728\u4e0d\u8868\u793a\u8be5\u8282\u70b9\u5fc5\u7136\u652f\u6301\u5171\u4eab\u5e76\u884c\u626b\u63cf\uff1b\u5728\u5e76\u884c\u5de5\u4f5c\u8fdb\u7a0b\u4e2d\u6267\u884c\u4e5f\u4e0d\u7b49\u4e8e\u5177\u6709\u5e76\u884c\u611f\u77e5\u80fd\u529b\u3002</p><h3>\u540c\u7248\u672c\u4e2d\u6587\u624b\u518c\u8282\u9009</h3><p>\n<code>EXPLAIN ANALYZE</code> \u6d4b\u5f97\u7684\u8fd0\u884c\u65f6\u95f4\uff0c\u53ef\u80fd\u4ee5\u4e24\u79cd\u91cd\u8981\u65b9\u5f0f\u504f\u79bb\u540c\u4e00\u67e5\u8be2\u7684\u6b63\u5e38\u6267\u884c\u65f6\u95f4\u3002\u7b2c\u4e00\uff0c\u7531\u4e8e\u4e0d\u4f1a\u5411\u5ba2\u6237\u7aef\u4f20\u9012\u4efb\u4f55\u8f93\u51fa\u884c\uff0c\u56e0\u6b64\u7f51\u7edc\u4f20\u8f93\u5f00\u9500\u548c I/O \u8f6c\u6362\u5f00\u9500\u5747\u4e0d\u4f1a\u88ab\u8ba1\u5165\u3002\u7b2c\u4e8c\uff0c<code>EXPLAIN ANALYZE</code> \u9644\u52a0\u7684\u6d4b\u91cf\u5f00\u9500\u672c\u8eab\u53ef\u80fd\u76f8\u5f53\u53ef\u89c2\uff0c\u5c24\u5176\u662f\u5728\u64cd\u4f5c\u7cfb\u7edf\u8c03\u7528 <code>gettimeofday()</code> \u8f83\u6162\u7684\u673a\u5668\u4e0a\u3002\u53ef\u4ee5\u4f7f\u7528 <a href=\"/zh/docs/14/pgtesttiming.html\" rel=\"nofollow\"><span><span>pg_test_timing</span></span></a> \u5de5\u5177\u6765\u6d4b\u91cf\u7cfb\u7edf\u4e0a\u7684\u8ba1\u65f6\u5f00\u9500\u3002\n   </p><p>\n    \u4e0d\u5e94\u5c06 <code>EXPLAIN</code> \u7ed3\u679c\u5916\u63a8\u5230\u4e0e\u5b9e\u9645\u6d4b\u8bd5\u573a\u666f\u5dee\u5f02\u5f88\u5927\u7684\u60c5\u51b5\u3002\u4f8b\u5982\uff0c\u5728\u4e00\u4e2a\u5f88\u5c0f\u7684\u8868\u4e0a\u5f97\u5230\u7684\u7ed3\u679c\uff0c\u4e0d\u80fd\u5047\u5b9a\u4e5f\u9002\u7528\u4e8e\u5927\u578b\u8868\u3002\u89c4\u5212\u5668\u7684\u4ee3\u4ef7\u4f30\u8ba1\u4e0d\u662f\u7ebf\u6027\u7684\uff0c\u56e0\u6b64\u5b83\u53ef\u80fd\u4f1a\u4e3a\u66f4\u5927\u6216\u66f4\u5c0f\u7684\u8868\u9009\u62e9\u4e0d\u540c\u7684\u8ba1\u5212\u3002\u4e00\u4e2a\u6781\u7aef\u793a\u4f8b\u662f\uff1a\u5bf9\u4e8e\u53ea\u5360\u7528\u4e00\u4e2a\u78c1\u76d8\u9875\u7684\u8868\uff0c\u65e0\u8bba\u7d22\u5f15\u662f\u5426\u53ef\u7528\uff0c\u51e0\u4e4e\u603b\u4f1a\u5f97\u5230\u987a\u5e8f\u626b\u63cf\u8ba1\u5212\u3002\u89c4\u5212\u5668\u8ba4\u8bc6\u5230\uff0c\u65e0\u8bba\u5982\u4f55\u5904\u7406\u8be5\u8868\u90fd\u9700\u8981\u4e00\u6b21\u78c1\u76d8\u9875\u8bfb\u53d6\uff0c\u56e0\u6b64\u518d\u989d\u5916\u8bfb\u53d6\u9875\u9762\u53bb\u67e5\u770b\u7d22\u5f15\u5e76\u6ca1\u6709\u4ef7\u503c\u3002\uff08\u524d\u9762\u7684 <code>polygon_tbl</code> \u793a\u4f8b\u5df2\u7ecf\u5c55\u793a\u8fc7\u8fd9\u79cd\u60c5\u51b5\u3002\uff09\n   </p><p>\u6709\u65f6\u5b9e\u9645\u503c\u4e0e\u4f30\u8ba1\u503c\u4e0d\u592a\u4e00\u81f4\uff0c\u4f46\u5b9e\u9645\u4e0a\u5e76\u6ca1\u6709\u95ee\u9898\u3002\u5176\u4e2d\u4e00\u79cd\u60c5\u51b5\u662f\uff0c\u8ba1\u5212\u8282\u70b9\u7684\u6267\u884c\u56e0 <code>LIMIT</code> \u6216\u7c7b\u4f3c\u6548\u679c\u800c\u63d0\u524d\u505c\u6b62\u3002\u4f8b\u5982\uff0c\u5728\u524d\u9762\u4f7f\u7528\u7684 <code>LIMIT</code> \u67e5\u8be2\u4e2d\uff1a</p><p>Index Scan \u8282\u70b9\u7684\u4f30\u8ba1\u4ee3\u4ef7\u548c\u884c\u6570\u6309\u8be5\u8282\u70b9\u6267\u884c\u5230\u5b8c\u6210\u7684\u60c5\u51b5\u663e\u793a\u3002\u4f46\u5b9e\u9645\u4e0a\uff0cLimit \u8282\u70b9\u53d6\u5f97\u4e24\u884c\u540e\u5c31\u505c\u6b62\u8bf7\u6c42\u884c\uff0c\u56e0\u6b64\u5b9e\u9645\u884c\u6570\u53ea\u6709 2\uff0c\u8fd0\u884c\u65f6\u95f4\u4e5f\u5c0f\u4e8e\u4f30\u8ba1\u4ee3\u4ef7\u6240\u6697\u793a\u7684\u65f6\u95f4\u3002\u8fd9\u4e0d\u662f\u4f30\u8ba1\u9519\u8bef\uff0c\u53ea\u662f\u4f30\u8ba1\u503c\u4e0e\u5b9e\u9645\u503c\u7684\u663e\u793a\u65b9\u5f0f\u5b58\u5728\u5dee\u522b\u3002</p><p><a href=\"/zh/docs/14/performance-tips.html#USING-EXPLAIN-CAVEATS\" rel=\"nofollow\">\u67e5\u770b\u5b8c\u6574\u4e2d\u6587\u624b\u518c\u4e0e\u4e0a\u4e0b\u6587</a>\u3002</p><p>\u672c\u9875\u5f00\u5934\u7684\u4e2d\u6587\u8bf4\u660e\u4e3a PG.CENTER \u5bf9\u7f16\u8f91\u8bf4\u660e\u7684\u7ffb\u8bd1\uff1b\u624b\u518c\u8282\u9009\u4fdd\u7559\u5bf9\u5e94\u7248\u672c\u4e2d\u6587\u6587\u6863\u539f\u6587\u3002\u6e90\u7801\u4fe1\u606f\u53ca\u624b\u518c\u793a\u4f8b\u4e0d\u4ee3\u8868\u91cd\u65b0\u8fdb\u884c\u8fc7\u8fd0\u884c\u6d4b\u8bd5\u3002</p>", "body_sha256": "0470b8d00a2b2779ec237abc62f6eb14a9f5d2df78b8f7f29969f3eb5941c517", "content_hash": "eac3f8c761e925970a44a2fd898f775385c537364bf884640c15befc10b7df9d", "source_database": "center", "source_revision": "a7fa7ed3d558172355f51406097a7bd4f6b473be80f311ef7cda96bf383d8897"}, "tables_zh": [{"key": "explain-labels", "rows": [{"label": "BitmapOr", "identity": "BitmapOr"}], "title": "\u672c\u6784\u5efa\u4e2d\u7684 EXPLAIN \u6807\u7b7e", "columns": [{"key": "label", "label": "\u6587\u672c\u683c\u5f0f\u6807\u7b7e"}, {"key": "identity", "label": "\u7ed3\u6784\u5316\u8282\u70b9\u6807\u8bc6"}]}], "strategies": [], "description": ["\u5bf9\u5404\u5b50\u8ba1\u5212\u751f\u6210\u7684\u4f4d\u56fe\u6c42\u5e76\u96c6\u3002"], "sections_zh": [{"title": "EXPLAIN \u540d\u79f0\u4e0e\u5c5e\u6027", "paragraphs": ["\u7ed3\u6784\u5316\u683c\u5f0f\u4f7f\u7528\u4e0a\u8ff0 Node Type\u3002\u6587\u672c\u683c\u5f0f\u540d\u79f0\u8fd8\u53ef\u80fd\u5305\u542b\u64cd\u4f5c\u3001\u7b56\u7565\u3001\u8fde\u63a5\u7c7b\u578b\u3001\u626b\u63cf\u65b9\u5411\u6216\u805a\u5408\u9636\u6bb5\u5c5e\u6027\u3002", "\u6b64\u6e90\u7801\u8bb0\u5f55\u7684\u6587\u672c\u540d\u79f0\uff1aBitmapOr.", "\u5e76\u884c\u611f\u77e5\u4e0e\u5e76\u884c\u5b89\u5168\u662f\u4e0d\u540c\u7684\u8ba1\u5212\u5c5e\u6027\u3002\u5728\u5e76\u884c\u5de5\u4f5c\u8fdb\u7a0b\u5185\u8fd0\u884c\u7684\u8282\u70b9\u4e0d\u4e00\u5b9a\u662f\u5e76\u884c\u611f\u77e5\u8282\u70b9\u3002"]}, {"title": "\u5185\u5b58\u4e0e\u4e34\u65f6\u5b58\u50a8", "paragraphs": ["\u6b64\u8282\u70b9\u6309\u57fa\u4e8e work_mem \u7684\u9884\u7b97\u5206\u914d\u5143\u7ec4\u4f4d\u7f6e\u4f4d\u56fe\u3002\u4f4d\u56fe\u53ef\u4ee5\u4fdd\u7559\u9875\u7ea7\u6709\u635f\u6761\u76ee\uff0c\u800c\u4e0d\u8bb0\u5f55\u6bcf\u4e2a\u5143\u7ec4\u4f4d\u7f6e\uff0c\u56e0\u6b64\u4ecd\u53ef\u80fd\u9700\u8981\u5806\u91cd\u68c0\u3002"]}, {"title": "\u5e76\u884c\u6267\u884c\u4e0e\u8fd0\u884c\u4fe1\u606f\u91c7\u96c6", "paragraphs": ["\u4ee5\u4e0b\u6e90\u7801\u56de\u8c03\u53ef\u4ee5\u534f\u8c03\u6267\u884c\u6216\u6536\u96c6\u5de5\u4f5c\u8fdb\u7a0b\u7684\u6d4b\u91cf\u6570\u636e\u3002\u56de\u8c03\u5b58\u5728\u4e0d\u4ee3\u8868\u8be5\u8282\u70b9\u666e\u904d\u652f\u6301\u5171\u4eab\u5e76\u884c\u626b\u63cf\u6216\u5171\u4eab\u72b6\u6001\u3002", "\u6b64\u6784\u5efa\u7684\u56de\u8c03\uff1anone extracted from this node implementation."]}, {"title": "\u540c\u7248\u672c\u624b\u518c\u8bf4\u660e", "paragraphs": ["\u7531\u4e8e\u5b9e\u73b0\u4e0a\u7684\u9650\u5236\uff0cBitmapAnd \u548c BitmapOr \u8282\u70b9\u62a5\u544a\u7684\u5b9e\u9645\u884c\u6570\u59cb\u7ec8\u4e3a\u96f6\u3002"]}, {"title": "\u6267\u884c\u5668\u5b9e\u73b0\u8bf4\u660e", "paragraphs": ["\u8bf4\u660e\uff1aBitmapOr \u4e0d\u4f7f\u7528\u5de6\u53f3\u5b50\u6811\uff0c\u800c\u50cf Append \u4e00\u6837\u7ef4\u62a4\u5b50\u8ba1\u5212\u5217\u8868\u3002\u4e0d\u8fc7\u5176\u903b\u8f91\u6bd4 Append \u7b80\u5355\u5f97\u591a\uff0c\u56e0\u4e3a\u65e0\u9700\u5904\u7406\u6b63\u5411\u6216\u53cd\u5411\u6267\u884c\u3002", "\u5bf9\u6bcf\u4e2a\u5f85\u6267\u884c\u8ba1\u5212\u8c03\u7528 ExecInitNode\uff0c\u5e76\u5c06\u7ed3\u679c\u4fdd\u5b58\u5230 bitmapplanstates \u6570\u7ec4\u3002", "BitmapOr \u8ba1\u5212\u6ca1\u6709\u8868\u8fbe\u5f0f\u4e0a\u4e0b\u6587\uff0c\u56e0\u4e3a\u5b83\u4eec\u4ece\u4e0d\u8c03\u7528 ExecQual \u6216 ExecProject\uff0c\u4e5f\u4e0d\u9700\u8981\u5143\u7ec4\u69fd\u3002", "\u53ef\u5bf9 BitmapIndexScan \u5b50\u8282\u70b9\u4f5c\u7279\u6b8a\u5904\u7406\uff0c\u907f\u514d\u4e3a\u6bcf\u4e2a\u5b50\u8282\u70b9\u663e\u5f0f\u8c03\u7528 tbm_union\uff1a\u76f4\u63a5\u4e0b\u4f20\u5f53\u524d\u7ed3\u679c\u4f4d\u56fe\uff0c\u8ba9\u5b50\u8282\u70b9\u5c06\u7ed3\u679c\u6309\u4f4d OR \u5408\u5e76\u8fdb\u53bb\u3002", "ExecReScan \u4e0d\u77e5\u9053\u5f53\u524d\u8282\u70b9\u7684\u5b50\u8ba1\u5212\uff0c\u56e0\u6b64\u5fc5\u987b\u81ea\u884c\u901a\u77e5\u5b50\u8ba1\u5212\u54ea\u4e9b\u53c2\u6570\u53d1\u751f\u4e86\u53d8\u5316\u3002"]}, {"code": "case T_BitmapOr:\n\t\t\tpname = sname = \"BitmapOr\";\n\t\t\tbreak;", "title": "\u6838\u5fc3\u6e90\u7801\u4e2d\u7684 EXPLAIN \u6807\u8bc6"}], "localization": {"status": "complete", "sources": [], "language": "zh", "original_text": {"/versions/14/description/0": "Unions bitmaps produced by its child plans.", "/versions/14/facts/0/label": "Core node tag", "/versions/14/facts/1/label": "Structured EXPLAIN Node Type", "/versions/14/facts/2/label": "Inputs", "/versions/14/facts/2/value": "Bitmap-producing child plans", "/versions/14/facts/3/label": "Output", "/versions/14/facts/3/value": "Tuple-location bitmap, not a tuple stream", "/versions/14/facts/4/label": "Executor initializer", "/versions/14/facts/5/label": "Memory mechanism", "/versions/14/tables/0/title": "EXPLAIN labels in this source build", "/versions/14/related/1/label": "Using EXPLAIN", "/versions/14/related/2/label": "Parallel plans", "/versions/14/sections/0/title": "EXPLAIN names and attributes", "/versions/14/sections/1/title": "Memory and temporary storage", "/versions/14/sections/2/title": "Parallel execution and instrumentation", "/versions/14/sections/3/title": "Same-version manual discussion", "/versions/14/sections/4/title": "Executor implementation notes", "/versions/14/sections/5/title": "EXPLAIN identity in core source", "/versions/14/memory/description": "The node allocates a tuple-location bitmap using a work_mem-derived budget. A bitmap can retain page-level lossy entries instead of every tuple location; heap rechecks then remain necessary.", "/versions/14/sections/0/paragraphs/0": "Structured formats use the Node Type above. Text-format spellings can also include operation, strategy, join type, scan direction or aggregation-stage attributes.", "/versions/14/sections/0/paragraphs/1": "Text names recorded by this source: BitmapOr.", "/versions/14/sections/0/paragraphs/2": "Parallel-aware and parallel-safe are different plan properties. A node running inside a parallel worker is not necessarily a parallel-aware node.", "/versions/14/sections/1/paragraphs/0": "The node allocates a tuple-location bitmap using a work_mem-derived budget. A bitmap can retain page-level lossy entries instead of every tuple location; heap rechecks then remain necessary.", "/versions/14/sections/2/paragraphs/0": "The source callbacks below can coordinate execution or collect worker instrumentation. Their presence is not a blanket claim that this node supports a shared parallel scan or shared state.", "/versions/14/sections/2/paragraphs/1": "Callbacks in this build: none extracted from this node implementation.", "/versions/14/sections/3/paragraphs/0": "BitmapAnd and BitmapOr nodes always report their actual row counts as zero, due to implementation limitations.", "/versions/14/sections/4/paragraphs/0": "NOTES BitmapOr nodes don't make use of their left and right subtrees, rather they maintain a list of subplans, much like Append nodes. The logic is much simpler than Append, however, since we needn't cope with forward/backward execution.", "/versions/14/sections/4/paragraphs/1": "call ExecInitNode on each of the plans to be executed and save the results into the array \"bitmapplanstates\".", "/versions/14/sections/4/paragraphs/2": "BitmapOr plans don't have expression contexts because they never call ExecQual or ExecProject. They don't need any tuple slots either.", "/versions/14/sections/4/paragraphs/3": "We can special-case BitmapIndexScan children to avoid an explicit tbm_union step for each child: just pass down the current result bitmap and let the child OR directly into it.", "/versions/14/sections/4/paragraphs/4": "ExecReScan doesn't know about my subplans, so I have to do changed-parameter signaling myself.", "/versions/14/tables/0/columns/0/label": "Text-format label", "/versions/14/tables/0/columns/1/label": "Structured node identity"}, "fallback_fields": [], "source_language": "en", "original_snapshot_sha256": "559f5ce17a482181babd42c3ec9646a95652bcd9e288e72c443cc04ea8d05437", "canonical_center_text_hash": "eac3f8c761e925970a44a2fd898f775385c537364bf884640c15befc10b7df9d"}, "evidence_kind": "source and documentation", "explain_names": ["BitmapOr"], "partial_modes": [], "description_zh": "\u5bf9\u5404\u5b50\u8ba1\u5212\u751f\u6210\u7684\u4f4d\u56fe\u6c42\u5e76\u96c6\u3002", "comparison_data": {"node_tag": "T_BitmapOr", "strategies": [], "text_names": ["BitmapOr"], "initializer": "ExecInitBitmapOr", "partial_modes": [], "memory_mechanism": "bitmap-lossification", "parallel_callbacks": []}, "comparison_hash": "c0ca503a6029c37ec720213dcdc3094997eb194d4920da68f94a7420d3e8f1d2", "manual_language": "zh", "explain_prefixes": ["Parallel", "Async"], "runtime_verified": false, "source_inventory": {"explain": "src/backend/commands/explain.c", "executor": "src/backend/executor/execProcnode.c", "implementation": "src/backend/executor/nodeBitmapOr.c"}, "parallel_callbacks": [], "description_zh_html": "<p>\u5bf9\u5404\u5b50\u8ba1\u5212\u751f\u6210\u7684\u4f4d\u56fe\u6c42\u5e76\u96c6\u3002</p><p>\u6838\u5fc3\u8282\u70b9\u6807\u8bc6\uff1a<code>T_BitmapOr</code>\uff1bEXPLAIN \u540d\u79f0\uff1a<code>BitmapOr</code>\u3002</p><p>\u672c\u7248\u672c\u6e90\u7801\u4e2d\u7684\u5e76\u884c\u6267\u884c\u6216\u89c2\u6d4b\u56de\u8c03\uff1a\u8be5\u8282\u70b9\u5b9e\u73b0\u4e2d\u672a\u63d0\u53d6\u5230\u6b64\u7c7b\u56de\u8c03\u3002\u56de\u8c03\u7684\u5b58\u5728\u4e0d\u8868\u793a\u8be5\u8282\u70b9\u5fc5\u7136\u652f\u6301\u5171\u4eab\u5e76\u884c\u626b\u63cf\uff1b\u5728\u5e76\u884c\u5de5\u4f5c\u8fdb\u7a0b\u4e2d\u6267\u884c\u4e5f\u4e0d\u7b49\u4e8e\u5177\u6709\u5e76\u884c\u611f\u77e5\u80fd\u529b\u3002</p><h3>\u540c\u7248\u672c\u4e2d\u6587\u624b\u518c\u8282\u9009</h3><p>\n<code>EXPLAIN ANALYZE</code> \u6d4b\u5f97\u7684\u8fd0\u884c\u65f6\u95f4\uff0c\u53ef\u80fd\u4ee5\u4e24\u79cd\u91cd\u8981\u65b9\u5f0f\u504f\u79bb\u540c\u4e00\u67e5\u8be2\u7684\u6b63\u5e38\u6267\u884c\u65f6\u95f4\u3002\u7b2c\u4e00\uff0c\u7531\u4e8e\u4e0d\u4f1a\u5411\u5ba2\u6237\u7aef\u4f20\u9012\u4efb\u4f55\u8f93\u51fa\u884c\uff0c\u56e0\u6b64\u7f51\u7edc\u4f20\u8f93\u5f00\u9500\u548c I/O \u8f6c\u6362\u5f00\u9500\u5747\u4e0d\u4f1a\u88ab\u8ba1\u5165\u3002\u7b2c\u4e8c\uff0c<code>EXPLAIN ANALYZE</code> \u9644\u52a0\u7684\u6d4b\u91cf\u5f00\u9500\u672c\u8eab\u53ef\u80fd\u76f8\u5f53\u53ef\u89c2\uff0c\u5c24\u5176\u662f\u5728\u64cd\u4f5c\u7cfb\u7edf\u8c03\u7528 <code>gettimeofday()</code> \u8f83\u6162\u7684\u673a\u5668\u4e0a\u3002\u53ef\u4ee5\u4f7f\u7528 <a href=\"/zh/docs/14/pgtesttiming.html\" rel=\"nofollow\"><span><span>pg_test_timing</span></span></a> \u5de5\u5177\u6765\u6d4b\u91cf\u7cfb\u7edf\u4e0a\u7684\u8ba1\u65f6\u5f00\u9500\u3002\n   </p><p>\n    \u4e0d\u5e94\u5c06 <code>EXPLAIN</code> \u7ed3\u679c\u5916\u63a8\u5230\u4e0e\u5b9e\u9645\u6d4b\u8bd5\u573a\u666f\u5dee\u5f02\u5f88\u5927\u7684\u60c5\u51b5\u3002\u4f8b\u5982\uff0c\u5728\u4e00\u4e2a\u5f88\u5c0f\u7684\u8868\u4e0a\u5f97\u5230\u7684\u7ed3\u679c\uff0c\u4e0d\u80fd\u5047\u5b9a\u4e5f\u9002\u7528\u4e8e\u5927\u578b\u8868\u3002\u89c4\u5212\u5668\u7684\u4ee3\u4ef7\u4f30\u8ba1\u4e0d\u662f\u7ebf\u6027\u7684\uff0c\u56e0\u6b64\u5b83\u53ef\u80fd\u4f1a\u4e3a\u66f4\u5927\u6216\u66f4\u5c0f\u7684\u8868\u9009\u62e9\u4e0d\u540c\u7684\u8ba1\u5212\u3002\u4e00\u4e2a\u6781\u7aef\u793a\u4f8b\u662f\uff1a\u5bf9\u4e8e\u53ea\u5360\u7528\u4e00\u4e2a\u78c1\u76d8\u9875\u7684\u8868\uff0c\u65e0\u8bba\u7d22\u5f15\u662f\u5426\u53ef\u7528\uff0c\u51e0\u4e4e\u603b\u4f1a\u5f97\u5230\u987a\u5e8f\u626b\u63cf\u8ba1\u5212\u3002\u89c4\u5212\u5668\u8ba4\u8bc6\u5230\uff0c\u65e0\u8bba\u5982\u4f55\u5904\u7406\u8be5\u8868\u90fd\u9700\u8981\u4e00\u6b21\u78c1\u76d8\u9875\u8bfb\u53d6\uff0c\u56e0\u6b64\u518d\u989d\u5916\u8bfb\u53d6\u9875\u9762\u53bb\u67e5\u770b\u7d22\u5f15\u5e76\u6ca1\u6709\u4ef7\u503c\u3002\uff08\u524d\u9762\u7684 <code>polygon_tbl</code> \u793a\u4f8b\u5df2\u7ecf\u5c55\u793a\u8fc7\u8fd9\u79cd\u60c5\u51b5\u3002\uff09\n   </p><p>\u6709\u65f6\u5b9e\u9645\u503c\u4e0e\u4f30\u8ba1\u503c\u4e0d\u592a\u4e00\u81f4\uff0c\u4f46\u5b9e\u9645\u4e0a\u5e76\u6ca1\u6709\u95ee\u9898\u3002\u5176\u4e2d\u4e00\u79cd\u60c5\u51b5\u662f\uff0c\u8ba1\u5212\u8282\u70b9\u7684\u6267\u884c\u56e0 <code>LIMIT</code> \u6216\u7c7b\u4f3c\u6548\u679c\u800c\u63d0\u524d\u505c\u6b62\u3002\u4f8b\u5982\uff0c\u5728\u524d\u9762\u4f7f\u7528\u7684 <code>LIMIT</code> \u67e5\u8be2\u4e2d\uff1a</p><p>Index Scan \u8282\u70b9\u7684\u4f30\u8ba1\u4ee3\u4ef7\u548c\u884c\u6570\u6309\u8be5\u8282\u70b9\u6267\u884c\u5230\u5b8c\u6210\u7684\u60c5\u51b5\u663e\u793a\u3002\u4f46\u5b9e\u9645\u4e0a\uff0cLimit \u8282\u70b9\u53d6\u5f97\u4e24\u884c\u540e\u5c31\u505c\u6b62\u8bf7\u6c42\u884c\uff0c\u56e0\u6b64\u5b9e\u9645\u884c\u6570\u53ea\u6709 2\uff0c\u8fd0\u884c\u65f6\u95f4\u4e5f\u5c0f\u4e8e\u4f30\u8ba1\u4ee3\u4ef7\u6240\u6697\u793a\u7684\u65f6\u95f4\u3002\u8fd9\u4e0d\u662f\u4f30\u8ba1\u9519\u8bef\uff0c\u53ea\u662f\u4f30\u8ba1\u503c\u4e0e\u5b9e\u9645\u503c\u7684\u663e\u793a\u65b9\u5f0f\u5b58\u5728\u5dee\u522b\u3002</p><p><a href=\"/zh/docs/14/performance-tips.html#USING-EXPLAIN-CAVEATS\" rel=\"nofollow\">\u67e5\u770b\u5b8c\u6574\u4e2d\u6587\u624b\u518c\u4e0e\u4e0a\u4e0b\u6587</a>\u3002</p><p>\u672c\u9875\u5f00\u5934\u7684\u4e2d\u6587\u8bf4\u660e\u4e3a PG.CENTER \u5bf9\u7f16\u8f91\u8bf4\u660e\u7684\u7ffb\u8bd1\uff1b\u624b\u518c\u8282\u9009\u4fdd\u7559\u5bf9\u5e94\u7248\u672c\u4e2d\u6587\u6587\u6863\u539f\u6587\u3002\u6e90\u7801\u4fe1\u606f\u53ca\u624b\u518c\u793a\u4f8b\u4e0d\u4ee3\u8868\u91cd\u65b0\u8fdb\u884c\u8fc7\u8fd0\u884c\u6d4b\u8bd5\u3002</p>"}, "15": {"facts": [{"label": "\u6838\u5fc3\u8282\u70b9\u6807\u7b7e", "value": "T_BitmapOr"}, {"label": "\u7ed3\u6784\u5316 EXPLAIN \u8282\u70b9\u7c7b\u578b", "value": "BitmapOr"}, {"label": "\u8f93\u5165", "value": "\u4ea7\u751f\u4f4d\u56fe\u7684\u5b50\u8ba1\u5212"}, {"label": "\u8f93\u51fa", "value": "\u5143\u7ec4\u4f4d\u7f6e\u4f4d\u56fe\uff0c\u4e0d\u662f\u5143\u7ec4\u6d41"}, {"label": "\u6267\u884c\u5668\u521d\u59cb\u5316\u51fd\u6570", "value": "ExecInitBitmapOr"}, {"label": "\u5185\u5b58\u673a\u5236", "value": "bitmap-lossification"}], "memory": {"evidence": [{"url": "https://ftp.postgresql.org/pub/source/v15.19/postgresql-15.19.tar.bz2", "path": "src/backend/executor/nodeBitmapOr.c", "label": "src/backend/executor/nodeBitmapOr.c", "sha256": "d6831e8f332aba276ea49ee76e308e60ad324800640ac5722556af7b337cb030", "archive_sha256": "e1a64a87a46b825b88c082e4518161a47aab53c45694964f8ba1df28f7859f89"}, {"url": "https://ftp.postgresql.org/pub/source/v15.19/postgresql-15.19.tar.bz2", "path": "src/backend/nodes/tidbitmap.c", "label": "src/backend/nodes/tidbitmap.c", "sha256": "4abf4a8e67412488d65490b4e292043351122be09f03af97150b384dc7ee11bb", "archive_sha256": "e1a64a87a46b825b88c082e4518161a47aab53c45694964f8ba1df28f7859f89"}], "mechanism": "bitmap-lossification", "description": "The node allocates a tuple-location bitmap using a work_mem-derived budget. 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"\u5e76\u884c\u6267\u884c\u4e0e\u8fd0\u884c\u4fe1\u606f\u91c7\u96c6", "paragraphs": ["\u4ee5\u4e0b\u6e90\u7801\u56de\u8c03\u53ef\u4ee5\u534f\u8c03\u6267\u884c\u6216\u6536\u96c6\u5de5\u4f5c\u8fdb\u7a0b\u7684\u6d4b\u91cf\u6570\u636e\u3002\u56de\u8c03\u5b58\u5728\u4e0d\u4ee3\u8868\u8be5\u8282\u70b9\u666e\u904d\u652f\u6301\u5171\u4eab\u5e76\u884c\u626b\u63cf\u6216\u5171\u4eab\u72b6\u6001\u3002", "\u6b64\u6784\u5efa\u7684\u56de\u8c03\uff1anone extracted from this node implementation."]}, {"title": "\u540c\u7248\u672c\u624b\u518c\u8bf4\u660e", "paragraphs": ["\u7531\u4e8e\u5b9e\u73b0\u4e0a\u7684\u9650\u5236\uff0cBitmapAnd \u548c BitmapOr \u8282\u70b9\u62a5\u544a\u7684\u5b9e\u9645\u884c\u6570\u59cb\u7ec8\u4e3a\u96f6\u3002"]}, {"title": "\u6267\u884c\u5668\u5b9e\u73b0\u8bf4\u660e", "paragraphs": ["\u8bf4\u660e\uff1aBitmapOr \u4e0d\u4f7f\u7528\u5de6\u53f3\u5b50\u6811\uff0c\u800c\u50cf Append \u4e00\u6837\u7ef4\u62a4\u5b50\u8ba1\u5212\u5217\u8868\u3002\u4e0d\u8fc7\u5176\u903b\u8f91\u6bd4 Append \u7b80\u5355\u5f97\u591a\uff0c\u56e0\u4e3a\u65e0\u9700\u5904\u7406\u6b63\u5411\u6216\u53cd\u5411\u6267\u884c\u3002", "\u5bf9\u6bcf\u4e2a\u5f85\u6267\u884c\u8ba1\u5212\u8c03\u7528 ExecInitNode\uff0c\u5e76\u5c06\u7ed3\u679c\u4fdd\u5b58\u5230 bitmapplanstates \u6570\u7ec4\u3002", "BitmapOr \u8ba1\u5212\u6ca1\u6709\u8868\u8fbe\u5f0f\u4e0a\u4e0b\u6587\uff0c\u56e0\u4e3a\u5b83\u4eec\u4ece\u4e0d\u8c03\u7528 ExecQual \u6216 ExecProject\uff0c\u4e5f\u4e0d\u9700\u8981\u5143\u7ec4\u69fd\u3002", "\u53ef\u5bf9 BitmapIndexScan \u5b50\u8282\u70b9\u4f5c\u7279\u6b8a\u5904\u7406\uff0c\u907f\u514d\u4e3a\u6bcf\u4e2a\u5b50\u8282\u70b9\u663e\u5f0f\u8c03\u7528 tbm_union\uff1a\u76f4\u63a5\u4e0b\u4f20\u5f53\u524d\u7ed3\u679c\u4f4d\u56fe\uff0c\u8ba9\u5b50\u8282\u70b9\u5c06\u7ed3\u679c\u6309\u4f4d OR \u5408\u5e76\u8fdb\u53bb\u3002", "ExecReScan \u4e0d\u77e5\u9053\u5f53\u524d\u8282\u70b9\u7684\u5b50\u8ba1\u5212\uff0c\u56e0\u6b64\u5fc5\u987b\u81ea\u884c\u901a\u77e5\u5b50\u8ba1\u5212\u54ea\u4e9b\u53c2\u6570\u53d1\u751f\u4e86\u53d8\u5316\u3002"]}, {"code": "case T_BitmapOr:\n\t\t\tpname = sname = \"BitmapOr\";\n\t\t\tbreak;", "title": "\u6838\u5fc3\u6e90\u7801\u4e2d\u7684 EXPLAIN \u6807\u8bc6"}], "description_zh": "\u5bf9\u5404\u5b50\u8ba1\u5212\u751f\u6210\u7684\u4f4d\u56fe\u6c42\u5e76\u96c6\u3002", "description_zh_html": "<p>\u5bf9\u5404\u5b50\u8ba1\u5212\u751f\u6210\u7684\u4f4d\u56fe\u6c42\u5e76\u96c6\u3002</p><p>\u6838\u5fc3\u8282\u70b9\u6807\u8bc6\uff1a<code>T_BitmapOr</code>\uff1bEXPLAIN \u540d\u79f0\uff1a<code>BitmapOr</code>\u3002</p><p>\u672c\u7248\u672c\u6e90\u7801\u4e2d\u7684\u5e76\u884c\u6267\u884c\u6216\u89c2\u6d4b\u56de\u8c03\uff1a\u8be5\u8282\u70b9\u5b9e\u73b0\u4e2d\u672a\u63d0\u53d6\u5230\u6b64\u7c7b\u56de\u8c03\u3002\u56de\u8c03\u7684\u5b58\u5728\u4e0d\u8868\u793a\u8be5\u8282\u70b9\u5fc5\u7136\u652f\u6301\u5171\u4eab\u5e76\u884c\u626b\u63cf\uff1b\u5728\u5e76\u884c\u5de5\u4f5c\u8fdb\u7a0b\u4e2d\u6267\u884c\u4e5f\u4e0d\u7b49\u4e8e\u5177\u6709\u5e76\u884c\u611f\u77e5\u80fd\u529b\u3002</p><h3>\u540c\u7248\u672c\u4e2d\u6587\u624b\u518c\u8282\u9009</h3><p>\n<code class=\"command\">EXPLAIN ANALYZE</code> \u6d4b\u5f97\u7684\u8fd0\u884c\u65f6\u95f4\uff0c\u53ef\u80fd\u4ee5\u4e24\u79cd\u91cd\u8981\u65b9\u5f0f\u504f\u79bb\u540c\u4e00\u67e5\u8be2\u7684\u6b63\u5e38\u6267\u884c\u65f6\u95f4\u3002\u7b2c\u4e00\uff0c\u7531\u4e8e\u4e0d\u4f1a\u5411\u5ba2\u6237\u7aef\u4f20\u9012\u4efb\u4f55\u8f93\u51fa\u884c\uff0c\u56e0\u6b64\u7f51\u7edc\u4f20\u8f93\u5f00\u9500\u548c I/O \u8f6c\u6362\u5f00\u9500\u5747\u4e0d\u4f1a\u88ab\u8ba1\u5165\u3002\u7b2c\u4e8c\uff0c<code class=\"command\">EXPLAIN ANALYZE</code> \u9644\u52a0\u7684\u6d4b\u91cf\u5f00\u9500\u672c\u8eab\u53ef\u80fd\u76f8\u5f53\u53ef\u89c2\uff0c\u5c24\u5176\u662f\u5728\u64cd\u4f5c\u7cfb\u7edf\u8c03\u7528 <code class=\"function\">gettimeofday()</code> \u8f83\u6162\u7684\u673a\u5668\u4e0a\u3002\u53ef\u4ee5\u4f7f\u7528 <a class=\"xref\" href=\"/zh/docs/15/pgtesttiming.html\"><span class=\"refentrytitle\"><span class=\"application\">pg_test_timing</span></span></a> \u5de5\u5177\u6765\u6d4b\u91cf\u7cfb\u7edf\u4e0a\u7684\u8ba1\u65f6\u5f00\u9500\u3002\n   </p><p>\n    \u4e0d\u5e94\u5c06 <code class=\"command\">EXPLAIN</code> \u7ed3\u679c\u5916\u63a8\u5230\u4e0e\u5b9e\u9645\u6d4b\u8bd5\u573a\u666f\u5dee\u5f02\u5f88\u5927\u7684\u60c5\u51b5\u3002\u4f8b\u5982\uff0c\u5728\u4e00\u4e2a\u5f88\u5c0f\u7684\u8868\u4e0a\u5f97\u5230\u7684\u7ed3\u679c\uff0c\u4e0d\u80fd\u5047\u5b9a\u4e5f\u9002\u7528\u4e8e\u5927\u578b\u8868\u3002\u89c4\u5212\u5668\u7684\u4ee3\u4ef7\u4f30\u8ba1\u4e0d\u662f\u7ebf\u6027\u7684\uff0c\u56e0\u6b64\u5b83\u53ef\u80fd\u4f1a\u4e3a\u66f4\u5927\u6216\u66f4\u5c0f\u7684\u8868\u9009\u62e9\u4e0d\u540c\u7684\u8ba1\u5212\u3002\u4e00\u4e2a\u6781\u7aef\u793a\u4f8b\u662f\uff1a\u5bf9\u4e8e\u53ea\u5360\u7528\u4e00\u4e2a\u78c1\u76d8\u9875\u7684\u8868\uff0c\u65e0\u8bba\u7d22\u5f15\u662f\u5426\u53ef\u7528\uff0c\u51e0\u4e4e\u603b\u4f1a\u5f97\u5230\u987a\u5e8f\u626b\u63cf\u8ba1\u5212\u3002\u89c4\u5212\u5668\u8ba4\u8bc6\u5230\uff0c\u65e0\u8bba\u5982\u4f55\u5904\u7406\u8be5\u8868\u90fd\u9700\u8981\u4e00\u6b21\u78c1\u76d8\u9875\u8bfb\u53d6\uff0c\u56e0\u6b64\u518d\u989d\u5916\u8bfb\u53d6\u9875\u9762\u53bb\u67e5\u770b\u7d22\u5f15\u5e76\u6ca1\u6709\u4ef7\u503c\u3002\uff08\u524d\u9762\u7684 <code class=\"literal\">polygon_tbl</code> \u793a\u4f8b\u5df2\u7ecf\u5c55\u793a\u8fc7\u8fd9\u79cd\u60c5\u51b5\u3002\uff09\n   </p><p>\u6709\u65f6\u5b9e\u9645\u503c\u4e0e\u4f30\u8ba1\u503c\u4e0d\u592a\u4e00\u81f4\uff0c\u4f46\u5b9e\u9645\u4e0a\u5e76\u6ca1\u6709\u95ee\u9898\u3002\u5176\u4e2d\u4e00\u79cd\u60c5\u51b5\u662f\uff0c\u8ba1\u5212\u8282\u70b9\u7684\u6267\u884c\u56e0 <code class=\"literal\">LIMIT</code> \u6216\u7c7b\u4f3c\u6548\u679c\u800c\u63d0\u524d\u505c\u6b62\u3002\u4f8b\u5982\uff0c\u5728\u524d\u9762\u4f7f\u7528\u7684 <code class=\"literal\">LIMIT</code> \u67e5\u8be2\u4e2d\uff1a</p><p>Index Scan \u8282\u70b9\u7684\u4f30\u8ba1\u4ee3\u4ef7\u548c\u884c\u6570\u6309\u8be5\u8282\u70b9\u6267\u884c\u5230\u5b8c\u6210\u7684\u60c5\u51b5\u663e\u793a\u3002\u4f46\u5b9e\u9645\u4e0a\uff0cLimit \u8282\u70b9\u53d6\u5f97\u4e24\u884c\u540e\u5c31\u505c\u6b62\u8bf7\u6c42\u884c\uff0c\u56e0\u6b64\u5b9e\u9645\u884c\u6570\u53ea\u6709 2\uff0c\u8fd0\u884c\u65f6\u95f4\u4e5f\u5c0f\u4e8e\u4f30\u8ba1\u4ee3\u4ef7\u6240\u6697\u793a\u7684\u65f6\u95f4\u3002\u8fd9\u4e0d\u662f\u4f30\u8ba1\u9519\u8bef\uff0c\u53ea\u662f\u4f30\u8ba1\u503c\u4e0e\u5b9e\u9645\u503c\u7684\u663e\u793a\u65b9\u5f0f\u5b58\u5728\u5dee\u522b\u3002</p><p><a href=\"/zh/docs/15/performance-tips.html#USING-EXPLAIN-CAVEATS\">\u67e5\u770b\u5b8c\u6574\u4e2d\u6587\u624b\u518c\u4e0e\u4e0a\u4e0b\u6587</a>\u3002</p><p>\u672c\u9875\u5f00\u5934\u7684\u4e2d\u6587\u8bf4\u660e\u4e3a PG.CENTER \u5bf9\u7f16\u8f91\u8bf4\u660e\u7684\u7ffb\u8bd1\uff1b\u624b\u518c\u8282\u9009\u4fdd\u7559\u5bf9\u5e94\u7248\u672c\u4e2d\u6587\u6587\u6863\u539f\u6587\u3002\u6e90\u7801\u4fe1\u606f\u53ca\u624b\u518c\u793a\u4f8b\u4e0d\u4ee3\u8868\u91cd\u65b0\u8fdb\u884c\u8fc7\u8fd0\u884c\u6d4b\u8bd5\u3002</p>"}, "summary": "\u5bf9\u5404\u5b50\u8ba1\u5212\u751f\u6210\u7684\u4f4d\u56fe\u6c42\u5e76\u96c6\u3002", "version": "15", "link_map": {"/zh/docs/15/pgtesttiming.html": "/docs/15/pgtesttiming.html", "/zh/docs/15/performance-tips.html#USING-EXPLAIN-CAVEATS": "/docs/15/performance-tips.html#USING-EXPLAIN-CAVEATS"}, "body_html": "<p>\u5bf9\u5404\u5b50\u8ba1\u5212\u751f\u6210\u7684\u4f4d\u56fe\u6c42\u5e76\u96c6\u3002</p><p>\u6838\u5fc3\u8282\u70b9\u6807\u8bc6\uff1a<code>T_BitmapOr</code>\uff1bEXPLAIN \u540d\u79f0\uff1a<code>BitmapOr</code>\u3002</p><p>\u672c\u7248\u672c\u6e90\u7801\u4e2d\u7684\u5e76\u884c\u6267\u884c\u6216\u89c2\u6d4b\u56de\u8c03\uff1a\u8be5\u8282\u70b9\u5b9e\u73b0\u4e2d\u672a\u63d0\u53d6\u5230\u6b64\u7c7b\u56de\u8c03\u3002\u56de\u8c03\u7684\u5b58\u5728\u4e0d\u8868\u793a\u8be5\u8282\u70b9\u5fc5\u7136\u652f\u6301\u5171\u4eab\u5e76\u884c\u626b\u63cf\uff1b\u5728\u5e76\u884c\u5de5\u4f5c\u8fdb\u7a0b\u4e2d\u6267\u884c\u4e5f\u4e0d\u7b49\u4e8e\u5177\u6709\u5e76\u884c\u611f\u77e5\u80fd\u529b\u3002</p><h3>\u540c\u7248\u672c\u4e2d\u6587\u624b\u518c\u8282\u9009</h3><p>\n<code>EXPLAIN ANALYZE</code> \u6d4b\u5f97\u7684\u8fd0\u884c\u65f6\u95f4\uff0c\u53ef\u80fd\u4ee5\u4e24\u79cd\u91cd\u8981\u65b9\u5f0f\u504f\u79bb\u540c\u4e00\u67e5\u8be2\u7684\u6b63\u5e38\u6267\u884c\u65f6\u95f4\u3002\u7b2c\u4e00\uff0c\u7531\u4e8e\u4e0d\u4f1a\u5411\u5ba2\u6237\u7aef\u4f20\u9012\u4efb\u4f55\u8f93\u51fa\u884c\uff0c\u56e0\u6b64\u7f51\u7edc\u4f20\u8f93\u5f00\u9500\u548c I/O \u8f6c\u6362\u5f00\u9500\u5747\u4e0d\u4f1a\u88ab\u8ba1\u5165\u3002\u7b2c\u4e8c\uff0c<code>EXPLAIN ANALYZE</code> \u9644\u52a0\u7684\u6d4b\u91cf\u5f00\u9500\u672c\u8eab\u53ef\u80fd\u76f8\u5f53\u53ef\u89c2\uff0c\u5c24\u5176\u662f\u5728\u64cd\u4f5c\u7cfb\u7edf\u8c03\u7528 <code>gettimeofday()</code> \u8f83\u6162\u7684\u673a\u5668\u4e0a\u3002\u53ef\u4ee5\u4f7f\u7528 <a href=\"/zh/docs/15/pgtesttiming.html\" rel=\"nofollow\"><span><span>pg_test_timing</span></span></a> \u5de5\u5177\u6765\u6d4b\u91cf\u7cfb\u7edf\u4e0a\u7684\u8ba1\u65f6\u5f00\u9500\u3002\n   </p><p>\n    \u4e0d\u5e94\u5c06 <code>EXPLAIN</code> \u7ed3\u679c\u5916\u63a8\u5230\u4e0e\u5b9e\u9645\u6d4b\u8bd5\u573a\u666f\u5dee\u5f02\u5f88\u5927\u7684\u60c5\u51b5\u3002\u4f8b\u5982\uff0c\u5728\u4e00\u4e2a\u5f88\u5c0f\u7684\u8868\u4e0a\u5f97\u5230\u7684\u7ed3\u679c\uff0c\u4e0d\u80fd\u5047\u5b9a\u4e5f\u9002\u7528\u4e8e\u5927\u578b\u8868\u3002\u89c4\u5212\u5668\u7684\u4ee3\u4ef7\u4f30\u8ba1\u4e0d\u662f\u7ebf\u6027\u7684\uff0c\u56e0\u6b64\u5b83\u53ef\u80fd\u4f1a\u4e3a\u66f4\u5927\u6216\u66f4\u5c0f\u7684\u8868\u9009\u62e9\u4e0d\u540c\u7684\u8ba1\u5212\u3002\u4e00\u4e2a\u6781\u7aef\u793a\u4f8b\u662f\uff1a\u5bf9\u4e8e\u53ea\u5360\u7528\u4e00\u4e2a\u78c1\u76d8\u9875\u7684\u8868\uff0c\u65e0\u8bba\u7d22\u5f15\u662f\u5426\u53ef\u7528\uff0c\u51e0\u4e4e\u603b\u4f1a\u5f97\u5230\u987a\u5e8f\u626b\u63cf\u8ba1\u5212\u3002\u89c4\u5212\u5668\u8ba4\u8bc6\u5230\uff0c\u65e0\u8bba\u5982\u4f55\u5904\u7406\u8be5\u8868\u90fd\u9700\u8981\u4e00\u6b21\u78c1\u76d8\u9875\u8bfb\u53d6\uff0c\u56e0\u6b64\u518d\u989d\u5916\u8bfb\u53d6\u9875\u9762\u53bb\u67e5\u770b\u7d22\u5f15\u5e76\u6ca1\u6709\u4ef7\u503c\u3002\uff08\u524d\u9762\u7684 <code>polygon_tbl</code> \u793a\u4f8b\u5df2\u7ecf\u5c55\u793a\u8fc7\u8fd9\u79cd\u60c5\u51b5\u3002\uff09\n   </p><p>\u6709\u65f6\u5b9e\u9645\u503c\u4e0e\u4f30\u8ba1\u503c\u4e0d\u592a\u4e00\u81f4\uff0c\u4f46\u5b9e\u9645\u4e0a\u5e76\u6ca1\u6709\u95ee\u9898\u3002\u5176\u4e2d\u4e00\u79cd\u60c5\u51b5\u662f\uff0c\u8ba1\u5212\u8282\u70b9\u7684\u6267\u884c\u56e0 <code>LIMIT</code> \u6216\u7c7b\u4f3c\u6548\u679c\u800c\u63d0\u524d\u505c\u6b62\u3002\u4f8b\u5982\uff0c\u5728\u524d\u9762\u4f7f\u7528\u7684 <code>LIMIT</code> \u67e5\u8be2\u4e2d\uff1a</p><p>Index Scan \u8282\u70b9\u7684\u4f30\u8ba1\u4ee3\u4ef7\u548c\u884c\u6570\u6309\u8be5\u8282\u70b9\u6267\u884c\u5230\u5b8c\u6210\u7684\u60c5\u51b5\u663e\u793a\u3002\u4f46\u5b9e\u9645\u4e0a\uff0cLimit \u8282\u70b9\u53d6\u5f97\u4e24\u884c\u540e\u5c31\u505c\u6b62\u8bf7\u6c42\u884c\uff0c\u56e0\u6b64\u5b9e\u9645\u884c\u6570\u53ea\u6709 2\uff0c\u8fd0\u884c\u65f6\u95f4\u4e5f\u5c0f\u4e8e\u4f30\u8ba1\u4ee3\u4ef7\u6240\u6697\u793a\u7684\u65f6\u95f4\u3002\u8fd9\u4e0d\u662f\u4f30\u8ba1\u9519\u8bef\uff0c\u53ea\u662f\u4f30\u8ba1\u503c\u4e0e\u5b9e\u9645\u503c\u7684\u663e\u793a\u65b9\u5f0f\u5b58\u5728\u5dee\u522b\u3002</p><p><a href=\"/zh/docs/15/performance-tips.html#USING-EXPLAIN-CAVEATS\" rel=\"nofollow\">\u67e5\u770b\u5b8c\u6574\u4e2d\u6587\u624b\u518c\u4e0e\u4e0a\u4e0b\u6587</a>\u3002</p><p>\u672c\u9875\u5f00\u5934\u7684\u4e2d\u6587\u8bf4\u660e\u4e3a PG.CENTER \u5bf9\u7f16\u8f91\u8bf4\u660e\u7684\u7ffb\u8bd1\uff1b\u624b\u518c\u8282\u9009\u4fdd\u7559\u5bf9\u5e94\u7248\u672c\u4e2d\u6587\u6587\u6863\u539f\u6587\u3002\u6e90\u7801\u4fe1\u606f\u53ca\u624b\u518c\u793a\u4f8b\u4e0d\u4ee3\u8868\u91cd\u65b0\u8fdb\u884c\u8fc7\u8fd0\u884c\u6d4b\u8bd5\u3002</p>", "body_sha256": "d04d576ec45d9fe0db53c3c8569750bfdc224b6b5ba8ecad4abf6a1931ae9977", "content_hash": "22c8a64fe74bfbfcc03b9a8ea994e35ab4de1bf3166edc7c068da24398eaf3cc", "source_database": "center", "source_revision": "e1a64a87a46b825b88c082e4518161a47aab53c45694964f8ba1df28f7859f89"}, "tables_zh": [{"key": "explain-labels", "rows": [{"label": "BitmapOr", "identity": "BitmapOr"}], "title": "\u672c\u6784\u5efa\u4e2d\u7684 EXPLAIN \u6807\u7b7e", "columns": [{"key": "label", "label": "\u6587\u672c\u683c\u5f0f\u6807\u7b7e"}, {"key": "identity", "label": "\u7ed3\u6784\u5316\u8282\u70b9\u6807\u8bc6"}]}], "strategies": [], "description": ["\u5bf9\u5404\u5b50\u8ba1\u5212\u751f\u6210\u7684\u4f4d\u56fe\u6c42\u5e76\u96c6\u3002"], "sections_zh": [{"title": "EXPLAIN \u540d\u79f0\u4e0e\u5c5e\u6027", "paragraphs": ["\u7ed3\u6784\u5316\u683c\u5f0f\u4f7f\u7528\u4e0a\u8ff0 Node Type\u3002\u6587\u672c\u683c\u5f0f\u540d\u79f0\u8fd8\u53ef\u80fd\u5305\u542b\u64cd\u4f5c\u3001\u7b56\u7565\u3001\u8fde\u63a5\u7c7b\u578b\u3001\u626b\u63cf\u65b9\u5411\u6216\u805a\u5408\u9636\u6bb5\u5c5e\u6027\u3002", "\u6b64\u6e90\u7801\u8bb0\u5f55\u7684\u6587\u672c\u540d\u79f0\uff1aBitmapOr.", "\u5e76\u884c\u611f\u77e5\u4e0e\u5e76\u884c\u5b89\u5168\u662f\u4e0d\u540c\u7684\u8ba1\u5212\u5c5e\u6027\u3002\u5728\u5e76\u884c\u5de5\u4f5c\u8fdb\u7a0b\u5185\u8fd0\u884c\u7684\u8282\u70b9\u4e0d\u4e00\u5b9a\u662f\u5e76\u884c\u611f\u77e5\u8282\u70b9\u3002"]}, {"title": "\u5185\u5b58\u4e0e\u4e34\u65f6\u5b58\u50a8", "paragraphs": ["\u6b64\u8282\u70b9\u6309\u57fa\u4e8e work_mem \u7684\u9884\u7b97\u5206\u914d\u5143\u7ec4\u4f4d\u7f6e\u4f4d\u56fe\u3002\u4f4d\u56fe\u53ef\u4ee5\u4fdd\u7559\u9875\u7ea7\u6709\u635f\u6761\u76ee\uff0c\u800c\u4e0d\u8bb0\u5f55\u6bcf\u4e2a\u5143\u7ec4\u4f4d\u7f6e\uff0c\u56e0\u6b64\u4ecd\u53ef\u80fd\u9700\u8981\u5806\u91cd\u68c0\u3002"]}, {"title": "\u5e76\u884c\u6267\u884c\u4e0e\u8fd0\u884c\u4fe1\u606f\u91c7\u96c6", "paragraphs": ["\u4ee5\u4e0b\u6e90\u7801\u56de\u8c03\u53ef\u4ee5\u534f\u8c03\u6267\u884c\u6216\u6536\u96c6\u5de5\u4f5c\u8fdb\u7a0b\u7684\u6d4b\u91cf\u6570\u636e\u3002\u56de\u8c03\u5b58\u5728\u4e0d\u4ee3\u8868\u8be5\u8282\u70b9\u666e\u904d\u652f\u6301\u5171\u4eab\u5e76\u884c\u626b\u63cf\u6216\u5171\u4eab\u72b6\u6001\u3002", "\u6b64\u6784\u5efa\u7684\u56de\u8c03\uff1anone extracted from this node implementation."]}, {"title": "\u540c\u7248\u672c\u624b\u518c\u8bf4\u660e", "paragraphs": ["\u7531\u4e8e\u5b9e\u73b0\u4e0a\u7684\u9650\u5236\uff0cBitmapAnd \u548c BitmapOr \u8282\u70b9\u62a5\u544a\u7684\u5b9e\u9645\u884c\u6570\u59cb\u7ec8\u4e3a\u96f6\u3002"]}, {"title": "\u6267\u884c\u5668\u5b9e\u73b0\u8bf4\u660e", "paragraphs": ["\u8bf4\u660e\uff1aBitmapOr \u4e0d\u4f7f\u7528\u5de6\u53f3\u5b50\u6811\uff0c\u800c\u50cf Append \u4e00\u6837\u7ef4\u62a4\u5b50\u8ba1\u5212\u5217\u8868\u3002\u4e0d\u8fc7\u5176\u903b\u8f91\u6bd4 Append \u7b80\u5355\u5f97\u591a\uff0c\u56e0\u4e3a\u65e0\u9700\u5904\u7406\u6b63\u5411\u6216\u53cd\u5411\u6267\u884c\u3002", "\u5bf9\u6bcf\u4e2a\u5f85\u6267\u884c\u8ba1\u5212\u8c03\u7528 ExecInitNode\uff0c\u5e76\u5c06\u7ed3\u679c\u4fdd\u5b58\u5230 bitmapplanstates \u6570\u7ec4\u3002", "BitmapOr \u8ba1\u5212\u6ca1\u6709\u8868\u8fbe\u5f0f\u4e0a\u4e0b\u6587\uff0c\u56e0\u4e3a\u5b83\u4eec\u4ece\u4e0d\u8c03\u7528 ExecQual \u6216 ExecProject\uff0c\u4e5f\u4e0d\u9700\u8981\u5143\u7ec4\u69fd\u3002", "\u53ef\u5bf9 BitmapIndexScan \u5b50\u8282\u70b9\u4f5c\u7279\u6b8a\u5904\u7406\uff0c\u907f\u514d\u4e3a\u6bcf\u4e2a\u5b50\u8282\u70b9\u663e\u5f0f\u8c03\u7528 tbm_union\uff1a\u76f4\u63a5\u4e0b\u4f20\u5f53\u524d\u7ed3\u679c\u4f4d\u56fe\uff0c\u8ba9\u5b50\u8282\u70b9\u5c06\u7ed3\u679c\u6309\u4f4d OR \u5408\u5e76\u8fdb\u53bb\u3002", "ExecReScan \u4e0d\u77e5\u9053\u5f53\u524d\u8282\u70b9\u7684\u5b50\u8ba1\u5212\uff0c\u56e0\u6b64\u5fc5\u987b\u81ea\u884c\u901a\u77e5\u5b50\u8ba1\u5212\u54ea\u4e9b\u53c2\u6570\u53d1\u751f\u4e86\u53d8\u5316\u3002"]}, {"code": "case T_BitmapOr:\n\t\t\tpname = sname = \"BitmapOr\";\n\t\t\tbreak;", "title": "\u6838\u5fc3\u6e90\u7801\u4e2d\u7684 EXPLAIN \u6807\u8bc6"}], "localization": {"status": "complete", "sources": [], "language": "zh", "original_text": {"/versions/15/description/0": "Unions bitmaps produced by its child plans.", "/versions/15/facts/0/label": "Core node tag", "/versions/15/facts/1/label": "Structured EXPLAIN Node Type", "/versions/15/facts/2/label": "Inputs", "/versions/15/facts/2/value": "Bitmap-producing child plans", "/versions/15/facts/3/label": "Output", "/versions/15/facts/3/value": "Tuple-location bitmap, not a tuple stream", "/versions/15/facts/4/label": "Executor initializer", "/versions/15/facts/5/label": "Memory mechanism", "/versions/15/tables/0/title": "EXPLAIN labels in this source build", "/versions/15/related/1/label": "Using EXPLAIN", "/versions/15/related/2/label": "Parallel plans", "/versions/15/sections/0/title": "EXPLAIN names and attributes", "/versions/15/sections/1/title": "Memory and temporary storage", "/versions/15/sections/2/title": "Parallel execution and instrumentation", "/versions/15/sections/3/title": "Same-version manual discussion", "/versions/15/sections/4/title": "Executor implementation notes", "/versions/15/sections/5/title": "EXPLAIN identity in core source", "/versions/15/memory/description": "The node allocates a tuple-location bitmap using a work_mem-derived budget. A bitmap can retain page-level lossy entries instead of every tuple location; heap rechecks then remain necessary.", "/versions/15/sections/0/paragraphs/0": "Structured formats use the Node Type above. Text-format spellings can also include operation, strategy, join type, scan direction or aggregation-stage attributes.", "/versions/15/sections/0/paragraphs/1": "Text names recorded by this source: BitmapOr.", "/versions/15/sections/0/paragraphs/2": "Parallel-aware and parallel-safe are different plan properties. A node running inside a parallel worker is not necessarily a parallel-aware node.", "/versions/15/sections/1/paragraphs/0": "The node allocates a tuple-location bitmap using a work_mem-derived budget. A bitmap can retain page-level lossy entries instead of every tuple location; heap rechecks then remain necessary.", "/versions/15/sections/2/paragraphs/0": "The source callbacks below can coordinate execution or collect worker instrumentation. Their presence is not a blanket claim that this node supports a shared parallel scan or shared state.", "/versions/15/sections/2/paragraphs/1": "Callbacks in this build: none extracted from this node implementation.", "/versions/15/sections/3/paragraphs/0": "BitmapAnd and BitmapOr nodes always report their actual row counts as zero, due to implementation limitations.", "/versions/15/sections/4/paragraphs/0": "NOTES BitmapOr nodes don't make use of their left and right subtrees, rather they maintain a list of subplans, much like Append nodes. The logic is much simpler than Append, however, since we needn't cope with forward/backward execution.", "/versions/15/sections/4/paragraphs/1": "call ExecInitNode on each of the plans to be executed and save the results into the array \"bitmapplanstates\".", "/versions/15/sections/4/paragraphs/2": "BitmapOr plans don't have expression contexts because they never call ExecQual or ExecProject. They don't need any tuple slots either.", "/versions/15/sections/4/paragraphs/3": "We can special-case BitmapIndexScan children to avoid an explicit tbm_union step for each child: just pass down the current result bitmap and let the child OR directly into it.", "/versions/15/sections/4/paragraphs/4": "ExecReScan doesn't know about my subplans, so I have to do changed-parameter signaling myself.", "/versions/15/tables/0/columns/0/label": "Text-format label", "/versions/15/tables/0/columns/1/label": "Structured node identity"}, "fallback_fields": [], "source_language": "en", "original_snapshot_sha256": "8ce3d26dca50c69d59a1a86c2f581c4d38cd6d5c5347e681888f51b1de04253a", "canonical_center_text_hash": "22c8a64fe74bfbfcc03b9a8ea994e35ab4de1bf3166edc7c068da24398eaf3cc"}, "evidence_kind": "source and documentation", "explain_names": ["BitmapOr"], "partial_modes": [], "description_zh": "\u5bf9\u5404\u5b50\u8ba1\u5212\u751f\u6210\u7684\u4f4d\u56fe\u6c42\u5e76\u96c6\u3002", "comparison_data": {"node_tag": "T_BitmapOr", "strategies": [], "text_names": ["BitmapOr"], "initializer": "ExecInitBitmapOr", "partial_modes": [], "memory_mechanism": "bitmap-lossification", "parallel_callbacks": []}, "comparison_hash": "c0ca503a6029c37ec720213dcdc3094997eb194d4920da68f94a7420d3e8f1d2", "manual_language": "zh", "explain_prefixes": ["Parallel", "Async"], "runtime_verified": false, "source_inventory": {"explain": "src/backend/commands/explain.c", "executor": "src/backend/executor/execProcnode.c", "implementation": "src/backend/executor/nodeBitmapOr.c"}, "parallel_callbacks": [], "description_zh_html": "<p>\u5bf9\u5404\u5b50\u8ba1\u5212\u751f\u6210\u7684\u4f4d\u56fe\u6c42\u5e76\u96c6\u3002</p><p>\u6838\u5fc3\u8282\u70b9\u6807\u8bc6\uff1a<code>T_BitmapOr</code>\uff1bEXPLAIN \u540d\u79f0\uff1a<code>BitmapOr</code>\u3002</p><p>\u672c\u7248\u672c\u6e90\u7801\u4e2d\u7684\u5e76\u884c\u6267\u884c\u6216\u89c2\u6d4b\u56de\u8c03\uff1a\u8be5\u8282\u70b9\u5b9e\u73b0\u4e2d\u672a\u63d0\u53d6\u5230\u6b64\u7c7b\u56de\u8c03\u3002\u56de\u8c03\u7684\u5b58\u5728\u4e0d\u8868\u793a\u8be5\u8282\u70b9\u5fc5\u7136\u652f\u6301\u5171\u4eab\u5e76\u884c\u626b\u63cf\uff1b\u5728\u5e76\u884c\u5de5\u4f5c\u8fdb\u7a0b\u4e2d\u6267\u884c\u4e5f\u4e0d\u7b49\u4e8e\u5177\u6709\u5e76\u884c\u611f\u77e5\u80fd\u529b\u3002</p><h3>\u540c\u7248\u672c\u4e2d\u6587\u624b\u518c\u8282\u9009</h3><p>\n<code>EXPLAIN ANALYZE</code> \u6d4b\u5f97\u7684\u8fd0\u884c\u65f6\u95f4\uff0c\u53ef\u80fd\u4ee5\u4e24\u79cd\u91cd\u8981\u65b9\u5f0f\u504f\u79bb\u540c\u4e00\u67e5\u8be2\u7684\u6b63\u5e38\u6267\u884c\u65f6\u95f4\u3002\u7b2c\u4e00\uff0c\u7531\u4e8e\u4e0d\u4f1a\u5411\u5ba2\u6237\u7aef\u4f20\u9012\u4efb\u4f55\u8f93\u51fa\u884c\uff0c\u56e0\u6b64\u7f51\u7edc\u4f20\u8f93\u5f00\u9500\u548c I/O \u8f6c\u6362\u5f00\u9500\u5747\u4e0d\u4f1a\u88ab\u8ba1\u5165\u3002\u7b2c\u4e8c\uff0c<code>EXPLAIN ANALYZE</code> \u9644\u52a0\u7684\u6d4b\u91cf\u5f00\u9500\u672c\u8eab\u53ef\u80fd\u76f8\u5f53\u53ef\u89c2\uff0c\u5c24\u5176\u662f\u5728\u64cd\u4f5c\u7cfb\u7edf\u8c03\u7528 <code>gettimeofday()</code> \u8f83\u6162\u7684\u673a\u5668\u4e0a\u3002\u53ef\u4ee5\u4f7f\u7528 <a href=\"/zh/docs/15/pgtesttiming.html\" rel=\"nofollow\"><span><span>pg_test_timing</span></span></a> \u5de5\u5177\u6765\u6d4b\u91cf\u7cfb\u7edf\u4e0a\u7684\u8ba1\u65f6\u5f00\u9500\u3002\n   </p><p>\n    \u4e0d\u5e94\u5c06 <code>EXPLAIN</code> \u7ed3\u679c\u5916\u63a8\u5230\u4e0e\u5b9e\u9645\u6d4b\u8bd5\u573a\u666f\u5dee\u5f02\u5f88\u5927\u7684\u60c5\u51b5\u3002\u4f8b\u5982\uff0c\u5728\u4e00\u4e2a\u5f88\u5c0f\u7684\u8868\u4e0a\u5f97\u5230\u7684\u7ed3\u679c\uff0c\u4e0d\u80fd\u5047\u5b9a\u4e5f\u9002\u7528\u4e8e\u5927\u578b\u8868\u3002\u89c4\u5212\u5668\u7684\u4ee3\u4ef7\u4f30\u8ba1\u4e0d\u662f\u7ebf\u6027\u7684\uff0c\u56e0\u6b64\u5b83\u53ef\u80fd\u4f1a\u4e3a\u66f4\u5927\u6216\u66f4\u5c0f\u7684\u8868\u9009\u62e9\u4e0d\u540c\u7684\u8ba1\u5212\u3002\u4e00\u4e2a\u6781\u7aef\u793a\u4f8b\u662f\uff1a\u5bf9\u4e8e\u53ea\u5360\u7528\u4e00\u4e2a\u78c1\u76d8\u9875\u7684\u8868\uff0c\u65e0\u8bba\u7d22\u5f15\u662f\u5426\u53ef\u7528\uff0c\u51e0\u4e4e\u603b\u4f1a\u5f97\u5230\u987a\u5e8f\u626b\u63cf\u8ba1\u5212\u3002\u89c4\u5212\u5668\u8ba4\u8bc6\u5230\uff0c\u65e0\u8bba\u5982\u4f55\u5904\u7406\u8be5\u8868\u90fd\u9700\u8981\u4e00\u6b21\u78c1\u76d8\u9875\u8bfb\u53d6\uff0c\u56e0\u6b64\u518d\u989d\u5916\u8bfb\u53d6\u9875\u9762\u53bb\u67e5\u770b\u7d22\u5f15\u5e76\u6ca1\u6709\u4ef7\u503c\u3002\uff08\u524d\u9762\u7684 <code>polygon_tbl</code> \u793a\u4f8b\u5df2\u7ecf\u5c55\u793a\u8fc7\u8fd9\u79cd\u60c5\u51b5\u3002\uff09\n   </p><p>\u6709\u65f6\u5b9e\u9645\u503c\u4e0e\u4f30\u8ba1\u503c\u4e0d\u592a\u4e00\u81f4\uff0c\u4f46\u5b9e\u9645\u4e0a\u5e76\u6ca1\u6709\u95ee\u9898\u3002\u5176\u4e2d\u4e00\u79cd\u60c5\u51b5\u662f\uff0c\u8ba1\u5212\u8282\u70b9\u7684\u6267\u884c\u56e0 <code>LIMIT</code> \u6216\u7c7b\u4f3c\u6548\u679c\u800c\u63d0\u524d\u505c\u6b62\u3002\u4f8b\u5982\uff0c\u5728\u524d\u9762\u4f7f\u7528\u7684 <code>LIMIT</code> \u67e5\u8be2\u4e2d\uff1a</p><p>Index Scan \u8282\u70b9\u7684\u4f30\u8ba1\u4ee3\u4ef7\u548c\u884c\u6570\u6309\u8be5\u8282\u70b9\u6267\u884c\u5230\u5b8c\u6210\u7684\u60c5\u51b5\u663e\u793a\u3002\u4f46\u5b9e\u9645\u4e0a\uff0cLimit \u8282\u70b9\u53d6\u5f97\u4e24\u884c\u540e\u5c31\u505c\u6b62\u8bf7\u6c42\u884c\uff0c\u56e0\u6b64\u5b9e\u9645\u884c\u6570\u53ea\u6709 2\uff0c\u8fd0\u884c\u65f6\u95f4\u4e5f\u5c0f\u4e8e\u4f30\u8ba1\u4ee3\u4ef7\u6240\u6697\u793a\u7684\u65f6\u95f4\u3002\u8fd9\u4e0d\u662f\u4f30\u8ba1\u9519\u8bef\uff0c\u53ea\u662f\u4f30\u8ba1\u503c\u4e0e\u5b9e\u9645\u503c\u7684\u663e\u793a\u65b9\u5f0f\u5b58\u5728\u5dee\u522b\u3002</p><p><a href=\"/zh/docs/15/performance-tips.html#USING-EXPLAIN-CAVEATS\" rel=\"nofollow\">\u67e5\u770b\u5b8c\u6574\u4e2d\u6587\u624b\u518c\u4e0e\u4e0a\u4e0b\u6587</a>\u3002</p><p>\u672c\u9875\u5f00\u5934\u7684\u4e2d\u6587\u8bf4\u660e\u4e3a PG.CENTER \u5bf9\u7f16\u8f91\u8bf4\u660e\u7684\u7ffb\u8bd1\uff1b\u624b\u518c\u8282\u9009\u4fdd\u7559\u5bf9\u5e94\u7248\u672c\u4e2d\u6587\u6587\u6863\u539f\u6587\u3002\u6e90\u7801\u4fe1\u606f\u53ca\u624b\u518c\u793a\u4f8b\u4e0d\u4ee3\u8868\u91cd\u65b0\u8fdb\u884c\u8fc7\u8fd0\u884c\u6d4b\u8bd5\u3002</p>"}, "16": {"facts": [{"label": "\u6838\u5fc3\u8282\u70b9\u6807\u7b7e", "value": "T_BitmapOr"}, {"label": "\u7ed3\u6784\u5316 EXPLAIN \u8282\u70b9\u7c7b\u578b", "value": "BitmapOr"}, {"label": "\u8f93\u5165", "value": "\u4ea7\u751f\u4f4d\u56fe\u7684\u5b50\u8ba1\u5212"}, {"label": "\u8f93\u51fa", "value": "\u5143\u7ec4\u4f4d\u7f6e\u4f4d\u56fe\uff0c\u4e0d\u662f\u5143\u7ec4\u6d41"}, {"label": "\u6267\u884c\u5668\u521d\u59cb\u5316\u51fd\u6570", "value": "ExecInitBitmapOr"}, {"label": "\u5185\u5b58\u673a\u5236", "value": "bitmap-lossification"}], "memory": {"evidence": [{"url": "https://ftp.postgresql.org/pub/source/v16.15/postgresql-16.15.tar.bz2", "path": "src/backend/executor/nodeBitmapOr.c", "label": "src/backend/executor/nodeBitmapOr.c", "sha256": "d29259efccb1b04f34599a20ae7ccb9970fc6fe2e19f39090b821b55399fbc41", "archive_sha256": "c1575341fa7bd40f5274ea465b34390f4dc64cdd0770af327005caaeb9f6b7ed"}, {"url": "https://ftp.postgresql.org/pub/source/v16.15/postgresql-16.15.tar.bz2", "path": "src/backend/nodes/tidbitmap.c", "label": "src/backend/nodes/tidbitmap.c", "sha256": "d0a2549a532f65299aea5599ee1bedffe47101a07d0de21bec07068547ae237e", "archive_sha256": "c1575341fa7bd40f5274ea465b34390f4dc64cdd0770af327005caaeb9f6b7ed"}], "mechanism": "bitmap-lossification", "description": "The node allocates a tuple-location bitmap using a work_mem-derived budget. 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"https://ftp.postgresql.org/pub/source/v16.15/postgresql-16.15.tar.bz2", "source_snapshot_utc": ""}, "sources": [{"url": "https://ftp.postgresql.org/pub/source/v16.15/postgresql-16.15.tar.bz2", "line": 1244, "path": "src/backend/commands/explain.c", "label": "src/backend/commands/explain.c:1244", "sha256": "8e017f0116dbea471339b40c37a667cc9f95039e7e0329c783e5e8ce194de7e1", "archive_sha256": "c1575341fa7bd40f5274ea465b34390f4dc64cdd0770af327005caaeb9f6b7ed"}, {"url": "https://ftp.postgresql.org/pub/source/v16.15/postgresql-16.15.tar.bz2", "line": 201, "path": "src/backend/executor/execProcnode.c", "label": "src/backend/executor/execProcnode.c:201", "sha256": "e48c08e555f8cb4e4bb43df516c4b8906ce9bc374b2a745d98a1fc8c22cc5099", "archive_sha256": "c1575341fa7bd40f5274ea465b34390f4dc64cdd0770af327005caaeb9f6b7ed"}, {"url": "https://ftp.postgresql.org/pub/source/v16.15/postgresql-16.15.tar.bz2", "path": "src/backend/executor/nodeBitmapOr.c", "label": "src/backend/executor/nodeBitmapOr.c", 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"source_facts_revision": "c1575341fa7bd40f5274ea465b34390f4dc64cdd0770af327005caaeb9f6b7ed"}, "facts_zh": [{"label": "\u6838\u5fc3\u8282\u70b9\u6807\u7b7e", "value": "T_BitmapOr"}, {"label": "\u7ed3\u6784\u5316 EXPLAIN \u8282\u70b9\u7c7b\u578b", "value": "BitmapOr"}, {"label": "\u8f93\u5165", "value": "\u4ea7\u751f\u4f4d\u56fe\u7684\u5b50\u8ba1\u5212"}, {"label": "\u8f93\u51fa", "value": "\u5143\u7ec4\u4f4d\u7f6e\u4f4d\u56fe\uff0c\u4e0d\u662f\u5143\u7ec4\u6d41"}, {"label": "\u6267\u884c\u5668\u521d\u59cb\u5316\u51fd\u6570", "value": "ExecInitBitmapOr"}, {"label": "\u5185\u5b58\u673a\u5236", "value": "bitmap-lossification"}], "node_tag": "T_BitmapOr", "sections": [{"title": "EXPLAIN \u540d\u79f0\u4e0e\u5c5e\u6027", "paragraphs": ["\u7ed3\u6784\u5316\u683c\u5f0f\u4f7f\u7528\u4e0a\u8ff0 Node Type\u3002\u6587\u672c\u683c\u5f0f\u540d\u79f0\u8fd8\u53ef\u80fd\u5305\u542b\u64cd\u4f5c\u3001\u7b56\u7565\u3001\u8fde\u63a5\u7c7b\u578b\u3001\u626b\u63cf\u65b9\u5411\u6216\u805a\u5408\u9636\u6bb5\u5c5e\u6027\u3002", "\u6b64\u6e90\u7801\u8bb0\u5f55\u7684\u6587\u672c\u540d\u79f0\uff1aBitmapOr.", "\u5e76\u884c\u611f\u77e5\u4e0e\u5e76\u884c\u5b89\u5168\u662f\u4e0d\u540c\u7684\u8ba1\u5212\u5c5e\u6027\u3002\u5728\u5e76\u884c\u5de5\u4f5c\u8fdb\u7a0b\u5185\u8fd0\u884c\u7684\u8282\u70b9\u4e0d\u4e00\u5b9a\u662f\u5e76\u884c\u611f\u77e5\u8282\u70b9\u3002"]}, {"title": "\u5185\u5b58\u4e0e\u4e34\u65f6\u5b58\u50a8", "paragraphs": ["\u6b64\u8282\u70b9\u6309\u57fa\u4e8e work_mem \u7684\u9884\u7b97\u5206\u914d\u5143\u7ec4\u4f4d\u7f6e\u4f4d\u56fe\u3002\u4f4d\u56fe\u53ef\u4ee5\u4fdd\u7559\u9875\u7ea7\u6709\u635f\u6761\u76ee\uff0c\u800c\u4e0d\u8bb0\u5f55\u6bcf\u4e2a\u5143\u7ec4\u4f4d\u7f6e\uff0c\u56e0\u6b64\u4ecd\u53ef\u80fd\u9700\u8981\u5806\u91cd\u68c0\u3002"]}, {"title": "\u5e76\u884c\u6267\u884c\u4e0e\u8fd0\u884c\u4fe1\u606f\u91c7\u96c6", "paragraphs": ["\u4ee5\u4e0b\u6e90\u7801\u56de\u8c03\u53ef\u4ee5\u534f\u8c03\u6267\u884c\u6216\u6536\u96c6\u5de5\u4f5c\u8fdb\u7a0b\u7684\u6d4b\u91cf\u6570\u636e\u3002\u56de\u8c03\u5b58\u5728\u4e0d\u4ee3\u8868\u8be5\u8282\u70b9\u666e\u904d\u652f\u6301\u5171\u4eab\u5e76\u884c\u626b\u63cf\u6216\u5171\u4eab\u72b6\u6001\u3002", "\u6b64\u6784\u5efa\u7684\u56de\u8c03\uff1anone extracted from this node implementation."]}, {"title": "\u540c\u7248\u672c\u624b\u518c\u8bf4\u660e", "paragraphs": ["\u7531\u4e8e\u5b9e\u73b0\u4e0a\u7684\u9650\u5236\uff0cBitmapAnd \u548c BitmapOr \u8282\u70b9\u62a5\u544a\u7684\u5b9e\u9645\u884c\u6570\u59cb\u7ec8\u4e3a\u96f6\u3002"]}, {"title": "\u6267\u884c\u5668\u5b9e\u73b0\u8bf4\u660e", "paragraphs": ["\u8bf4\u660e\uff1aBitmapOr \u4e0d\u4f7f\u7528\u5de6\u53f3\u5b50\u6811\uff0c\u800c\u50cf Append \u4e00\u6837\u7ef4\u62a4\u5b50\u8ba1\u5212\u5217\u8868\u3002\u4e0d\u8fc7\u5176\u903b\u8f91\u6bd4 Append \u7b80\u5355\u5f97\u591a\uff0c\u56e0\u4e3a\u65e0\u9700\u5904\u7406\u6b63\u5411\u6216\u53cd\u5411\u6267\u884c\u3002", "\u5bf9\u6bcf\u4e2a\u5f85\u6267\u884c\u8ba1\u5212\u8c03\u7528 ExecInitNode\uff0c\u5e76\u5c06\u7ed3\u679c\u4fdd\u5b58\u5230 bitmapplanstates \u6570\u7ec4\u3002", "BitmapOr \u8ba1\u5212\u6ca1\u6709\u8868\u8fbe\u5f0f\u4e0a\u4e0b\u6587\uff0c\u56e0\u4e3a\u5b83\u4eec\u4ece\u4e0d\u8c03\u7528 ExecQual \u6216 ExecProject\uff0c\u4e5f\u4e0d\u9700\u8981\u5143\u7ec4\u69fd\u3002", "\u53ef\u5bf9 BitmapIndexScan \u5b50\u8282\u70b9\u4f5c\u7279\u6b8a\u5904\u7406\uff0c\u907f\u514d\u4e3a\u6bcf\u4e2a\u5b50\u8282\u70b9\u663e\u5f0f\u8c03\u7528 tbm_union\uff1a\u76f4\u63a5\u4e0b\u4f20\u5f53\u524d\u7ed3\u679c\u4f4d\u56fe\uff0c\u8ba9\u5b50\u8282\u70b9\u5c06\u7ed3\u679c\u6309\u4f4d OR \u5408\u5e76\u8fdb\u53bb\u3002", "ExecReScan \u4e0d\u77e5\u9053\u5f53\u524d\u8282\u70b9\u7684\u5b50\u8ba1\u5212\uff0c\u56e0\u6b64\u5fc5\u987b\u81ea\u884c\u901a\u77e5\u5b50\u8ba1\u5212\u54ea\u4e9b\u53c2\u6570\u53d1\u751f\u4e86\u53d8\u5316\u3002"]}, {"code": "case T_BitmapOr:\n\t\t\tpname = sname = \"BitmapOr\";\n\t\t\tbreak;", "title": "\u6838\u5fc3\u6e90\u7801\u4e2d\u7684 EXPLAIN \u6807\u8bc6"}], "center_zh": {"title": "BitmapOr", "locale": "zh-Hans", "source": {"key": "bitmapor", "locale": "zh-Hans", "version": "16", "text_hash": "01d88612a790020858233efd76f6f935dc34dece1419e713c6da3270e5734fba", "collection": "plan", "dataset_hash": "7c31b524dfe136022d39a6ae8dcfac6b3bbd5f8fdaf422536599981252aff0c9", "source_database": "center", "source_revision": "c1575341fa7bd40f5274ea465b34390f4dc64cdd0770af327005caaeb9f6b7ed"}, "payload": {"facts": [{"label": "\u6838\u5fc3\u8282\u70b9\u6807\u7b7e", "value": "T_BitmapOr"}, {"label": "\u7ed3\u6784\u5316 EXPLAIN \u8282\u70b9\u7c7b\u578b", "value": "BitmapOr"}, {"label": "\u8f93\u5165", "value": "\u4ea7\u751f\u4f4d\u56fe\u7684\u5b50\u8ba1\u5212"}, {"label": "\u8f93\u51fa", "value": "\u5143\u7ec4\u4f4d\u7f6e\u4f4d\u56fe\uff0c\u4e0d\u662f\u5143\u7ec4\u6d41"}, {"label": "\u6267\u884c\u5668\u521d\u59cb\u5316\u51fd\u6570", "value": "ExecInitBitmapOr"}, {"label": "\u5185\u5b58\u673a\u5236", "value": "bitmap-lossification"}], "tables": [{"key": "explain-labels", "rows": [{"label": "BitmapOr", "identity": "BitmapOr"}], "title": "\u672c\u6784\u5efa\u4e2d\u7684 EXPLAIN \u6807\u7b7e", "columns": [{"key": "label", "label": "\u6587\u672c\u683c\u5f0f\u6807\u7b7e"}, {"key": "identity", "label": "\u7ed3\u6784\u5316\u8282\u70b9\u6807\u8bc6"}]}], "zh_from": {"kind": "same-version-chinese-manual-with-authored-translation-of-reviewed-guidance", "manual": {"url": "/zh/docs/16/using-explain.html#USING-EXPLAIN-CAVEATS", "anchor": "USING-EXPLAIN-CAVEATS", "locale": "zh-Hans", "version": "16", "build_id": 103, "page_key": "using-explain.html", "extraction": "concept-introduction", "source_hash": "394de9d6895c7909a1a823408b8c980c5415db8ca3c212e23d6e7e9b6e01c6cc", "fragment_sha256": "5b6d3cdd40d42b5da5b0810874e5bfbbb851bf334e8ca90eebe30c77816264e6", "source_revision": "unknown:rendered-translation-baseline", "translation_revision": "git:b1b500221dbe5437cfca004d6b04d3f6e422765d;html-sha256:80579a071736780f9c4022bb5148e1fb1256f1a33591306af67816e9e9bf3a9b", "translated_from_revision": null}, "body_sha256": "c55a2846f0c6c45d74c1e00646fdb6337528ed927c591eb5458df4e3185b9305", "runtime_rerun": false, "authored_translation": "authored-translation-of-reviewed-guidance", "source_facts_revision": "c1575341fa7bd40f5274ea465b34390f4dc64cdd0770af327005caaeb9f6b7ed"}, "sections": [{"title": "EXPLAIN \u540d\u79f0\u4e0e\u5c5e\u6027", "paragraphs": ["\u7ed3\u6784\u5316\u683c\u5f0f\u4f7f\u7528\u4e0a\u8ff0 Node Type\u3002\u6587\u672c\u683c\u5f0f\u540d\u79f0\u8fd8\u53ef\u80fd\u5305\u542b\u64cd\u4f5c\u3001\u7b56\u7565\u3001\u8fde\u63a5\u7c7b\u578b\u3001\u626b\u63cf\u65b9\u5411\u6216\u805a\u5408\u9636\u6bb5\u5c5e\u6027\u3002", "\u6b64\u6e90\u7801\u8bb0\u5f55\u7684\u6587\u672c\u540d\u79f0\uff1aBitmapOr.", "\u5e76\u884c\u611f\u77e5\u4e0e\u5e76\u884c\u5b89\u5168\u662f\u4e0d\u540c\u7684\u8ba1\u5212\u5c5e\u6027\u3002\u5728\u5e76\u884c\u5de5\u4f5c\u8fdb\u7a0b\u5185\u8fd0\u884c\u7684\u8282\u70b9\u4e0d\u4e00\u5b9a\u662f\u5e76\u884c\u611f\u77e5\u8282\u70b9\u3002"]}, {"title": "\u5185\u5b58\u4e0e\u4e34\u65f6\u5b58\u50a8", "paragraphs": ["\u6b64\u8282\u70b9\u6309\u57fa\u4e8e work_mem \u7684\u9884\u7b97\u5206\u914d\u5143\u7ec4\u4f4d\u7f6e\u4f4d\u56fe\u3002\u4f4d\u56fe\u53ef\u4ee5\u4fdd\u7559\u9875\u7ea7\u6709\u635f\u6761\u76ee\uff0c\u800c\u4e0d\u8bb0\u5f55\u6bcf\u4e2a\u5143\u7ec4\u4f4d\u7f6e\uff0c\u56e0\u6b64\u4ecd\u53ef\u80fd\u9700\u8981\u5806\u91cd\u68c0\u3002"]}, {"title": "\u5e76\u884c\u6267\u884c\u4e0e\u8fd0\u884c\u4fe1\u606f\u91c7\u96c6", "paragraphs": ["\u4ee5\u4e0b\u6e90\u7801\u56de\u8c03\u53ef\u4ee5\u534f\u8c03\u6267\u884c\u6216\u6536\u96c6\u5de5\u4f5c\u8fdb\u7a0b\u7684\u6d4b\u91cf\u6570\u636e\u3002\u56de\u8c03\u5b58\u5728\u4e0d\u4ee3\u8868\u8be5\u8282\u70b9\u666e\u904d\u652f\u6301\u5171\u4eab\u5e76\u884c\u626b\u63cf\u6216\u5171\u4eab\u72b6\u6001\u3002", "\u6b64\u6784\u5efa\u7684\u56de\u8c03\uff1anone extracted from this node implementation."]}, {"title": "\u540c\u7248\u672c\u624b\u518c\u8bf4\u660e", "paragraphs": ["\u7531\u4e8e\u5b9e\u73b0\u4e0a\u7684\u9650\u5236\uff0cBitmapAnd \u548c BitmapOr \u8282\u70b9\u62a5\u544a\u7684\u5b9e\u9645\u884c\u6570\u59cb\u7ec8\u4e3a\u96f6\u3002"]}, {"title": "\u6267\u884c\u5668\u5b9e\u73b0\u8bf4\u660e", "paragraphs": ["\u8bf4\u660e\uff1aBitmapOr \u4e0d\u4f7f\u7528\u5de6\u53f3\u5b50\u6811\uff0c\u800c\u50cf Append \u4e00\u6837\u7ef4\u62a4\u5b50\u8ba1\u5212\u5217\u8868\u3002\u4e0d\u8fc7\u5176\u903b\u8f91\u6bd4 Append \u7b80\u5355\u5f97\u591a\uff0c\u56e0\u4e3a\u65e0\u9700\u5904\u7406\u6b63\u5411\u6216\u53cd\u5411\u6267\u884c\u3002", "\u5bf9\u6bcf\u4e2a\u5f85\u6267\u884c\u8ba1\u5212\u8c03\u7528 ExecInitNode\uff0c\u5e76\u5c06\u7ed3\u679c\u4fdd\u5b58\u5230 bitmapplanstates \u6570\u7ec4\u3002", "BitmapOr \u8ba1\u5212\u6ca1\u6709\u8868\u8fbe\u5f0f\u4e0a\u4e0b\u6587\uff0c\u56e0\u4e3a\u5b83\u4eec\u4ece\u4e0d\u8c03\u7528 ExecQual \u6216 ExecProject\uff0c\u4e5f\u4e0d\u9700\u8981\u5143\u7ec4\u69fd\u3002", "\u53ef\u5bf9 BitmapIndexScan \u5b50\u8282\u70b9\u4f5c\u7279\u6b8a\u5904\u7406\uff0c\u907f\u514d\u4e3a\u6bcf\u4e2a\u5b50\u8282\u70b9\u663e\u5f0f\u8c03\u7528 tbm_union\uff1a\u76f4\u63a5\u4e0b\u4f20\u5f53\u524d\u7ed3\u679c\u4f4d\u56fe\uff0c\u8ba9\u5b50\u8282\u70b9\u5c06\u7ed3\u679c\u6309\u4f4d OR \u5408\u5e76\u8fdb\u53bb\u3002", "ExecReScan \u4e0d\u77e5\u9053\u5f53\u524d\u8282\u70b9\u7684\u5b50\u8ba1\u5212\uff0c\u56e0\u6b64\u5fc5\u987b\u81ea\u884c\u901a\u77e5\u5b50\u8ba1\u5212\u54ea\u4e9b\u53c2\u6570\u53d1\u751f\u4e86\u53d8\u5316\u3002"]}, {"code": "case T_BitmapOr:\n\t\t\tpname = sname = \"BitmapOr\";\n\t\t\tbreak;", "title": "\u6838\u5fc3\u6e90\u7801\u4e2d\u7684 EXPLAIN \u6807\u8bc6"}], "description_zh": "\u5bf9\u5404\u5b50\u8ba1\u5212\u751f\u6210\u7684\u4f4d\u56fe\u6c42\u5e76\u96c6\u3002", "description_zh_html": "<p>\u5bf9\u5404\u5b50\u8ba1\u5212\u751f\u6210\u7684\u4f4d\u56fe\u6c42\u5e76\u96c6\u3002</p><p>\u6838\u5fc3\u8282\u70b9\u6807\u8bc6\uff1a<code>T_BitmapOr</code>\uff1bEXPLAIN \u540d\u79f0\uff1a<code>BitmapOr</code>\u3002</p><p>\u672c\u7248\u672c\u6e90\u7801\u4e2d\u7684\u5e76\u884c\u6267\u884c\u6216\u89c2\u6d4b\u56de\u8c03\uff1a\u8be5\u8282\u70b9\u5b9e\u73b0\u4e2d\u672a\u63d0\u53d6\u5230\u6b64\u7c7b\u56de\u8c03\u3002\u56de\u8c03\u7684\u5b58\u5728\u4e0d\u8868\u793a\u8be5\u8282\u70b9\u5fc5\u7136\u652f\u6301\u5171\u4eab\u5e76\u884c\u626b\u63cf\uff1b\u5728\u5e76\u884c\u5de5\u4f5c\u8fdb\u7a0b\u4e2d\u6267\u884c\u4e5f\u4e0d\u7b49\u4e8e\u5177\u6709\u5e76\u884c\u611f\u77e5\u80fd\u529b\u3002</p><h3>\u540c\u7248\u672c\u4e2d\u6587\u624b\u518c\u8282\u9009</h3><p>\n<code class=\"command\">EXPLAIN ANALYZE</code> \u6d4b\u5f97\u7684\u8fd0\u884c\u65f6\u95f4\uff0c\u53ef\u80fd\u4ee5\u4e24\u79cd\u91cd\u8981\u65b9\u5f0f\u504f\u79bb\u540c\u4e00\u67e5\u8be2\u7684\u6b63\u5e38\u6267\u884c\u65f6\u95f4\u3002\u7b2c\u4e00\uff0c\u7531\u4e8e\u4e0d\u4f1a\u5411\u5ba2\u6237\u7aef\u4f20\u9012\u4efb\u4f55\u8f93\u51fa\u884c\uff0c\u56e0\u6b64\u7f51\u7edc\u4f20\u8f93\u5f00\u9500\u548c I/O \u8f6c\u6362\u5f00\u9500\u5747\u4e0d\u4f1a\u88ab\u8ba1\u5165\u3002\u7b2c\u4e8c\uff0c<code class=\"command\">EXPLAIN ANALYZE</code> \u9644\u52a0\u7684\u6d4b\u91cf\u5f00\u9500\u672c\u8eab\u53ef\u80fd\u76f8\u5f53\u53ef\u89c2\uff0c\u5c24\u5176\u662f\u5728\u64cd\u4f5c\u7cfb\u7edf\u8c03\u7528 <code class=\"function\">gettimeofday()</code> \u8f83\u6162\u7684\u673a\u5668\u4e0a\u3002\u53ef\u4ee5\u4f7f\u7528 <a class=\"xref\" href=\"/zh/docs/16/pgtesttiming.html\"><span class=\"refentrytitle\"><span class=\"application\">pg_test_timing</span></span></a> \u5de5\u5177\u6765\u6d4b\u91cf\u7cfb\u7edf\u4e0a\u7684\u8ba1\u65f6\u5f00\u9500\u3002\n   </p><p>\n    \u4e0d\u5e94\u5c06 <code class=\"command\">EXPLAIN</code> \u7ed3\u679c\u5916\u63a8\u5230\u4e0e\u5b9e\u9645\u6d4b\u8bd5\u573a\u666f\u5dee\u5f02\u5f88\u5927\u7684\u60c5\u51b5\u3002\u4f8b\u5982\uff0c\u5728\u4e00\u4e2a\u5f88\u5c0f\u7684\u8868\u4e0a\u5f97\u5230\u7684\u7ed3\u679c\uff0c\u4e0d\u80fd\u5047\u5b9a\u4e5f\u9002\u7528\u4e8e\u5927\u578b\u8868\u3002\u89c4\u5212\u5668\u7684\u4ee3\u4ef7\u4f30\u8ba1\u4e0d\u662f\u7ebf\u6027\u7684\uff0c\u56e0\u6b64\u5b83\u53ef\u80fd\u4f1a\u4e3a\u66f4\u5927\u6216\u66f4\u5c0f\u7684\u8868\u9009\u62e9\u4e0d\u540c\u7684\u8ba1\u5212\u3002\u4e00\u4e2a\u6781\u7aef\u793a\u4f8b\u662f\uff1a\u5bf9\u4e8e\u53ea\u5360\u7528\u4e00\u4e2a\u78c1\u76d8\u9875\u7684\u8868\uff0c\u65e0\u8bba\u7d22\u5f15\u662f\u5426\u53ef\u7528\uff0c\u51e0\u4e4e\u603b\u4f1a\u5f97\u5230\u987a\u5e8f\u626b\u63cf\u8ba1\u5212\u3002\u89c4\u5212\u5668\u8ba4\u8bc6\u5230\uff0c\u65e0\u8bba\u5982\u4f55\u5904\u7406\u8be5\u8868\u90fd\u9700\u8981\u4e00\u6b21\u78c1\u76d8\u9875\u8bfb\u53d6\uff0c\u56e0\u6b64\u518d\u989d\u5916\u8bfb\u53d6\u9875\u9762\u53bb\u67e5\u770b\u7d22\u5f15\u5e76\u6ca1\u6709\u4ef7\u503c\u3002\uff08\u524d\u9762\u7684 <code class=\"literal\">polygon_tbl</code> \u793a\u4f8b\u5df2\u7ecf\u5c55\u793a\u8fc7\u8fd9\u79cd\u60c5\u51b5\u3002\uff09\n   </p><p>\u6709\u65f6\u5b9e\u9645\u503c\u4e0e\u4f30\u8ba1\u503c\u4e0d\u592a\u4e00\u81f4\uff0c\u4f46\u5b9e\u9645\u4e0a\u5e76\u6ca1\u6709\u95ee\u9898\u3002\u5176\u4e2d\u4e00\u79cd\u60c5\u51b5\u662f\uff0c\u8ba1\u5212\u8282\u70b9\u7684\u6267\u884c\u56e0 <code class=\"literal\">LIMIT</code> \u6216\u7c7b\u4f3c\u6548\u679c\u800c\u63d0\u524d\u505c\u6b62\u3002\u4f8b\u5982\uff0c\u5728\u524d\u9762\u4f7f\u7528\u7684 <code class=\"literal\">LIMIT</code> \u67e5\u8be2\u4e2d\uff1a</p><p>Index Scan \u8282\u70b9\u7684\u4f30\u8ba1\u4ee3\u4ef7\u548c\u884c\u6570\u6309\u8be5\u8282\u70b9\u6267\u884c\u5230\u5b8c\u6210\u7684\u60c5\u51b5\u663e\u793a\u3002\u4f46\u5b9e\u9645\u4e0a\uff0cLimit \u8282\u70b9\u53d6\u5f97\u4e24\u884c\u540e\u5c31\u505c\u6b62\u8bf7\u6c42\u884c\uff0c\u56e0\u6b64\u5b9e\u9645\u884c\u6570\u53ea\u6709 2\uff0c\u8fd0\u884c\u65f6\u95f4\u4e5f\u5c0f\u4e8e\u4f30\u8ba1\u4ee3\u4ef7\u6240\u6697\u793a\u7684\u65f6\u95f4\u3002\u8fd9\u4e0d\u662f\u4f30\u8ba1\u9519\u8bef\uff0c\u53ea\u662f\u4f30\u8ba1\u503c\u4e0e\u5b9e\u9645\u503c\u7684\u663e\u793a\u65b9\u5f0f\u5b58\u5728\u5dee\u522b\u3002</p><p><a href=\"/zh/docs/16/using-explain.html#USING-EXPLAIN-CAVEATS\">\u67e5\u770b\u5b8c\u6574\u4e2d\u6587\u624b\u518c\u4e0e\u4e0a\u4e0b\u6587</a>\u3002</p><p>\u672c\u9875\u5f00\u5934\u7684\u4e2d\u6587\u8bf4\u660e\u4e3a PG.CENTER \u5bf9\u7f16\u8f91\u8bf4\u660e\u7684\u7ffb\u8bd1\uff1b\u624b\u518c\u8282\u9009\u4fdd\u7559\u5bf9\u5e94\u7248\u672c\u4e2d\u6587\u6587\u6863\u539f\u6587\u3002\u6e90\u7801\u4fe1\u606f\u53ca\u624b\u518c\u793a\u4f8b\u4e0d\u4ee3\u8868\u91cd\u65b0\u8fdb\u884c\u8fc7\u8fd0\u884c\u6d4b\u8bd5\u3002</p>"}, "summary": "\u5bf9\u5404\u5b50\u8ba1\u5212\u751f\u6210\u7684\u4f4d\u56fe\u6c42\u5e76\u96c6\u3002", "version": "16", "link_map": {"/zh/docs/16/pgtesttiming.html": "/docs/16/pgtesttiming.html", "/zh/docs/16/using-explain.html#USING-EXPLAIN-CAVEATS": "/docs/16/using-explain.html#USING-EXPLAIN-CAVEATS"}, "body_html": "<p>\u5bf9\u5404\u5b50\u8ba1\u5212\u751f\u6210\u7684\u4f4d\u56fe\u6c42\u5e76\u96c6\u3002</p><p>\u6838\u5fc3\u8282\u70b9\u6807\u8bc6\uff1a<code>T_BitmapOr</code>\uff1bEXPLAIN \u540d\u79f0\uff1a<code>BitmapOr</code>\u3002</p><p>\u672c\u7248\u672c\u6e90\u7801\u4e2d\u7684\u5e76\u884c\u6267\u884c\u6216\u89c2\u6d4b\u56de\u8c03\uff1a\u8be5\u8282\u70b9\u5b9e\u73b0\u4e2d\u672a\u63d0\u53d6\u5230\u6b64\u7c7b\u56de\u8c03\u3002\u56de\u8c03\u7684\u5b58\u5728\u4e0d\u8868\u793a\u8be5\u8282\u70b9\u5fc5\u7136\u652f\u6301\u5171\u4eab\u5e76\u884c\u626b\u63cf\uff1b\u5728\u5e76\u884c\u5de5\u4f5c\u8fdb\u7a0b\u4e2d\u6267\u884c\u4e5f\u4e0d\u7b49\u4e8e\u5177\u6709\u5e76\u884c\u611f\u77e5\u80fd\u529b\u3002</p><h3>\u540c\u7248\u672c\u4e2d\u6587\u624b\u518c\u8282\u9009</h3><p>\n<code>EXPLAIN ANALYZE</code> \u6d4b\u5f97\u7684\u8fd0\u884c\u65f6\u95f4\uff0c\u53ef\u80fd\u4ee5\u4e24\u79cd\u91cd\u8981\u65b9\u5f0f\u504f\u79bb\u540c\u4e00\u67e5\u8be2\u7684\u6b63\u5e38\u6267\u884c\u65f6\u95f4\u3002\u7b2c\u4e00\uff0c\u7531\u4e8e\u4e0d\u4f1a\u5411\u5ba2\u6237\u7aef\u4f20\u9012\u4efb\u4f55\u8f93\u51fa\u884c\uff0c\u56e0\u6b64\u7f51\u7edc\u4f20\u8f93\u5f00\u9500\u548c I/O \u8f6c\u6362\u5f00\u9500\u5747\u4e0d\u4f1a\u88ab\u8ba1\u5165\u3002\u7b2c\u4e8c\uff0c<code>EXPLAIN ANALYZE</code> \u9644\u52a0\u7684\u6d4b\u91cf\u5f00\u9500\u672c\u8eab\u53ef\u80fd\u76f8\u5f53\u53ef\u89c2\uff0c\u5c24\u5176\u662f\u5728\u64cd\u4f5c\u7cfb\u7edf\u8c03\u7528 <code>gettimeofday()</code> \u8f83\u6162\u7684\u673a\u5668\u4e0a\u3002\u53ef\u4ee5\u4f7f\u7528 <a href=\"/zh/docs/16/pgtesttiming.html\" rel=\"nofollow\"><span><span>pg_test_timing</span></span></a> \u5de5\u5177\u6765\u6d4b\u91cf\u7cfb\u7edf\u4e0a\u7684\u8ba1\u65f6\u5f00\u9500\u3002\n   </p><p>\n    \u4e0d\u5e94\u5c06 <code>EXPLAIN</code> \u7ed3\u679c\u5916\u63a8\u5230\u4e0e\u5b9e\u9645\u6d4b\u8bd5\u573a\u666f\u5dee\u5f02\u5f88\u5927\u7684\u60c5\u51b5\u3002\u4f8b\u5982\uff0c\u5728\u4e00\u4e2a\u5f88\u5c0f\u7684\u8868\u4e0a\u5f97\u5230\u7684\u7ed3\u679c\uff0c\u4e0d\u80fd\u5047\u5b9a\u4e5f\u9002\u7528\u4e8e\u5927\u578b\u8868\u3002\u89c4\u5212\u5668\u7684\u4ee3\u4ef7\u4f30\u8ba1\u4e0d\u662f\u7ebf\u6027\u7684\uff0c\u56e0\u6b64\u5b83\u53ef\u80fd\u4f1a\u4e3a\u66f4\u5927\u6216\u66f4\u5c0f\u7684\u8868\u9009\u62e9\u4e0d\u540c\u7684\u8ba1\u5212\u3002\u4e00\u4e2a\u6781\u7aef\u793a\u4f8b\u662f\uff1a\u5bf9\u4e8e\u53ea\u5360\u7528\u4e00\u4e2a\u78c1\u76d8\u9875\u7684\u8868\uff0c\u65e0\u8bba\u7d22\u5f15\u662f\u5426\u53ef\u7528\uff0c\u51e0\u4e4e\u603b\u4f1a\u5f97\u5230\u987a\u5e8f\u626b\u63cf\u8ba1\u5212\u3002\u89c4\u5212\u5668\u8ba4\u8bc6\u5230\uff0c\u65e0\u8bba\u5982\u4f55\u5904\u7406\u8be5\u8868\u90fd\u9700\u8981\u4e00\u6b21\u78c1\u76d8\u9875\u8bfb\u53d6\uff0c\u56e0\u6b64\u518d\u989d\u5916\u8bfb\u53d6\u9875\u9762\u53bb\u67e5\u770b\u7d22\u5f15\u5e76\u6ca1\u6709\u4ef7\u503c\u3002\uff08\u524d\u9762\u7684 <code>polygon_tbl</code> \u793a\u4f8b\u5df2\u7ecf\u5c55\u793a\u8fc7\u8fd9\u79cd\u60c5\u51b5\u3002\uff09\n   </p><p>\u6709\u65f6\u5b9e\u9645\u503c\u4e0e\u4f30\u8ba1\u503c\u4e0d\u592a\u4e00\u81f4\uff0c\u4f46\u5b9e\u9645\u4e0a\u5e76\u6ca1\u6709\u95ee\u9898\u3002\u5176\u4e2d\u4e00\u79cd\u60c5\u51b5\u662f\uff0c\u8ba1\u5212\u8282\u70b9\u7684\u6267\u884c\u56e0 <code>LIMIT</code> \u6216\u7c7b\u4f3c\u6548\u679c\u800c\u63d0\u524d\u505c\u6b62\u3002\u4f8b\u5982\uff0c\u5728\u524d\u9762\u4f7f\u7528\u7684 <code>LIMIT</code> \u67e5\u8be2\u4e2d\uff1a</p><p>Index Scan \u8282\u70b9\u7684\u4f30\u8ba1\u4ee3\u4ef7\u548c\u884c\u6570\u6309\u8be5\u8282\u70b9\u6267\u884c\u5230\u5b8c\u6210\u7684\u60c5\u51b5\u663e\u793a\u3002\u4f46\u5b9e\u9645\u4e0a\uff0cLimit \u8282\u70b9\u53d6\u5f97\u4e24\u884c\u540e\u5c31\u505c\u6b62\u8bf7\u6c42\u884c\uff0c\u56e0\u6b64\u5b9e\u9645\u884c\u6570\u53ea\u6709 2\uff0c\u8fd0\u884c\u65f6\u95f4\u4e5f\u5c0f\u4e8e\u4f30\u8ba1\u4ee3\u4ef7\u6240\u6697\u793a\u7684\u65f6\u95f4\u3002\u8fd9\u4e0d\u662f\u4f30\u8ba1\u9519\u8bef\uff0c\u53ea\u662f\u4f30\u8ba1\u503c\u4e0e\u5b9e\u9645\u503c\u7684\u663e\u793a\u65b9\u5f0f\u5b58\u5728\u5dee\u522b\u3002</p><p><a href=\"/zh/docs/16/using-explain.html#USING-EXPLAIN-CAVEATS\" rel=\"nofollow\">\u67e5\u770b\u5b8c\u6574\u4e2d\u6587\u624b\u518c\u4e0e\u4e0a\u4e0b\u6587</a>\u3002</p><p>\u672c\u9875\u5f00\u5934\u7684\u4e2d\u6587\u8bf4\u660e\u4e3a PG.CENTER \u5bf9\u7f16\u8f91\u8bf4\u660e\u7684\u7ffb\u8bd1\uff1b\u624b\u518c\u8282\u9009\u4fdd\u7559\u5bf9\u5e94\u7248\u672c\u4e2d\u6587\u6587\u6863\u539f\u6587\u3002\u6e90\u7801\u4fe1\u606f\u53ca\u624b\u518c\u793a\u4f8b\u4e0d\u4ee3\u8868\u91cd\u65b0\u8fdb\u884c\u8fc7\u8fd0\u884c\u6d4b\u8bd5\u3002</p>", "body_sha256": "5b93d7c202d4aa7ace839c4f10439d4452b52f83d6c95ebca12769e96dea8832", "content_hash": "01d88612a790020858233efd76f6f935dc34dece1419e713c6da3270e5734fba", "source_database": "center", "source_revision": "c1575341fa7bd40f5274ea465b34390f4dc64cdd0770af327005caaeb9f6b7ed"}, "tables_zh": [{"key": "explain-labels", "rows": [{"label": "BitmapOr", "identity": "BitmapOr"}], "title": "\u672c\u6784\u5efa\u4e2d\u7684 EXPLAIN \u6807\u7b7e", "columns": [{"key": "label", "label": "\u6587\u672c\u683c\u5f0f\u6807\u7b7e"}, {"key": "identity", "label": "\u7ed3\u6784\u5316\u8282\u70b9\u6807\u8bc6"}]}], "strategies": [], "description": ["\u5bf9\u5404\u5b50\u8ba1\u5212\u751f\u6210\u7684\u4f4d\u56fe\u6c42\u5e76\u96c6\u3002"], "sections_zh": [{"title": "EXPLAIN \u540d\u79f0\u4e0e\u5c5e\u6027", "paragraphs": ["\u7ed3\u6784\u5316\u683c\u5f0f\u4f7f\u7528\u4e0a\u8ff0 Node Type\u3002\u6587\u672c\u683c\u5f0f\u540d\u79f0\u8fd8\u53ef\u80fd\u5305\u542b\u64cd\u4f5c\u3001\u7b56\u7565\u3001\u8fde\u63a5\u7c7b\u578b\u3001\u626b\u63cf\u65b9\u5411\u6216\u805a\u5408\u9636\u6bb5\u5c5e\u6027\u3002", "\u6b64\u6e90\u7801\u8bb0\u5f55\u7684\u6587\u672c\u540d\u79f0\uff1aBitmapOr.", "\u5e76\u884c\u611f\u77e5\u4e0e\u5e76\u884c\u5b89\u5168\u662f\u4e0d\u540c\u7684\u8ba1\u5212\u5c5e\u6027\u3002\u5728\u5e76\u884c\u5de5\u4f5c\u8fdb\u7a0b\u5185\u8fd0\u884c\u7684\u8282\u70b9\u4e0d\u4e00\u5b9a\u662f\u5e76\u884c\u611f\u77e5\u8282\u70b9\u3002"]}, {"title": "\u5185\u5b58\u4e0e\u4e34\u65f6\u5b58\u50a8", "paragraphs": ["\u6b64\u8282\u70b9\u6309\u57fa\u4e8e work_mem \u7684\u9884\u7b97\u5206\u914d\u5143\u7ec4\u4f4d\u7f6e\u4f4d\u56fe\u3002\u4f4d\u56fe\u53ef\u4ee5\u4fdd\u7559\u9875\u7ea7\u6709\u635f\u6761\u76ee\uff0c\u800c\u4e0d\u8bb0\u5f55\u6bcf\u4e2a\u5143\u7ec4\u4f4d\u7f6e\uff0c\u56e0\u6b64\u4ecd\u53ef\u80fd\u9700\u8981\u5806\u91cd\u68c0\u3002"]}, {"title": "\u5e76\u884c\u6267\u884c\u4e0e\u8fd0\u884c\u4fe1\u606f\u91c7\u96c6", "paragraphs": ["\u4ee5\u4e0b\u6e90\u7801\u56de\u8c03\u53ef\u4ee5\u534f\u8c03\u6267\u884c\u6216\u6536\u96c6\u5de5\u4f5c\u8fdb\u7a0b\u7684\u6d4b\u91cf\u6570\u636e\u3002\u56de\u8c03\u5b58\u5728\u4e0d\u4ee3\u8868\u8be5\u8282\u70b9\u666e\u904d\u652f\u6301\u5171\u4eab\u5e76\u884c\u626b\u63cf\u6216\u5171\u4eab\u72b6\u6001\u3002", "\u6b64\u6784\u5efa\u7684\u56de\u8c03\uff1anone extracted from this node implementation."]}, {"title": "\u540c\u7248\u672c\u624b\u518c\u8bf4\u660e", "paragraphs": ["\u7531\u4e8e\u5b9e\u73b0\u4e0a\u7684\u9650\u5236\uff0cBitmapAnd \u548c BitmapOr \u8282\u70b9\u62a5\u544a\u7684\u5b9e\u9645\u884c\u6570\u59cb\u7ec8\u4e3a\u96f6\u3002"]}, {"title": "\u6267\u884c\u5668\u5b9e\u73b0\u8bf4\u660e", "paragraphs": ["\u8bf4\u660e\uff1aBitmapOr \u4e0d\u4f7f\u7528\u5de6\u53f3\u5b50\u6811\uff0c\u800c\u50cf Append \u4e00\u6837\u7ef4\u62a4\u5b50\u8ba1\u5212\u5217\u8868\u3002\u4e0d\u8fc7\u5176\u903b\u8f91\u6bd4 Append \u7b80\u5355\u5f97\u591a\uff0c\u56e0\u4e3a\u65e0\u9700\u5904\u7406\u6b63\u5411\u6216\u53cd\u5411\u6267\u884c\u3002", "\u5bf9\u6bcf\u4e2a\u5f85\u6267\u884c\u8ba1\u5212\u8c03\u7528 ExecInitNode\uff0c\u5e76\u5c06\u7ed3\u679c\u4fdd\u5b58\u5230 bitmapplanstates \u6570\u7ec4\u3002", "BitmapOr \u8ba1\u5212\u6ca1\u6709\u8868\u8fbe\u5f0f\u4e0a\u4e0b\u6587\uff0c\u56e0\u4e3a\u5b83\u4eec\u4ece\u4e0d\u8c03\u7528 ExecQual \u6216 ExecProject\uff0c\u4e5f\u4e0d\u9700\u8981\u5143\u7ec4\u69fd\u3002", "\u53ef\u5bf9 BitmapIndexScan \u5b50\u8282\u70b9\u4f5c\u7279\u6b8a\u5904\u7406\uff0c\u907f\u514d\u4e3a\u6bcf\u4e2a\u5b50\u8282\u70b9\u663e\u5f0f\u8c03\u7528 tbm_union\uff1a\u76f4\u63a5\u4e0b\u4f20\u5f53\u524d\u7ed3\u679c\u4f4d\u56fe\uff0c\u8ba9\u5b50\u8282\u70b9\u5c06\u7ed3\u679c\u6309\u4f4d OR \u5408\u5e76\u8fdb\u53bb\u3002", "ExecReScan \u4e0d\u77e5\u9053\u5f53\u524d\u8282\u70b9\u7684\u5b50\u8ba1\u5212\uff0c\u56e0\u6b64\u5fc5\u987b\u81ea\u884c\u901a\u77e5\u5b50\u8ba1\u5212\u54ea\u4e9b\u53c2\u6570\u53d1\u751f\u4e86\u53d8\u5316\u3002"]}, {"code": "case T_BitmapOr:\n\t\t\tpname = sname = \"BitmapOr\";\n\t\t\tbreak;", "title": "\u6838\u5fc3\u6e90\u7801\u4e2d\u7684 EXPLAIN \u6807\u8bc6"}], "localization": {"status": "complete", "sources": [], "language": "zh", "original_text": {"/versions/16/description/0": "Unions bitmaps produced by its child plans.", "/versions/16/facts/0/label": "Core node tag", "/versions/16/facts/1/label": "Structured EXPLAIN Node Type", "/versions/16/facts/2/label": "Inputs", "/versions/16/facts/2/value": "Bitmap-producing child plans", "/versions/16/facts/3/label": "Output", "/versions/16/facts/3/value": "Tuple-location bitmap, not a tuple stream", "/versions/16/facts/4/label": "Executor initializer", "/versions/16/facts/5/label": "Memory mechanism", "/versions/16/tables/0/title": "EXPLAIN labels in this source build", "/versions/16/related/1/label": "Using EXPLAIN", "/versions/16/related/2/label": "Parallel plans", "/versions/16/sections/0/title": "EXPLAIN names and attributes", "/versions/16/sections/1/title": "Memory and temporary storage", "/versions/16/sections/2/title": "Parallel execution and instrumentation", "/versions/16/sections/3/title": "Same-version manual discussion", "/versions/16/sections/4/title": "Executor implementation notes", "/versions/16/sections/5/title": "EXPLAIN identity in core source", "/versions/16/memory/description": "The node allocates a tuple-location bitmap using a work_mem-derived budget. A bitmap can retain page-level lossy entries instead of every tuple location; heap rechecks then remain necessary.", "/versions/16/sections/0/paragraphs/0": "Structured formats use the Node Type above. Text-format spellings can also include operation, strategy, join type, scan direction or aggregation-stage attributes.", "/versions/16/sections/0/paragraphs/1": "Text names recorded by this source: BitmapOr.", "/versions/16/sections/0/paragraphs/2": "Parallel-aware and parallel-safe are different plan properties. A node running inside a parallel worker is not necessarily a parallel-aware node.", "/versions/16/sections/1/paragraphs/0": "The node allocates a tuple-location bitmap using a work_mem-derived budget. A bitmap can retain page-level lossy entries instead of every tuple location; heap rechecks then remain necessary.", "/versions/16/sections/2/paragraphs/0": "The source callbacks below can coordinate execution or collect worker instrumentation. Their presence is not a blanket claim that this node supports a shared parallel scan or shared state.", "/versions/16/sections/2/paragraphs/1": "Callbacks in this build: none extracted from this node implementation.", "/versions/16/sections/3/paragraphs/0": "BitmapAnd and BitmapOr nodes always report their actual row counts as zero, due to implementation limitations.", "/versions/16/sections/4/paragraphs/0": "NOTES BitmapOr nodes don't make use of their left and right subtrees, rather they maintain a list of subplans, much like Append nodes. The logic is much simpler than Append, however, since we needn't cope with forward/backward execution.", "/versions/16/sections/4/paragraphs/1": "call ExecInitNode on each of the plans to be executed and save the results into the array \"bitmapplanstates\".", "/versions/16/sections/4/paragraphs/2": "BitmapOr plans don't have expression contexts because they never call ExecQual or ExecProject. They don't need any tuple slots either.", "/versions/16/sections/4/paragraphs/3": "We can special-case BitmapIndexScan children to avoid an explicit tbm_union step for each child: just pass down the current result bitmap and let the child OR directly into it.", "/versions/16/sections/4/paragraphs/4": "ExecReScan doesn't know about my subplans, so I have to do changed-parameter signaling myself.", "/versions/16/tables/0/columns/0/label": "Text-format label", "/versions/16/tables/0/columns/1/label": "Structured node identity"}, "fallback_fields": [], "source_language": "en", "original_snapshot_sha256": "e611663c8833de86047b2912f9a0945895b2c912476eae0d751d265cbafcda11", "canonical_center_text_hash": "01d88612a790020858233efd76f6f935dc34dece1419e713c6da3270e5734fba"}, "evidence_kind": "source and documentation", "explain_names": ["BitmapOr"], "partial_modes": [], "description_zh": "\u5bf9\u5404\u5b50\u8ba1\u5212\u751f\u6210\u7684\u4f4d\u56fe\u6c42\u5e76\u96c6\u3002", "comparison_data": {"node_tag": "T_BitmapOr", "strategies": [], "text_names": ["BitmapOr"], "initializer": "ExecInitBitmapOr", "partial_modes": [], "memory_mechanism": "bitmap-lossification", "parallel_callbacks": []}, "comparison_hash": "c0ca503a6029c37ec720213dcdc3094997eb194d4920da68f94a7420d3e8f1d2", "manual_language": "zh", "explain_prefixes": ["Parallel", "Async"], "runtime_verified": false, "source_inventory": {"explain": "src/backend/commands/explain.c", "executor": "src/backend/executor/execProcnode.c", "implementation": "src/backend/executor/nodeBitmapOr.c"}, "parallel_callbacks": [], "description_zh_html": "<p>\u5bf9\u5404\u5b50\u8ba1\u5212\u751f\u6210\u7684\u4f4d\u56fe\u6c42\u5e76\u96c6\u3002</p><p>\u6838\u5fc3\u8282\u70b9\u6807\u8bc6\uff1a<code>T_BitmapOr</code>\uff1bEXPLAIN \u540d\u79f0\uff1a<code>BitmapOr</code>\u3002</p><p>\u672c\u7248\u672c\u6e90\u7801\u4e2d\u7684\u5e76\u884c\u6267\u884c\u6216\u89c2\u6d4b\u56de\u8c03\uff1a\u8be5\u8282\u70b9\u5b9e\u73b0\u4e2d\u672a\u63d0\u53d6\u5230\u6b64\u7c7b\u56de\u8c03\u3002\u56de\u8c03\u7684\u5b58\u5728\u4e0d\u8868\u793a\u8be5\u8282\u70b9\u5fc5\u7136\u652f\u6301\u5171\u4eab\u5e76\u884c\u626b\u63cf\uff1b\u5728\u5e76\u884c\u5de5\u4f5c\u8fdb\u7a0b\u4e2d\u6267\u884c\u4e5f\u4e0d\u7b49\u4e8e\u5177\u6709\u5e76\u884c\u611f\u77e5\u80fd\u529b\u3002</p><h3>\u540c\u7248\u672c\u4e2d\u6587\u624b\u518c\u8282\u9009</h3><p>\n<code>EXPLAIN ANALYZE</code> \u6d4b\u5f97\u7684\u8fd0\u884c\u65f6\u95f4\uff0c\u53ef\u80fd\u4ee5\u4e24\u79cd\u91cd\u8981\u65b9\u5f0f\u504f\u79bb\u540c\u4e00\u67e5\u8be2\u7684\u6b63\u5e38\u6267\u884c\u65f6\u95f4\u3002\u7b2c\u4e00\uff0c\u7531\u4e8e\u4e0d\u4f1a\u5411\u5ba2\u6237\u7aef\u4f20\u9012\u4efb\u4f55\u8f93\u51fa\u884c\uff0c\u56e0\u6b64\u7f51\u7edc\u4f20\u8f93\u5f00\u9500\u548c I/O \u8f6c\u6362\u5f00\u9500\u5747\u4e0d\u4f1a\u88ab\u8ba1\u5165\u3002\u7b2c\u4e8c\uff0c<code>EXPLAIN ANALYZE</code> \u9644\u52a0\u7684\u6d4b\u91cf\u5f00\u9500\u672c\u8eab\u53ef\u80fd\u76f8\u5f53\u53ef\u89c2\uff0c\u5c24\u5176\u662f\u5728\u64cd\u4f5c\u7cfb\u7edf\u8c03\u7528 <code>gettimeofday()</code> \u8f83\u6162\u7684\u673a\u5668\u4e0a\u3002\u53ef\u4ee5\u4f7f\u7528 <a href=\"/zh/docs/16/pgtesttiming.html\" rel=\"nofollow\"><span><span>pg_test_timing</span></span></a> \u5de5\u5177\u6765\u6d4b\u91cf\u7cfb\u7edf\u4e0a\u7684\u8ba1\u65f6\u5f00\u9500\u3002\n   </p><p>\n    \u4e0d\u5e94\u5c06 <code>EXPLAIN</code> \u7ed3\u679c\u5916\u63a8\u5230\u4e0e\u5b9e\u9645\u6d4b\u8bd5\u573a\u666f\u5dee\u5f02\u5f88\u5927\u7684\u60c5\u51b5\u3002\u4f8b\u5982\uff0c\u5728\u4e00\u4e2a\u5f88\u5c0f\u7684\u8868\u4e0a\u5f97\u5230\u7684\u7ed3\u679c\uff0c\u4e0d\u80fd\u5047\u5b9a\u4e5f\u9002\u7528\u4e8e\u5927\u578b\u8868\u3002\u89c4\u5212\u5668\u7684\u4ee3\u4ef7\u4f30\u8ba1\u4e0d\u662f\u7ebf\u6027\u7684\uff0c\u56e0\u6b64\u5b83\u53ef\u80fd\u4f1a\u4e3a\u66f4\u5927\u6216\u66f4\u5c0f\u7684\u8868\u9009\u62e9\u4e0d\u540c\u7684\u8ba1\u5212\u3002\u4e00\u4e2a\u6781\u7aef\u793a\u4f8b\u662f\uff1a\u5bf9\u4e8e\u53ea\u5360\u7528\u4e00\u4e2a\u78c1\u76d8\u9875\u7684\u8868\uff0c\u65e0\u8bba\u7d22\u5f15\u662f\u5426\u53ef\u7528\uff0c\u51e0\u4e4e\u603b\u4f1a\u5f97\u5230\u987a\u5e8f\u626b\u63cf\u8ba1\u5212\u3002\u89c4\u5212\u5668\u8ba4\u8bc6\u5230\uff0c\u65e0\u8bba\u5982\u4f55\u5904\u7406\u8be5\u8868\u90fd\u9700\u8981\u4e00\u6b21\u78c1\u76d8\u9875\u8bfb\u53d6\uff0c\u56e0\u6b64\u518d\u989d\u5916\u8bfb\u53d6\u9875\u9762\u53bb\u67e5\u770b\u7d22\u5f15\u5e76\u6ca1\u6709\u4ef7\u503c\u3002\uff08\u524d\u9762\u7684 <code>polygon_tbl</code> \u793a\u4f8b\u5df2\u7ecf\u5c55\u793a\u8fc7\u8fd9\u79cd\u60c5\u51b5\u3002\uff09\n   </p><p>\u6709\u65f6\u5b9e\u9645\u503c\u4e0e\u4f30\u8ba1\u503c\u4e0d\u592a\u4e00\u81f4\uff0c\u4f46\u5b9e\u9645\u4e0a\u5e76\u6ca1\u6709\u95ee\u9898\u3002\u5176\u4e2d\u4e00\u79cd\u60c5\u51b5\u662f\uff0c\u8ba1\u5212\u8282\u70b9\u7684\u6267\u884c\u56e0 <code>LIMIT</code> \u6216\u7c7b\u4f3c\u6548\u679c\u800c\u63d0\u524d\u505c\u6b62\u3002\u4f8b\u5982\uff0c\u5728\u524d\u9762\u4f7f\u7528\u7684 <code>LIMIT</code> \u67e5\u8be2\u4e2d\uff1a</p><p>Index Scan \u8282\u70b9\u7684\u4f30\u8ba1\u4ee3\u4ef7\u548c\u884c\u6570\u6309\u8be5\u8282\u70b9\u6267\u884c\u5230\u5b8c\u6210\u7684\u60c5\u51b5\u663e\u793a\u3002\u4f46\u5b9e\u9645\u4e0a\uff0cLimit \u8282\u70b9\u53d6\u5f97\u4e24\u884c\u540e\u5c31\u505c\u6b62\u8bf7\u6c42\u884c\uff0c\u56e0\u6b64\u5b9e\u9645\u884c\u6570\u53ea\u6709 2\uff0c\u8fd0\u884c\u65f6\u95f4\u4e5f\u5c0f\u4e8e\u4f30\u8ba1\u4ee3\u4ef7\u6240\u6697\u793a\u7684\u65f6\u95f4\u3002\u8fd9\u4e0d\u662f\u4f30\u8ba1\u9519\u8bef\uff0c\u53ea\u662f\u4f30\u8ba1\u503c\u4e0e\u5b9e\u9645\u503c\u7684\u663e\u793a\u65b9\u5f0f\u5b58\u5728\u5dee\u522b\u3002</p><p><a href=\"/zh/docs/16/using-explain.html#USING-EXPLAIN-CAVEATS\" rel=\"nofollow\">\u67e5\u770b\u5b8c\u6574\u4e2d\u6587\u624b\u518c\u4e0e\u4e0a\u4e0b\u6587</a>\u3002</p><p>\u672c\u9875\u5f00\u5934\u7684\u4e2d\u6587\u8bf4\u660e\u4e3a PG.CENTER \u5bf9\u7f16\u8f91\u8bf4\u660e\u7684\u7ffb\u8bd1\uff1b\u624b\u518c\u8282\u9009\u4fdd\u7559\u5bf9\u5e94\u7248\u672c\u4e2d\u6587\u6587\u6863\u539f\u6587\u3002\u6e90\u7801\u4fe1\u606f\u53ca\u624b\u518c\u793a\u4f8b\u4e0d\u4ee3\u8868\u91cd\u65b0\u8fdb\u884c\u8fc7\u8fd0\u884c\u6d4b\u8bd5\u3002</p>"}, "17": {"facts": [{"label": "\u6838\u5fc3\u8282\u70b9\u6807\u7b7e", "value": "T_BitmapOr"}, {"label": "\u7ed3\u6784\u5316 EXPLAIN \u8282\u70b9\u7c7b\u578b", "value": "BitmapOr"}, {"label": "\u8f93\u5165", "value": "\u4ea7\u751f\u4f4d\u56fe\u7684\u5b50\u8ba1\u5212"}, {"label": "\u8f93\u51fa", "value": "\u5143\u7ec4\u4f4d\u7f6e\u4f4d\u56fe\uff0c\u4e0d\u662f\u5143\u7ec4\u6d41"}, {"label": "\u6267\u884c\u5668\u521d\u59cb\u5316\u51fd\u6570", "value": "ExecInitBitmapOr"}, {"label": "\u5185\u5b58\u673a\u5236", "value": "bitmap-lossification"}], "memory": {"evidence": [{"url": "https://ftp.postgresql.org/pub/source/v17.11/postgresql-17.11.tar.bz2", "path": "src/backend/executor/nodeBitmapOr.c", "label": "src/backend/executor/nodeBitmapOr.c", "sha256": "dbf4227a43dd8570fd4ff6fc12312a0e7e96f1e9f79b35b46204fbe01d483188", "archive_sha256": "dd27f2b3c59e73ed14aa3324901242bf69a032a6347805f274e6260322d42979"}, {"url": "https://ftp.postgresql.org/pub/source/v17.11/postgresql-17.11.tar.bz2", "path": "src/backend/nodes/tidbitmap.c", "label": "src/backend/nodes/tidbitmap.c", "sha256": "10f9875b7384fddcd0750b41f7357933769a840c57a7bc0e29eecd4cdc5b8f4c", "archive_sha256": "dd27f2b3c59e73ed14aa3324901242bf69a032a6347805f274e6260322d42979"}], "mechanism": "bitmap-lossification", "description": "The node allocates a tuple-location bitmap using a work_mem-derived budget. A bitmap can retain page-level lossy entries instead of every tuple location; heap rechecks then remain necessary.", "source_notes": []}, "tables": [{"key": "explain-labels", "rows": [{"label": "BitmapOr", "identity": "BitmapOr"}], "title": "\u672c\u6784\u5efa\u4e2d\u7684 EXPLAIN \u6807\u7b7e", "columns": [{"key": "label", "label": "\u6587\u672c\u683c\u5f0f\u6807\u7b7e"}, {"key": "identity", "label": "\u7ed3\u6784\u5316\u8282\u70b9\u6807\u8bc6"}]}], "related": [{"url": "/wiki/sql/explain/?v=17", "label": "EXPLAIN"}, {"url": "/docs/17/using-explain.html", "label": "\u4f7f\u7528 EXPLAIN"}, {"url": "/docs/17/parallel-plans.html", "label": "\u5e76\u884c\u8ba1\u5212"}, {"url": "/wiki/guc/work_mem/?v=17", "label": "work_mem"}], "release": {"ref": "PostgreSQL 17.11 source archive", "label": "17.11", "major": "17", "channel": "stable", "revision": "dd27f2b3c59e73ed14aa3324901242bf69a032a6347805f274e6260322d42979", "source_url": "https://ftp.postgresql.org/pub/source/v17.11/postgresql-17.11.tar.bz2", "source_snapshot_utc": ""}, "sources": [{"url": "https://ftp.postgresql.org/pub/source/v17.11/postgresql-17.11.tar.bz2", "line": 1433, "path": "src/backend/commands/explain.c", "label": "src/backend/commands/explain.c:1433", "sha256": "741251b1a3b6d269a52a673d42eb63b02e13a5872db7b359b137086ab21b63c8", "archive_sha256": "dd27f2b3c59e73ed14aa3324901242bf69a032a6347805f274e6260322d42979"}, {"url": "https://ftp.postgresql.org/pub/source/v17.11/postgresql-17.11.tar.bz2", "line": 201, "path": "src/backend/executor/execProcnode.c", "label": "src/backend/executor/execProcnode.c:201", "sha256": "a77576e158b94cb01fa8c5174ba133004eabdd727660323f8afc66c8d2e757b8", "archive_sha256": "dd27f2b3c59e73ed14aa3324901242bf69a032a6347805f274e6260322d42979"}, {"url": "https://ftp.postgresql.org/pub/source/v17.11/postgresql-17.11.tar.bz2", "path": "src/backend/executor/nodeBitmapOr.c", "label": "src/backend/executor/nodeBitmapOr.c", "sha256": "dbf4227a43dd8570fd4ff6fc12312a0e7e96f1e9f79b35b46204fbe01d483188", "archive_sha256": "dd27f2b3c59e73ed14aa3324901242bf69a032a6347805f274e6260322d42979"}, {"url": "https://ftp.postgresql.org/pub/source/v17.11/postgresql-17.11.tar.bz2", "path": "src/include/nodes/plannodes.h", "label": "src/include/nodes/plannodes.h", "sha256": "d390dd69e2d3f5085beb42b33e46ff0676a2959b916a12b82118a7e545f8e562", "archive_sha256": "dd27f2b3c59e73ed14aa3324901242bf69a032a6347805f274e6260322d42979"}, {"url": "https://ftp.postgresql.org/pub/source/v17.11/postgresql-17.11.tar.bz2", "path": "src/backend/nodes/tidbitmap.c", "label": "src/backend/nodes/tidbitmap.c", "sha256": "10f9875b7384fddcd0750b41f7357933769a840c57a7bc0e29eecd4cdc5b8f4c", "archive_sha256": "dd27f2b3c59e73ed14aa3324901242bf69a032a6347805f274e6260322d42979"}, {"url": "/docs/17/using-explain.html#USING-EXPLAIN-CAVEATS", "path": "using-explain.html", "label": "PostgreSQL 17.11 \u00b7 using-explain", "sha256": 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"source_facts_revision": "dd27f2b3c59e73ed14aa3324901242bf69a032a6347805f274e6260322d42979"}, "facts_zh": [{"label": "\u6838\u5fc3\u8282\u70b9\u6807\u7b7e", "value": "T_BitmapOr"}, {"label": "\u7ed3\u6784\u5316 EXPLAIN \u8282\u70b9\u7c7b\u578b", "value": "BitmapOr"}, {"label": "\u8f93\u5165", "value": "\u4ea7\u751f\u4f4d\u56fe\u7684\u5b50\u8ba1\u5212"}, {"label": "\u8f93\u51fa", "value": "\u5143\u7ec4\u4f4d\u7f6e\u4f4d\u56fe\uff0c\u4e0d\u662f\u5143\u7ec4\u6d41"}, {"label": "\u6267\u884c\u5668\u521d\u59cb\u5316\u51fd\u6570", "value": "ExecInitBitmapOr"}, {"label": "\u5185\u5b58\u673a\u5236", "value": "bitmap-lossification"}], "node_tag": "T_BitmapOr", "sections": [{"title": "EXPLAIN \u540d\u79f0\u4e0e\u5c5e\u6027", "paragraphs": ["\u7ed3\u6784\u5316\u683c\u5f0f\u4f7f\u7528\u4e0a\u8ff0 Node Type\u3002\u6587\u672c\u683c\u5f0f\u540d\u79f0\u8fd8\u53ef\u80fd\u5305\u542b\u64cd\u4f5c\u3001\u7b56\u7565\u3001\u8fde\u63a5\u7c7b\u578b\u3001\u626b\u63cf\u65b9\u5411\u6216\u805a\u5408\u9636\u6bb5\u5c5e\u6027\u3002", "\u6b64\u6e90\u7801\u8bb0\u5f55\u7684\u6587\u672c\u540d\u79f0\uff1aBitmapOr.", "\u5e76\u884c\u611f\u77e5\u4e0e\u5e76\u884c\u5b89\u5168\u662f\u4e0d\u540c\u7684\u8ba1\u5212\u5c5e\u6027\u3002\u5728\u5e76\u884c\u5de5\u4f5c\u8fdb\u7a0b\u5185\u8fd0\u884c\u7684\u8282\u70b9\u4e0d\u4e00\u5b9a\u662f\u5e76\u884c\u611f\u77e5\u8282\u70b9\u3002"]}, {"title": "\u5185\u5b58\u4e0e\u4e34\u65f6\u5b58\u50a8", "paragraphs": ["\u6b64\u8282\u70b9\u6309\u57fa\u4e8e work_mem \u7684\u9884\u7b97\u5206\u914d\u5143\u7ec4\u4f4d\u7f6e\u4f4d\u56fe\u3002\u4f4d\u56fe\u53ef\u4ee5\u4fdd\u7559\u9875\u7ea7\u6709\u635f\u6761\u76ee\uff0c\u800c\u4e0d\u8bb0\u5f55\u6bcf\u4e2a\u5143\u7ec4\u4f4d\u7f6e\uff0c\u56e0\u6b64\u4ecd\u53ef\u80fd\u9700\u8981\u5806\u91cd\u68c0\u3002"]}, {"title": "\u5e76\u884c\u6267\u884c\u4e0e\u8fd0\u884c\u4fe1\u606f\u91c7\u96c6", "paragraphs": ["\u4ee5\u4e0b\u6e90\u7801\u56de\u8c03\u53ef\u4ee5\u534f\u8c03\u6267\u884c\u6216\u6536\u96c6\u5de5\u4f5c\u8fdb\u7a0b\u7684\u6d4b\u91cf\u6570\u636e\u3002\u56de\u8c03\u5b58\u5728\u4e0d\u4ee3\u8868\u8be5\u8282\u70b9\u666e\u904d\u652f\u6301\u5171\u4eab\u5e76\u884c\u626b\u63cf\u6216\u5171\u4eab\u72b6\u6001\u3002", "\u6b64\u6784\u5efa\u7684\u56de\u8c03\uff1anone extracted from this node implementation."]}, {"title": "\u540c\u7248\u672c\u624b\u518c\u8bf4\u660e", "paragraphs": ["\u7531\u4e8e\u5b9e\u73b0\u4e0a\u7684\u9650\u5236\uff0cBitmapAnd \u548c BitmapOr \u8282\u70b9\u62a5\u544a\u7684\u5b9e\u9645\u884c\u6570\u59cb\u7ec8\u4e3a\u96f6\u3002"]}, {"title": "\u6267\u884c\u5668\u5b9e\u73b0\u8bf4\u660e", "paragraphs": ["\u8bf4\u660e\uff1aBitmapOr \u4e0d\u4f7f\u7528\u5de6\u53f3\u5b50\u6811\uff0c\u800c\u50cf Append \u4e00\u6837\u7ef4\u62a4\u5b50\u8ba1\u5212\u5217\u8868\u3002\u4e0d\u8fc7\u5176\u903b\u8f91\u6bd4 Append \u7b80\u5355\u5f97\u591a\uff0c\u56e0\u4e3a\u65e0\u9700\u5904\u7406\u6b63\u5411\u6216\u53cd\u5411\u6267\u884c\u3002", "\u5bf9\u6bcf\u4e2a\u5f85\u6267\u884c\u8ba1\u5212\u8c03\u7528 ExecInitNode\uff0c\u5e76\u5c06\u7ed3\u679c\u4fdd\u5b58\u5230 bitmapplanstates \u6570\u7ec4\u3002", "BitmapOr \u8ba1\u5212\u6ca1\u6709\u8868\u8fbe\u5f0f\u4e0a\u4e0b\u6587\uff0c\u56e0\u4e3a\u5b83\u4eec\u4ece\u4e0d\u8c03\u7528 ExecQual \u6216 ExecProject\uff0c\u4e5f\u4e0d\u9700\u8981\u5143\u7ec4\u69fd\u3002", "\u53ef\u5bf9 BitmapIndexScan \u5b50\u8282\u70b9\u4f5c\u7279\u6b8a\u5904\u7406\uff0c\u907f\u514d\u4e3a\u6bcf\u4e2a\u5b50\u8282\u70b9\u663e\u5f0f\u8c03\u7528 tbm_union\uff1a\u76f4\u63a5\u4e0b\u4f20\u5f53\u524d\u7ed3\u679c\u4f4d\u56fe\uff0c\u8ba9\u5b50\u8282\u70b9\u5c06\u7ed3\u679c\u6309\u4f4d OR \u5408\u5e76\u8fdb\u53bb\u3002", "ExecReScan \u4e0d\u77e5\u9053\u5f53\u524d\u8282\u70b9\u7684\u5b50\u8ba1\u5212\uff0c\u56e0\u6b64\u5fc5\u987b\u81ea\u884c\u901a\u77e5\u5b50\u8ba1\u5212\u54ea\u4e9b\u53c2\u6570\u53d1\u751f\u4e86\u53d8\u5316\u3002"]}, {"code": "case T_BitmapOr:\n\t\t\tpname = sname = \"BitmapOr\";\n\t\t\tbreak;", "title": "\u6838\u5fc3\u6e90\u7801\u4e2d\u7684 EXPLAIN \u6807\u8bc6"}], "center_zh": {"title": "BitmapOr", "locale": "zh-Hans", "source": {"key": "bitmapor", "locale": "zh-Hans", "version": "17", "text_hash": "9c8fff66925480b2231cab7d66426e2268bbc84576c424ff7e44f1ba70e31fcb", "collection": "plan", "dataset_hash": "7c31b524dfe136022d39a6ae8dcfac6b3bbd5f8fdaf422536599981252aff0c9", "source_database": "center", "source_revision": "dd27f2b3c59e73ed14aa3324901242bf69a032a6347805f274e6260322d42979"}, "payload": {"facts": [{"label": "\u6838\u5fc3\u8282\u70b9\u6807\u7b7e", "value": "T_BitmapOr"}, {"label": "\u7ed3\u6784\u5316 EXPLAIN \u8282\u70b9\u7c7b\u578b", "value": "BitmapOr"}, {"label": "\u8f93\u5165", "value": "\u4ea7\u751f\u4f4d\u56fe\u7684\u5b50\u8ba1\u5212"}, {"label": "\u8f93\u51fa", "value": "\u5143\u7ec4\u4f4d\u7f6e\u4f4d\u56fe\uff0c\u4e0d\u662f\u5143\u7ec4\u6d41"}, {"label": "\u6267\u884c\u5668\u521d\u59cb\u5316\u51fd\u6570", "value": "ExecInitBitmapOr"}, {"label": "\u5185\u5b58\u673a\u5236", "value": "bitmap-lossification"}], "tables": [{"key": "explain-labels", "rows": [{"label": "BitmapOr", "identity": "BitmapOr"}], "title": "\u672c\u6784\u5efa\u4e2d\u7684 EXPLAIN \u6807\u7b7e", "columns": [{"key": "label", "label": "\u6587\u672c\u683c\u5f0f\u6807\u7b7e"}, {"key": "identity", "label": "\u7ed3\u6784\u5316\u8282\u70b9\u6807\u8bc6"}]}], "zh_from": {"kind": "same-version-chinese-manual-with-authored-translation-of-reviewed-guidance", "manual": {"url": "/zh/docs/17/using-explain.html#USING-EXPLAIN-CAVEATS", "anchor": "USING-EXPLAIN-CAVEATS", "locale": "zh-Hans", "version": "17", "build_id": 105, "page_key": "using-explain.html", "extraction": "concept-introduction", "source_hash": "b1252952c6d796f5e38c223b74ff667f2d19d677dcf85fe5269b782b830e5013", "fragment_sha256": "5d3a6050d0c0209bbd45c283cdb6f959fb16429f074a4c4d6a90e653b45f6b37", "source_revision": "unknown:rendered-translation-baseline", "translation_revision": "git:b1b500221dbe5437cfca004d6b04d3f6e422765d;html-sha256:7340767258d21c21b36f373f1fff6bab2be18e0daca13a865129db6105c09efd", "translated_from_revision": null}, "body_sha256": "79247c6c9efee14553c126502daf0cbdf6628e4bd190645b2dcd91aca9087e4e", "runtime_rerun": false, "authored_translation": "authored-translation-of-reviewed-guidance", "source_facts_revision": "dd27f2b3c59e73ed14aa3324901242bf69a032a6347805f274e6260322d42979"}, "sections": [{"title": "EXPLAIN \u540d\u79f0\u4e0e\u5c5e\u6027", "paragraphs": ["\u7ed3\u6784\u5316\u683c\u5f0f\u4f7f\u7528\u4e0a\u8ff0 Node Type\u3002\u6587\u672c\u683c\u5f0f\u540d\u79f0\u8fd8\u53ef\u80fd\u5305\u542b\u64cd\u4f5c\u3001\u7b56\u7565\u3001\u8fde\u63a5\u7c7b\u578b\u3001\u626b\u63cf\u65b9\u5411\u6216\u805a\u5408\u9636\u6bb5\u5c5e\u6027\u3002", "\u6b64\u6e90\u7801\u8bb0\u5f55\u7684\u6587\u672c\u540d\u79f0\uff1aBitmapOr.", "\u5e76\u884c\u611f\u77e5\u4e0e\u5e76\u884c\u5b89\u5168\u662f\u4e0d\u540c\u7684\u8ba1\u5212\u5c5e\u6027\u3002\u5728\u5e76\u884c\u5de5\u4f5c\u8fdb\u7a0b\u5185\u8fd0\u884c\u7684\u8282\u70b9\u4e0d\u4e00\u5b9a\u662f\u5e76\u884c\u611f\u77e5\u8282\u70b9\u3002"]}, {"title": "\u5185\u5b58\u4e0e\u4e34\u65f6\u5b58\u50a8", "paragraphs": ["\u6b64\u8282\u70b9\u6309\u57fa\u4e8e work_mem \u7684\u9884\u7b97\u5206\u914d\u5143\u7ec4\u4f4d\u7f6e\u4f4d\u56fe\u3002\u4f4d\u56fe\u53ef\u4ee5\u4fdd\u7559\u9875\u7ea7\u6709\u635f\u6761\u76ee\uff0c\u800c\u4e0d\u8bb0\u5f55\u6bcf\u4e2a\u5143\u7ec4\u4f4d\u7f6e\uff0c\u56e0\u6b64\u4ecd\u53ef\u80fd\u9700\u8981\u5806\u91cd\u68c0\u3002"]}, {"title": "\u5e76\u884c\u6267\u884c\u4e0e\u8fd0\u884c\u4fe1\u606f\u91c7\u96c6", "paragraphs": ["\u4ee5\u4e0b\u6e90\u7801\u56de\u8c03\u53ef\u4ee5\u534f\u8c03\u6267\u884c\u6216\u6536\u96c6\u5de5\u4f5c\u8fdb\u7a0b\u7684\u6d4b\u91cf\u6570\u636e\u3002\u56de\u8c03\u5b58\u5728\u4e0d\u4ee3\u8868\u8be5\u8282\u70b9\u666e\u904d\u652f\u6301\u5171\u4eab\u5e76\u884c\u626b\u63cf\u6216\u5171\u4eab\u72b6\u6001\u3002", "\u6b64\u6784\u5efa\u7684\u56de\u8c03\uff1anone extracted from this node implementation."]}, {"title": "\u540c\u7248\u672c\u624b\u518c\u8bf4\u660e", "paragraphs": ["\u7531\u4e8e\u5b9e\u73b0\u4e0a\u7684\u9650\u5236\uff0cBitmapAnd \u548c BitmapOr \u8282\u70b9\u62a5\u544a\u7684\u5b9e\u9645\u884c\u6570\u59cb\u7ec8\u4e3a\u96f6\u3002"]}, {"title": "\u6267\u884c\u5668\u5b9e\u73b0\u8bf4\u660e", "paragraphs": ["\u8bf4\u660e\uff1aBitmapOr \u4e0d\u4f7f\u7528\u5de6\u53f3\u5b50\u6811\uff0c\u800c\u50cf Append \u4e00\u6837\u7ef4\u62a4\u5b50\u8ba1\u5212\u5217\u8868\u3002\u4e0d\u8fc7\u5176\u903b\u8f91\u6bd4 Append \u7b80\u5355\u5f97\u591a\uff0c\u56e0\u4e3a\u65e0\u9700\u5904\u7406\u6b63\u5411\u6216\u53cd\u5411\u6267\u884c\u3002", "\u5bf9\u6bcf\u4e2a\u5f85\u6267\u884c\u8ba1\u5212\u8c03\u7528 ExecInitNode\uff0c\u5e76\u5c06\u7ed3\u679c\u4fdd\u5b58\u5230 bitmapplanstates \u6570\u7ec4\u3002", "BitmapOr \u8ba1\u5212\u6ca1\u6709\u8868\u8fbe\u5f0f\u4e0a\u4e0b\u6587\uff0c\u56e0\u4e3a\u5b83\u4eec\u4ece\u4e0d\u8c03\u7528 ExecQual \u6216 ExecProject\uff0c\u4e5f\u4e0d\u9700\u8981\u5143\u7ec4\u69fd\u3002", "\u53ef\u5bf9 BitmapIndexScan \u5b50\u8282\u70b9\u4f5c\u7279\u6b8a\u5904\u7406\uff0c\u907f\u514d\u4e3a\u6bcf\u4e2a\u5b50\u8282\u70b9\u663e\u5f0f\u8c03\u7528 tbm_union\uff1a\u76f4\u63a5\u4e0b\u4f20\u5f53\u524d\u7ed3\u679c\u4f4d\u56fe\uff0c\u8ba9\u5b50\u8282\u70b9\u5c06\u7ed3\u679c\u6309\u4f4d OR \u5408\u5e76\u8fdb\u53bb\u3002", "ExecReScan \u4e0d\u77e5\u9053\u5f53\u524d\u8282\u70b9\u7684\u5b50\u8ba1\u5212\uff0c\u56e0\u6b64\u5fc5\u987b\u81ea\u884c\u901a\u77e5\u5b50\u8ba1\u5212\u54ea\u4e9b\u53c2\u6570\u53d1\u751f\u4e86\u53d8\u5316\u3002"]}, {"code": "case T_BitmapOr:\n\t\t\tpname = sname = \"BitmapOr\";\n\t\t\tbreak;", "title": "\u6838\u5fc3\u6e90\u7801\u4e2d\u7684 EXPLAIN \u6807\u8bc6"}], "description_zh": "\u5bf9\u5404\u5b50\u8ba1\u5212\u751f\u6210\u7684\u4f4d\u56fe\u6c42\u5e76\u96c6\u3002", "description_zh_html": "<p>\u5bf9\u5404\u5b50\u8ba1\u5212\u751f\u6210\u7684\u4f4d\u56fe\u6c42\u5e76\u96c6\u3002</p><p>\u6838\u5fc3\u8282\u70b9\u6807\u8bc6\uff1a<code>T_BitmapOr</code>\uff1bEXPLAIN \u540d\u79f0\uff1a<code>BitmapOr</code>\u3002</p><p>\u672c\u7248\u672c\u6e90\u7801\u4e2d\u7684\u5e76\u884c\u6267\u884c\u6216\u89c2\u6d4b\u56de\u8c03\uff1a\u8be5\u8282\u70b9\u5b9e\u73b0\u4e2d\u672a\u63d0\u53d6\u5230\u6b64\u7c7b\u56de\u8c03\u3002\u56de\u8c03\u7684\u5b58\u5728\u4e0d\u8868\u793a\u8be5\u8282\u70b9\u5fc5\u7136\u652f\u6301\u5171\u4eab\u5e76\u884c\u626b\u63cf\uff1b\u5728\u5e76\u884c\u5de5\u4f5c\u8fdb\u7a0b\u4e2d\u6267\u884c\u4e5f\u4e0d\u7b49\u4e8e\u5177\u6709\u5e76\u884c\u611f\u77e5\u80fd\u529b\u3002</p><h3>\u540c\u7248\u672c\u4e2d\u6587\u624b\u518c\u8282\u9009</h3><p>\n<code class=\"command\">EXPLAIN ANALYZE</code> \u6d4b\u5f97\u7684\u8fd0\u884c\u65f6\u95f4\uff0c\u53ef\u80fd\u4ee5\u4e24\u79cd\u91cd\u8981\u65b9\u5f0f\u504f\u79bb\u540c\u4e00\u67e5\u8be2\u7684\u6b63\u5e38\u6267\u884c\u65f6\u95f4\u3002\u7b2c\u4e00\uff0c\u7531\u4e8e\u4e0d\u4f1a\u5411\u5ba2\u6237\u7aef\u4f20\u9012\u4efb\u4f55\u8f93\u51fa\u884c\uff0c\u56e0\u6b64\u7f51\u7edc\u4f20\u8f93\u5f00\u9500\u4e0d\u4f1a\u88ab\u8ba1\u5165\u3002\u9664\u975e\u6307\u5b9a\u4e86 <code class=\"literal\">SERIALIZE</code>\uff0cI/O \u8f6c\u6362\u5f00\u9500\u540c\u6837\u4e5f\u4e0d\u4f1a\u88ab\u8ba1\u5165\u3002\u7b2c\u4e8c\uff0c<code class=\"command\">EXPLAIN ANALYZE</code> \u9644\u52a0\u7684\u6d4b\u91cf\u5f00\u9500\u672c\u8eab\u53ef\u80fd\u76f8\u5f53\u53ef\u89c2\uff0c\u5c24\u5176\u662f\u5728\u64cd\u4f5c\u7cfb\u7edf\u8c03\u7528 <code class=\"function\">gettimeofday()</code> \u8f83\u6162\u7684\u673a\u5668\u4e0a\u3002\u53ef\u4ee5\u4f7f\u7528 <a class=\"xref\" href=\"/zh/docs/17/pgtesttiming.html\"><span class=\"refentrytitle\"><span class=\"application\">pg_test_timing</span></span></a> \u5de5\u5177\u6765\u6d4b\u91cf\u7cfb\u7edf\u4e0a\u7684\u8ba1\u65f6\u5f00\u9500\u3002\n   </p><p>\n    \u4e0d\u5e94\u5c06 <code class=\"command\">EXPLAIN</code> \u7ed3\u679c\u5916\u63a8\u5230\u4e0e\u5b9e\u9645\u6d4b\u8bd5\u573a\u666f\u5dee\u5f02\u5f88\u5927\u7684\u60c5\u51b5\u3002\u4f8b\u5982\uff0c\u5728\u4e00\u4e2a\u5f88\u5c0f\u7684\u8868\u4e0a\u5f97\u5230\u7684\u7ed3\u679c\uff0c\u4e0d\u80fd\u5047\u5b9a\u4e5f\u9002\u7528\u4e8e\u5927\u578b\u8868\u3002\u89c4\u5212\u5668\u7684\u4ee3\u4ef7\u4f30\u8ba1\u4e0d\u662f\u7ebf\u6027\u7684\uff0c\u56e0\u6b64\u5b83\u53ef\u80fd\u4f1a\u4e3a\u66f4\u5927\u6216\u66f4\u5c0f\u7684\u8868\u9009\u62e9\u4e0d\u540c\u7684\u8ba1\u5212\u3002\u4e00\u4e2a\u6781\u7aef\u793a\u4f8b\u662f\uff1a\u5bf9\u4e8e\u53ea\u5360\u7528\u4e00\u4e2a\u78c1\u76d8\u9875\u7684\u8868\uff0c\u65e0\u8bba\u7d22\u5f15\u662f\u5426\u53ef\u7528\uff0c\u51e0\u4e4e\u603b\u4f1a\u5f97\u5230\u987a\u5e8f\u626b\u63cf\u8ba1\u5212\u3002\u89c4\u5212\u5668\u8ba4\u8bc6\u5230\uff0c\u65e0\u8bba\u5982\u4f55\u5904\u7406\u8be5\u8868\u90fd\u9700\u8981\u4e00\u6b21\u78c1\u76d8\u9875\u8bfb\u53d6\uff0c\u56e0\u6b64\u518d\u989d\u5916\u8bfb\u53d6\u9875\u9762\u53bb\u67e5\u770b\u7d22\u5f15\u5e76\u6ca1\u6709\u4ef7\u503c\u3002\uff08\u524d\u9762\u7684 <code class=\"literal\">polygon_tbl</code> \u793a\u4f8b\u5df2\u7ecf\u5c55\u793a\u8fc7\u8fd9\u79cd\u60c5\u51b5\u3002\uff09\n   </p><p>\n    \u5728\u67d0\u4e9b\u60c5\u51b5\u4e0b\uff0c\u5b9e\u9645\u503c\u548c\u4f30\u8ba1\u503c\u4e0d\u4f1a\u5f88\u597d\u5730\u5bf9\u5e94\uff0c\u4f46\u8fd9\u5e76\u4e0d\u8868\u793a\u51fa\u73b0\u4e86\u95ee\u9898\u3002\u5176\u4e2d\u4e00\u79cd\u60c5\u51b5\u662f\uff0c\u8ba1\u5212\u8282\u70b9\u7684\u6267\u884c\u4f1a\u88ab <code class=\"literal\">LIMIT</code> \u6216\u7c7b\u4f3c\u6548\u679c\u63d0\u524d\u622a\u65ad\u3002\u4f8b\u5982\uff0c\u5728\u524d\u9762\u7528\u8fc7\u7684 <code class=\"literal\">LIMIT</code> \u67e5\u8be2\u4e2d\uff1a\n\n</p><p>\n\n    Index Scan \u8282\u70b9\u7684\u4f30\u8ba1\u4ee3\u4ef7\u548c\u884c\u8ba1\u6570\u663e\u793a\u5f97\u50cf\u662f\u5b83\u4f1a\u8fd0\u884c\u5230\u7ed3\u675f\u4e00\u6837\u3002\u4f46\u5b9e\u9645\u4e0a\uff0cLimit \u8282\u70b9\u5728\u62ff\u5230\u4e24\u884c\u4e4b\u540e\u5c31\u505c\u6b62\u8bf7\u6c42\u66f4\u591a\u884c\uff0c\u56e0\u6b64\u5b9e\u9645\u884c\u8ba1\u6570\u53ea\u6709 2\uff0c\u8fd0\u884c\u65f6\u95f4\u4e5f\u4f4e\u4e8e\u4ee3\u4ef7\u4f30\u8ba1\u6240\u6697\u793a\u7684\u6c34\u5e73\u3002\u8fd9\u5e76\u4e0d\u662f\u4f30\u8ba1\u9519\u8bef\uff0c\u53ea\u662f\u4f30\u8ba1\u503c\u4e0e\u771f\u5b9e\u503c\u7684\u663e\u793a\u65b9\u5f0f\u4e0d\u540c\u800c\u5df2\u3002\n   </p><p><a href=\"/zh/docs/17/using-explain.html#USING-EXPLAIN-CAVEATS\">\u67e5\u770b\u5b8c\u6574\u4e2d\u6587\u624b\u518c\u4e0e\u4e0a\u4e0b\u6587</a>\u3002</p><p>\u672c\u9875\u5f00\u5934\u7684\u4e2d\u6587\u8bf4\u660e\u4e3a PG.CENTER \u5bf9\u7f16\u8f91\u8bf4\u660e\u7684\u7ffb\u8bd1\uff1b\u624b\u518c\u8282\u9009\u4fdd\u7559\u5bf9\u5e94\u7248\u672c\u4e2d\u6587\u6587\u6863\u539f\u6587\u3002\u6e90\u7801\u4fe1\u606f\u53ca\u624b\u518c\u793a\u4f8b\u4e0d\u4ee3\u8868\u91cd\u65b0\u8fdb\u884c\u8fc7\u8fd0\u884c\u6d4b\u8bd5\u3002</p>"}, "summary": "\u5bf9\u5404\u5b50\u8ba1\u5212\u751f\u6210\u7684\u4f4d\u56fe\u6c42\u5e76\u96c6\u3002", "version": "17", "link_map": {"/zh/docs/17/pgtesttiming.html": "/docs/17/pgtesttiming.html", "/zh/docs/17/using-explain.html#USING-EXPLAIN-CAVEATS": "/docs/17/using-explain.html#USING-EXPLAIN-CAVEATS"}, "body_html": "<p>\u5bf9\u5404\u5b50\u8ba1\u5212\u751f\u6210\u7684\u4f4d\u56fe\u6c42\u5e76\u96c6\u3002</p><p>\u6838\u5fc3\u8282\u70b9\u6807\u8bc6\uff1a<code>T_BitmapOr</code>\uff1bEXPLAIN \u540d\u79f0\uff1a<code>BitmapOr</code>\u3002</p><p>\u672c\u7248\u672c\u6e90\u7801\u4e2d\u7684\u5e76\u884c\u6267\u884c\u6216\u89c2\u6d4b\u56de\u8c03\uff1a\u8be5\u8282\u70b9\u5b9e\u73b0\u4e2d\u672a\u63d0\u53d6\u5230\u6b64\u7c7b\u56de\u8c03\u3002\u56de\u8c03\u7684\u5b58\u5728\u4e0d\u8868\u793a\u8be5\u8282\u70b9\u5fc5\u7136\u652f\u6301\u5171\u4eab\u5e76\u884c\u626b\u63cf\uff1b\u5728\u5e76\u884c\u5de5\u4f5c\u8fdb\u7a0b\u4e2d\u6267\u884c\u4e5f\u4e0d\u7b49\u4e8e\u5177\u6709\u5e76\u884c\u611f\u77e5\u80fd\u529b\u3002</p><h3>\u540c\u7248\u672c\u4e2d\u6587\u624b\u518c\u8282\u9009</h3><p>\n<code>EXPLAIN ANALYZE</code> \u6d4b\u5f97\u7684\u8fd0\u884c\u65f6\u95f4\uff0c\u53ef\u80fd\u4ee5\u4e24\u79cd\u91cd\u8981\u65b9\u5f0f\u504f\u79bb\u540c\u4e00\u67e5\u8be2\u7684\u6b63\u5e38\u6267\u884c\u65f6\u95f4\u3002\u7b2c\u4e00\uff0c\u7531\u4e8e\u4e0d\u4f1a\u5411\u5ba2\u6237\u7aef\u4f20\u9012\u4efb\u4f55\u8f93\u51fa\u884c\uff0c\u56e0\u6b64\u7f51\u7edc\u4f20\u8f93\u5f00\u9500\u4e0d\u4f1a\u88ab\u8ba1\u5165\u3002\u9664\u975e\u6307\u5b9a\u4e86 <code>SERIALIZE</code>\uff0cI/O \u8f6c\u6362\u5f00\u9500\u540c\u6837\u4e5f\u4e0d\u4f1a\u88ab\u8ba1\u5165\u3002\u7b2c\u4e8c\uff0c<code>EXPLAIN ANALYZE</code> \u9644\u52a0\u7684\u6d4b\u91cf\u5f00\u9500\u672c\u8eab\u53ef\u80fd\u76f8\u5f53\u53ef\u89c2\uff0c\u5c24\u5176\u662f\u5728\u64cd\u4f5c\u7cfb\u7edf\u8c03\u7528 <code>gettimeofday()</code> \u8f83\u6162\u7684\u673a\u5668\u4e0a\u3002\u53ef\u4ee5\u4f7f\u7528 <a href=\"/zh/docs/17/pgtesttiming.html\" rel=\"nofollow\"><span><span>pg_test_timing</span></span></a> \u5de5\u5177\u6765\u6d4b\u91cf\u7cfb\u7edf\u4e0a\u7684\u8ba1\u65f6\u5f00\u9500\u3002\n   </p><p>\n    \u4e0d\u5e94\u5c06 <code>EXPLAIN</code> \u7ed3\u679c\u5916\u63a8\u5230\u4e0e\u5b9e\u9645\u6d4b\u8bd5\u573a\u666f\u5dee\u5f02\u5f88\u5927\u7684\u60c5\u51b5\u3002\u4f8b\u5982\uff0c\u5728\u4e00\u4e2a\u5f88\u5c0f\u7684\u8868\u4e0a\u5f97\u5230\u7684\u7ed3\u679c\uff0c\u4e0d\u80fd\u5047\u5b9a\u4e5f\u9002\u7528\u4e8e\u5927\u578b\u8868\u3002\u89c4\u5212\u5668\u7684\u4ee3\u4ef7\u4f30\u8ba1\u4e0d\u662f\u7ebf\u6027\u7684\uff0c\u56e0\u6b64\u5b83\u53ef\u80fd\u4f1a\u4e3a\u66f4\u5927\u6216\u66f4\u5c0f\u7684\u8868\u9009\u62e9\u4e0d\u540c\u7684\u8ba1\u5212\u3002\u4e00\u4e2a\u6781\u7aef\u793a\u4f8b\u662f\uff1a\u5bf9\u4e8e\u53ea\u5360\u7528\u4e00\u4e2a\u78c1\u76d8\u9875\u7684\u8868\uff0c\u65e0\u8bba\u7d22\u5f15\u662f\u5426\u53ef\u7528\uff0c\u51e0\u4e4e\u603b\u4f1a\u5f97\u5230\u987a\u5e8f\u626b\u63cf\u8ba1\u5212\u3002\u89c4\u5212\u5668\u8ba4\u8bc6\u5230\uff0c\u65e0\u8bba\u5982\u4f55\u5904\u7406\u8be5\u8868\u90fd\u9700\u8981\u4e00\u6b21\u78c1\u76d8\u9875\u8bfb\u53d6\uff0c\u56e0\u6b64\u518d\u989d\u5916\u8bfb\u53d6\u9875\u9762\u53bb\u67e5\u770b\u7d22\u5f15\u5e76\u6ca1\u6709\u4ef7\u503c\u3002\uff08\u524d\u9762\u7684 <code>polygon_tbl</code> \u793a\u4f8b\u5df2\u7ecf\u5c55\u793a\u8fc7\u8fd9\u79cd\u60c5\u51b5\u3002\uff09\n   </p><p>\n    \u5728\u67d0\u4e9b\u60c5\u51b5\u4e0b\uff0c\u5b9e\u9645\u503c\u548c\u4f30\u8ba1\u503c\u4e0d\u4f1a\u5f88\u597d\u5730\u5bf9\u5e94\uff0c\u4f46\u8fd9\u5e76\u4e0d\u8868\u793a\u51fa\u73b0\u4e86\u95ee\u9898\u3002\u5176\u4e2d\u4e00\u79cd\u60c5\u51b5\u662f\uff0c\u8ba1\u5212\u8282\u70b9\u7684\u6267\u884c\u4f1a\u88ab <code>LIMIT</code> \u6216\u7c7b\u4f3c\u6548\u679c\u63d0\u524d\u622a\u65ad\u3002\u4f8b\u5982\uff0c\u5728\u524d\u9762\u7528\u8fc7\u7684 <code>LIMIT</code> \u67e5\u8be2\u4e2d\uff1a\n\n</p><p>\n\n    Index Scan \u8282\u70b9\u7684\u4f30\u8ba1\u4ee3\u4ef7\u548c\u884c\u8ba1\u6570\u663e\u793a\u5f97\u50cf\u662f\u5b83\u4f1a\u8fd0\u884c\u5230\u7ed3\u675f\u4e00\u6837\u3002\u4f46\u5b9e\u9645\u4e0a\uff0cLimit \u8282\u70b9\u5728\u62ff\u5230\u4e24\u884c\u4e4b\u540e\u5c31\u505c\u6b62\u8bf7\u6c42\u66f4\u591a\u884c\uff0c\u56e0\u6b64\u5b9e\u9645\u884c\u8ba1\u6570\u53ea\u6709 2\uff0c\u8fd0\u884c\u65f6\u95f4\u4e5f\u4f4e\u4e8e\u4ee3\u4ef7\u4f30\u8ba1\u6240\u6697\u793a\u7684\u6c34\u5e73\u3002\u8fd9\u5e76\u4e0d\u662f\u4f30\u8ba1\u9519\u8bef\uff0c\u53ea\u662f\u4f30\u8ba1\u503c\u4e0e\u771f\u5b9e\u503c\u7684\u663e\u793a\u65b9\u5f0f\u4e0d\u540c\u800c\u5df2\u3002\n   </p><p><a href=\"/zh/docs/17/using-explain.html#USING-EXPLAIN-CAVEATS\" rel=\"nofollow\">\u67e5\u770b\u5b8c\u6574\u4e2d\u6587\u624b\u518c\u4e0e\u4e0a\u4e0b\u6587</a>\u3002</p><p>\u672c\u9875\u5f00\u5934\u7684\u4e2d\u6587\u8bf4\u660e\u4e3a PG.CENTER \u5bf9\u7f16\u8f91\u8bf4\u660e\u7684\u7ffb\u8bd1\uff1b\u624b\u518c\u8282\u9009\u4fdd\u7559\u5bf9\u5e94\u7248\u672c\u4e2d\u6587\u6587\u6863\u539f\u6587\u3002\u6e90\u7801\u4fe1\u606f\u53ca\u624b\u518c\u793a\u4f8b\u4e0d\u4ee3\u8868\u91cd\u65b0\u8fdb\u884c\u8fc7\u8fd0\u884c\u6d4b\u8bd5\u3002</p>", "body_sha256": "cbda5ec4517bfa0a98c6a45ae122cb6e2d6bef37638881d88c0cc6b779566584", "content_hash": "9c8fff66925480b2231cab7d66426e2268bbc84576c424ff7e44f1ba70e31fcb", "source_database": "center", "source_revision": "dd27f2b3c59e73ed14aa3324901242bf69a032a6347805f274e6260322d42979"}, "tables_zh": [{"key": "explain-labels", "rows": [{"label": "BitmapOr", "identity": "BitmapOr"}], "title": "\u672c\u6784\u5efa\u4e2d\u7684 EXPLAIN \u6807\u7b7e", "columns": [{"key": "label", "label": "\u6587\u672c\u683c\u5f0f\u6807\u7b7e"}, {"key": "identity", "label": "\u7ed3\u6784\u5316\u8282\u70b9\u6807\u8bc6"}]}], "strategies": [], "description": ["\u5bf9\u5404\u5b50\u8ba1\u5212\u751f\u6210\u7684\u4f4d\u56fe\u6c42\u5e76\u96c6\u3002"], "sections_zh": [{"title": "EXPLAIN \u540d\u79f0\u4e0e\u5c5e\u6027", "paragraphs": ["\u7ed3\u6784\u5316\u683c\u5f0f\u4f7f\u7528\u4e0a\u8ff0 Node Type\u3002\u6587\u672c\u683c\u5f0f\u540d\u79f0\u8fd8\u53ef\u80fd\u5305\u542b\u64cd\u4f5c\u3001\u7b56\u7565\u3001\u8fde\u63a5\u7c7b\u578b\u3001\u626b\u63cf\u65b9\u5411\u6216\u805a\u5408\u9636\u6bb5\u5c5e\u6027\u3002", "\u6b64\u6e90\u7801\u8bb0\u5f55\u7684\u6587\u672c\u540d\u79f0\uff1aBitmapOr.", "\u5e76\u884c\u611f\u77e5\u4e0e\u5e76\u884c\u5b89\u5168\u662f\u4e0d\u540c\u7684\u8ba1\u5212\u5c5e\u6027\u3002\u5728\u5e76\u884c\u5de5\u4f5c\u8fdb\u7a0b\u5185\u8fd0\u884c\u7684\u8282\u70b9\u4e0d\u4e00\u5b9a\u662f\u5e76\u884c\u611f\u77e5\u8282\u70b9\u3002"]}, {"title": "\u5185\u5b58\u4e0e\u4e34\u65f6\u5b58\u50a8", "paragraphs": ["\u6b64\u8282\u70b9\u6309\u57fa\u4e8e work_mem \u7684\u9884\u7b97\u5206\u914d\u5143\u7ec4\u4f4d\u7f6e\u4f4d\u56fe\u3002\u4f4d\u56fe\u53ef\u4ee5\u4fdd\u7559\u9875\u7ea7\u6709\u635f\u6761\u76ee\uff0c\u800c\u4e0d\u8bb0\u5f55\u6bcf\u4e2a\u5143\u7ec4\u4f4d\u7f6e\uff0c\u56e0\u6b64\u4ecd\u53ef\u80fd\u9700\u8981\u5806\u91cd\u68c0\u3002"]}, {"title": "\u5e76\u884c\u6267\u884c\u4e0e\u8fd0\u884c\u4fe1\u606f\u91c7\u96c6", "paragraphs": ["\u4ee5\u4e0b\u6e90\u7801\u56de\u8c03\u53ef\u4ee5\u534f\u8c03\u6267\u884c\u6216\u6536\u96c6\u5de5\u4f5c\u8fdb\u7a0b\u7684\u6d4b\u91cf\u6570\u636e\u3002\u56de\u8c03\u5b58\u5728\u4e0d\u4ee3\u8868\u8be5\u8282\u70b9\u666e\u904d\u652f\u6301\u5171\u4eab\u5e76\u884c\u626b\u63cf\u6216\u5171\u4eab\u72b6\u6001\u3002", "\u6b64\u6784\u5efa\u7684\u56de\u8c03\uff1anone extracted from this node implementation."]}, {"title": "\u540c\u7248\u672c\u624b\u518c\u8bf4\u660e", "paragraphs": ["\u7531\u4e8e\u5b9e\u73b0\u4e0a\u7684\u9650\u5236\uff0cBitmapAnd \u548c BitmapOr \u8282\u70b9\u62a5\u544a\u7684\u5b9e\u9645\u884c\u6570\u59cb\u7ec8\u4e3a\u96f6\u3002"]}, {"title": "\u6267\u884c\u5668\u5b9e\u73b0\u8bf4\u660e", "paragraphs": ["\u8bf4\u660e\uff1aBitmapOr \u4e0d\u4f7f\u7528\u5de6\u53f3\u5b50\u6811\uff0c\u800c\u50cf Append \u4e00\u6837\u7ef4\u62a4\u5b50\u8ba1\u5212\u5217\u8868\u3002\u4e0d\u8fc7\u5176\u903b\u8f91\u6bd4 Append \u7b80\u5355\u5f97\u591a\uff0c\u56e0\u4e3a\u65e0\u9700\u5904\u7406\u6b63\u5411\u6216\u53cd\u5411\u6267\u884c\u3002", "\u5bf9\u6bcf\u4e2a\u5f85\u6267\u884c\u8ba1\u5212\u8c03\u7528 ExecInitNode\uff0c\u5e76\u5c06\u7ed3\u679c\u4fdd\u5b58\u5230 bitmapplanstates \u6570\u7ec4\u3002", "BitmapOr \u8ba1\u5212\u6ca1\u6709\u8868\u8fbe\u5f0f\u4e0a\u4e0b\u6587\uff0c\u56e0\u4e3a\u5b83\u4eec\u4ece\u4e0d\u8c03\u7528 ExecQual \u6216 ExecProject\uff0c\u4e5f\u4e0d\u9700\u8981\u5143\u7ec4\u69fd\u3002", "\u53ef\u5bf9 BitmapIndexScan \u5b50\u8282\u70b9\u4f5c\u7279\u6b8a\u5904\u7406\uff0c\u907f\u514d\u4e3a\u6bcf\u4e2a\u5b50\u8282\u70b9\u663e\u5f0f\u8c03\u7528 tbm_union\uff1a\u76f4\u63a5\u4e0b\u4f20\u5f53\u524d\u7ed3\u679c\u4f4d\u56fe\uff0c\u8ba9\u5b50\u8282\u70b9\u5c06\u7ed3\u679c\u6309\u4f4d OR \u5408\u5e76\u8fdb\u53bb\u3002", "ExecReScan \u4e0d\u77e5\u9053\u5f53\u524d\u8282\u70b9\u7684\u5b50\u8ba1\u5212\uff0c\u56e0\u6b64\u5fc5\u987b\u81ea\u884c\u901a\u77e5\u5b50\u8ba1\u5212\u54ea\u4e9b\u53c2\u6570\u53d1\u751f\u4e86\u53d8\u5316\u3002"]}, {"code": "case T_BitmapOr:\n\t\t\tpname = sname = \"BitmapOr\";\n\t\t\tbreak;", "title": "\u6838\u5fc3\u6e90\u7801\u4e2d\u7684 EXPLAIN \u6807\u8bc6"}], "localization": {"status": "complete", "sources": [], "language": "zh", "original_text": {"/versions/17/description/0": "Unions bitmaps produced by its child plans.", "/versions/17/facts/0/label": "Core node tag", "/versions/17/facts/1/label": "Structured EXPLAIN Node Type", "/versions/17/facts/2/label": "Inputs", "/versions/17/facts/2/value": "Bitmap-producing child plans", "/versions/17/facts/3/label": "Output", "/versions/17/facts/3/value": "Tuple-location bitmap, not a tuple stream", "/versions/17/facts/4/label": "Executor initializer", "/versions/17/facts/5/label": "Memory mechanism", "/versions/17/tables/0/title": "EXPLAIN labels in this source build", "/versions/17/related/1/label": "Using EXPLAIN", "/versions/17/related/2/label": "Parallel plans", "/versions/17/sections/0/title": "EXPLAIN names and attributes", "/versions/17/sections/1/title": "Memory and temporary storage", "/versions/17/sections/2/title": "Parallel execution and instrumentation", "/versions/17/sections/3/title": "Same-version manual discussion", "/versions/17/sections/4/title": "Executor implementation notes", "/versions/17/sections/5/title": "EXPLAIN identity in core source", "/versions/17/memory/description": "The node allocates a tuple-location bitmap using a work_mem-derived budget. A bitmap can retain page-level lossy entries instead of every tuple location; heap rechecks then remain necessary.", "/versions/17/sections/0/paragraphs/0": "Structured formats use the Node Type above. Text-format spellings can also include operation, strategy, join type, scan direction or aggregation-stage attributes.", "/versions/17/sections/0/paragraphs/1": "Text names recorded by this source: BitmapOr.", "/versions/17/sections/0/paragraphs/2": "Parallel-aware and parallel-safe are different plan properties. A node running inside a parallel worker is not necessarily a parallel-aware node.", "/versions/17/sections/1/paragraphs/0": "The node allocates a tuple-location bitmap using a work_mem-derived budget. A bitmap can retain page-level lossy entries instead of every tuple location; heap rechecks then remain necessary.", "/versions/17/sections/2/paragraphs/0": "The source callbacks below can coordinate execution or collect worker instrumentation. Their presence is not a blanket claim that this node supports a shared parallel scan or shared state.", "/versions/17/sections/2/paragraphs/1": "Callbacks in this build: none extracted from this node implementation.", "/versions/17/sections/3/paragraphs/0": "BitmapAnd and BitmapOr nodes always report their actual row counts as zero, due to implementation limitations.", "/versions/17/sections/4/paragraphs/0": "NOTES BitmapOr nodes don't make use of their left and right subtrees, rather they maintain a list of subplans, much like Append nodes. The logic is much simpler than Append, however, since we needn't cope with forward/backward execution.", "/versions/17/sections/4/paragraphs/1": "call ExecInitNode on each of the plans to be executed and save the results into the array \"bitmapplanstates\".", "/versions/17/sections/4/paragraphs/2": "BitmapOr plans don't have expression contexts because they never call ExecQual or ExecProject. They don't need any tuple slots either.", "/versions/17/sections/4/paragraphs/3": "We can special-case BitmapIndexScan children to avoid an explicit tbm_union step for each child: just pass down the current result bitmap and let the child OR directly into it.", "/versions/17/sections/4/paragraphs/4": "ExecReScan doesn't know about my subplans, so I have to do changed-parameter signaling myself.", "/versions/17/tables/0/columns/0/label": "Text-format label", "/versions/17/tables/0/columns/1/label": "Structured node identity"}, "fallback_fields": [], "source_language": "en", "original_snapshot_sha256": "3c6a5f9570908e97f551a4c854a25536827db55ad6c8ba9330da8d6a39248d92", "canonical_center_text_hash": "9c8fff66925480b2231cab7d66426e2268bbc84576c424ff7e44f1ba70e31fcb"}, "evidence_kind": "source and documentation", "explain_names": ["BitmapOr"], "partial_modes": [], "description_zh": "\u5bf9\u5404\u5b50\u8ba1\u5212\u751f\u6210\u7684\u4f4d\u56fe\u6c42\u5e76\u96c6\u3002", "comparison_data": {"node_tag": "T_BitmapOr", "strategies": [], "text_names": ["BitmapOr"], "initializer": "ExecInitBitmapOr", "partial_modes": [], "memory_mechanism": "bitmap-lossification", "parallel_callbacks": []}, "comparison_hash": "c0ca503a6029c37ec720213dcdc3094997eb194d4920da68f94a7420d3e8f1d2", "manual_language": "zh", "explain_prefixes": ["Parallel", "Async"], "runtime_verified": false, "source_inventory": {"explain": "src/backend/commands/explain.c", "executor": "src/backend/executor/execProcnode.c", "implementation": "src/backend/executor/nodeBitmapOr.c"}, "parallel_callbacks": [], "description_zh_html": "<p>\u5bf9\u5404\u5b50\u8ba1\u5212\u751f\u6210\u7684\u4f4d\u56fe\u6c42\u5e76\u96c6\u3002</p><p>\u6838\u5fc3\u8282\u70b9\u6807\u8bc6\uff1a<code>T_BitmapOr</code>\uff1bEXPLAIN \u540d\u79f0\uff1a<code>BitmapOr</code>\u3002</p><p>\u672c\u7248\u672c\u6e90\u7801\u4e2d\u7684\u5e76\u884c\u6267\u884c\u6216\u89c2\u6d4b\u56de\u8c03\uff1a\u8be5\u8282\u70b9\u5b9e\u73b0\u4e2d\u672a\u63d0\u53d6\u5230\u6b64\u7c7b\u56de\u8c03\u3002\u56de\u8c03\u7684\u5b58\u5728\u4e0d\u8868\u793a\u8be5\u8282\u70b9\u5fc5\u7136\u652f\u6301\u5171\u4eab\u5e76\u884c\u626b\u63cf\uff1b\u5728\u5e76\u884c\u5de5\u4f5c\u8fdb\u7a0b\u4e2d\u6267\u884c\u4e5f\u4e0d\u7b49\u4e8e\u5177\u6709\u5e76\u884c\u611f\u77e5\u80fd\u529b\u3002</p><h3>\u540c\u7248\u672c\u4e2d\u6587\u624b\u518c\u8282\u9009</h3><p>\n<code>EXPLAIN ANALYZE</code> \u6d4b\u5f97\u7684\u8fd0\u884c\u65f6\u95f4\uff0c\u53ef\u80fd\u4ee5\u4e24\u79cd\u91cd\u8981\u65b9\u5f0f\u504f\u79bb\u540c\u4e00\u67e5\u8be2\u7684\u6b63\u5e38\u6267\u884c\u65f6\u95f4\u3002\u7b2c\u4e00\uff0c\u7531\u4e8e\u4e0d\u4f1a\u5411\u5ba2\u6237\u7aef\u4f20\u9012\u4efb\u4f55\u8f93\u51fa\u884c\uff0c\u56e0\u6b64\u7f51\u7edc\u4f20\u8f93\u5f00\u9500\u4e0d\u4f1a\u88ab\u8ba1\u5165\u3002\u9664\u975e\u6307\u5b9a\u4e86 <code>SERIALIZE</code>\uff0cI/O \u8f6c\u6362\u5f00\u9500\u540c\u6837\u4e5f\u4e0d\u4f1a\u88ab\u8ba1\u5165\u3002\u7b2c\u4e8c\uff0c<code>EXPLAIN ANALYZE</code> \u9644\u52a0\u7684\u6d4b\u91cf\u5f00\u9500\u672c\u8eab\u53ef\u80fd\u76f8\u5f53\u53ef\u89c2\uff0c\u5c24\u5176\u662f\u5728\u64cd\u4f5c\u7cfb\u7edf\u8c03\u7528 <code>gettimeofday()</code> \u8f83\u6162\u7684\u673a\u5668\u4e0a\u3002\u53ef\u4ee5\u4f7f\u7528 <a href=\"/zh/docs/17/pgtesttiming.html\" rel=\"nofollow\"><span><span>pg_test_timing</span></span></a> \u5de5\u5177\u6765\u6d4b\u91cf\u7cfb\u7edf\u4e0a\u7684\u8ba1\u65f6\u5f00\u9500\u3002\n   </p><p>\n    \u4e0d\u5e94\u5c06 <code>EXPLAIN</code> \u7ed3\u679c\u5916\u63a8\u5230\u4e0e\u5b9e\u9645\u6d4b\u8bd5\u573a\u666f\u5dee\u5f02\u5f88\u5927\u7684\u60c5\u51b5\u3002\u4f8b\u5982\uff0c\u5728\u4e00\u4e2a\u5f88\u5c0f\u7684\u8868\u4e0a\u5f97\u5230\u7684\u7ed3\u679c\uff0c\u4e0d\u80fd\u5047\u5b9a\u4e5f\u9002\u7528\u4e8e\u5927\u578b\u8868\u3002\u89c4\u5212\u5668\u7684\u4ee3\u4ef7\u4f30\u8ba1\u4e0d\u662f\u7ebf\u6027\u7684\uff0c\u56e0\u6b64\u5b83\u53ef\u80fd\u4f1a\u4e3a\u66f4\u5927\u6216\u66f4\u5c0f\u7684\u8868\u9009\u62e9\u4e0d\u540c\u7684\u8ba1\u5212\u3002\u4e00\u4e2a\u6781\u7aef\u793a\u4f8b\u662f\uff1a\u5bf9\u4e8e\u53ea\u5360\u7528\u4e00\u4e2a\u78c1\u76d8\u9875\u7684\u8868\uff0c\u65e0\u8bba\u7d22\u5f15\u662f\u5426\u53ef\u7528\uff0c\u51e0\u4e4e\u603b\u4f1a\u5f97\u5230\u987a\u5e8f\u626b\u63cf\u8ba1\u5212\u3002\u89c4\u5212\u5668\u8ba4\u8bc6\u5230\uff0c\u65e0\u8bba\u5982\u4f55\u5904\u7406\u8be5\u8868\u90fd\u9700\u8981\u4e00\u6b21\u78c1\u76d8\u9875\u8bfb\u53d6\uff0c\u56e0\u6b64\u518d\u989d\u5916\u8bfb\u53d6\u9875\u9762\u53bb\u67e5\u770b\u7d22\u5f15\u5e76\u6ca1\u6709\u4ef7\u503c\u3002\uff08\u524d\u9762\u7684 <code>polygon_tbl</code> \u793a\u4f8b\u5df2\u7ecf\u5c55\u793a\u8fc7\u8fd9\u79cd\u60c5\u51b5\u3002\uff09\n   </p><p>\n    \u5728\u67d0\u4e9b\u60c5\u51b5\u4e0b\uff0c\u5b9e\u9645\u503c\u548c\u4f30\u8ba1\u503c\u4e0d\u4f1a\u5f88\u597d\u5730\u5bf9\u5e94\uff0c\u4f46\u8fd9\u5e76\u4e0d\u8868\u793a\u51fa\u73b0\u4e86\u95ee\u9898\u3002\u5176\u4e2d\u4e00\u79cd\u60c5\u51b5\u662f\uff0c\u8ba1\u5212\u8282\u70b9\u7684\u6267\u884c\u4f1a\u88ab <code>LIMIT</code> \u6216\u7c7b\u4f3c\u6548\u679c\u63d0\u524d\u622a\u65ad\u3002\u4f8b\u5982\uff0c\u5728\u524d\u9762\u7528\u8fc7\u7684 <code>LIMIT</code> \u67e5\u8be2\u4e2d\uff1a\n\n</p><p>\n\n    Index Scan \u8282\u70b9\u7684\u4f30\u8ba1\u4ee3\u4ef7\u548c\u884c\u8ba1\u6570\u663e\u793a\u5f97\u50cf\u662f\u5b83\u4f1a\u8fd0\u884c\u5230\u7ed3\u675f\u4e00\u6837\u3002\u4f46\u5b9e\u9645\u4e0a\uff0cLimit \u8282\u70b9\u5728\u62ff\u5230\u4e24\u884c\u4e4b\u540e\u5c31\u505c\u6b62\u8bf7\u6c42\u66f4\u591a\u884c\uff0c\u56e0\u6b64\u5b9e\u9645\u884c\u8ba1\u6570\u53ea\u6709 2\uff0c\u8fd0\u884c\u65f6\u95f4\u4e5f\u4f4e\u4e8e\u4ee3\u4ef7\u4f30\u8ba1\u6240\u6697\u793a\u7684\u6c34\u5e73\u3002\u8fd9\u5e76\u4e0d\u662f\u4f30\u8ba1\u9519\u8bef\uff0c\u53ea\u662f\u4f30\u8ba1\u503c\u4e0e\u771f\u5b9e\u503c\u7684\u663e\u793a\u65b9\u5f0f\u4e0d\u540c\u800c\u5df2\u3002\n   </p><p><a href=\"/zh/docs/17/using-explain.html#USING-EXPLAIN-CAVEATS\" rel=\"nofollow\">\u67e5\u770b\u5b8c\u6574\u4e2d\u6587\u624b\u518c\u4e0e\u4e0a\u4e0b\u6587</a>\u3002</p><p>\u672c\u9875\u5f00\u5934\u7684\u4e2d\u6587\u8bf4\u660e\u4e3a PG.CENTER \u5bf9\u7f16\u8f91\u8bf4\u660e\u7684\u7ffb\u8bd1\uff1b\u624b\u518c\u8282\u9009\u4fdd\u7559\u5bf9\u5e94\u7248\u672c\u4e2d\u6587\u6587\u6863\u539f\u6587\u3002\u6e90\u7801\u4fe1\u606f\u53ca\u624b\u518c\u793a\u4f8b\u4e0d\u4ee3\u8868\u91cd\u65b0\u8fdb\u884c\u8fc7\u8fd0\u884c\u6d4b\u8bd5\u3002</p>"}, "18": {"facts": [{"label": "\u6838\u5fc3\u8282\u70b9\u6807\u7b7e", "value": "T_BitmapOr"}, {"label": "\u7ed3\u6784\u5316 EXPLAIN \u8282\u70b9\u7c7b\u578b", "value": "BitmapOr"}, {"label": "\u8f93\u5165", "value": "\u4ea7\u751f\u4f4d\u56fe\u7684\u5b50\u8ba1\u5212"}, {"label": "\u8f93\u51fa", "value": "\u5143\u7ec4\u4f4d\u7f6e\u4f4d\u56fe\uff0c\u4e0d\u662f\u5143\u7ec4\u6d41"}, {"label": "\u6267\u884c\u5668\u521d\u59cb\u5316\u51fd\u6570", "value": "ExecInitBitmapOr"}, {"label": "\u5185\u5b58\u673a\u5236", "value": "bitmap-lossification"}], "memory": {"evidence": [{"url": "https://ftp.postgresql.org/pub/source/v18.6/postgresql-18.6.tar.bz2", "path": "src/backend/executor/nodeBitmapOr.c", "label": "src/backend/executor/nodeBitmapOr.c", "sha256": "81e2aeb0cc0d4cece84b7514385636cd11ea0e1faab93c721d4c3b86c20c9104", "archive_sha256": "555610c24d53e4316da5b7d3fc25c279d96856d5e0e23ee308c328c5fa881d9f"}, {"url": "https://ftp.postgresql.org/pub/source/v18.6/postgresql-18.6.tar.bz2", "path": "src/backend/nodes/tidbitmap.c", "label": "src/backend/nodes/tidbitmap.c", "sha256": "e2453b7155d55db8c3a59bc929362f01d3f9692b0a483e5aa81a7b6c50db6102", "archive_sha256": "555610c24d53e4316da5b7d3fc25c279d96856d5e0e23ee308c328c5fa881d9f"}], "mechanism": "bitmap-lossification", "description": "The node allocates a tuple-location bitmap using a work_mem-derived budget. A bitmap can retain page-level lossy entries instead of every tuple location; heap rechecks then remain necessary.", "source_notes": []}, "tables": [{"key": "explain-labels", "rows": [{"label": "BitmapOr", "identity": "BitmapOr"}], "title": "\u672c\u6784\u5efa\u4e2d\u7684 EXPLAIN \u6807\u7b7e", "columns": [{"key": "label", "label": "\u6587\u672c\u683c\u5f0f\u6807\u7b7e"}, {"key": "identity", "label": "\u7ed3\u6784\u5316\u8282\u70b9\u6807\u8bc6"}]}], "related": [{"url": "/wiki/sql/explain/?v=18", "label": "EXPLAIN"}, {"url": "/docs/18/using-explain.html", "label": "\u4f7f\u7528 EXPLAIN"}, {"url": "/docs/18/parallel-plans.html", "label": "\u5e76\u884c\u8ba1\u5212"}, {"url": "/wiki/guc/work_mem/?v=18", "label": "work_mem"}], "release": {"ref": "PostgreSQL 18.6 source archive", "label": "18.6", "major": "18", "channel": "stable", "revision": "555610c24d53e4316da5b7d3fc25c279d96856d5e0e23ee308c328c5fa881d9f", "source_url": "https://ftp.postgresql.org/pub/source/v18.6/postgresql-18.6.tar.bz2", "source_snapshot_utc": ""}, "sources": [{"url": "https://ftp.postgresql.org/pub/source/v18.6/postgresql-18.6.tar.bz2", "line": 1418, "path": "src/backend/commands/explain.c", "label": "src/backend/commands/explain.c:1418", "sha256": "34c86d6070224a0e981efef51f79101d6d505e5874f1684ace183034bab14bb4", "archive_sha256": "555610c24d53e4316da5b7d3fc25c279d96856d5e0e23ee308c328c5fa881d9f"}, {"url": "https://ftp.postgresql.org/pub/source/v18.6/postgresql-18.6.tar.bz2", "line": 201, "path": "src/backend/executor/execProcnode.c", "label": "src/backend/executor/execProcnode.c:201", "sha256": "f8a06a3f539077249b20664b2812433db6d7bd12b2c0ca633525db43d06f112a", "archive_sha256": "555610c24d53e4316da5b7d3fc25c279d96856d5e0e23ee308c328c5fa881d9f"}, {"url": "https://ftp.postgresql.org/pub/source/v18.6/postgresql-18.6.tar.bz2", "path": "src/backend/executor/nodeBitmapOr.c", "label": "src/backend/executor/nodeBitmapOr.c", "sha256": 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"60040c30180093418a0affe56dd27dff9df2504b705b38039589e458bf5c31ed"}], "zh_from": {"kind": "same-version-chinese-manual-with-authored-translation-of-reviewed-guidance", "manual": {"url": "/zh/docs/18/using-explain.html#USING-EXPLAIN-CAVEATS", "anchor": "USING-EXPLAIN-CAVEATS", "locale": "zh-Hans", "version": "18", "build_id": 107, "page_key": "using-explain.html", "extraction": "concept-introduction", "source_hash": "d2f749744b3ac5aa2eb0154f295e8163903cd20fcc130c74c6172cdf2ae3a9df", "fragment_sha256": "1726362ef840934bdec0f9ec72c682b2350a203639c9fd1e22dc5d29ac24ca1f", "source_revision": "unknown:rendered-translation-baseline", "translation_revision": "git:b1b500221dbe5437cfca004d6b04d3f6e422765d;html-sha256:08e987a66af27b98444a8057c256314eafa13611a3fb9e888214fc436824244b", "translated_from_revision": null}, "body_sha256": "37580fd1b2ebc05aad556ddf2ff36fd8835329c1778da435bf49486cd53a86ff", "runtime_rerun": false, "authored_translation": "authored-translation-of-reviewed-guidance", "source_facts_revision": "555610c24d53e4316da5b7d3fc25c279d96856d5e0e23ee308c328c5fa881d9f"}, "facts_zh": [{"label": "\u6838\u5fc3\u8282\u70b9\u6807\u7b7e", "value": "T_BitmapOr"}, {"label": "\u7ed3\u6784\u5316 EXPLAIN \u8282\u70b9\u7c7b\u578b", "value": "BitmapOr"}, {"label": "\u8f93\u5165", "value": "\u4ea7\u751f\u4f4d\u56fe\u7684\u5b50\u8ba1\u5212"}, {"label": "\u8f93\u51fa", "value": "\u5143\u7ec4\u4f4d\u7f6e\u4f4d\u56fe\uff0c\u4e0d\u662f\u5143\u7ec4\u6d41"}, {"label": "\u6267\u884c\u5668\u521d\u59cb\u5316\u51fd\u6570", "value": "ExecInitBitmapOr"}, {"label": "\u5185\u5b58\u673a\u5236", "value": "bitmap-lossification"}], "node_tag": "T_BitmapOr", "sections": [{"title": "EXPLAIN \u540d\u79f0\u4e0e\u5c5e\u6027", "paragraphs": ["\u7ed3\u6784\u5316\u683c\u5f0f\u4f7f\u7528\u4e0a\u8ff0 Node Type\u3002\u6587\u672c\u683c\u5f0f\u540d\u79f0\u8fd8\u53ef\u80fd\u5305\u542b\u64cd\u4f5c\u3001\u7b56\u7565\u3001\u8fde\u63a5\u7c7b\u578b\u3001\u626b\u63cf\u65b9\u5411\u6216\u805a\u5408\u9636\u6bb5\u5c5e\u6027\u3002", "\u6b64\u6e90\u7801\u8bb0\u5f55\u7684\u6587\u672c\u540d\u79f0\uff1aBitmapOr.", "\u5e76\u884c\u611f\u77e5\u4e0e\u5e76\u884c\u5b89\u5168\u662f\u4e0d\u540c\u7684\u8ba1\u5212\u5c5e\u6027\u3002\u5728\u5e76\u884c\u5de5\u4f5c\u8fdb\u7a0b\u5185\u8fd0\u884c\u7684\u8282\u70b9\u4e0d\u4e00\u5b9a\u662f\u5e76\u884c\u611f\u77e5\u8282\u70b9\u3002"]}, {"title": "\u5185\u5b58\u4e0e\u4e34\u65f6\u5b58\u50a8", "paragraphs": ["\u6b64\u8282\u70b9\u6309\u57fa\u4e8e work_mem \u7684\u9884\u7b97\u5206\u914d\u5143\u7ec4\u4f4d\u7f6e\u4f4d\u56fe\u3002\u4f4d\u56fe\u53ef\u4ee5\u4fdd\u7559\u9875\u7ea7\u6709\u635f\u6761\u76ee\uff0c\u800c\u4e0d\u8bb0\u5f55\u6bcf\u4e2a\u5143\u7ec4\u4f4d\u7f6e\uff0c\u56e0\u6b64\u4ecd\u53ef\u80fd\u9700\u8981\u5806\u91cd\u68c0\u3002"]}, {"title": "\u5e76\u884c\u6267\u884c\u4e0e\u8fd0\u884c\u4fe1\u606f\u91c7\u96c6", "paragraphs": ["\u4ee5\u4e0b\u6e90\u7801\u56de\u8c03\u53ef\u4ee5\u534f\u8c03\u6267\u884c\u6216\u6536\u96c6\u5de5\u4f5c\u8fdb\u7a0b\u7684\u6d4b\u91cf\u6570\u636e\u3002\u56de\u8c03\u5b58\u5728\u4e0d\u4ee3\u8868\u8be5\u8282\u70b9\u666e\u904d\u652f\u6301\u5171\u4eab\u5e76\u884c\u626b\u63cf\u6216\u5171\u4eab\u72b6\u6001\u3002", "\u6b64\u6784\u5efa\u7684\u56de\u8c03\uff1anone extracted from this node implementation."]}, {"title": "\u540c\u7248\u672c\u624b\u518c\u8bf4\u660e", "paragraphs": ["\u7531\u4e8e\u5b9e\u73b0\u4e0a\u7684\u9650\u5236\uff0cBitmapAnd \u548c BitmapOr \u8282\u70b9\u62a5\u544a\u7684\u5b9e\u9645\u884c\u6570\u59cb\u7ec8\u4e3a\u96f6\u3002"]}, {"title": "\u6267\u884c\u5668\u5b9e\u73b0\u8bf4\u660e", "paragraphs": ["\u8bf4\u660e\uff1aBitmapOr \u4e0d\u4f7f\u7528\u5de6\u53f3\u5b50\u6811\uff0c\u800c\u50cf Append \u4e00\u6837\u7ef4\u62a4\u5b50\u8ba1\u5212\u5217\u8868\u3002\u4e0d\u8fc7\u5176\u903b\u8f91\u6bd4 Append \u7b80\u5355\u5f97\u591a\uff0c\u56e0\u4e3a\u65e0\u9700\u5904\u7406\u6b63\u5411\u6216\u53cd\u5411\u6267\u884c\u3002", "\u5bf9\u6bcf\u4e2a\u5f85\u6267\u884c\u8ba1\u5212\u8c03\u7528 ExecInitNode\uff0c\u5e76\u5c06\u7ed3\u679c\u4fdd\u5b58\u5230 bitmapplanstates \u6570\u7ec4\u3002", "BitmapOr \u8ba1\u5212\u6ca1\u6709\u8868\u8fbe\u5f0f\u4e0a\u4e0b\u6587\uff0c\u56e0\u4e3a\u5b83\u4eec\u4ece\u4e0d\u8c03\u7528 ExecQual \u6216 ExecProject\uff0c\u4e5f\u4e0d\u9700\u8981\u5143\u7ec4\u69fd\u3002", "\u53ef\u5bf9 BitmapIndexScan \u5b50\u8282\u70b9\u4f5c\u7279\u6b8a\u5904\u7406\uff0c\u907f\u514d\u4e3a\u6bcf\u4e2a\u5b50\u8282\u70b9\u663e\u5f0f\u8c03\u7528 tbm_union\uff1a\u76f4\u63a5\u4e0b\u4f20\u5f53\u524d\u7ed3\u679c\u4f4d\u56fe\uff0c\u8ba9\u5b50\u8282\u70b9\u5c06\u7ed3\u679c\u6309\u4f4d OR \u5408\u5e76\u8fdb\u53bb\u3002", "ExecReScan \u4e0d\u77e5\u9053\u5f53\u524d\u8282\u70b9\u7684\u5b50\u8ba1\u5212\uff0c\u56e0\u6b64\u5fc5\u987b\u81ea\u884c\u901a\u77e5\u5b50\u8ba1\u5212\u54ea\u4e9b\u53c2\u6570\u53d1\u751f\u4e86\u53d8\u5316\u3002"]}, {"code": "case T_BitmapOr:\n\t\t\tpname = sname = \"BitmapOr\";\n\t\t\tbreak;", "title": "\u6838\u5fc3\u6e90\u7801\u4e2d\u7684 EXPLAIN \u6807\u8bc6"}], "center_zh": {"title": "BitmapOr", "locale": "zh-Hans", "source": {"key": "bitmapor", "locale": "zh-Hans", "version": "18", "text_hash": "f8d78c3bdfda27d2cc2ca9143972699fbb0d6b91be2489b419984d0e16d7a1ba", "collection": "plan", "dataset_hash": "7c31b524dfe136022d39a6ae8dcfac6b3bbd5f8fdaf422536599981252aff0c9", "source_database": "center", "source_revision": "555610c24d53e4316da5b7d3fc25c279d96856d5e0e23ee308c328c5fa881d9f"}, "payload": {"facts": [{"label": "\u6838\u5fc3\u8282\u70b9\u6807\u7b7e", "value": "T_BitmapOr"}, {"label": "\u7ed3\u6784\u5316 EXPLAIN \u8282\u70b9\u7c7b\u578b", "value": "BitmapOr"}, {"label": "\u8f93\u5165", "value": "\u4ea7\u751f\u4f4d\u56fe\u7684\u5b50\u8ba1\u5212"}, {"label": "\u8f93\u51fa", "value": "\u5143\u7ec4\u4f4d\u7f6e\u4f4d\u56fe\uff0c\u4e0d\u662f\u5143\u7ec4\u6d41"}, {"label": "\u6267\u884c\u5668\u521d\u59cb\u5316\u51fd\u6570", "value": "ExecInitBitmapOr"}, {"label": "\u5185\u5b58\u673a\u5236", "value": "bitmap-lossification"}], "tables": [{"key": "explain-labels", "rows": [{"label": "BitmapOr", "identity": "BitmapOr"}], "title": "\u672c\u6784\u5efa\u4e2d\u7684 EXPLAIN \u6807\u7b7e", "columns": [{"key": "label", "label": "\u6587\u672c\u683c\u5f0f\u6807\u7b7e"}, {"key": "identity", "label": "\u7ed3\u6784\u5316\u8282\u70b9\u6807\u8bc6"}]}], "zh_from": {"kind": "same-version-chinese-manual-with-authored-translation-of-reviewed-guidance", "manual": {"url": "/zh/docs/18/using-explain.html#USING-EXPLAIN-CAVEATS", "anchor": "USING-EXPLAIN-CAVEATS", "locale": "zh-Hans", "version": "18", "build_id": 107, "page_key": "using-explain.html", "extraction": "concept-introduction", "source_hash": "d2f749744b3ac5aa2eb0154f295e8163903cd20fcc130c74c6172cdf2ae3a9df", "fragment_sha256": "1726362ef840934bdec0f9ec72c682b2350a203639c9fd1e22dc5d29ac24ca1f", "source_revision": "unknown:rendered-translation-baseline", "translation_revision": "git:b1b500221dbe5437cfca004d6b04d3f6e422765d;html-sha256:08e987a66af27b98444a8057c256314eafa13611a3fb9e888214fc436824244b", "translated_from_revision": null}, "body_sha256": "37580fd1b2ebc05aad556ddf2ff36fd8835329c1778da435bf49486cd53a86ff", "runtime_rerun": false, "authored_translation": "authored-translation-of-reviewed-guidance", "source_facts_revision": "555610c24d53e4316da5b7d3fc25c279d96856d5e0e23ee308c328c5fa881d9f"}, "sections": [{"title": "EXPLAIN \u540d\u79f0\u4e0e\u5c5e\u6027", "paragraphs": ["\u7ed3\u6784\u5316\u683c\u5f0f\u4f7f\u7528\u4e0a\u8ff0 Node Type\u3002\u6587\u672c\u683c\u5f0f\u540d\u79f0\u8fd8\u53ef\u80fd\u5305\u542b\u64cd\u4f5c\u3001\u7b56\u7565\u3001\u8fde\u63a5\u7c7b\u578b\u3001\u626b\u63cf\u65b9\u5411\u6216\u805a\u5408\u9636\u6bb5\u5c5e\u6027\u3002", "\u6b64\u6e90\u7801\u8bb0\u5f55\u7684\u6587\u672c\u540d\u79f0\uff1aBitmapOr.", "\u5e76\u884c\u611f\u77e5\u4e0e\u5e76\u884c\u5b89\u5168\u662f\u4e0d\u540c\u7684\u8ba1\u5212\u5c5e\u6027\u3002\u5728\u5e76\u884c\u5de5\u4f5c\u8fdb\u7a0b\u5185\u8fd0\u884c\u7684\u8282\u70b9\u4e0d\u4e00\u5b9a\u662f\u5e76\u884c\u611f\u77e5\u8282\u70b9\u3002"]}, {"title": "\u5185\u5b58\u4e0e\u4e34\u65f6\u5b58\u50a8", "paragraphs": ["\u6b64\u8282\u70b9\u6309\u57fa\u4e8e work_mem \u7684\u9884\u7b97\u5206\u914d\u5143\u7ec4\u4f4d\u7f6e\u4f4d\u56fe\u3002\u4f4d\u56fe\u53ef\u4ee5\u4fdd\u7559\u9875\u7ea7\u6709\u635f\u6761\u76ee\uff0c\u800c\u4e0d\u8bb0\u5f55\u6bcf\u4e2a\u5143\u7ec4\u4f4d\u7f6e\uff0c\u56e0\u6b64\u4ecd\u53ef\u80fd\u9700\u8981\u5806\u91cd\u68c0\u3002"]}, {"title": "\u5e76\u884c\u6267\u884c\u4e0e\u8fd0\u884c\u4fe1\u606f\u91c7\u96c6", "paragraphs": ["\u4ee5\u4e0b\u6e90\u7801\u56de\u8c03\u53ef\u4ee5\u534f\u8c03\u6267\u884c\u6216\u6536\u96c6\u5de5\u4f5c\u8fdb\u7a0b\u7684\u6d4b\u91cf\u6570\u636e\u3002\u56de\u8c03\u5b58\u5728\u4e0d\u4ee3\u8868\u8be5\u8282\u70b9\u666e\u904d\u652f\u6301\u5171\u4eab\u5e76\u884c\u626b\u63cf\u6216\u5171\u4eab\u72b6\u6001\u3002", "\u6b64\u6784\u5efa\u7684\u56de\u8c03\uff1anone extracted from this node implementation."]}, {"title": "\u540c\u7248\u672c\u624b\u518c\u8bf4\u660e", "paragraphs": ["\u7531\u4e8e\u5b9e\u73b0\u4e0a\u7684\u9650\u5236\uff0cBitmapAnd \u548c BitmapOr \u8282\u70b9\u62a5\u544a\u7684\u5b9e\u9645\u884c\u6570\u59cb\u7ec8\u4e3a\u96f6\u3002"]}, {"title": "\u6267\u884c\u5668\u5b9e\u73b0\u8bf4\u660e", "paragraphs": ["\u8bf4\u660e\uff1aBitmapOr \u4e0d\u4f7f\u7528\u5de6\u53f3\u5b50\u6811\uff0c\u800c\u50cf Append \u4e00\u6837\u7ef4\u62a4\u5b50\u8ba1\u5212\u5217\u8868\u3002\u4e0d\u8fc7\u5176\u903b\u8f91\u6bd4 Append \u7b80\u5355\u5f97\u591a\uff0c\u56e0\u4e3a\u65e0\u9700\u5904\u7406\u6b63\u5411\u6216\u53cd\u5411\u6267\u884c\u3002", "\u5bf9\u6bcf\u4e2a\u5f85\u6267\u884c\u8ba1\u5212\u8c03\u7528 ExecInitNode\uff0c\u5e76\u5c06\u7ed3\u679c\u4fdd\u5b58\u5230 bitmapplanstates \u6570\u7ec4\u3002", "BitmapOr \u8ba1\u5212\u6ca1\u6709\u8868\u8fbe\u5f0f\u4e0a\u4e0b\u6587\uff0c\u56e0\u4e3a\u5b83\u4eec\u4ece\u4e0d\u8c03\u7528 ExecQual \u6216 ExecProject\uff0c\u4e5f\u4e0d\u9700\u8981\u5143\u7ec4\u69fd\u3002", "\u53ef\u5bf9 BitmapIndexScan \u5b50\u8282\u70b9\u4f5c\u7279\u6b8a\u5904\u7406\uff0c\u907f\u514d\u4e3a\u6bcf\u4e2a\u5b50\u8282\u70b9\u663e\u5f0f\u8c03\u7528 tbm_union\uff1a\u76f4\u63a5\u4e0b\u4f20\u5f53\u524d\u7ed3\u679c\u4f4d\u56fe\uff0c\u8ba9\u5b50\u8282\u70b9\u5c06\u7ed3\u679c\u6309\u4f4d OR \u5408\u5e76\u8fdb\u53bb\u3002", "ExecReScan \u4e0d\u77e5\u9053\u5f53\u524d\u8282\u70b9\u7684\u5b50\u8ba1\u5212\uff0c\u56e0\u6b64\u5fc5\u987b\u81ea\u884c\u901a\u77e5\u5b50\u8ba1\u5212\u54ea\u4e9b\u53c2\u6570\u53d1\u751f\u4e86\u53d8\u5316\u3002"]}, {"code": "case T_BitmapOr:\n\t\t\tpname = sname = \"BitmapOr\";\n\t\t\tbreak;", "title": "\u6838\u5fc3\u6e90\u7801\u4e2d\u7684 EXPLAIN \u6807\u8bc6"}], "description_zh": "\u5bf9\u5404\u5b50\u8ba1\u5212\u751f\u6210\u7684\u4f4d\u56fe\u6c42\u5e76\u96c6\u3002", "description_zh_html": "<p>\u5bf9\u5404\u5b50\u8ba1\u5212\u751f\u6210\u7684\u4f4d\u56fe\u6c42\u5e76\u96c6\u3002</p><p>\u6838\u5fc3\u8282\u70b9\u6807\u8bc6\uff1a<code>T_BitmapOr</code>\uff1bEXPLAIN \u540d\u79f0\uff1a<code>BitmapOr</code>\u3002</p><p>\u672c\u7248\u672c\u6e90\u7801\u4e2d\u7684\u5e76\u884c\u6267\u884c\u6216\u89c2\u6d4b\u56de\u8c03\uff1a\u8be5\u8282\u70b9\u5b9e\u73b0\u4e2d\u672a\u63d0\u53d6\u5230\u6b64\u7c7b\u56de\u8c03\u3002\u56de\u8c03\u7684\u5b58\u5728\u4e0d\u8868\u793a\u8be5\u8282\u70b9\u5fc5\u7136\u652f\u6301\u5171\u4eab\u5e76\u884c\u626b\u63cf\uff1b\u5728\u5e76\u884c\u5de5\u4f5c\u8fdb\u7a0b\u4e2d\u6267\u884c\u4e5f\u4e0d\u7b49\u4e8e\u5177\u6709\u5e76\u884c\u611f\u77e5\u80fd\u529b\u3002</p><h3>\u540c\u7248\u672c\u4e2d\u6587\u624b\u518c\u8282\u9009</h3><p>\n<code class=\"command\">EXPLAIN ANALYZE</code> \u6d4b\u5f97\u7684\u8fd0\u884c\u65f6\u95f4\uff0c\u53ef\u80fd\u4ee5\u4e24\u79cd\u91cd\u8981\u65b9\u5f0f\u504f\u79bb\u540c\u4e00\u67e5\u8be2\u7684\u6b63\u5e38\u6267\u884c\u65f6\u95f4\u3002\u7b2c\u4e00\uff0c\u7531\u4e8e\u4e0d\u4f1a\u5411\u5ba2\u6237\u7aef\u4f20\u9012\u4efb\u4f55\u8f93\u51fa\u884c\uff0c\u56e0\u6b64\u7f51\u7edc\u4f20\u8f93\u5f00\u9500\u4e0d\u4f1a\u88ab\u8ba1\u5165\u3002\u9664\u975e\u6307\u5b9a\u4e86 <code class=\"literal\">SERIALIZE</code>\uff0cI/O \u8f6c\u6362\u5f00\u9500\u540c\u6837\u4e5f\u4e0d\u4f1a\u88ab\u8ba1\u5165\u3002\u7b2c\u4e8c\uff0c<code class=\"command\">EXPLAIN ANALYZE</code> \u9644\u52a0\u7684\u6d4b\u91cf\u5f00\u9500\u672c\u8eab\u53ef\u80fd\u76f8\u5f53\u53ef\u89c2\uff0c\u5c24\u5176\u662f\u5728\u64cd\u4f5c\u7cfb\u7edf\u8c03\u7528 <code class=\"function\">gettimeofday()</code> \u8f83\u6162\u7684\u673a\u5668\u4e0a\u3002\u53ef\u4ee5\u4f7f\u7528 <a class=\"xref\" href=\"/zh/docs/18/pgtesttiming.html\"><span class=\"refentrytitle\"><span class=\"application\">pg_test_timing</span></span></a> \u5de5\u5177\u6765\u6d4b\u91cf\u7cfb\u7edf\u4e0a\u7684\u8ba1\u65f6\u5f00\u9500\u3002\n   </p><p>\n    \u4e0d\u5e94\u5c06 <code class=\"command\">EXPLAIN</code> \u7ed3\u679c\u5916\u63a8\u5230\u4e0e\u5b9e\u9645\u6d4b\u8bd5\u573a\u666f\u5dee\u5f02\u5f88\u5927\u7684\u60c5\u51b5\u3002\u4f8b\u5982\uff0c\u5728\u4e00\u4e2a\u5f88\u5c0f\u7684\u8868\u4e0a\u5f97\u5230\u7684\u7ed3\u679c\uff0c\u4e0d\u80fd\u5047\u5b9a\u4e5f\u9002\u7528\u4e8e\u5927\u578b\u8868\u3002\u89c4\u5212\u5668\u7684\u4ee3\u4ef7\u4f30\u8ba1\u4e0d\u662f\u7ebf\u6027\u7684\uff0c\u56e0\u6b64\u5b83\u53ef\u80fd\u4f1a\u4e3a\u66f4\u5927\u6216\u66f4\u5c0f\u7684\u8868\u9009\u62e9\u4e0d\u540c\u7684\u8ba1\u5212\u3002\u4e00\u4e2a\u6781\u7aef\u793a\u4f8b\u662f\uff1a\u5bf9\u4e8e\u53ea\u5360\u7528\u4e00\u4e2a\u78c1\u76d8\u9875\u7684\u8868\uff0c\u65e0\u8bba\u7d22\u5f15\u662f\u5426\u53ef\u7528\uff0c\u51e0\u4e4e\u603b\u4f1a\u5f97\u5230\u987a\u5e8f\u626b\u63cf\u8ba1\u5212\u3002\u89c4\u5212\u5668\u8ba4\u8bc6\u5230\uff0c\u65e0\u8bba\u5982\u4f55\u5904\u7406\u8be5\u8868\u90fd\u9700\u8981\u4e00\u6b21\u78c1\u76d8\u9875\u8bfb\u53d6\uff0c\u56e0\u6b64\u518d\u989d\u5916\u8bfb\u53d6\u9875\u9762\u53bb\u67e5\u770b\u7d22\u5f15\u5e76\u6ca1\u6709\u4ef7\u503c\u3002\uff08\u524d\u9762\u7684 <code class=\"literal\">polygon_tbl</code> \u793a\u4f8b\u5df2\u7ecf\u5c55\u793a\u8fc7\u8fd9\u79cd\u60c5\u51b5\u3002\uff09\n   </p><p>\n    \u5728\u67d0\u4e9b\u60c5\u51b5\u4e0b\uff0c\u5b9e\u9645\u503c\u548c\u4f30\u8ba1\u503c\u4e0d\u4f1a\u5f88\u597d\u5730\u5bf9\u5e94\uff0c\u4f46\u8fd9\u5e76\u4e0d\u8868\u793a\u51fa\u73b0\u4e86\u95ee\u9898\u3002\u5176\u4e2d\u4e00\u79cd\u60c5\u51b5\u662f\uff0c\u8ba1\u5212\u8282\u70b9\u7684\u6267\u884c\u4f1a\u88ab <code class=\"literal\">LIMIT</code> \u6216\u7c7b\u4f3c\u6548\u679c\u63d0\u524d\u622a\u65ad\u3002\u4f8b\u5982\uff0c\u5728\u524d\u9762\u7528\u8fc7\u7684 <code class=\"literal\">LIMIT</code> \u67e5\u8be2\u4e2d\uff1a\n\n</p><p>\n\n    Index Scan \u8282\u70b9\u7684\u4f30\u8ba1\u4ee3\u4ef7\u548c\u884c\u8ba1\u6570\u663e\u793a\u5f97\u50cf\u662f\u5b83\u4f1a\u8fd0\u884c\u5230\u7ed3\u675f\u4e00\u6837\u3002\u4f46\u5b9e\u9645\u4e0a\uff0cLimit \u8282\u70b9\u5728\u62ff\u5230\u4e24\u884c\u4e4b\u540e\u5c31\u505c\u6b62\u8bf7\u6c42\u66f4\u591a\u884c\uff0c\u56e0\u6b64\u5b9e\u9645\u884c\u8ba1\u6570\u53ea\u6709 2\uff0c\u8fd0\u884c\u65f6\u95f4\u4e5f\u4f4e\u4e8e\u4ee3\u4ef7\u4f30\u8ba1\u6240\u6697\u793a\u7684\u6c34\u5e73\u3002\u8fd9\u5e76\u4e0d\u662f\u4f30\u8ba1\u9519\u8bef\uff0c\u53ea\u662f\u4f30\u8ba1\u503c\u4e0e\u771f\u5b9e\u503c\u7684\u663e\u793a\u65b9\u5f0f\u4e0d\u540c\u800c\u5df2\u3002\n   </p><p><a href=\"/zh/docs/18/using-explain.html#USING-EXPLAIN-CAVEATS\">\u67e5\u770b\u5b8c\u6574\u4e2d\u6587\u624b\u518c\u4e0e\u4e0a\u4e0b\u6587</a>\u3002</p><p>\u672c\u9875\u5f00\u5934\u7684\u4e2d\u6587\u8bf4\u660e\u4e3a PG.CENTER \u5bf9\u7f16\u8f91\u8bf4\u660e\u7684\u7ffb\u8bd1\uff1b\u624b\u518c\u8282\u9009\u4fdd\u7559\u5bf9\u5e94\u7248\u672c\u4e2d\u6587\u6587\u6863\u539f\u6587\u3002\u6e90\u7801\u4fe1\u606f\u53ca\u624b\u518c\u793a\u4f8b\u4e0d\u4ee3\u8868\u91cd\u65b0\u8fdb\u884c\u8fc7\u8fd0\u884c\u6d4b\u8bd5\u3002</p>"}, "summary": "\u5bf9\u5404\u5b50\u8ba1\u5212\u751f\u6210\u7684\u4f4d\u56fe\u6c42\u5e76\u96c6\u3002", "version": "18", "link_map": {"/zh/docs/18/pgtesttiming.html": "/docs/18/pgtesttiming.html", "/zh/docs/18/using-explain.html#USING-EXPLAIN-CAVEATS": "/docs/18/using-explain.html#USING-EXPLAIN-CAVEATS"}, "body_html": "<p>\u5bf9\u5404\u5b50\u8ba1\u5212\u751f\u6210\u7684\u4f4d\u56fe\u6c42\u5e76\u96c6\u3002</p><p>\u6838\u5fc3\u8282\u70b9\u6807\u8bc6\uff1a<code>T_BitmapOr</code>\uff1bEXPLAIN \u540d\u79f0\uff1a<code>BitmapOr</code>\u3002</p><p>\u672c\u7248\u672c\u6e90\u7801\u4e2d\u7684\u5e76\u884c\u6267\u884c\u6216\u89c2\u6d4b\u56de\u8c03\uff1a\u8be5\u8282\u70b9\u5b9e\u73b0\u4e2d\u672a\u63d0\u53d6\u5230\u6b64\u7c7b\u56de\u8c03\u3002\u56de\u8c03\u7684\u5b58\u5728\u4e0d\u8868\u793a\u8be5\u8282\u70b9\u5fc5\u7136\u652f\u6301\u5171\u4eab\u5e76\u884c\u626b\u63cf\uff1b\u5728\u5e76\u884c\u5de5\u4f5c\u8fdb\u7a0b\u4e2d\u6267\u884c\u4e5f\u4e0d\u7b49\u4e8e\u5177\u6709\u5e76\u884c\u611f\u77e5\u80fd\u529b\u3002</p><h3>\u540c\u7248\u672c\u4e2d\u6587\u624b\u518c\u8282\u9009</h3><p>\n<code>EXPLAIN ANALYZE</code> \u6d4b\u5f97\u7684\u8fd0\u884c\u65f6\u95f4\uff0c\u53ef\u80fd\u4ee5\u4e24\u79cd\u91cd\u8981\u65b9\u5f0f\u504f\u79bb\u540c\u4e00\u67e5\u8be2\u7684\u6b63\u5e38\u6267\u884c\u65f6\u95f4\u3002\u7b2c\u4e00\uff0c\u7531\u4e8e\u4e0d\u4f1a\u5411\u5ba2\u6237\u7aef\u4f20\u9012\u4efb\u4f55\u8f93\u51fa\u884c\uff0c\u56e0\u6b64\u7f51\u7edc\u4f20\u8f93\u5f00\u9500\u4e0d\u4f1a\u88ab\u8ba1\u5165\u3002\u9664\u975e\u6307\u5b9a\u4e86 <code>SERIALIZE</code>\uff0cI/O \u8f6c\u6362\u5f00\u9500\u540c\u6837\u4e5f\u4e0d\u4f1a\u88ab\u8ba1\u5165\u3002\u7b2c\u4e8c\uff0c<code>EXPLAIN ANALYZE</code> \u9644\u52a0\u7684\u6d4b\u91cf\u5f00\u9500\u672c\u8eab\u53ef\u80fd\u76f8\u5f53\u53ef\u89c2\uff0c\u5c24\u5176\u662f\u5728\u64cd\u4f5c\u7cfb\u7edf\u8c03\u7528 <code>gettimeofday()</code> \u8f83\u6162\u7684\u673a\u5668\u4e0a\u3002\u53ef\u4ee5\u4f7f\u7528 <a href=\"/zh/docs/18/pgtesttiming.html\" rel=\"nofollow\"><span><span>pg_test_timing</span></span></a> \u5de5\u5177\u6765\u6d4b\u91cf\u7cfb\u7edf\u4e0a\u7684\u8ba1\u65f6\u5f00\u9500\u3002\n   </p><p>\n    \u4e0d\u5e94\u5c06 <code>EXPLAIN</code> \u7ed3\u679c\u5916\u63a8\u5230\u4e0e\u5b9e\u9645\u6d4b\u8bd5\u573a\u666f\u5dee\u5f02\u5f88\u5927\u7684\u60c5\u51b5\u3002\u4f8b\u5982\uff0c\u5728\u4e00\u4e2a\u5f88\u5c0f\u7684\u8868\u4e0a\u5f97\u5230\u7684\u7ed3\u679c\uff0c\u4e0d\u80fd\u5047\u5b9a\u4e5f\u9002\u7528\u4e8e\u5927\u578b\u8868\u3002\u89c4\u5212\u5668\u7684\u4ee3\u4ef7\u4f30\u8ba1\u4e0d\u662f\u7ebf\u6027\u7684\uff0c\u56e0\u6b64\u5b83\u53ef\u80fd\u4f1a\u4e3a\u66f4\u5927\u6216\u66f4\u5c0f\u7684\u8868\u9009\u62e9\u4e0d\u540c\u7684\u8ba1\u5212\u3002\u4e00\u4e2a\u6781\u7aef\u793a\u4f8b\u662f\uff1a\u5bf9\u4e8e\u53ea\u5360\u7528\u4e00\u4e2a\u78c1\u76d8\u9875\u7684\u8868\uff0c\u65e0\u8bba\u7d22\u5f15\u662f\u5426\u53ef\u7528\uff0c\u51e0\u4e4e\u603b\u4f1a\u5f97\u5230\u987a\u5e8f\u626b\u63cf\u8ba1\u5212\u3002\u89c4\u5212\u5668\u8ba4\u8bc6\u5230\uff0c\u65e0\u8bba\u5982\u4f55\u5904\u7406\u8be5\u8868\u90fd\u9700\u8981\u4e00\u6b21\u78c1\u76d8\u9875\u8bfb\u53d6\uff0c\u56e0\u6b64\u518d\u989d\u5916\u8bfb\u53d6\u9875\u9762\u53bb\u67e5\u770b\u7d22\u5f15\u5e76\u6ca1\u6709\u4ef7\u503c\u3002\uff08\u524d\u9762\u7684 <code>polygon_tbl</code> \u793a\u4f8b\u5df2\u7ecf\u5c55\u793a\u8fc7\u8fd9\u79cd\u60c5\u51b5\u3002\uff09\n   </p><p>\n    \u5728\u67d0\u4e9b\u60c5\u51b5\u4e0b\uff0c\u5b9e\u9645\u503c\u548c\u4f30\u8ba1\u503c\u4e0d\u4f1a\u5f88\u597d\u5730\u5bf9\u5e94\uff0c\u4f46\u8fd9\u5e76\u4e0d\u8868\u793a\u51fa\u73b0\u4e86\u95ee\u9898\u3002\u5176\u4e2d\u4e00\u79cd\u60c5\u51b5\u662f\uff0c\u8ba1\u5212\u8282\u70b9\u7684\u6267\u884c\u4f1a\u88ab <code>LIMIT</code> \u6216\u7c7b\u4f3c\u6548\u679c\u63d0\u524d\u622a\u65ad\u3002\u4f8b\u5982\uff0c\u5728\u524d\u9762\u7528\u8fc7\u7684 <code>LIMIT</code> \u67e5\u8be2\u4e2d\uff1a\n\n</p><p>\n\n    Index Scan \u8282\u70b9\u7684\u4f30\u8ba1\u4ee3\u4ef7\u548c\u884c\u8ba1\u6570\u663e\u793a\u5f97\u50cf\u662f\u5b83\u4f1a\u8fd0\u884c\u5230\u7ed3\u675f\u4e00\u6837\u3002\u4f46\u5b9e\u9645\u4e0a\uff0cLimit \u8282\u70b9\u5728\u62ff\u5230\u4e24\u884c\u4e4b\u540e\u5c31\u505c\u6b62\u8bf7\u6c42\u66f4\u591a\u884c\uff0c\u56e0\u6b64\u5b9e\u9645\u884c\u8ba1\u6570\u53ea\u6709 2\uff0c\u8fd0\u884c\u65f6\u95f4\u4e5f\u4f4e\u4e8e\u4ee3\u4ef7\u4f30\u8ba1\u6240\u6697\u793a\u7684\u6c34\u5e73\u3002\u8fd9\u5e76\u4e0d\u662f\u4f30\u8ba1\u9519\u8bef\uff0c\u53ea\u662f\u4f30\u8ba1\u503c\u4e0e\u771f\u5b9e\u503c\u7684\u663e\u793a\u65b9\u5f0f\u4e0d\u540c\u800c\u5df2\u3002\n   </p><p><a href=\"/zh/docs/18/using-explain.html#USING-EXPLAIN-CAVEATS\" rel=\"nofollow\">\u67e5\u770b\u5b8c\u6574\u4e2d\u6587\u624b\u518c\u4e0e\u4e0a\u4e0b\u6587</a>\u3002</p><p>\u672c\u9875\u5f00\u5934\u7684\u4e2d\u6587\u8bf4\u660e\u4e3a PG.CENTER \u5bf9\u7f16\u8f91\u8bf4\u660e\u7684\u7ffb\u8bd1\uff1b\u624b\u518c\u8282\u9009\u4fdd\u7559\u5bf9\u5e94\u7248\u672c\u4e2d\u6587\u6587\u6863\u539f\u6587\u3002\u6e90\u7801\u4fe1\u606f\u53ca\u624b\u518c\u793a\u4f8b\u4e0d\u4ee3\u8868\u91cd\u65b0\u8fdb\u884c\u8fc7\u8fd0\u884c\u6d4b\u8bd5\u3002</p>", "body_sha256": "a85c98c108dd0a6d20ad2a0cc957445b7b345e7b52b6abc55c73b047fc6bd771", "content_hash": "f8d78c3bdfda27d2cc2ca9143972699fbb0d6b91be2489b419984d0e16d7a1ba", "source_database": "center", "source_revision": "555610c24d53e4316da5b7d3fc25c279d96856d5e0e23ee308c328c5fa881d9f"}, "tables_zh": [{"key": "explain-labels", "rows": [{"label": "BitmapOr", "identity": "BitmapOr"}], "title": "\u672c\u6784\u5efa\u4e2d\u7684 EXPLAIN \u6807\u7b7e", "columns": [{"key": "label", "label": "\u6587\u672c\u683c\u5f0f\u6807\u7b7e"}, {"key": "identity", "label": "\u7ed3\u6784\u5316\u8282\u70b9\u6807\u8bc6"}]}], "strategies": [], "description": ["\u5bf9\u5404\u5b50\u8ba1\u5212\u751f\u6210\u7684\u4f4d\u56fe\u6c42\u5e76\u96c6\u3002"], "sections_zh": [{"title": "EXPLAIN \u540d\u79f0\u4e0e\u5c5e\u6027", "paragraphs": ["\u7ed3\u6784\u5316\u683c\u5f0f\u4f7f\u7528\u4e0a\u8ff0 Node Type\u3002\u6587\u672c\u683c\u5f0f\u540d\u79f0\u8fd8\u53ef\u80fd\u5305\u542b\u64cd\u4f5c\u3001\u7b56\u7565\u3001\u8fde\u63a5\u7c7b\u578b\u3001\u626b\u63cf\u65b9\u5411\u6216\u805a\u5408\u9636\u6bb5\u5c5e\u6027\u3002", "\u6b64\u6e90\u7801\u8bb0\u5f55\u7684\u6587\u672c\u540d\u79f0\uff1aBitmapOr.", "\u5e76\u884c\u611f\u77e5\u4e0e\u5e76\u884c\u5b89\u5168\u662f\u4e0d\u540c\u7684\u8ba1\u5212\u5c5e\u6027\u3002\u5728\u5e76\u884c\u5de5\u4f5c\u8fdb\u7a0b\u5185\u8fd0\u884c\u7684\u8282\u70b9\u4e0d\u4e00\u5b9a\u662f\u5e76\u884c\u611f\u77e5\u8282\u70b9\u3002"]}, {"title": "\u5185\u5b58\u4e0e\u4e34\u65f6\u5b58\u50a8", "paragraphs": ["\u6b64\u8282\u70b9\u6309\u57fa\u4e8e work_mem \u7684\u9884\u7b97\u5206\u914d\u5143\u7ec4\u4f4d\u7f6e\u4f4d\u56fe\u3002\u4f4d\u56fe\u53ef\u4ee5\u4fdd\u7559\u9875\u7ea7\u6709\u635f\u6761\u76ee\uff0c\u800c\u4e0d\u8bb0\u5f55\u6bcf\u4e2a\u5143\u7ec4\u4f4d\u7f6e\uff0c\u56e0\u6b64\u4ecd\u53ef\u80fd\u9700\u8981\u5806\u91cd\u68c0\u3002"]}, {"title": "\u5e76\u884c\u6267\u884c\u4e0e\u8fd0\u884c\u4fe1\u606f\u91c7\u96c6", "paragraphs": ["\u4ee5\u4e0b\u6e90\u7801\u56de\u8c03\u53ef\u4ee5\u534f\u8c03\u6267\u884c\u6216\u6536\u96c6\u5de5\u4f5c\u8fdb\u7a0b\u7684\u6d4b\u91cf\u6570\u636e\u3002\u56de\u8c03\u5b58\u5728\u4e0d\u4ee3\u8868\u8be5\u8282\u70b9\u666e\u904d\u652f\u6301\u5171\u4eab\u5e76\u884c\u626b\u63cf\u6216\u5171\u4eab\u72b6\u6001\u3002", "\u6b64\u6784\u5efa\u7684\u56de\u8c03\uff1anone extracted from this node implementation."]}, {"title": "\u540c\u7248\u672c\u624b\u518c\u8bf4\u660e", "paragraphs": ["\u7531\u4e8e\u5b9e\u73b0\u4e0a\u7684\u9650\u5236\uff0cBitmapAnd \u548c BitmapOr \u8282\u70b9\u62a5\u544a\u7684\u5b9e\u9645\u884c\u6570\u59cb\u7ec8\u4e3a\u96f6\u3002"]}, {"title": "\u6267\u884c\u5668\u5b9e\u73b0\u8bf4\u660e", "paragraphs": ["\u8bf4\u660e\uff1aBitmapOr \u4e0d\u4f7f\u7528\u5de6\u53f3\u5b50\u6811\uff0c\u800c\u50cf Append \u4e00\u6837\u7ef4\u62a4\u5b50\u8ba1\u5212\u5217\u8868\u3002\u4e0d\u8fc7\u5176\u903b\u8f91\u6bd4 Append \u7b80\u5355\u5f97\u591a\uff0c\u56e0\u4e3a\u65e0\u9700\u5904\u7406\u6b63\u5411\u6216\u53cd\u5411\u6267\u884c\u3002", "\u5bf9\u6bcf\u4e2a\u5f85\u6267\u884c\u8ba1\u5212\u8c03\u7528 ExecInitNode\uff0c\u5e76\u5c06\u7ed3\u679c\u4fdd\u5b58\u5230 bitmapplanstates \u6570\u7ec4\u3002", "BitmapOr \u8ba1\u5212\u6ca1\u6709\u8868\u8fbe\u5f0f\u4e0a\u4e0b\u6587\uff0c\u56e0\u4e3a\u5b83\u4eec\u4ece\u4e0d\u8c03\u7528 ExecQual \u6216 ExecProject\uff0c\u4e5f\u4e0d\u9700\u8981\u5143\u7ec4\u69fd\u3002", "\u53ef\u5bf9 BitmapIndexScan \u5b50\u8282\u70b9\u4f5c\u7279\u6b8a\u5904\u7406\uff0c\u907f\u514d\u4e3a\u6bcf\u4e2a\u5b50\u8282\u70b9\u663e\u5f0f\u8c03\u7528 tbm_union\uff1a\u76f4\u63a5\u4e0b\u4f20\u5f53\u524d\u7ed3\u679c\u4f4d\u56fe\uff0c\u8ba9\u5b50\u8282\u70b9\u5c06\u7ed3\u679c\u6309\u4f4d OR \u5408\u5e76\u8fdb\u53bb\u3002", "ExecReScan \u4e0d\u77e5\u9053\u5f53\u524d\u8282\u70b9\u7684\u5b50\u8ba1\u5212\uff0c\u56e0\u6b64\u5fc5\u987b\u81ea\u884c\u901a\u77e5\u5b50\u8ba1\u5212\u54ea\u4e9b\u53c2\u6570\u53d1\u751f\u4e86\u53d8\u5316\u3002"]}, {"code": "case T_BitmapOr:\n\t\t\tpname = sname = \"BitmapOr\";\n\t\t\tbreak;", "title": "\u6838\u5fc3\u6e90\u7801\u4e2d\u7684 EXPLAIN \u6807\u8bc6"}], "localization": {"status": "complete", "sources": [], "language": "zh", "original_text": {"/versions/18/description/0": "Unions bitmaps produced by its child plans.", "/versions/18/facts/0/label": "Core node tag", "/versions/18/facts/1/label": "Structured EXPLAIN Node Type", "/versions/18/facts/2/label": "Inputs", "/versions/18/facts/2/value": "Bitmap-producing child plans", "/versions/18/facts/3/label": "Output", "/versions/18/facts/3/value": "Tuple-location bitmap, not a tuple stream", "/versions/18/facts/4/label": "Executor initializer", "/versions/18/facts/5/label": "Memory mechanism", "/versions/18/tables/0/title": "EXPLAIN labels in this source build", "/versions/18/related/1/label": "Using EXPLAIN", "/versions/18/related/2/label": "Parallel plans", "/versions/18/sections/0/title": "EXPLAIN names and attributes", "/versions/18/sections/1/title": "Memory and temporary storage", "/versions/18/sections/2/title": "Parallel execution and instrumentation", "/versions/18/sections/3/title": "Same-version manual discussion", "/versions/18/sections/4/title": "Executor implementation notes", "/versions/18/sections/5/title": "EXPLAIN identity in core source", "/versions/18/memory/description": "The node allocates a tuple-location bitmap using a work_mem-derived budget. A bitmap can retain page-level lossy entries instead of every tuple location; heap rechecks then remain necessary.", "/versions/18/sections/0/paragraphs/0": "Structured formats use the Node Type above. Text-format spellings can also include operation, strategy, join type, scan direction or aggregation-stage attributes.", "/versions/18/sections/0/paragraphs/1": "Text names recorded by this source: BitmapOr.", "/versions/18/sections/0/paragraphs/2": "Parallel-aware and parallel-safe are different plan properties. A node running inside a parallel worker is not necessarily a parallel-aware node.", "/versions/18/sections/1/paragraphs/0": "The node allocates a tuple-location bitmap using a work_mem-derived budget. A bitmap can retain page-level lossy entries instead of every tuple location; heap rechecks then remain necessary.", "/versions/18/sections/2/paragraphs/0": "The source callbacks below can coordinate execution or collect worker instrumentation. Their presence is not a blanket claim that this node supports a shared parallel scan or shared state.", "/versions/18/sections/2/paragraphs/1": "Callbacks in this build: none extracted from this node implementation.", "/versions/18/sections/3/paragraphs/0": "BitmapAnd and BitmapOr nodes always report their actual row counts as zero, due to implementation limitations.", "/versions/18/sections/4/paragraphs/0": "NOTES BitmapOr nodes don't make use of their left and right subtrees, rather they maintain a list of subplans, much like Append nodes. The logic is much simpler than Append, however, since we needn't cope with forward/backward execution.", "/versions/18/sections/4/paragraphs/1": "call ExecInitNode on each of the plans to be executed and save the results into the array \"bitmapplanstates\".", "/versions/18/sections/4/paragraphs/2": "BitmapOr plans don't have expression contexts because they never call ExecQual or ExecProject. They don't need any tuple slots either.", "/versions/18/sections/4/paragraphs/3": "We can special-case BitmapIndexScan children to avoid an explicit tbm_union step for each child: just pass down the current result bitmap and let the child OR directly into it.", "/versions/18/sections/4/paragraphs/4": "ExecReScan doesn't know about my subplans, so I have to do changed-parameter signaling myself.", "/versions/18/tables/0/columns/0/label": "Text-format label", "/versions/18/tables/0/columns/1/label": "Structured node identity"}, "fallback_fields": [], "source_language": "en", "original_snapshot_sha256": "6555fae880f7d80cecb472ac63d57e5c11bc60d158b34b99d1d8c4be9c3c8829", "canonical_center_text_hash": "f8d78c3bdfda27d2cc2ca9143972699fbb0d6b91be2489b419984d0e16d7a1ba"}, "evidence_kind": "source and documentation", "explain_names": ["BitmapOr"], "partial_modes": [], "description_zh": "\u5bf9\u5404\u5b50\u8ba1\u5212\u751f\u6210\u7684\u4f4d\u56fe\u6c42\u5e76\u96c6\u3002", "comparison_data": {"node_tag": "T_BitmapOr", "strategies": [], "text_names": ["BitmapOr"], "initializer": "ExecInitBitmapOr", "partial_modes": [], "memory_mechanism": "bitmap-lossification", "parallel_callbacks": []}, "comparison_hash": "c0ca503a6029c37ec720213dcdc3094997eb194d4920da68f94a7420d3e8f1d2", "manual_language": "zh", "explain_prefixes": ["Parallel", "Async"], "runtime_verified": false, "source_inventory": {"explain": "src/backend/commands/explain.c", "executor": "src/backend/executor/execProcnode.c", "implementation": "src/backend/executor/nodeBitmapOr.c"}, "parallel_callbacks": [], "description_zh_html": "<p>\u5bf9\u5404\u5b50\u8ba1\u5212\u751f\u6210\u7684\u4f4d\u56fe\u6c42\u5e76\u96c6\u3002</p><p>\u6838\u5fc3\u8282\u70b9\u6807\u8bc6\uff1a<code>T_BitmapOr</code>\uff1bEXPLAIN \u540d\u79f0\uff1a<code>BitmapOr</code>\u3002</p><p>\u672c\u7248\u672c\u6e90\u7801\u4e2d\u7684\u5e76\u884c\u6267\u884c\u6216\u89c2\u6d4b\u56de\u8c03\uff1a\u8be5\u8282\u70b9\u5b9e\u73b0\u4e2d\u672a\u63d0\u53d6\u5230\u6b64\u7c7b\u56de\u8c03\u3002\u56de\u8c03\u7684\u5b58\u5728\u4e0d\u8868\u793a\u8be5\u8282\u70b9\u5fc5\u7136\u652f\u6301\u5171\u4eab\u5e76\u884c\u626b\u63cf\uff1b\u5728\u5e76\u884c\u5de5\u4f5c\u8fdb\u7a0b\u4e2d\u6267\u884c\u4e5f\u4e0d\u7b49\u4e8e\u5177\u6709\u5e76\u884c\u611f\u77e5\u80fd\u529b\u3002</p><h3>\u540c\u7248\u672c\u4e2d\u6587\u624b\u518c\u8282\u9009</h3><p>\n<code>EXPLAIN ANALYZE</code> \u6d4b\u5f97\u7684\u8fd0\u884c\u65f6\u95f4\uff0c\u53ef\u80fd\u4ee5\u4e24\u79cd\u91cd\u8981\u65b9\u5f0f\u504f\u79bb\u540c\u4e00\u67e5\u8be2\u7684\u6b63\u5e38\u6267\u884c\u65f6\u95f4\u3002\u7b2c\u4e00\uff0c\u7531\u4e8e\u4e0d\u4f1a\u5411\u5ba2\u6237\u7aef\u4f20\u9012\u4efb\u4f55\u8f93\u51fa\u884c\uff0c\u56e0\u6b64\u7f51\u7edc\u4f20\u8f93\u5f00\u9500\u4e0d\u4f1a\u88ab\u8ba1\u5165\u3002\u9664\u975e\u6307\u5b9a\u4e86 <code>SERIALIZE</code>\uff0cI/O \u8f6c\u6362\u5f00\u9500\u540c\u6837\u4e5f\u4e0d\u4f1a\u88ab\u8ba1\u5165\u3002\u7b2c\u4e8c\uff0c<code>EXPLAIN ANALYZE</code> \u9644\u52a0\u7684\u6d4b\u91cf\u5f00\u9500\u672c\u8eab\u53ef\u80fd\u76f8\u5f53\u53ef\u89c2\uff0c\u5c24\u5176\u662f\u5728\u64cd\u4f5c\u7cfb\u7edf\u8c03\u7528 <code>gettimeofday()</code> \u8f83\u6162\u7684\u673a\u5668\u4e0a\u3002\u53ef\u4ee5\u4f7f\u7528 <a href=\"/zh/docs/18/pgtesttiming.html\" rel=\"nofollow\"><span><span>pg_test_timing</span></span></a> \u5de5\u5177\u6765\u6d4b\u91cf\u7cfb\u7edf\u4e0a\u7684\u8ba1\u65f6\u5f00\u9500\u3002\n   </p><p>\n    \u4e0d\u5e94\u5c06 <code>EXPLAIN</code> \u7ed3\u679c\u5916\u63a8\u5230\u4e0e\u5b9e\u9645\u6d4b\u8bd5\u573a\u666f\u5dee\u5f02\u5f88\u5927\u7684\u60c5\u51b5\u3002\u4f8b\u5982\uff0c\u5728\u4e00\u4e2a\u5f88\u5c0f\u7684\u8868\u4e0a\u5f97\u5230\u7684\u7ed3\u679c\uff0c\u4e0d\u80fd\u5047\u5b9a\u4e5f\u9002\u7528\u4e8e\u5927\u578b\u8868\u3002\u89c4\u5212\u5668\u7684\u4ee3\u4ef7\u4f30\u8ba1\u4e0d\u662f\u7ebf\u6027\u7684\uff0c\u56e0\u6b64\u5b83\u53ef\u80fd\u4f1a\u4e3a\u66f4\u5927\u6216\u66f4\u5c0f\u7684\u8868\u9009\u62e9\u4e0d\u540c\u7684\u8ba1\u5212\u3002\u4e00\u4e2a\u6781\u7aef\u793a\u4f8b\u662f\uff1a\u5bf9\u4e8e\u53ea\u5360\u7528\u4e00\u4e2a\u78c1\u76d8\u9875\u7684\u8868\uff0c\u65e0\u8bba\u7d22\u5f15\u662f\u5426\u53ef\u7528\uff0c\u51e0\u4e4e\u603b\u4f1a\u5f97\u5230\u987a\u5e8f\u626b\u63cf\u8ba1\u5212\u3002\u89c4\u5212\u5668\u8ba4\u8bc6\u5230\uff0c\u65e0\u8bba\u5982\u4f55\u5904\u7406\u8be5\u8868\u90fd\u9700\u8981\u4e00\u6b21\u78c1\u76d8\u9875\u8bfb\u53d6\uff0c\u56e0\u6b64\u518d\u989d\u5916\u8bfb\u53d6\u9875\u9762\u53bb\u67e5\u770b\u7d22\u5f15\u5e76\u6ca1\u6709\u4ef7\u503c\u3002\uff08\u524d\u9762\u7684 <code>polygon_tbl</code> \u793a\u4f8b\u5df2\u7ecf\u5c55\u793a\u8fc7\u8fd9\u79cd\u60c5\u51b5\u3002\uff09\n   </p><p>\n    \u5728\u67d0\u4e9b\u60c5\u51b5\u4e0b\uff0c\u5b9e\u9645\u503c\u548c\u4f30\u8ba1\u503c\u4e0d\u4f1a\u5f88\u597d\u5730\u5bf9\u5e94\uff0c\u4f46\u8fd9\u5e76\u4e0d\u8868\u793a\u51fa\u73b0\u4e86\u95ee\u9898\u3002\u5176\u4e2d\u4e00\u79cd\u60c5\u51b5\u662f\uff0c\u8ba1\u5212\u8282\u70b9\u7684\u6267\u884c\u4f1a\u88ab <code>LIMIT</code> \u6216\u7c7b\u4f3c\u6548\u679c\u63d0\u524d\u622a\u65ad\u3002\u4f8b\u5982\uff0c\u5728\u524d\u9762\u7528\u8fc7\u7684 <code>LIMIT</code> \u67e5\u8be2\u4e2d\uff1a\n\n</p><p>\n\n    Index Scan \u8282\u70b9\u7684\u4f30\u8ba1\u4ee3\u4ef7\u548c\u884c\u8ba1\u6570\u663e\u793a\u5f97\u50cf\u662f\u5b83\u4f1a\u8fd0\u884c\u5230\u7ed3\u675f\u4e00\u6837\u3002\u4f46\u5b9e\u9645\u4e0a\uff0cLimit \u8282\u70b9\u5728\u62ff\u5230\u4e24\u884c\u4e4b\u540e\u5c31\u505c\u6b62\u8bf7\u6c42\u66f4\u591a\u884c\uff0c\u56e0\u6b64\u5b9e\u9645\u884c\u8ba1\u6570\u53ea\u6709 2\uff0c\u8fd0\u884c\u65f6\u95f4\u4e5f\u4f4e\u4e8e\u4ee3\u4ef7\u4f30\u8ba1\u6240\u6697\u793a\u7684\u6c34\u5e73\u3002\u8fd9\u5e76\u4e0d\u662f\u4f30\u8ba1\u9519\u8bef\uff0c\u53ea\u662f\u4f30\u8ba1\u503c\u4e0e\u771f\u5b9e\u503c\u7684\u663e\u793a\u65b9\u5f0f\u4e0d\u540c\u800c\u5df2\u3002\n   </p><p><a href=\"/zh/docs/18/using-explain.html#USING-EXPLAIN-CAVEATS\" rel=\"nofollow\">\u67e5\u770b\u5b8c\u6574\u4e2d\u6587\u624b\u518c\u4e0e\u4e0a\u4e0b\u6587</a>\u3002</p><p>\u672c\u9875\u5f00\u5934\u7684\u4e2d\u6587\u8bf4\u660e\u4e3a PG.CENTER \u5bf9\u7f16\u8f91\u8bf4\u660e\u7684\u7ffb\u8bd1\uff1b\u624b\u518c\u8282\u9009\u4fdd\u7559\u5bf9\u5e94\u7248\u672c\u4e2d\u6587\u6587\u6863\u539f\u6587\u3002\u6e90\u7801\u4fe1\u606f\u53ca\u624b\u518c\u793a\u4f8b\u4e0d\u4ee3\u8868\u91cd\u65b0\u8fdb\u884c\u8fc7\u8fd0\u884c\u6d4b\u8bd5\u3002</p>", "center_zh_rendered": "<p>\u5bf9\u5404\u5b50\u8ba1\u5212\u751f\u6210\u7684\u4f4d\u56fe\u6c42\u5e76\u96c6\u3002</p><p>\u6838\u5fc3\u8282\u70b9\u6807\u8bc6\uff1a<code>T_BitmapOr</code>\uff1bEXPLAIN \u540d\u79f0\uff1a<code>BitmapOr</code>\u3002</p><p>\u672c\u7248\u672c\u6e90\u7801\u4e2d\u7684\u5e76\u884c\u6267\u884c\u6216\u89c2\u6d4b\u56de\u8c03\uff1a\u8be5\u8282\u70b9\u5b9e\u73b0\u4e2d\u672a\u63d0\u53d6\u5230\u6b64\u7c7b\u56de\u8c03\u3002\u56de\u8c03\u7684\u5b58\u5728\u4e0d\u8868\u793a\u8be5\u8282\u70b9\u5fc5\u7136\u652f\u6301\u5171\u4eab\u5e76\u884c\u626b\u63cf\uff1b\u5728\u5e76\u884c\u5de5\u4f5c\u8fdb\u7a0b\u4e2d\u6267\u884c\u4e5f\u4e0d\u7b49\u4e8e\u5177\u6709\u5e76\u884c\u611f\u77e5\u80fd\u529b\u3002</p><h3>\u540c\u7248\u672c\u4e2d\u6587\u624b\u518c\u8282\u9009</h3><p>\n<code>EXPLAIN ANALYZE</code> \u6d4b\u5f97\u7684\u8fd0\u884c\u65f6\u95f4\uff0c\u53ef\u80fd\u4ee5\u4e24\u79cd\u91cd\u8981\u65b9\u5f0f\u504f\u79bb\u540c\u4e00\u67e5\u8be2\u7684\u6b63\u5e38\u6267\u884c\u65f6\u95f4\u3002\u7b2c\u4e00\uff0c\u7531\u4e8e\u4e0d\u4f1a\u5411\u5ba2\u6237\u7aef\u4f20\u9012\u4efb\u4f55\u8f93\u51fa\u884c\uff0c\u56e0\u6b64\u7f51\u7edc\u4f20\u8f93\u5f00\u9500\u4e0d\u4f1a\u88ab\u8ba1\u5165\u3002\u9664\u975e\u6307\u5b9a\u4e86 <code>SERIALIZE</code>\uff0cI/O \u8f6c\u6362\u5f00\u9500\u540c\u6837\u4e5f\u4e0d\u4f1a\u88ab\u8ba1\u5165\u3002\u7b2c\u4e8c\uff0c<code>EXPLAIN ANALYZE</code> \u9644\u52a0\u7684\u6d4b\u91cf\u5f00\u9500\u672c\u8eab\u53ef\u80fd\u76f8\u5f53\u53ef\u89c2\uff0c\u5c24\u5176\u662f\u5728\u64cd\u4f5c\u7cfb\u7edf\u8c03\u7528 <code>gettimeofday()</code> \u8f83\u6162\u7684\u673a\u5668\u4e0a\u3002\u53ef\u4ee5\u4f7f\u7528 <a href=\"/docs/18/pgtesttiming.html\"><span><span>pg_test_timing</span></span></a> \u5de5\u5177\u6765\u6d4b\u91cf\u7cfb\u7edf\u4e0a\u7684\u8ba1\u65f6\u5f00\u9500\u3002\n   </p><p>\n    \u4e0d\u5e94\u5c06 <code>EXPLAIN</code> \u7ed3\u679c\u5916\u63a8\u5230\u4e0e\u5b9e\u9645\u6d4b\u8bd5\u573a\u666f\u5dee\u5f02\u5f88\u5927\u7684\u60c5\u51b5\u3002\u4f8b\u5982\uff0c\u5728\u4e00\u4e2a\u5f88\u5c0f\u7684\u8868\u4e0a\u5f97\u5230\u7684\u7ed3\u679c\uff0c\u4e0d\u80fd\u5047\u5b9a\u4e5f\u9002\u7528\u4e8e\u5927\u578b\u8868\u3002\u89c4\u5212\u5668\u7684\u4ee3\u4ef7\u4f30\u8ba1\u4e0d\u662f\u7ebf\u6027\u7684\uff0c\u56e0\u6b64\u5b83\u53ef\u80fd\u4f1a\u4e3a\u66f4\u5927\u6216\u66f4\u5c0f\u7684\u8868\u9009\u62e9\u4e0d\u540c\u7684\u8ba1\u5212\u3002\u4e00\u4e2a\u6781\u7aef\u793a\u4f8b\u662f\uff1a\u5bf9\u4e8e\u53ea\u5360\u7528\u4e00\u4e2a\u78c1\u76d8\u9875\u7684\u8868\uff0c\u65e0\u8bba\u7d22\u5f15\u662f\u5426\u53ef\u7528\uff0c\u51e0\u4e4e\u603b\u4f1a\u5f97\u5230\u987a\u5e8f\u626b\u63cf\u8ba1\u5212\u3002\u89c4\u5212\u5668\u8ba4\u8bc6\u5230\uff0c\u65e0\u8bba\u5982\u4f55\u5904\u7406\u8be5\u8868\u90fd\u9700\u8981\u4e00\u6b21\u78c1\u76d8\u9875\u8bfb\u53d6\uff0c\u56e0\u6b64\u518d\u989d\u5916\u8bfb\u53d6\u9875\u9762\u53bb\u67e5\u770b\u7d22\u5f15\u5e76\u6ca1\u6709\u4ef7\u503c\u3002\uff08\u524d\u9762\u7684 <code>polygon_tbl</code> \u793a\u4f8b\u5df2\u7ecf\u5c55\u793a\u8fc7\u8fd9\u79cd\u60c5\u51b5\u3002\uff09\n   </p><p>\n    \u5728\u67d0\u4e9b\u60c5\u51b5\u4e0b\uff0c\u5b9e\u9645\u503c\u548c\u4f30\u8ba1\u503c\u4e0d\u4f1a\u5f88\u597d\u5730\u5bf9\u5e94\uff0c\u4f46\u8fd9\u5e76\u4e0d\u8868\u793a\u51fa\u73b0\u4e86\u95ee\u9898\u3002\u5176\u4e2d\u4e00\u79cd\u60c5\u51b5\u662f\uff0c\u8ba1\u5212\u8282\u70b9\u7684\u6267\u884c\u4f1a\u88ab <code>LIMIT</code> \u6216\u7c7b\u4f3c\u6548\u679c\u63d0\u524d\u622a\u65ad\u3002\u4f8b\u5982\uff0c\u5728\u524d\u9762\u7528\u8fc7\u7684 <code>LIMIT</code> \u67e5\u8be2\u4e2d\uff1a\n\n</p><p>\n\n    Index Scan \u8282\u70b9\u7684\u4f30\u8ba1\u4ee3\u4ef7\u548c\u884c\u8ba1\u6570\u663e\u793a\u5f97\u50cf\u662f\u5b83\u4f1a\u8fd0\u884c\u5230\u7ed3\u675f\u4e00\u6837\u3002\u4f46\u5b9e\u9645\u4e0a\uff0cLimit \u8282\u70b9\u5728\u62ff\u5230\u4e24\u884c\u4e4b\u540e\u5c31\u505c\u6b62\u8bf7\u6c42\u66f4\u591a\u884c\uff0c\u56e0\u6b64\u5b9e\u9645\u884c\u8ba1\u6570\u53ea\u6709 2\uff0c\u8fd0\u884c\u65f6\u95f4\u4e5f\u4f4e\u4e8e\u4ee3\u4ef7\u4f30\u8ba1\u6240\u6697\u793a\u7684\u6c34\u5e73\u3002\u8fd9\u5e76\u4e0d\u662f\u4f30\u8ba1\u9519\u8bef\uff0c\u53ea\u662f\u4f30\u8ba1\u503c\u4e0e\u771f\u5b9e\u503c\u7684\u663e\u793a\u65b9\u5f0f\u4e0d\u540c\u800c\u5df2\u3002\n   </p><p><a href=\"/docs/18/using-explain.html#USING-EXPLAIN-CAVEATS\">\u67e5\u770b\u5b8c\u6574\u4e2d\u6587\u624b\u518c\u4e0e\u4e0a\u4e0b\u6587</a>\u3002</p><p>\u672c\u9875\u5f00\u5934\u7684\u4e2d\u6587\u8bf4\u660e\u4e3a PG.CENTER \u5bf9\u7f16\u8f91\u8bf4\u660e\u7684\u7ffb\u8bd1\uff1b\u624b\u518c\u8282\u9009\u4fdd\u7559\u5bf9\u5e94\u7248\u672c\u4e2d\u6587\u6587\u6863\u539f\u6587\u3002\u6e90\u7801\u4fe1\u606f\u53ca\u624b\u518c\u793a\u4f8b\u4e0d\u4ee3\u8868\u91cd\u65b0\u8fdb\u884c\u8fc7\u8fd0\u884c\u6d4b\u8bd5\u3002</p>"}, "19": {"facts": [{"label": "\u6838\u5fc3\u8282\u70b9\u6807\u7b7e", "value": "T_BitmapOr"}, {"label": "\u7ed3\u6784\u5316 EXPLAIN \u8282\u70b9\u7c7b\u578b", "value": "BitmapOr"}, {"label": "\u8f93\u5165", "value": "\u4ea7\u751f\u4f4d\u56fe\u7684\u5b50\u8ba1\u5212"}, {"label": "\u8f93\u51fa", "value": "\u5143\u7ec4\u4f4d\u7f6e\u4f4d\u56fe\uff0c\u4e0d\u662f\u5143\u7ec4\u6d41"}, {"label": "\u6267\u884c\u5668\u521d\u59cb\u5316\u51fd\u6570", "value": "ExecInitBitmapOr"}, {"label": "\u5185\u5b58\u673a\u5236", "value": "bitmap-lossification"}], "memory": {"evidence": [{"url": "https://ftp.postgresql.org/pub/source/v19beta4/postgresql-19beta4.tar.bz2", "path": "src/backend/executor/nodeBitmapOr.c", "label": "src/backend/executor/nodeBitmapOr.c", "sha256": "14f9eed6e8f71de94c064f7265c0724022326d6acf2ab4d2da6d17ccbd206188", "archive_sha256": "83157ee9c599d03b2f7a3d73ef3a56ec24e0e79cc2b3501a64d1364f56398c86"}, {"url": "https://ftp.postgresql.org/pub/source/v19beta4/postgresql-19beta4.tar.bz2", "path": "src/backend/nodes/tidbitmap.c", "label": "src/backend/nodes/tidbitmap.c", "sha256": "3394cc4f8c9e397b78f6b0d99fba931fd809450ec7b5ff051798ecbd0dcf3b32", "archive_sha256": "83157ee9c599d03b2f7a3d73ef3a56ec24e0e79cc2b3501a64d1364f56398c86"}], "mechanism": "bitmap-lossification", "description": "The node allocates a tuple-location bitmap using a work_mem-derived budget. 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Type\u3002\u6587\u672c\u683c\u5f0f\u540d\u79f0\u8fd8\u53ef\u80fd\u5305\u542b\u64cd\u4f5c\u3001\u7b56\u7565\u3001\u8fde\u63a5\u7c7b\u578b\u3001\u626b\u63cf\u65b9\u5411\u6216\u805a\u5408\u9636\u6bb5\u5c5e\u6027\u3002", "\u6b64\u6e90\u7801\u8bb0\u5f55\u7684\u6587\u672c\u540d\u79f0\uff1aBitmapOr.", "\u5e76\u884c\u611f\u77e5\u4e0e\u5e76\u884c\u5b89\u5168\u662f\u4e0d\u540c\u7684\u8ba1\u5212\u5c5e\u6027\u3002\u5728\u5e76\u884c\u5de5\u4f5c\u8fdb\u7a0b\u5185\u8fd0\u884c\u7684\u8282\u70b9\u4e0d\u4e00\u5b9a\u662f\u5e76\u884c\u611f\u77e5\u8282\u70b9\u3002"]}, {"title": "\u5185\u5b58\u4e0e\u4e34\u65f6\u5b58\u50a8", "paragraphs": ["\u6b64\u8282\u70b9\u6309\u57fa\u4e8e work_mem \u7684\u9884\u7b97\u5206\u914d\u5143\u7ec4\u4f4d\u7f6e\u4f4d\u56fe\u3002\u4f4d\u56fe\u53ef\u4ee5\u4fdd\u7559\u9875\u7ea7\u6709\u635f\u6761\u76ee\uff0c\u800c\u4e0d\u8bb0\u5f55\u6bcf\u4e2a\u5143\u7ec4\u4f4d\u7f6e\uff0c\u56e0\u6b64\u4ecd\u53ef\u80fd\u9700\u8981\u5806\u91cd\u68c0\u3002"]}, {"title": "\u5e76\u884c\u6267\u884c\u4e0e\u8fd0\u884c\u4fe1\u606f\u91c7\u96c6", "paragraphs": ["\u4ee5\u4e0b\u6e90\u7801\u56de\u8c03\u53ef\u4ee5\u534f\u8c03\u6267\u884c\u6216\u6536\u96c6\u5de5\u4f5c\u8fdb\u7a0b\u7684\u6d4b\u91cf\u6570\u636e\u3002\u56de\u8c03\u5b58\u5728\u4e0d\u4ee3\u8868\u8be5\u8282\u70b9\u666e\u904d\u652f\u6301\u5171\u4eab\u5e76\u884c\u626b\u63cf\u6216\u5171\u4eab\u72b6\u6001\u3002", "\u6b64\u6784\u5efa\u7684\u56de\u8c03\uff1anone extracted from this node implementation."]}, {"title": "\u540c\u7248\u672c\u624b\u518c\u8bf4\u660e", "paragraphs": ["\u7531\u4e8e\u5b9e\u73b0\u4e0a\u7684\u9650\u5236\uff0cBitmapAnd \u548c BitmapOr \u8282\u70b9\u62a5\u544a\u7684\u5b9e\u9645\u884c\u6570\u59cb\u7ec8\u4e3a\u96f6\u3002"]}, {"title": "\u6267\u884c\u5668\u5b9e\u73b0\u8bf4\u660e", "paragraphs": ["\u8bf4\u660e\uff1aBitmapOr \u4e0d\u4f7f\u7528\u5de6\u53f3\u5b50\u6811\uff0c\u800c\u50cf Append \u4e00\u6837\u7ef4\u62a4\u5b50\u8ba1\u5212\u5217\u8868\u3002\u4e0d\u8fc7\u5176\u903b\u8f91\u6bd4 Append \u7b80\u5355\u5f97\u591a\uff0c\u56e0\u4e3a\u65e0\u9700\u5904\u7406\u6b63\u5411\u6216\u53cd\u5411\u6267\u884c\u3002", "\u5bf9\u6bcf\u4e2a\u5f85\u6267\u884c\u8ba1\u5212\u8c03\u7528 ExecInitNode\uff0c\u5e76\u5c06\u7ed3\u679c\u4fdd\u5b58\u5230 bitmapplanstates \u6570\u7ec4\u3002", "BitmapOr \u8ba1\u5212\u6ca1\u6709\u8868\u8fbe\u5f0f\u4e0a\u4e0b\u6587\uff0c\u56e0\u4e3a\u5b83\u4eec\u4ece\u4e0d\u8c03\u7528 ExecQual \u6216 ExecProject\uff0c\u4e5f\u4e0d\u9700\u8981\u5143\u7ec4\u69fd\u3002", "\u53ef\u5bf9 BitmapIndexScan \u5b50\u8282\u70b9\u4f5c\u7279\u6b8a\u5904\u7406\uff0c\u907f\u514d\u4e3a\u6bcf\u4e2a\u5b50\u8282\u70b9\u663e\u5f0f\u8c03\u7528 tbm_union\uff1a\u76f4\u63a5\u4e0b\u4f20\u5f53\u524d\u7ed3\u679c\u4f4d\u56fe\uff0c\u8ba9\u5b50\u8282\u70b9\u5c06\u7ed3\u679c\u6309\u4f4d OR \u5408\u5e76\u8fdb\u53bb\u3002", "ExecReScan \u4e0d\u77e5\u9053\u5f53\u524d\u8282\u70b9\u7684\u5b50\u8ba1\u5212\uff0c\u56e0\u6b64\u5fc5\u987b\u81ea\u884c\u901a\u77e5\u5b50\u8ba1\u5212\u54ea\u4e9b\u53c2\u6570\u53d1\u751f\u4e86\u53d8\u5316\u3002"]}, {"code": "case T_BitmapOr:\n\t\t\tpname = sname = \"BitmapOr\";\n\t\t\tbreak;", "title": "\u6838\u5fc3\u6e90\u7801\u4e2d\u7684 EXPLAIN \u6807\u8bc6"}], "description_zh": "\u5bf9\u5404\u5b50\u8ba1\u5212\u751f\u6210\u7684\u4f4d\u56fe\u6c42\u5e76\u96c6\u3002", "description_zh_html": "<p>\u5bf9\u5404\u5b50\u8ba1\u5212\u751f\u6210\u7684\u4f4d\u56fe\u6c42\u5e76\u96c6\u3002</p><p>\u6838\u5fc3\u8282\u70b9\u6807\u8bc6\uff1a<code>T_BitmapOr</code>\uff1bEXPLAIN \u540d\u79f0\uff1a<code>BitmapOr</code>\u3002</p><p>\u672c\u7248\u672c\u6e90\u7801\u4e2d\u7684\u5e76\u884c\u6267\u884c\u6216\u89c2\u6d4b\u56de\u8c03\uff1a\u8be5\u8282\u70b9\u5b9e\u73b0\u4e2d\u672a\u63d0\u53d6\u5230\u6b64\u7c7b\u56de\u8c03\u3002\u56de\u8c03\u7684\u5b58\u5728\u4e0d\u8868\u793a\u8be5\u8282\u70b9\u5fc5\u7136\u652f\u6301\u5171\u4eab\u5e76\u884c\u626b\u63cf\uff1b\u5728\u5e76\u884c\u5de5\u4f5c\u8fdb\u7a0b\u4e2d\u6267\u884c\u4e5f\u4e0d\u7b49\u4e8e\u5177\u6709\u5e76\u884c\u611f\u77e5\u80fd\u529b\u3002</p><h3>\u540c\u7248\u672c\u4e2d\u6587\u624b\u518c\u8282\u9009</h3><p>\n<code class=\"command\">EXPLAIN ANALYZE</code> \u6d4b\u5f97\u7684\u8fd0\u884c\u65f6\u95f4\uff0c\u53ef\u80fd\u4ee5\u4e24\u79cd\u91cd\u8981\u65b9\u5f0f\u504f\u79bb\u540c\u4e00\u67e5\u8be2\u7684\u6b63\u5e38\u6267\u884c\u65f6\u95f4\u3002\u7b2c\u4e00\uff0c\u7531\u4e8e\u4e0d\u4f1a\u5411\u5ba2\u6237\u7aef\u4f20\u9012\u4efb\u4f55\u8f93\u51fa\u884c\uff0c\u56e0\u6b64\u7f51\u7edc\u4f20\u8f93\u5f00\u9500\u4e0d\u4f1a\u88ab\u8ba1\u5165\u3002\u9664\u975e\u6307\u5b9a\u4e86 <code class=\"literal\">SERIALIZE</code>\uff0cI/O \u8f6c\u6362\u5f00\u9500\u540c\u6837\u4e5f\u4e0d\u4f1a\u88ab\u8ba1\u5165\u3002\u7b2c\u4e8c\uff0c<code class=\"command\">EXPLAIN ANALYZE</code> \u9644\u52a0\u7684\u6d4b\u91cf\u5f00\u9500\u672c\u8eab\u53ef\u80fd\u76f8\u5f53\u53ef\u89c2\uff0c\u5c24\u5176\u662f\u5728\u64cd\u4f5c\u7cfb\u7edf\u8c03\u7528 <code class=\"function\">gettimeofday()</code> \u8f83\u6162\u7684\u673a\u5668\u4e0a\u3002\u53ef\u4ee5\u4f7f\u7528 <a class=\"xref\" href=\"/zh/docs/19/pgtesttiming.html\"><span class=\"refentrytitle\"><span class=\"application\">pg_test_timing</span></span></a> \u5de5\u5177\u6765\u6d4b\u91cf\u7cfb\u7edf\u4e0a\u7684\u8ba1\u65f6\u5f00\u9500\u3002\n   </p><p>\n    \u4e0d\u5e94\u5c06 <code class=\"command\">EXPLAIN</code> \u7ed3\u679c\u5916\u63a8\u5230\u4e0e\u5b9e\u9645\u6d4b\u8bd5\u573a\u666f\u5dee\u5f02\u5f88\u5927\u7684\u60c5\u51b5\u3002\u4f8b\u5982\uff0c\u5728\u4e00\u4e2a\u5f88\u5c0f\u7684\u8868\u4e0a\u5f97\u5230\u7684\u7ed3\u679c\uff0c\u4e0d\u80fd\u5047\u5b9a\u4e5f\u9002\u7528\u4e8e\u5927\u578b\u8868\u3002\u89c4\u5212\u5668\u7684\u4ee3\u4ef7\u4f30\u8ba1\u4e0d\u662f\u7ebf\u6027\u7684\uff0c\u56e0\u6b64\u5b83\u53ef\u80fd\u4f1a\u4e3a\u66f4\u5927\u6216\u66f4\u5c0f\u7684\u8868\u9009\u62e9\u4e0d\u540c\u7684\u8ba1\u5212\u3002\u4e00\u4e2a\u6781\u7aef\u793a\u4f8b\u662f\uff1a\u5bf9\u4e8e\u53ea\u5360\u7528\u4e00\u4e2a\u78c1\u76d8\u9875\u7684\u8868\uff0c\u65e0\u8bba\u7d22\u5f15\u662f\u5426\u53ef\u7528\uff0c\u51e0\u4e4e\u603b\u4f1a\u5f97\u5230\u987a\u5e8f\u626b\u63cf\u8ba1\u5212\u3002\u89c4\u5212\u5668\u8ba4\u8bc6\u5230\uff0c\u65e0\u8bba\u5982\u4f55\u5904\u7406\u8be5\u8868\u90fd\u9700\u8981\u4e00\u6b21\u78c1\u76d8\u9875\u8bfb\u53d6\uff0c\u56e0\u6b64\u518d\u989d\u5916\u8bfb\u53d6\u9875\u9762\u53bb\u67e5\u770b\u7d22\u5f15\u5e76\u6ca1\u6709\u4ef7\u503c\u3002\uff08\u524d\u9762\u7684 <code class=\"literal\">polygon_tbl</code> \u793a\u4f8b\u5df2\u7ecf\u5c55\u793a\u8fc7\u8fd9\u79cd\u60c5\u51b5\u3002\uff09\n   </p><p>\n    \u5728\u67d0\u4e9b\u60c5\u51b5\u4e0b\uff0c\u5b9e\u9645\u503c\u548c\u4f30\u8ba1\u503c\u4e0d\u4f1a\u5f88\u597d\u5730\u5bf9\u5e94\uff0c\u4f46\u8fd9\u5e76\u4e0d\u8868\u793a\u51fa\u73b0\u4e86\u95ee\u9898\u3002\u5176\u4e2d\u4e00\u79cd\u60c5\u51b5\u662f\uff0c\u8ba1\u5212\u8282\u70b9\u7684\u6267\u884c\u4f1a\u88ab <code class=\"literal\">LIMIT</code> \u6216\u7c7b\u4f3c\u6548\u679c\u63d0\u524d\u622a\u65ad\u3002\u4f8b\u5982\uff0c\u5728\u524d\u9762\u7528\u8fc7\u7684 <code class=\"literal\">LIMIT</code> \u67e5\u8be2\u4e2d\uff1a\n\n</p><p>\n\n    Index Scan \u8282\u70b9\u7684\u4f30\u8ba1\u4ee3\u4ef7\u548c\u884c\u8ba1\u6570\u663e\u793a\u5f97\u50cf\u662f\u5b83\u4f1a\u8fd0\u884c\u5230\u7ed3\u675f\u4e00\u6837\u3002\u4f46\u5b9e\u9645\u4e0a\uff0cLimit \u8282\u70b9\u5728\u62ff\u5230\u4e24\u884c\u4e4b\u540e\u5c31\u505c\u6b62\u8bf7\u6c42\u66f4\u591a\u884c\uff0c\u56e0\u6b64\u5b9e\u9645\u884c\u8ba1\u6570\u53ea\u6709 2\uff0c\u8fd0\u884c\u65f6\u95f4\u4e5f\u4f4e\u4e8e\u4ee3\u4ef7\u4f30\u8ba1\u6240\u6697\u793a\u7684\u6c34\u5e73\u3002\u8fd9\u5e76\u4e0d\u662f\u4f30\u8ba1\u9519\u8bef\uff0c\u53ea\u662f\u4f30\u8ba1\u503c\u4e0e\u771f\u5b9e\u503c\u7684\u663e\u793a\u65b9\u5f0f\u4e0d\u540c\u800c\u5df2\u3002\n   </p><p><a href=\"/zh/docs/19/using-explain.html#USING-EXPLAIN-CAVEATS\">\u67e5\u770b\u5b8c\u6574\u4e2d\u6587\u624b\u518c\u4e0e\u4e0a\u4e0b\u6587</a>\u3002</p><p>\u672c\u9875\u5f00\u5934\u7684\u4e2d\u6587\u8bf4\u660e\u4e3a PG.CENTER \u5bf9\u7f16\u8f91\u8bf4\u660e\u7684\u7ffb\u8bd1\uff1b\u624b\u518c\u8282\u9009\u4fdd\u7559\u5bf9\u5e94\u7248\u672c\u4e2d\u6587\u6587\u6863\u539f\u6587\u3002\u6e90\u7801\u4fe1\u606f\u53ca\u624b\u518c\u793a\u4f8b\u4e0d\u4ee3\u8868\u91cd\u65b0\u8fdb\u884c\u8fc7\u8fd0\u884c\u6d4b\u8bd5\u3002</p>"}, "summary": "\u5bf9\u5404\u5b50\u8ba1\u5212\u751f\u6210\u7684\u4f4d\u56fe\u6c42\u5e76\u96c6\u3002", "version": "19", "link_map": {"/zh/docs/19/pgtesttiming.html": "/docs/19/pgtesttiming.html", "/zh/docs/19/using-explain.html#USING-EXPLAIN-CAVEATS": "/docs/19/using-explain.html#USING-EXPLAIN-CAVEATS"}, "body_html": "<p>\u5bf9\u5404\u5b50\u8ba1\u5212\u751f\u6210\u7684\u4f4d\u56fe\u6c42\u5e76\u96c6\u3002</p><p>\u6838\u5fc3\u8282\u70b9\u6807\u8bc6\uff1a<code>T_BitmapOr</code>\uff1bEXPLAIN \u540d\u79f0\uff1a<code>BitmapOr</code>\u3002</p><p>\u672c\u7248\u672c\u6e90\u7801\u4e2d\u7684\u5e76\u884c\u6267\u884c\u6216\u89c2\u6d4b\u56de\u8c03\uff1a\u8be5\u8282\u70b9\u5b9e\u73b0\u4e2d\u672a\u63d0\u53d6\u5230\u6b64\u7c7b\u56de\u8c03\u3002\u56de\u8c03\u7684\u5b58\u5728\u4e0d\u8868\u793a\u8be5\u8282\u70b9\u5fc5\u7136\u652f\u6301\u5171\u4eab\u5e76\u884c\u626b\u63cf\uff1b\u5728\u5e76\u884c\u5de5\u4f5c\u8fdb\u7a0b\u4e2d\u6267\u884c\u4e5f\u4e0d\u7b49\u4e8e\u5177\u6709\u5e76\u884c\u611f\u77e5\u80fd\u529b\u3002</p><h3>\u540c\u7248\u672c\u4e2d\u6587\u624b\u518c\u8282\u9009</h3><p>\n<code>EXPLAIN ANALYZE</code> \u6d4b\u5f97\u7684\u8fd0\u884c\u65f6\u95f4\uff0c\u53ef\u80fd\u4ee5\u4e24\u79cd\u91cd\u8981\u65b9\u5f0f\u504f\u79bb\u540c\u4e00\u67e5\u8be2\u7684\u6b63\u5e38\u6267\u884c\u65f6\u95f4\u3002\u7b2c\u4e00\uff0c\u7531\u4e8e\u4e0d\u4f1a\u5411\u5ba2\u6237\u7aef\u4f20\u9012\u4efb\u4f55\u8f93\u51fa\u884c\uff0c\u56e0\u6b64\u7f51\u7edc\u4f20\u8f93\u5f00\u9500\u4e0d\u4f1a\u88ab\u8ba1\u5165\u3002\u9664\u975e\u6307\u5b9a\u4e86 <code>SERIALIZE</code>\uff0cI/O \u8f6c\u6362\u5f00\u9500\u540c\u6837\u4e5f\u4e0d\u4f1a\u88ab\u8ba1\u5165\u3002\u7b2c\u4e8c\uff0c<code>EXPLAIN ANALYZE</code> \u9644\u52a0\u7684\u6d4b\u91cf\u5f00\u9500\u672c\u8eab\u53ef\u80fd\u76f8\u5f53\u53ef\u89c2\uff0c\u5c24\u5176\u662f\u5728\u64cd\u4f5c\u7cfb\u7edf\u8c03\u7528 <code>gettimeofday()</code> \u8f83\u6162\u7684\u673a\u5668\u4e0a\u3002\u53ef\u4ee5\u4f7f\u7528 <a href=\"/zh/docs/19/pgtesttiming.html\" rel=\"nofollow\"><span><span>pg_test_timing</span></span></a> \u5de5\u5177\u6765\u6d4b\u91cf\u7cfb\u7edf\u4e0a\u7684\u8ba1\u65f6\u5f00\u9500\u3002\n   </p><p>\n    \u4e0d\u5e94\u5c06 <code>EXPLAIN</code> \u7ed3\u679c\u5916\u63a8\u5230\u4e0e\u5b9e\u9645\u6d4b\u8bd5\u573a\u666f\u5dee\u5f02\u5f88\u5927\u7684\u60c5\u51b5\u3002\u4f8b\u5982\uff0c\u5728\u4e00\u4e2a\u5f88\u5c0f\u7684\u8868\u4e0a\u5f97\u5230\u7684\u7ed3\u679c\uff0c\u4e0d\u80fd\u5047\u5b9a\u4e5f\u9002\u7528\u4e8e\u5927\u578b\u8868\u3002\u89c4\u5212\u5668\u7684\u4ee3\u4ef7\u4f30\u8ba1\u4e0d\u662f\u7ebf\u6027\u7684\uff0c\u56e0\u6b64\u5b83\u53ef\u80fd\u4f1a\u4e3a\u66f4\u5927\u6216\u66f4\u5c0f\u7684\u8868\u9009\u62e9\u4e0d\u540c\u7684\u8ba1\u5212\u3002\u4e00\u4e2a\u6781\u7aef\u793a\u4f8b\u662f\uff1a\u5bf9\u4e8e\u53ea\u5360\u7528\u4e00\u4e2a\u78c1\u76d8\u9875\u7684\u8868\uff0c\u65e0\u8bba\u7d22\u5f15\u662f\u5426\u53ef\u7528\uff0c\u51e0\u4e4e\u603b\u4f1a\u5f97\u5230\u987a\u5e8f\u626b\u63cf\u8ba1\u5212\u3002\u89c4\u5212\u5668\u8ba4\u8bc6\u5230\uff0c\u65e0\u8bba\u5982\u4f55\u5904\u7406\u8be5\u8868\u90fd\u9700\u8981\u4e00\u6b21\u78c1\u76d8\u9875\u8bfb\u53d6\uff0c\u56e0\u6b64\u518d\u989d\u5916\u8bfb\u53d6\u9875\u9762\u53bb\u67e5\u770b\u7d22\u5f15\u5e76\u6ca1\u6709\u4ef7\u503c\u3002\uff08\u524d\u9762\u7684 <code>polygon_tbl</code> \u793a\u4f8b\u5df2\u7ecf\u5c55\u793a\u8fc7\u8fd9\u79cd\u60c5\u51b5\u3002\uff09\n   </p><p>\n    \u5728\u67d0\u4e9b\u60c5\u51b5\u4e0b\uff0c\u5b9e\u9645\u503c\u548c\u4f30\u8ba1\u503c\u4e0d\u4f1a\u5f88\u597d\u5730\u5bf9\u5e94\uff0c\u4f46\u8fd9\u5e76\u4e0d\u8868\u793a\u51fa\u73b0\u4e86\u95ee\u9898\u3002\u5176\u4e2d\u4e00\u79cd\u60c5\u51b5\u662f\uff0c\u8ba1\u5212\u8282\u70b9\u7684\u6267\u884c\u4f1a\u88ab <code>LIMIT</code> \u6216\u7c7b\u4f3c\u6548\u679c\u63d0\u524d\u622a\u65ad\u3002\u4f8b\u5982\uff0c\u5728\u524d\u9762\u7528\u8fc7\u7684 <code>LIMIT</code> \u67e5\u8be2\u4e2d\uff1a\n\n</p><p>\n\n    Index Scan \u8282\u70b9\u7684\u4f30\u8ba1\u4ee3\u4ef7\u548c\u884c\u8ba1\u6570\u663e\u793a\u5f97\u50cf\u662f\u5b83\u4f1a\u8fd0\u884c\u5230\u7ed3\u675f\u4e00\u6837\u3002\u4f46\u5b9e\u9645\u4e0a\uff0cLimit \u8282\u70b9\u5728\u62ff\u5230\u4e24\u884c\u4e4b\u540e\u5c31\u505c\u6b62\u8bf7\u6c42\u66f4\u591a\u884c\uff0c\u56e0\u6b64\u5b9e\u9645\u884c\u8ba1\u6570\u53ea\u6709 2\uff0c\u8fd0\u884c\u65f6\u95f4\u4e5f\u4f4e\u4e8e\u4ee3\u4ef7\u4f30\u8ba1\u6240\u6697\u793a\u7684\u6c34\u5e73\u3002\u8fd9\u5e76\u4e0d\u662f\u4f30\u8ba1\u9519\u8bef\uff0c\u53ea\u662f\u4f30\u8ba1\u503c\u4e0e\u771f\u5b9e\u503c\u7684\u663e\u793a\u65b9\u5f0f\u4e0d\u540c\u800c\u5df2\u3002\n   </p><p><a href=\"/zh/docs/19/using-explain.html#USING-EXPLAIN-CAVEATS\" rel=\"nofollow\">\u67e5\u770b\u5b8c\u6574\u4e2d\u6587\u624b\u518c\u4e0e\u4e0a\u4e0b\u6587</a>\u3002</p><p>\u672c\u9875\u5f00\u5934\u7684\u4e2d\u6587\u8bf4\u660e\u4e3a PG.CENTER \u5bf9\u7f16\u8f91\u8bf4\u660e\u7684\u7ffb\u8bd1\uff1b\u624b\u518c\u8282\u9009\u4fdd\u7559\u5bf9\u5e94\u7248\u672c\u4e2d\u6587\u6587\u6863\u539f\u6587\u3002\u6e90\u7801\u4fe1\u606f\u53ca\u624b\u518c\u793a\u4f8b\u4e0d\u4ee3\u8868\u91cd\u65b0\u8fdb\u884c\u8fc7\u8fd0\u884c\u6d4b\u8bd5\u3002</p>", "body_sha256": "cbcf1c5fa312fb7ef58c6df250e7b7122c787795c8d456f63b2bae83733d74e5", "content_hash": "57da19217f1646f9647cb8252463657ea23214405d047fb69a6f9ab840424c60", "source_database": "center", "source_revision": "af105fc8e960fc836a09fc2cd7f582b49fd17675d9d36631abe3a565bfd7d701"}, "tables_zh": [{"key": "explain-labels", "rows": [{"label": "BitmapOr", "identity": "BitmapOr"}], "title": "\u672c\u6784\u5efa\u4e2d\u7684 EXPLAIN \u6807\u7b7e", "columns": [{"key": "label", "label": "\u6587\u672c\u683c\u5f0f\u6807\u7b7e"}, {"key": "identity", "label": "\u7ed3\u6784\u5316\u8282\u70b9\u6807\u8bc6"}]}], "strategies": [], "description": ["\u5bf9\u5404\u5b50\u8ba1\u5212\u751f\u6210\u7684\u4f4d\u56fe\u6c42\u5e76\u96c6\u3002"], "sections_zh": [{"title": "EXPLAIN \u540d\u79f0\u4e0e\u5c5e\u6027", "paragraphs": ["\u7ed3\u6784\u5316\u683c\u5f0f\u4f7f\u7528\u4e0a\u8ff0 Node Type\u3002\u6587\u672c\u683c\u5f0f\u540d\u79f0\u8fd8\u53ef\u80fd\u5305\u542b\u64cd\u4f5c\u3001\u7b56\u7565\u3001\u8fde\u63a5\u7c7b\u578b\u3001\u626b\u63cf\u65b9\u5411\u6216\u805a\u5408\u9636\u6bb5\u5c5e\u6027\u3002", "\u6b64\u6e90\u7801\u8bb0\u5f55\u7684\u6587\u672c\u540d\u79f0\uff1aBitmapOr.", "\u5e76\u884c\u611f\u77e5\u4e0e\u5e76\u884c\u5b89\u5168\u662f\u4e0d\u540c\u7684\u8ba1\u5212\u5c5e\u6027\u3002\u5728\u5e76\u884c\u5de5\u4f5c\u8fdb\u7a0b\u5185\u8fd0\u884c\u7684\u8282\u70b9\u4e0d\u4e00\u5b9a\u662f\u5e76\u884c\u611f\u77e5\u8282\u70b9\u3002"]}, {"title": "\u5185\u5b58\u4e0e\u4e34\u65f6\u5b58\u50a8", "paragraphs": ["\u6b64\u8282\u70b9\u6309\u57fa\u4e8e work_mem \u7684\u9884\u7b97\u5206\u914d\u5143\u7ec4\u4f4d\u7f6e\u4f4d\u56fe\u3002\u4f4d\u56fe\u53ef\u4ee5\u4fdd\u7559\u9875\u7ea7\u6709\u635f\u6761\u76ee\uff0c\u800c\u4e0d\u8bb0\u5f55\u6bcf\u4e2a\u5143\u7ec4\u4f4d\u7f6e\uff0c\u56e0\u6b64\u4ecd\u53ef\u80fd\u9700\u8981\u5806\u91cd\u68c0\u3002"]}, {"title": "\u5e76\u884c\u6267\u884c\u4e0e\u8fd0\u884c\u4fe1\u606f\u91c7\u96c6", "paragraphs": ["\u4ee5\u4e0b\u6e90\u7801\u56de\u8c03\u53ef\u4ee5\u534f\u8c03\u6267\u884c\u6216\u6536\u96c6\u5de5\u4f5c\u8fdb\u7a0b\u7684\u6d4b\u91cf\u6570\u636e\u3002\u56de\u8c03\u5b58\u5728\u4e0d\u4ee3\u8868\u8be5\u8282\u70b9\u666e\u904d\u652f\u6301\u5171\u4eab\u5e76\u884c\u626b\u63cf\u6216\u5171\u4eab\u72b6\u6001\u3002", "\u6b64\u6784\u5efa\u7684\u56de\u8c03\uff1anone extracted from this node implementation."]}, {"title": "\u540c\u7248\u672c\u624b\u518c\u8bf4\u660e", "paragraphs": ["\u7531\u4e8e\u5b9e\u73b0\u4e0a\u7684\u9650\u5236\uff0cBitmapAnd \u548c BitmapOr \u8282\u70b9\u62a5\u544a\u7684\u5b9e\u9645\u884c\u6570\u59cb\u7ec8\u4e3a\u96f6\u3002"]}, {"title": "\u6267\u884c\u5668\u5b9e\u73b0\u8bf4\u660e", "paragraphs": ["\u8bf4\u660e\uff1aBitmapOr \u4e0d\u4f7f\u7528\u5de6\u53f3\u5b50\u6811\uff0c\u800c\u50cf Append \u4e00\u6837\u7ef4\u62a4\u5b50\u8ba1\u5212\u5217\u8868\u3002\u4e0d\u8fc7\u5176\u903b\u8f91\u6bd4 Append \u7b80\u5355\u5f97\u591a\uff0c\u56e0\u4e3a\u65e0\u9700\u5904\u7406\u6b63\u5411\u6216\u53cd\u5411\u6267\u884c\u3002", "\u5bf9\u6bcf\u4e2a\u5f85\u6267\u884c\u8ba1\u5212\u8c03\u7528 ExecInitNode\uff0c\u5e76\u5c06\u7ed3\u679c\u4fdd\u5b58\u5230 bitmapplanstates \u6570\u7ec4\u3002", "BitmapOr \u8ba1\u5212\u6ca1\u6709\u8868\u8fbe\u5f0f\u4e0a\u4e0b\u6587\uff0c\u56e0\u4e3a\u5b83\u4eec\u4ece\u4e0d\u8c03\u7528 ExecQual \u6216 ExecProject\uff0c\u4e5f\u4e0d\u9700\u8981\u5143\u7ec4\u69fd\u3002", "\u53ef\u5bf9 BitmapIndexScan \u5b50\u8282\u70b9\u4f5c\u7279\u6b8a\u5904\u7406\uff0c\u907f\u514d\u4e3a\u6bcf\u4e2a\u5b50\u8282\u70b9\u663e\u5f0f\u8c03\u7528 tbm_union\uff1a\u76f4\u63a5\u4e0b\u4f20\u5f53\u524d\u7ed3\u679c\u4f4d\u56fe\uff0c\u8ba9\u5b50\u8282\u70b9\u5c06\u7ed3\u679c\u6309\u4f4d OR \u5408\u5e76\u8fdb\u53bb\u3002", "ExecReScan \u4e0d\u77e5\u9053\u5f53\u524d\u8282\u70b9\u7684\u5b50\u8ba1\u5212\uff0c\u56e0\u6b64\u5fc5\u987b\u81ea\u884c\u901a\u77e5\u5b50\u8ba1\u5212\u54ea\u4e9b\u53c2\u6570\u53d1\u751f\u4e86\u53d8\u5316\u3002"]}, {"code": "case T_BitmapOr:\n\t\t\tpname = sname = \"BitmapOr\";\n\t\t\tbreak;", "title": "\u6838\u5fc3\u6e90\u7801\u4e2d\u7684 EXPLAIN \u6807\u8bc6"}], "localization": {"status": "complete", "sources": [], "language": "zh", "original_text": {"/versions/19/description/0": "Unions bitmaps produced by its child plans.", "/versions/19/facts/0/label": "Core node tag", "/versions/19/facts/1/label": "Structured EXPLAIN Node Type", "/versions/19/facts/2/label": "Inputs", "/versions/19/facts/2/value": "Bitmap-producing child plans", "/versions/19/facts/3/label": "Output", "/versions/19/facts/3/value": "Tuple-location bitmap, not a tuple stream", "/versions/19/facts/4/label": "Executor initializer", "/versions/19/facts/5/label": "Memory mechanism", "/versions/19/tables/0/title": "EXPLAIN labels in this source build", "/versions/19/related/1/label": "Using EXPLAIN", "/versions/19/related/2/label": "Parallel plans", "/versions/19/sections/0/title": "EXPLAIN names and attributes", "/versions/19/sections/1/title": "Memory and temporary storage", "/versions/19/sections/2/title": "Parallel execution and instrumentation", "/versions/19/sections/3/title": "Same-version manual discussion", "/versions/19/sections/4/title": "Executor implementation notes", "/versions/19/sections/5/title": "EXPLAIN identity in core source", "/versions/19/memory/description": "The node allocates a tuple-location bitmap using a work_mem-derived budget. A bitmap can retain page-level lossy entries instead of every tuple location; heap rechecks then remain necessary.", "/versions/19/sections/0/paragraphs/0": "Structured formats use the Node Type above. Text-format spellings can also include operation, strategy, join type, scan direction or aggregation-stage attributes.", "/versions/19/sections/0/paragraphs/1": "Text names recorded by this source: BitmapOr.", "/versions/19/sections/0/paragraphs/2": "Parallel-aware and parallel-safe are different plan properties. A node running inside a parallel worker is not necessarily a parallel-aware node.", "/versions/19/sections/1/paragraphs/0": "The node allocates a tuple-location bitmap using a work_mem-derived budget. A bitmap can retain page-level lossy entries instead of every tuple location; heap rechecks then remain necessary.", "/versions/19/sections/2/paragraphs/0": "The source callbacks below can coordinate execution or collect worker instrumentation. Their presence is not a blanket claim that this node supports a shared parallel scan or shared state.", "/versions/19/sections/2/paragraphs/1": "Callbacks in this build: none extracted from this node implementation.", "/versions/19/sections/3/paragraphs/0": "BitmapAnd and BitmapOr nodes always report their actual row counts as zero, due to implementation limitations.", "/versions/19/sections/4/paragraphs/0": "NOTES BitmapOr nodes don't make use of their left and right subtrees, rather they maintain a list of subplans, much like Append nodes. The logic is much simpler than Append, however, since we needn't cope with forward/backward execution.", "/versions/19/sections/4/paragraphs/1": "call ExecInitNode on each of the plans to be executed and save the results into the array \"bitmapplanstates\".", "/versions/19/sections/4/paragraphs/2": "BitmapOr plans don't have expression contexts because they never call ExecQual or ExecProject. They don't need any tuple slots either.", "/versions/19/sections/4/paragraphs/3": "We can special-case BitmapIndexScan children to avoid an explicit tbm_union step for each child: just pass down the current result bitmap and let the child OR directly into it.", "/versions/19/sections/4/paragraphs/4": "ExecReScan doesn't know about my subplans, so I have to do changed-parameter signaling myself.", "/versions/19/tables/0/columns/0/label": "Text-format label", "/versions/19/tables/0/columns/1/label": "Structured node identity"}, "fallback_fields": [], "source_language": "en", "original_snapshot_sha256": "45f6044deb0018ef45cefd36063994778b5f09c3f2961c5b86c163860a85f222", "canonical_center_text_hash": "57da19217f1646f9647cb8252463657ea23214405d047fb69a6f9ab840424c60"}, "evidence_kind": "source and documentation", "explain_names": ["BitmapOr"], "partial_modes": [], "description_zh": "\u5bf9\u5404\u5b50\u8ba1\u5212\u751f\u6210\u7684\u4f4d\u56fe\u6c42\u5e76\u96c6\u3002", "comparison_data": {"node_tag": "T_BitmapOr", "strategies": [], "text_names": ["BitmapOr"], "initializer": "ExecInitBitmapOr", "partial_modes": [], "memory_mechanism": "bitmap-lossification", "parallel_callbacks": []}, "comparison_hash": "c0ca503a6029c37ec720213dcdc3094997eb194d4920da68f94a7420d3e8f1d2", "manual_language": "zh", "explain_prefixes": ["Parallel", "Async"], "runtime_verified": false, "source_inventory": {"explain": "src/backend/commands/explain.c", "executor": "src/backend/executor/execProcnode.c", "implementation": "src/backend/executor/nodeBitmapOr.c"}, "parallel_callbacks": [], "description_zh_html": "<p>\u5bf9\u5404\u5b50\u8ba1\u5212\u751f\u6210\u7684\u4f4d\u56fe\u6c42\u5e76\u96c6\u3002</p><p>\u6838\u5fc3\u8282\u70b9\u6807\u8bc6\uff1a<code>T_BitmapOr</code>\uff1bEXPLAIN \u540d\u79f0\uff1a<code>BitmapOr</code>\u3002</p><p>\u672c\u7248\u672c\u6e90\u7801\u4e2d\u7684\u5e76\u884c\u6267\u884c\u6216\u89c2\u6d4b\u56de\u8c03\uff1a\u8be5\u8282\u70b9\u5b9e\u73b0\u4e2d\u672a\u63d0\u53d6\u5230\u6b64\u7c7b\u56de\u8c03\u3002\u56de\u8c03\u7684\u5b58\u5728\u4e0d\u8868\u793a\u8be5\u8282\u70b9\u5fc5\u7136\u652f\u6301\u5171\u4eab\u5e76\u884c\u626b\u63cf\uff1b\u5728\u5e76\u884c\u5de5\u4f5c\u8fdb\u7a0b\u4e2d\u6267\u884c\u4e5f\u4e0d\u7b49\u4e8e\u5177\u6709\u5e76\u884c\u611f\u77e5\u80fd\u529b\u3002</p><h3>\u540c\u7248\u672c\u4e2d\u6587\u624b\u518c\u8282\u9009</h3><p>\n<code>EXPLAIN ANALYZE</code> \u6d4b\u5f97\u7684\u8fd0\u884c\u65f6\u95f4\uff0c\u53ef\u80fd\u4ee5\u4e24\u79cd\u91cd\u8981\u65b9\u5f0f\u504f\u79bb\u540c\u4e00\u67e5\u8be2\u7684\u6b63\u5e38\u6267\u884c\u65f6\u95f4\u3002\u7b2c\u4e00\uff0c\u7531\u4e8e\u4e0d\u4f1a\u5411\u5ba2\u6237\u7aef\u4f20\u9012\u4efb\u4f55\u8f93\u51fa\u884c\uff0c\u56e0\u6b64\u7f51\u7edc\u4f20\u8f93\u5f00\u9500\u4e0d\u4f1a\u88ab\u8ba1\u5165\u3002\u9664\u975e\u6307\u5b9a\u4e86 <code>SERIALIZE</code>\uff0cI/O \u8f6c\u6362\u5f00\u9500\u540c\u6837\u4e5f\u4e0d\u4f1a\u88ab\u8ba1\u5165\u3002\u7b2c\u4e8c\uff0c<code>EXPLAIN ANALYZE</code> \u9644\u52a0\u7684\u6d4b\u91cf\u5f00\u9500\u672c\u8eab\u53ef\u80fd\u76f8\u5f53\u53ef\u89c2\uff0c\u5c24\u5176\u662f\u5728\u64cd\u4f5c\u7cfb\u7edf\u8c03\u7528 <code>gettimeofday()</code> \u8f83\u6162\u7684\u673a\u5668\u4e0a\u3002\u53ef\u4ee5\u4f7f\u7528 <a href=\"/zh/docs/19/pgtesttiming.html\" rel=\"nofollow\"><span><span>pg_test_timing</span></span></a> \u5de5\u5177\u6765\u6d4b\u91cf\u7cfb\u7edf\u4e0a\u7684\u8ba1\u65f6\u5f00\u9500\u3002\n   </p><p>\n    \u4e0d\u5e94\u5c06 <code>EXPLAIN</code> \u7ed3\u679c\u5916\u63a8\u5230\u4e0e\u5b9e\u9645\u6d4b\u8bd5\u573a\u666f\u5dee\u5f02\u5f88\u5927\u7684\u60c5\u51b5\u3002\u4f8b\u5982\uff0c\u5728\u4e00\u4e2a\u5f88\u5c0f\u7684\u8868\u4e0a\u5f97\u5230\u7684\u7ed3\u679c\uff0c\u4e0d\u80fd\u5047\u5b9a\u4e5f\u9002\u7528\u4e8e\u5927\u578b\u8868\u3002\u89c4\u5212\u5668\u7684\u4ee3\u4ef7\u4f30\u8ba1\u4e0d\u662f\u7ebf\u6027\u7684\uff0c\u56e0\u6b64\u5b83\u53ef\u80fd\u4f1a\u4e3a\u66f4\u5927\u6216\u66f4\u5c0f\u7684\u8868\u9009\u62e9\u4e0d\u540c\u7684\u8ba1\u5212\u3002\u4e00\u4e2a\u6781\u7aef\u793a\u4f8b\u662f\uff1a\u5bf9\u4e8e\u53ea\u5360\u7528\u4e00\u4e2a\u78c1\u76d8\u9875\u7684\u8868\uff0c\u65e0\u8bba\u7d22\u5f15\u662f\u5426\u53ef\u7528\uff0c\u51e0\u4e4e\u603b\u4f1a\u5f97\u5230\u987a\u5e8f\u626b\u63cf\u8ba1\u5212\u3002\u89c4\u5212\u5668\u8ba4\u8bc6\u5230\uff0c\u65e0\u8bba\u5982\u4f55\u5904\u7406\u8be5\u8868\u90fd\u9700\u8981\u4e00\u6b21\u78c1\u76d8\u9875\u8bfb\u53d6\uff0c\u56e0\u6b64\u518d\u989d\u5916\u8bfb\u53d6\u9875\u9762\u53bb\u67e5\u770b\u7d22\u5f15\u5e76\u6ca1\u6709\u4ef7\u503c\u3002\uff08\u524d\u9762\u7684 <code>polygon_tbl</code> \u793a\u4f8b\u5df2\u7ecf\u5c55\u793a\u8fc7\u8fd9\u79cd\u60c5\u51b5\u3002\uff09\n   </p><p>\n    \u5728\u67d0\u4e9b\u60c5\u51b5\u4e0b\uff0c\u5b9e\u9645\u503c\u548c\u4f30\u8ba1\u503c\u4e0d\u4f1a\u5f88\u597d\u5730\u5bf9\u5e94\uff0c\u4f46\u8fd9\u5e76\u4e0d\u8868\u793a\u51fa\u73b0\u4e86\u95ee\u9898\u3002\u5176\u4e2d\u4e00\u79cd\u60c5\u51b5\u662f\uff0c\u8ba1\u5212\u8282\u70b9\u7684\u6267\u884c\u4f1a\u88ab <code>LIMIT</code> \u6216\u7c7b\u4f3c\u6548\u679c\u63d0\u524d\u622a\u65ad\u3002\u4f8b\u5982\uff0c\u5728\u524d\u9762\u7528\u8fc7\u7684 <code>LIMIT</code> \u67e5\u8be2\u4e2d\uff1a\n\n</p><p>\n\n    Index Scan \u8282\u70b9\u7684\u4f30\u8ba1\u4ee3\u4ef7\u548c\u884c\u8ba1\u6570\u663e\u793a\u5f97\u50cf\u662f\u5b83\u4f1a\u8fd0\u884c\u5230\u7ed3\u675f\u4e00\u6837\u3002\u4f46\u5b9e\u9645\u4e0a\uff0cLimit \u8282\u70b9\u5728\u62ff\u5230\u4e24\u884c\u4e4b\u540e\u5c31\u505c\u6b62\u8bf7\u6c42\u66f4\u591a\u884c\uff0c\u56e0\u6b64\u5b9e\u9645\u884c\u8ba1\u6570\u53ea\u6709 2\uff0c\u8fd0\u884c\u65f6\u95f4\u4e5f\u4f4e\u4e8e\u4ee3\u4ef7\u4f30\u8ba1\u6240\u6697\u793a\u7684\u6c34\u5e73\u3002\u8fd9\u5e76\u4e0d\u662f\u4f30\u8ba1\u9519\u8bef\uff0c\u53ea\u662f\u4f30\u8ba1\u503c\u4e0e\u771f\u5b9e\u503c\u7684\u663e\u793a\u65b9\u5f0f\u4e0d\u540c\u800c\u5df2\u3002\n   </p><p><a href=\"/zh/docs/19/using-explain.html#USING-EXPLAIN-CAVEATS\" rel=\"nofollow\">\u67e5\u770b\u5b8c\u6574\u4e2d\u6587\u624b\u518c\u4e0e\u4e0a\u4e0b\u6587</a>\u3002</p><p>\u672c\u9875\u5f00\u5934\u7684\u4e2d\u6587\u8bf4\u660e\u4e3a PG.CENTER \u5bf9\u7f16\u8f91\u8bf4\u660e\u7684\u7ffb\u8bd1\uff1b\u624b\u518c\u8282\u9009\u4fdd\u7559\u5bf9\u5e94\u7248\u672c\u4e2d\u6587\u6587\u6863\u539f\u6587\u3002\u6e90\u7801\u4fe1\u606f\u53ca\u624b\u518c\u793a\u4f8b\u4e0d\u4ee3\u8868\u91cd\u65b0\u8fdb\u884c\u8fc7\u8fd0\u884c\u6d4b\u8bd5\u3002</p>", "source_revalidation": {"kind": "static-same-version-source-and-manual-replay", "audit": "wiki-audit-20261023", "runtime_rerun": false, "compared_fields": "entity membership and source-derived facts; presentation markup normalized", "source_revision": "af105fc8e960fc836a09fc2cd7f582b49fd17675d9d36631abe3a565bfd7d701", "previous_source_revision": "83157ee9c599d03b2f7a3d73ef3a56ec24e0e79cc2b3501a64d1364f56398c86"}}, "20": {"facts": [{"label": "\u6838\u5fc3\u8282\u70b9\u6807\u7b7e", "value": "T_BitmapOr"}, {"label": "\u7ed3\u6784\u5316 EXPLAIN \u8282\u70b9\u7c7b\u578b", "value": "BitmapOr"}, {"label": "\u8f93\u5165", "value": "\u4ea7\u751f\u4f4d\u56fe\u7684\u5b50\u8ba1\u5212"}, {"label": "\u8f93\u51fa", "value": "\u5143\u7ec4\u4f4d\u7f6e\u4f4d\u56fe\uff0c\u4e0d\u662f\u5143\u7ec4\u6d41"}, {"label": "\u6267\u884c\u5668\u521d\u59cb\u5316\u51fd\u6570", "value": "ExecInitBitmapOr"}, {"label": "\u5185\u5b58\u673a\u5236", "value": "bitmap-lossification"}], "memory": {"evidence": [{"url": "https://ftp.postgresql.org/pub/snapshot/dev/postgresql-snapshot.tar.bz2", "path": "src/backend/executor/nodeBitmapOr.c", "label": "src/backend/executor/nodeBitmapOr.c", "sha256": "4534aeb178af033afae2e3fbccd9318785fb6869e553e697b0bf73e1fe5b3798", "archive_sha256": "4d3346909b201ac1648232cf290462a7070c119326f56196f1f0253ed80fae41"}, {"url": "https://ftp.postgresql.org/pub/snapshot/dev/postgresql-snapshot.tar.bz2", "path": "src/backend/nodes/tidbitmap.c", "label": "src/backend/nodes/tidbitmap.c", "sha256": "3394cc4f8c9e397b78f6b0d99fba931fd809450ec7b5ff051798ecbd0dcf3b32", "archive_sha256": "4d3346909b201ac1648232cf290462a7070c119326f56196f1f0253ed80fae41"}], "mechanism": "bitmap-lossification", "description": "The node allocates a tuple-location bitmap using a work_mem-derived budget. A bitmap can retain page-level lossy entries instead of every tuple location; heap rechecks then remain necessary.", "source_notes": []}, "tables": [{"key": "explain-labels", "rows": [{"label": "BitmapOr", "identity": "BitmapOr"}], "title": "\u672c\u6784\u5efa\u4e2d\u7684 EXPLAIN \u6807\u7b7e", "columns": [{"key": "label", "label": "\u6587\u672c\u683c\u5f0f\u6807\u7b7e"}, {"key": "identity", "label": "\u7ed3\u6784\u5316\u8282\u70b9\u6807\u8bc6"}]}], "related": [{"url": "/wiki/sql/explain/?v=20", "label": "EXPLAIN"}, {"url": "/docs/devel/using-explain.html", "label": "\u4f7f\u7528 EXPLAIN"}, {"url": "/docs/devel/parallel-plans.html", "label": "\u5e76\u884c\u8ba1\u5212"}, {"url": "/wiki/guc/work_mem/?v=20", "label": "work_mem"}], "release": {"ref": "PostgreSQL 20devel source archive", "label": "20devel", "major": "20", "channel": "devel", "revision": "49c73aa4c9cacef8ca979276a28ac416c08e9e54c9baee4ae5fd116a35fa13ac", "source_url": "https://ftp.postgresql.org/pub/snapshot/dev/postgresql-snapshot.tar.bz2", "source_snapshot_utc": ""}, "sources": [{"url": "https://ftp.postgresql.org/pub/snapshot/dev/postgresql-snapshot.tar.bz2", "line": 1430, "path": "src/backend/commands/explain.c", "label": "src/backend/commands/explain.c:1430", "sha256": "f82f238e2e6e249e10daf2e257728494ec10de1695fcf05feaadfd7f6bf78600", "archive_sha256": "49c73aa4c9cacef8ca979276a28ac416c08e9e54c9baee4ae5fd116a35fa13ac"}, {"url": "https://ftp.postgresql.org/pub/snapshot/dev/postgresql-snapshot.tar.bz2", "line": 201, "path": "src/backend/executor/execProcnode.c", "label": "src/backend/executor/execProcnode.c:201", "sha256": "5e39b2037bed672da55104229ecc32da5abde44c26bcad01479edcfa044d09ed", "archive_sha256": "49c73aa4c9cacef8ca979276a28ac416c08e9e54c9baee4ae5fd116a35fa13ac"}, {"url": "https://ftp.postgresql.org/pub/snapshot/dev/postgresql-snapshot.tar.bz2", "path": "src/backend/executor/nodeBitmapOr.c", "label": "src/backend/executor/nodeBitmapOr.c", "sha256": "4534aeb178af033afae2e3fbccd9318785fb6869e553e697b0bf73e1fe5b3798", "archive_sha256": "49c73aa4c9cacef8ca979276a28ac416c08e9e54c9baee4ae5fd116a35fa13ac"}, {"url": "https://ftp.postgresql.org/pub/snapshot/dev/postgresql-snapshot.tar.bz2", "path": "src/include/nodes/plannodes.h", "label": "src/include/nodes/plannodes.h", "sha256": "aa3c27b465209c0ecd1f5e0186d39110a75ed7aafb9a196d483fccb5fc641c6b", "archive_sha256": "49c73aa4c9cacef8ca979276a28ac416c08e9e54c9baee4ae5fd116a35fa13ac"}, {"url": "https://ftp.postgresql.org/pub/snapshot/dev/postgresql-snapshot.tar.bz2", "path": "src/backend/nodes/tidbitmap.c", "label": "src/backend/nodes/tidbitmap.c", "sha256": "3394cc4f8c9e397b78f6b0d99fba931fd809450ec7b5ff051798ecbd0dcf3b32", "archive_sha256": "49c73aa4c9cacef8ca979276a28ac416c08e9e54c9baee4ae5fd116a35fa13ac"}, {"url": "/docs/devel/using-explain.html#USING-EXPLAIN-CAVEATS", "path": "using-explain.html", "label": "PostgreSQL 20devel \u00b7 using-explain", "sha256": "afce066fbaecd0b7ce78ba30d776557731e46ad057c9dda332754a90e5fe59ac"}], "zh_from": {"kind": "same-version-chinese-manual-with-authored-translation-of-reviewed-guidance", "manual": {"url": "/zh/docs/devel/using-explain.html#USING-EXPLAIN-CAVEATS", "anchor": "USING-EXPLAIN-CAVEATS", "locale": "zh-Hans", "version": "20", "build_id": 111, "page_key": "using-explain.html", "extraction": "concept-introduction", "source_hash": "436517563e51b6d851ef143e70d01f5f68fe0a01e00a0d507e7bd79d7570aa25", "fragment_sha256": "dba9d16f9a93a7d8919a8787f6004c8091f38795fc92b7ccfce3200887ce14b5", "source_revision": "sha256:49c73aa4c9cacef8ca979276a28ac416c08e9e54c9baee4ae5fd116a35fa13ac", "translation_revision": "git:b1b500221dbe5437cfca004d6b04d3f6e422765d;html-sha256:98c980963b401d40bd50df72b909e7523e3148b8fdb48edd897de2efb67e5235", "translated_from_revision": "sha256:49c73aa4c9cacef8ca979276a28ac416c08e9e54c9baee4ae5fd116a35fa13ac"}, "body_sha256": "7035148892f19ecacee5a084ae3214c02aba1f0666dd39d30c99348e53fdced5", "runtime_rerun": false, "authored_translation": "authored-translation-of-reviewed-guidance", "source_facts_revision": "49c73aa4c9cacef8ca979276a28ac416c08e9e54c9baee4ae5fd116a35fa13ac"}, "facts_zh": [{"label": "\u6838\u5fc3\u8282\u70b9\u6807\u7b7e", "value": "T_BitmapOr"}, {"label": "\u7ed3\u6784\u5316 EXPLAIN \u8282\u70b9\u7c7b\u578b", "value": "BitmapOr"}, {"label": "\u8f93\u5165", "value": "\u4ea7\u751f\u4f4d\u56fe\u7684\u5b50\u8ba1\u5212"}, {"label": "\u8f93\u51fa", "value": "\u5143\u7ec4\u4f4d\u7f6e\u4f4d\u56fe\uff0c\u4e0d\u662f\u5143\u7ec4\u6d41"}, {"label": "\u6267\u884c\u5668\u521d\u59cb\u5316\u51fd\u6570", "value": "ExecInitBitmapOr"}, {"label": "\u5185\u5b58\u673a\u5236", "value": "bitmap-lossification"}], "node_tag": "T_BitmapOr", "sections": [{"title": "EXPLAIN \u540d\u79f0\u4e0e\u5c5e\u6027", "paragraphs": ["\u7ed3\u6784\u5316\u683c\u5f0f\u4f7f\u7528\u4e0a\u8ff0 Node Type\u3002\u6587\u672c\u683c\u5f0f\u540d\u79f0\u8fd8\u53ef\u80fd\u5305\u542b\u64cd\u4f5c\u3001\u7b56\u7565\u3001\u8fde\u63a5\u7c7b\u578b\u3001\u626b\u63cf\u65b9\u5411\u6216\u805a\u5408\u9636\u6bb5\u5c5e\u6027\u3002", "\u6b64\u6e90\u7801\u8bb0\u5f55\u7684\u6587\u672c\u540d\u79f0\uff1aBitmapOr.", "\u5e76\u884c\u611f\u77e5\u4e0e\u5e76\u884c\u5b89\u5168\u662f\u4e0d\u540c\u7684\u8ba1\u5212\u5c5e\u6027\u3002\u5728\u5e76\u884c\u5de5\u4f5c\u8fdb\u7a0b\u5185\u8fd0\u884c\u7684\u8282\u70b9\u4e0d\u4e00\u5b9a\u662f\u5e76\u884c\u611f\u77e5\u8282\u70b9\u3002"]}, {"title": "\u5185\u5b58\u4e0e\u4e34\u65f6\u5b58\u50a8", "paragraphs": ["\u6b64\u8282\u70b9\u6309\u57fa\u4e8e work_mem \u7684\u9884\u7b97\u5206\u914d\u5143\u7ec4\u4f4d\u7f6e\u4f4d\u56fe\u3002\u4f4d\u56fe\u53ef\u4ee5\u4fdd\u7559\u9875\u7ea7\u6709\u635f\u6761\u76ee\uff0c\u800c\u4e0d\u8bb0\u5f55\u6bcf\u4e2a\u5143\u7ec4\u4f4d\u7f6e\uff0c\u56e0\u6b64\u4ecd\u53ef\u80fd\u9700\u8981\u5806\u91cd\u68c0\u3002"]}, {"title": "\u5e76\u884c\u6267\u884c\u4e0e\u8fd0\u884c\u4fe1\u606f\u91c7\u96c6", "paragraphs": ["\u4ee5\u4e0b\u6e90\u7801\u56de\u8c03\u53ef\u4ee5\u534f\u8c03\u6267\u884c\u6216\u6536\u96c6\u5de5\u4f5c\u8fdb\u7a0b\u7684\u6d4b\u91cf\u6570\u636e\u3002\u56de\u8c03\u5b58\u5728\u4e0d\u4ee3\u8868\u8be5\u8282\u70b9\u666e\u904d\u652f\u6301\u5171\u4eab\u5e76\u884c\u626b\u63cf\u6216\u5171\u4eab\u72b6\u6001\u3002", "\u6b64\u6784\u5efa\u7684\u56de\u8c03\uff1anone extracted from this node implementation."]}, {"title": "\u540c\u7248\u672c\u624b\u518c\u8bf4\u660e", "paragraphs": ["\u7531\u4e8e\u5b9e\u73b0\u4e0a\u7684\u9650\u5236\uff0cBitmapAnd \u548c BitmapOr \u8282\u70b9\u62a5\u544a\u7684\u5b9e\u9645\u884c\u6570\u59cb\u7ec8\u4e3a\u96f6\u3002"]}, {"title": "\u6267\u884c\u5668\u5b9e\u73b0\u8bf4\u660e", "paragraphs": ["\u8bf4\u660e\uff1aBitmapOr \u4e0d\u4f7f\u7528\u5de6\u53f3\u5b50\u6811\uff0c\u800c\u50cf Append \u4e00\u6837\u7ef4\u62a4\u5b50\u8ba1\u5212\u5217\u8868\u3002\u4e0d\u8fc7\u5176\u903b\u8f91\u6bd4 Append \u7b80\u5355\u5f97\u591a\uff0c\u56e0\u4e3a\u65e0\u9700\u5904\u7406\u6b63\u5411\u6216\u53cd\u5411\u6267\u884c\u3002", "\u5bf9\u6bcf\u4e2a\u5f85\u6267\u884c\u8ba1\u5212\u8c03\u7528 ExecInitNode\uff0c\u5e76\u5c06\u7ed3\u679c\u4fdd\u5b58\u5230 bitmapplanstates \u6570\u7ec4\u3002", "BitmapOr \u8ba1\u5212\u6ca1\u6709\u8868\u8fbe\u5f0f\u4e0a\u4e0b\u6587\uff0c\u56e0\u4e3a\u5b83\u4eec\u4ece\u4e0d\u8c03\u7528 ExecQual \u6216 ExecProject\uff0c\u4e5f\u4e0d\u9700\u8981\u5143\u7ec4\u69fd\u3002", "\u53ef\u5bf9 BitmapIndexScan \u5b50\u8282\u70b9\u4f5c\u7279\u6b8a\u5904\u7406\uff0c\u907f\u514d\u4e3a\u6bcf\u4e2a\u5b50\u8282\u70b9\u663e\u5f0f\u8c03\u7528 tbm_union\uff1a\u76f4\u63a5\u4e0b\u4f20\u5f53\u524d\u7ed3\u679c\u4f4d\u56fe\uff0c\u8ba9\u5b50\u8282\u70b9\u5c06\u7ed3\u679c\u6309\u4f4d OR \u5408\u5e76\u8fdb\u53bb\u3002", "ExecReScan \u4e0d\u77e5\u9053\u5f53\u524d\u8282\u70b9\u7684\u5b50\u8ba1\u5212\uff0c\u56e0\u6b64\u5fc5\u987b\u81ea\u884c\u901a\u77e5\u5b50\u8ba1\u5212\u54ea\u4e9b\u53c2\u6570\u53d1\u751f\u4e86\u53d8\u5316\u3002"]}, {"code": "case T_BitmapOr:\n\t\t\tpname = sname = \"BitmapOr\";\n\t\t\tbreak;", "title": "\u6838\u5fc3\u6e90\u7801\u4e2d\u7684 EXPLAIN \u6807\u8bc6"}], "center_zh": {"title": "BitmapOr", "locale": "zh-Hans", "source": {"key": "bitmapor", "locale": "zh-Hans", "version": "20", "text_hash": "c78f61d69267940ef957d4f63a855ea00bc519149f009cfed41f462c82cf8efa", "collection": "plan", "dataset_hash": "7c31b524dfe136022d39a6ae8dcfac6b3bbd5f8fdaf422536599981252aff0c9", "source_database": "center", "source_revision": "49c73aa4c9cacef8ca979276a28ac416c08e9e54c9baee4ae5fd116a35fa13ac"}, "payload": {"facts": [{"label": "\u6838\u5fc3\u8282\u70b9\u6807\u7b7e", "value": "T_BitmapOr"}, {"label": "\u7ed3\u6784\u5316 EXPLAIN \u8282\u70b9\u7c7b\u578b", "value": "BitmapOr"}, {"label": "\u8f93\u5165", "value": "\u4ea7\u751f\u4f4d\u56fe\u7684\u5b50\u8ba1\u5212"}, {"label": "\u8f93\u51fa", "value": "\u5143\u7ec4\u4f4d\u7f6e\u4f4d\u56fe\uff0c\u4e0d\u662f\u5143\u7ec4\u6d41"}, {"label": "\u6267\u884c\u5668\u521d\u59cb\u5316\u51fd\u6570", "value": "ExecInitBitmapOr"}, {"label": "\u5185\u5b58\u673a\u5236", "value": "bitmap-lossification"}], "tables": [{"key": "explain-labels", "rows": [{"label": "BitmapOr", "identity": "BitmapOr"}], "title": "\u672c\u6784\u5efa\u4e2d\u7684 EXPLAIN \u6807\u7b7e", "columns": [{"key": "label", "label": "\u6587\u672c\u683c\u5f0f\u6807\u7b7e"}, {"key": "identity", "label": "\u7ed3\u6784\u5316\u8282\u70b9\u6807\u8bc6"}]}], "zh_from": {"kind": "same-version-chinese-manual-with-authored-translation-of-reviewed-guidance", "manual": {"url": "/zh/docs/devel/using-explain.html#USING-EXPLAIN-CAVEATS", "anchor": "USING-EXPLAIN-CAVEATS", "locale": "zh-Hans", "version": "20", "build_id": 111, "page_key": "using-explain.html", "extraction": "concept-introduction", "source_hash": "436517563e51b6d851ef143e70d01f5f68fe0a01e00a0d507e7bd79d7570aa25", "fragment_sha256": "dba9d16f9a93a7d8919a8787f6004c8091f38795fc92b7ccfce3200887ce14b5", "source_revision": "sha256:49c73aa4c9cacef8ca979276a28ac416c08e9e54c9baee4ae5fd116a35fa13ac", "translation_revision": "git:b1b500221dbe5437cfca004d6b04d3f6e422765d;html-sha256:98c980963b401d40bd50df72b909e7523e3148b8fdb48edd897de2efb67e5235", "translated_from_revision": "sha256:49c73aa4c9cacef8ca979276a28ac416c08e9e54c9baee4ae5fd116a35fa13ac"}, "body_sha256": "7035148892f19ecacee5a084ae3214c02aba1f0666dd39d30c99348e53fdced5", "runtime_rerun": false, "authored_translation": "authored-translation-of-reviewed-guidance", "source_facts_revision": "49c73aa4c9cacef8ca979276a28ac416c08e9e54c9baee4ae5fd116a35fa13ac"}, "sections": [{"title": "EXPLAIN \u540d\u79f0\u4e0e\u5c5e\u6027", "paragraphs": ["\u7ed3\u6784\u5316\u683c\u5f0f\u4f7f\u7528\u4e0a\u8ff0 Node Type\u3002\u6587\u672c\u683c\u5f0f\u540d\u79f0\u8fd8\u53ef\u80fd\u5305\u542b\u64cd\u4f5c\u3001\u7b56\u7565\u3001\u8fde\u63a5\u7c7b\u578b\u3001\u626b\u63cf\u65b9\u5411\u6216\u805a\u5408\u9636\u6bb5\u5c5e\u6027\u3002", "\u6b64\u6e90\u7801\u8bb0\u5f55\u7684\u6587\u672c\u540d\u79f0\uff1aBitmapOr.", "\u5e76\u884c\u611f\u77e5\u4e0e\u5e76\u884c\u5b89\u5168\u662f\u4e0d\u540c\u7684\u8ba1\u5212\u5c5e\u6027\u3002\u5728\u5e76\u884c\u5de5\u4f5c\u8fdb\u7a0b\u5185\u8fd0\u884c\u7684\u8282\u70b9\u4e0d\u4e00\u5b9a\u662f\u5e76\u884c\u611f\u77e5\u8282\u70b9\u3002"]}, {"title": "\u5185\u5b58\u4e0e\u4e34\u65f6\u5b58\u50a8", "paragraphs": ["\u6b64\u8282\u70b9\u6309\u57fa\u4e8e work_mem \u7684\u9884\u7b97\u5206\u914d\u5143\u7ec4\u4f4d\u7f6e\u4f4d\u56fe\u3002\u4f4d\u56fe\u53ef\u4ee5\u4fdd\u7559\u9875\u7ea7\u6709\u635f\u6761\u76ee\uff0c\u800c\u4e0d\u8bb0\u5f55\u6bcf\u4e2a\u5143\u7ec4\u4f4d\u7f6e\uff0c\u56e0\u6b64\u4ecd\u53ef\u80fd\u9700\u8981\u5806\u91cd\u68c0\u3002"]}, {"title": "\u5e76\u884c\u6267\u884c\u4e0e\u8fd0\u884c\u4fe1\u606f\u91c7\u96c6", "paragraphs": ["\u4ee5\u4e0b\u6e90\u7801\u56de\u8c03\u53ef\u4ee5\u534f\u8c03\u6267\u884c\u6216\u6536\u96c6\u5de5\u4f5c\u8fdb\u7a0b\u7684\u6d4b\u91cf\u6570\u636e\u3002\u56de\u8c03\u5b58\u5728\u4e0d\u4ee3\u8868\u8be5\u8282\u70b9\u666e\u904d\u652f\u6301\u5171\u4eab\u5e76\u884c\u626b\u63cf\u6216\u5171\u4eab\u72b6\u6001\u3002", "\u6b64\u6784\u5efa\u7684\u56de\u8c03\uff1anone extracted from this node implementation."]}, {"title": "\u540c\u7248\u672c\u624b\u518c\u8bf4\u660e", "paragraphs": ["\u7531\u4e8e\u5b9e\u73b0\u4e0a\u7684\u9650\u5236\uff0cBitmapAnd \u548c BitmapOr \u8282\u70b9\u62a5\u544a\u7684\u5b9e\u9645\u884c\u6570\u59cb\u7ec8\u4e3a\u96f6\u3002"]}, {"title": "\u6267\u884c\u5668\u5b9e\u73b0\u8bf4\u660e", "paragraphs": ["\u8bf4\u660e\uff1aBitmapOr \u4e0d\u4f7f\u7528\u5de6\u53f3\u5b50\u6811\uff0c\u800c\u50cf Append \u4e00\u6837\u7ef4\u62a4\u5b50\u8ba1\u5212\u5217\u8868\u3002\u4e0d\u8fc7\u5176\u903b\u8f91\u6bd4 Append \u7b80\u5355\u5f97\u591a\uff0c\u56e0\u4e3a\u65e0\u9700\u5904\u7406\u6b63\u5411\u6216\u53cd\u5411\u6267\u884c\u3002", "\u5bf9\u6bcf\u4e2a\u5f85\u6267\u884c\u8ba1\u5212\u8c03\u7528 ExecInitNode\uff0c\u5e76\u5c06\u7ed3\u679c\u4fdd\u5b58\u5230 bitmapplanstates \u6570\u7ec4\u3002", "BitmapOr \u8ba1\u5212\u6ca1\u6709\u8868\u8fbe\u5f0f\u4e0a\u4e0b\u6587\uff0c\u56e0\u4e3a\u5b83\u4eec\u4ece\u4e0d\u8c03\u7528 ExecQual \u6216 ExecProject\uff0c\u4e5f\u4e0d\u9700\u8981\u5143\u7ec4\u69fd\u3002", "\u53ef\u5bf9 BitmapIndexScan \u5b50\u8282\u70b9\u4f5c\u7279\u6b8a\u5904\u7406\uff0c\u907f\u514d\u4e3a\u6bcf\u4e2a\u5b50\u8282\u70b9\u663e\u5f0f\u8c03\u7528 tbm_union\uff1a\u76f4\u63a5\u4e0b\u4f20\u5f53\u524d\u7ed3\u679c\u4f4d\u56fe\uff0c\u8ba9\u5b50\u8282\u70b9\u5c06\u7ed3\u679c\u6309\u4f4d OR \u5408\u5e76\u8fdb\u53bb\u3002", "ExecReScan \u4e0d\u77e5\u9053\u5f53\u524d\u8282\u70b9\u7684\u5b50\u8ba1\u5212\uff0c\u56e0\u6b64\u5fc5\u987b\u81ea\u884c\u901a\u77e5\u5b50\u8ba1\u5212\u54ea\u4e9b\u53c2\u6570\u53d1\u751f\u4e86\u53d8\u5316\u3002"]}, {"code": "case T_BitmapOr:\n\t\t\tpname = sname = \"BitmapOr\";\n\t\t\tbreak;", "title": "\u6838\u5fc3\u6e90\u7801\u4e2d\u7684 EXPLAIN \u6807\u8bc6"}], "description_zh": "\u5bf9\u5404\u5b50\u8ba1\u5212\u751f\u6210\u7684\u4f4d\u56fe\u6c42\u5e76\u96c6\u3002", "description_zh_html": "<p>\u5bf9\u5404\u5b50\u8ba1\u5212\u751f\u6210\u7684\u4f4d\u56fe\u6c42\u5e76\u96c6\u3002</p><p>\u6838\u5fc3\u8282\u70b9\u6807\u8bc6\uff1a<code>T_BitmapOr</code>\uff1bEXPLAIN \u540d\u79f0\uff1a<code>BitmapOr</code>\u3002</p><p>\u672c\u7248\u672c\u6e90\u7801\u4e2d\u7684\u5e76\u884c\u6267\u884c\u6216\u89c2\u6d4b\u56de\u8c03\uff1a\u8be5\u8282\u70b9\u5b9e\u73b0\u4e2d\u672a\u63d0\u53d6\u5230\u6b64\u7c7b\u56de\u8c03\u3002\u56de\u8c03\u7684\u5b58\u5728\u4e0d\u8868\u793a\u8be5\u8282\u70b9\u5fc5\u7136\u652f\u6301\u5171\u4eab\u5e76\u884c\u626b\u63cf\uff1b\u5728\u5e76\u884c\u5de5\u4f5c\u8fdb\u7a0b\u4e2d\u6267\u884c\u4e5f\u4e0d\u7b49\u4e8e\u5177\u6709\u5e76\u884c\u611f\u77e5\u80fd\u529b\u3002</p><h3>\u540c\u7248\u672c\u4e2d\u6587\u624b\u518c\u8282\u9009</h3><p>\n<code class=\"command\">EXPLAIN ANALYZE</code> \u6d4b\u5f97\u7684\u8fd0\u884c\u65f6\u95f4\uff0c\u53ef\u80fd\u4ee5\u4e24\u79cd\u91cd\u8981\u65b9\u5f0f\u504f\u79bb\u540c\u4e00\u67e5\u8be2\u7684\u6b63\u5e38\u6267\u884c\u65f6\u95f4\u3002\u7b2c\u4e00\uff0c\u7531\u4e8e\u4e0d\u4f1a\u5411\u5ba2\u6237\u7aef\u4f20\u9012\u4efb\u4f55\u8f93\u51fa\u884c\uff0c\u56e0\u6b64\u7f51\u7edc\u4f20\u8f93\u5f00\u9500\u4e0d\u4f1a\u88ab\u8ba1\u5165\u3002\u9664\u975e\u6307\u5b9a\u4e86 <code class=\"literal\">SERIALIZE</code>\uff0cI/O \u8f6c\u6362\u5f00\u9500\u540c\u6837\u4e5f\u4e0d\u4f1a\u88ab\u8ba1\u5165\u3002\u7b2c\u4e8c\uff0c<code class=\"command\">EXPLAIN ANALYZE</code> \u9644\u52a0\u7684\u6d4b\u91cf\u5f00\u9500\u672c\u8eab\u53ef\u80fd\u76f8\u5f53\u53ef\u89c2\uff0c\u5c24\u5176\u662f\u5728\u64cd\u4f5c\u7cfb\u7edf\u8c03\u7528 <code class=\"function\">gettimeofday()</code> \u8f83\u6162\u7684\u673a\u5668\u4e0a\u3002\u53ef\u4ee5\u4f7f\u7528 <a class=\"xref\" href=\"/zh/docs/devel/pgtesttiming.html\"><span class=\"refentrytitle\"><span class=\"application\">pg_test_timing</span></span></a> \u5de5\u5177\u6765\u6d4b\u91cf\u7cfb\u7edf\u4e0a\u7684\u8ba1\u65f6\u5f00\u9500\u3002\n   </p><p>\n    \u4e0d\u5e94\u5c06 <code class=\"command\">EXPLAIN</code> \u7ed3\u679c\u5916\u63a8\u5230\u4e0e\u5b9e\u9645\u6d4b\u8bd5\u573a\u666f\u5dee\u5f02\u5f88\u5927\u7684\u60c5\u51b5\u3002\u4f8b\u5982\uff0c\u5728\u4e00\u4e2a\u5f88\u5c0f\u7684\u8868\u4e0a\u5f97\u5230\u7684\u7ed3\u679c\uff0c\u4e0d\u80fd\u5047\u5b9a\u4e5f\u9002\u7528\u4e8e\u5927\u578b\u8868\u3002\u89c4\u5212\u5668\u7684\u4ee3\u4ef7\u4f30\u8ba1\u4e0d\u662f\u7ebf\u6027\u7684\uff0c\u56e0\u6b64\u5b83\u53ef\u80fd\u4f1a\u4e3a\u66f4\u5927\u6216\u66f4\u5c0f\u7684\u8868\u9009\u62e9\u4e0d\u540c\u7684\u8ba1\u5212\u3002\u4e00\u4e2a\u6781\u7aef\u793a\u4f8b\u662f\uff1a\u5bf9\u4e8e\u53ea\u5360\u7528\u4e00\u4e2a\u78c1\u76d8\u9875\u7684\u8868\uff0c\u65e0\u8bba\u7d22\u5f15\u662f\u5426\u53ef\u7528\uff0c\u51e0\u4e4e\u603b\u4f1a\u5f97\u5230\u987a\u5e8f\u626b\u63cf\u8ba1\u5212\u3002\u89c4\u5212\u5668\u8ba4\u8bc6\u5230\uff0c\u65e0\u8bba\u5982\u4f55\u5904\u7406\u8be5\u8868\u90fd\u9700\u8981\u4e00\u6b21\u78c1\u76d8\u9875\u8bfb\u53d6\uff0c\u56e0\u6b64\u518d\u989d\u5916\u8bfb\u53d6\u9875\u9762\u53bb\u67e5\u770b\u7d22\u5f15\u5e76\u6ca1\u6709\u4ef7\u503c\u3002\uff08\u524d\u9762\u7684 <code class=\"literal\">polygon_tbl</code> \u793a\u4f8b\u5df2\u7ecf\u5c55\u793a\u8fc7\u8fd9\u79cd\u60c5\u51b5\u3002\uff09\n   </p><p>\n    \u5728\u67d0\u4e9b\u60c5\u51b5\u4e0b\uff0c\u5b9e\u9645\u503c\u548c\u4f30\u8ba1\u503c\u4e0d\u4f1a\u5f88\u597d\u5730\u5bf9\u5e94\uff0c\u4f46\u8fd9\u5e76\u4e0d\u8868\u793a\u51fa\u73b0\u4e86\u95ee\u9898\u3002\u5176\u4e2d\u4e00\u79cd\u60c5\u51b5\u662f\uff0c\u8ba1\u5212\u8282\u70b9\u7684\u6267\u884c\u4f1a\u88ab <code class=\"literal\">LIMIT</code> \u6216\u7c7b\u4f3c\u6548\u679c\u63d0\u524d\u622a\u65ad\u3002\u4f8b\u5982\uff0c\u5728\u524d\u9762\u7528\u8fc7\u7684 <code class=\"literal\">LIMIT</code> \u67e5\u8be2\u4e2d\uff1a\n\n</p><p>\n\n    Index Scan \u8282\u70b9\u7684\u4f30\u8ba1\u4ee3\u4ef7\u548c\u884c\u8ba1\u6570\u663e\u793a\u5f97\u50cf\u662f\u5b83\u4f1a\u8fd0\u884c\u5230\u7ed3\u675f\u4e00\u6837\u3002\u4f46\u5b9e\u9645\u4e0a\uff0cLimit \u8282\u70b9\u5728\u62ff\u5230\u4e24\u884c\u4e4b\u540e\u5c31\u505c\u6b62\u8bf7\u6c42\u66f4\u591a\u884c\uff0c\u56e0\u6b64\u5b9e\u9645\u884c\u8ba1\u6570\u53ea\u6709 2\uff0c\u8fd0\u884c\u65f6\u95f4\u4e5f\u4f4e\u4e8e\u4ee3\u4ef7\u4f30\u8ba1\u6240\u6697\u793a\u7684\u6c34\u5e73\u3002\u8fd9\u5e76\u4e0d\u662f\u4f30\u8ba1\u9519\u8bef\uff0c\u53ea\u662f\u4f30\u8ba1\u503c\u4e0e\u771f\u5b9e\u503c\u7684\u663e\u793a\u65b9\u5f0f\u4e0d\u540c\u800c\u5df2\u3002\n   </p><p><a href=\"/zh/docs/devel/using-explain.html#USING-EXPLAIN-CAVEATS\">\u67e5\u770b\u5b8c\u6574\u4e2d\u6587\u624b\u518c\u4e0e\u4e0a\u4e0b\u6587</a>\u3002</p><p>\u672c\u9875\u5f00\u5934\u7684\u4e2d\u6587\u8bf4\u660e\u4e3a PG.CENTER \u5bf9\u7f16\u8f91\u8bf4\u660e\u7684\u7ffb\u8bd1\uff1b\u624b\u518c\u8282\u9009\u4fdd\u7559\u5bf9\u5e94\u7248\u672c\u4e2d\u6587\u6587\u6863\u539f\u6587\u3002\u6e90\u7801\u4fe1\u606f\u53ca\u624b\u518c\u793a\u4f8b\u4e0d\u4ee3\u8868\u91cd\u65b0\u8fdb\u884c\u8fc7\u8fd0\u884c\u6d4b\u8bd5\u3002</p>"}, "summary": "\u5bf9\u5404\u5b50\u8ba1\u5212\u751f\u6210\u7684\u4f4d\u56fe\u6c42\u5e76\u96c6\u3002", "version": "20", "link_map": {"/zh/docs/devel/pgtesttiming.html": "/docs/devel/pgtesttiming.html", "/zh/docs/devel/using-explain.html#USING-EXPLAIN-CAVEATS": "/docs/devel/using-explain.html#USING-EXPLAIN-CAVEATS"}, "body_html": "<p>\u5bf9\u5404\u5b50\u8ba1\u5212\u751f\u6210\u7684\u4f4d\u56fe\u6c42\u5e76\u96c6\u3002</p><p>\u6838\u5fc3\u8282\u70b9\u6807\u8bc6\uff1a<code>T_BitmapOr</code>\uff1bEXPLAIN \u540d\u79f0\uff1a<code>BitmapOr</code>\u3002</p><p>\u672c\u7248\u672c\u6e90\u7801\u4e2d\u7684\u5e76\u884c\u6267\u884c\u6216\u89c2\u6d4b\u56de\u8c03\uff1a\u8be5\u8282\u70b9\u5b9e\u73b0\u4e2d\u672a\u63d0\u53d6\u5230\u6b64\u7c7b\u56de\u8c03\u3002\u56de\u8c03\u7684\u5b58\u5728\u4e0d\u8868\u793a\u8be5\u8282\u70b9\u5fc5\u7136\u652f\u6301\u5171\u4eab\u5e76\u884c\u626b\u63cf\uff1b\u5728\u5e76\u884c\u5de5\u4f5c\u8fdb\u7a0b\u4e2d\u6267\u884c\u4e5f\u4e0d\u7b49\u4e8e\u5177\u6709\u5e76\u884c\u611f\u77e5\u80fd\u529b\u3002</p><h3>\u540c\u7248\u672c\u4e2d\u6587\u624b\u518c\u8282\u9009</h3><p>\n<code>EXPLAIN ANALYZE</code> \u6d4b\u5f97\u7684\u8fd0\u884c\u65f6\u95f4\uff0c\u53ef\u80fd\u4ee5\u4e24\u79cd\u91cd\u8981\u65b9\u5f0f\u504f\u79bb\u540c\u4e00\u67e5\u8be2\u7684\u6b63\u5e38\u6267\u884c\u65f6\u95f4\u3002\u7b2c\u4e00\uff0c\u7531\u4e8e\u4e0d\u4f1a\u5411\u5ba2\u6237\u7aef\u4f20\u9012\u4efb\u4f55\u8f93\u51fa\u884c\uff0c\u56e0\u6b64\u7f51\u7edc\u4f20\u8f93\u5f00\u9500\u4e0d\u4f1a\u88ab\u8ba1\u5165\u3002\u9664\u975e\u6307\u5b9a\u4e86 <code>SERIALIZE</code>\uff0cI/O \u8f6c\u6362\u5f00\u9500\u540c\u6837\u4e5f\u4e0d\u4f1a\u88ab\u8ba1\u5165\u3002\u7b2c\u4e8c\uff0c<code>EXPLAIN ANALYZE</code> \u9644\u52a0\u7684\u6d4b\u91cf\u5f00\u9500\u672c\u8eab\u53ef\u80fd\u76f8\u5f53\u53ef\u89c2\uff0c\u5c24\u5176\u662f\u5728\u64cd\u4f5c\u7cfb\u7edf\u8c03\u7528 <code>gettimeofday()</code> \u8f83\u6162\u7684\u673a\u5668\u4e0a\u3002\u53ef\u4ee5\u4f7f\u7528 <a href=\"/zh/docs/devel/pgtesttiming.html\" rel=\"nofollow\"><span><span>pg_test_timing</span></span></a> \u5de5\u5177\u6765\u6d4b\u91cf\u7cfb\u7edf\u4e0a\u7684\u8ba1\u65f6\u5f00\u9500\u3002\n   </p><p>\n    \u4e0d\u5e94\u5c06 <code>EXPLAIN</code> \u7ed3\u679c\u5916\u63a8\u5230\u4e0e\u5b9e\u9645\u6d4b\u8bd5\u573a\u666f\u5dee\u5f02\u5f88\u5927\u7684\u60c5\u51b5\u3002\u4f8b\u5982\uff0c\u5728\u4e00\u4e2a\u5f88\u5c0f\u7684\u8868\u4e0a\u5f97\u5230\u7684\u7ed3\u679c\uff0c\u4e0d\u80fd\u5047\u5b9a\u4e5f\u9002\u7528\u4e8e\u5927\u578b\u8868\u3002\u89c4\u5212\u5668\u7684\u4ee3\u4ef7\u4f30\u8ba1\u4e0d\u662f\u7ebf\u6027\u7684\uff0c\u56e0\u6b64\u5b83\u53ef\u80fd\u4f1a\u4e3a\u66f4\u5927\u6216\u66f4\u5c0f\u7684\u8868\u9009\u62e9\u4e0d\u540c\u7684\u8ba1\u5212\u3002\u4e00\u4e2a\u6781\u7aef\u793a\u4f8b\u662f\uff1a\u5bf9\u4e8e\u53ea\u5360\u7528\u4e00\u4e2a\u78c1\u76d8\u9875\u7684\u8868\uff0c\u65e0\u8bba\u7d22\u5f15\u662f\u5426\u53ef\u7528\uff0c\u51e0\u4e4e\u603b\u4f1a\u5f97\u5230\u987a\u5e8f\u626b\u63cf\u8ba1\u5212\u3002\u89c4\u5212\u5668\u8ba4\u8bc6\u5230\uff0c\u65e0\u8bba\u5982\u4f55\u5904\u7406\u8be5\u8868\u90fd\u9700\u8981\u4e00\u6b21\u78c1\u76d8\u9875\u8bfb\u53d6\uff0c\u56e0\u6b64\u518d\u989d\u5916\u8bfb\u53d6\u9875\u9762\u53bb\u67e5\u770b\u7d22\u5f15\u5e76\u6ca1\u6709\u4ef7\u503c\u3002\uff08\u524d\u9762\u7684 <code>polygon_tbl</code> \u793a\u4f8b\u5df2\u7ecf\u5c55\u793a\u8fc7\u8fd9\u79cd\u60c5\u51b5\u3002\uff09\n   </p><p>\n    \u5728\u67d0\u4e9b\u60c5\u51b5\u4e0b\uff0c\u5b9e\u9645\u503c\u548c\u4f30\u8ba1\u503c\u4e0d\u4f1a\u5f88\u597d\u5730\u5bf9\u5e94\uff0c\u4f46\u8fd9\u5e76\u4e0d\u8868\u793a\u51fa\u73b0\u4e86\u95ee\u9898\u3002\u5176\u4e2d\u4e00\u79cd\u60c5\u51b5\u662f\uff0c\u8ba1\u5212\u8282\u70b9\u7684\u6267\u884c\u4f1a\u88ab <code>LIMIT</code> \u6216\u7c7b\u4f3c\u6548\u679c\u63d0\u524d\u622a\u65ad\u3002\u4f8b\u5982\uff0c\u5728\u524d\u9762\u7528\u8fc7\u7684 <code>LIMIT</code> \u67e5\u8be2\u4e2d\uff1a\n\n</p><p>\n\n    Index Scan \u8282\u70b9\u7684\u4f30\u8ba1\u4ee3\u4ef7\u548c\u884c\u8ba1\u6570\u663e\u793a\u5f97\u50cf\u662f\u5b83\u4f1a\u8fd0\u884c\u5230\u7ed3\u675f\u4e00\u6837\u3002\u4f46\u5b9e\u9645\u4e0a\uff0cLimit \u8282\u70b9\u5728\u62ff\u5230\u4e24\u884c\u4e4b\u540e\u5c31\u505c\u6b62\u8bf7\u6c42\u66f4\u591a\u884c\uff0c\u56e0\u6b64\u5b9e\u9645\u884c\u8ba1\u6570\u53ea\u6709 2\uff0c\u8fd0\u884c\u65f6\u95f4\u4e5f\u4f4e\u4e8e\u4ee3\u4ef7\u4f30\u8ba1\u6240\u6697\u793a\u7684\u6c34\u5e73\u3002\u8fd9\u5e76\u4e0d\u662f\u4f30\u8ba1\u9519\u8bef\uff0c\u53ea\u662f\u4f30\u8ba1\u503c\u4e0e\u771f\u5b9e\u503c\u7684\u663e\u793a\u65b9\u5f0f\u4e0d\u540c\u800c\u5df2\u3002\n   </p><p><a href=\"/zh/docs/devel/using-explain.html#USING-EXPLAIN-CAVEATS\" rel=\"nofollow\">\u67e5\u770b\u5b8c\u6574\u4e2d\u6587\u624b\u518c\u4e0e\u4e0a\u4e0b\u6587</a>\u3002</p><p>\u672c\u9875\u5f00\u5934\u7684\u4e2d\u6587\u8bf4\u660e\u4e3a PG.CENTER \u5bf9\u7f16\u8f91\u8bf4\u660e\u7684\u7ffb\u8bd1\uff1b\u624b\u518c\u8282\u9009\u4fdd\u7559\u5bf9\u5e94\u7248\u672c\u4e2d\u6587\u6587\u6863\u539f\u6587\u3002\u6e90\u7801\u4fe1\u606f\u53ca\u624b\u518c\u793a\u4f8b\u4e0d\u4ee3\u8868\u91cd\u65b0\u8fdb\u884c\u8fc7\u8fd0\u884c\u6d4b\u8bd5\u3002</p>", "body_sha256": "a3e5b4961bd18f734fcc30ccce0ded8e9e9f8997350fd2143b086567e66d8e59", "content_hash": "c78f61d69267940ef957d4f63a855ea00bc519149f009cfed41f462c82cf8efa", "source_database": "center", "source_revision": "49c73aa4c9cacef8ca979276a28ac416c08e9e54c9baee4ae5fd116a35fa13ac"}, "tables_zh": [{"key": "explain-labels", "rows": [{"label": "BitmapOr", "identity": "BitmapOr"}], "title": "\u672c\u6784\u5efa\u4e2d\u7684 EXPLAIN \u6807\u7b7e", "columns": [{"key": "label", "label": "\u6587\u672c\u683c\u5f0f\u6807\u7b7e"}, {"key": "identity", "label": "\u7ed3\u6784\u5316\u8282\u70b9\u6807\u8bc6"}]}], "strategies": [], "description": ["\u5bf9\u5404\u5b50\u8ba1\u5212\u751f\u6210\u7684\u4f4d\u56fe\u6c42\u5e76\u96c6\u3002"], "sections_zh": [{"title": "EXPLAIN \u540d\u79f0\u4e0e\u5c5e\u6027", "paragraphs": ["\u7ed3\u6784\u5316\u683c\u5f0f\u4f7f\u7528\u4e0a\u8ff0 Node Type\u3002\u6587\u672c\u683c\u5f0f\u540d\u79f0\u8fd8\u53ef\u80fd\u5305\u542b\u64cd\u4f5c\u3001\u7b56\u7565\u3001\u8fde\u63a5\u7c7b\u578b\u3001\u626b\u63cf\u65b9\u5411\u6216\u805a\u5408\u9636\u6bb5\u5c5e\u6027\u3002", "\u6b64\u6e90\u7801\u8bb0\u5f55\u7684\u6587\u672c\u540d\u79f0\uff1aBitmapOr.", "\u5e76\u884c\u611f\u77e5\u4e0e\u5e76\u884c\u5b89\u5168\u662f\u4e0d\u540c\u7684\u8ba1\u5212\u5c5e\u6027\u3002\u5728\u5e76\u884c\u5de5\u4f5c\u8fdb\u7a0b\u5185\u8fd0\u884c\u7684\u8282\u70b9\u4e0d\u4e00\u5b9a\u662f\u5e76\u884c\u611f\u77e5\u8282\u70b9\u3002"]}, {"title": "\u5185\u5b58\u4e0e\u4e34\u65f6\u5b58\u50a8", "paragraphs": ["\u6b64\u8282\u70b9\u6309\u57fa\u4e8e work_mem \u7684\u9884\u7b97\u5206\u914d\u5143\u7ec4\u4f4d\u7f6e\u4f4d\u56fe\u3002\u4f4d\u56fe\u53ef\u4ee5\u4fdd\u7559\u9875\u7ea7\u6709\u635f\u6761\u76ee\uff0c\u800c\u4e0d\u8bb0\u5f55\u6bcf\u4e2a\u5143\u7ec4\u4f4d\u7f6e\uff0c\u56e0\u6b64\u4ecd\u53ef\u80fd\u9700\u8981\u5806\u91cd\u68c0\u3002"]}, {"title": "\u5e76\u884c\u6267\u884c\u4e0e\u8fd0\u884c\u4fe1\u606f\u91c7\u96c6", "paragraphs": ["\u4ee5\u4e0b\u6e90\u7801\u56de\u8c03\u53ef\u4ee5\u534f\u8c03\u6267\u884c\u6216\u6536\u96c6\u5de5\u4f5c\u8fdb\u7a0b\u7684\u6d4b\u91cf\u6570\u636e\u3002\u56de\u8c03\u5b58\u5728\u4e0d\u4ee3\u8868\u8be5\u8282\u70b9\u666e\u904d\u652f\u6301\u5171\u4eab\u5e76\u884c\u626b\u63cf\u6216\u5171\u4eab\u72b6\u6001\u3002", "\u6b64\u6784\u5efa\u7684\u56de\u8c03\uff1anone extracted from this node implementation."]}, {"title": "\u540c\u7248\u672c\u624b\u518c\u8bf4\u660e", "paragraphs": ["\u7531\u4e8e\u5b9e\u73b0\u4e0a\u7684\u9650\u5236\uff0cBitmapAnd \u548c BitmapOr \u8282\u70b9\u62a5\u544a\u7684\u5b9e\u9645\u884c\u6570\u59cb\u7ec8\u4e3a\u96f6\u3002"]}, {"title": "\u6267\u884c\u5668\u5b9e\u73b0\u8bf4\u660e", "paragraphs": ["\u8bf4\u660e\uff1aBitmapOr \u4e0d\u4f7f\u7528\u5de6\u53f3\u5b50\u6811\uff0c\u800c\u50cf Append \u4e00\u6837\u7ef4\u62a4\u5b50\u8ba1\u5212\u5217\u8868\u3002\u4e0d\u8fc7\u5176\u903b\u8f91\u6bd4 Append \u7b80\u5355\u5f97\u591a\uff0c\u56e0\u4e3a\u65e0\u9700\u5904\u7406\u6b63\u5411\u6216\u53cd\u5411\u6267\u884c\u3002", "\u5bf9\u6bcf\u4e2a\u5f85\u6267\u884c\u8ba1\u5212\u8c03\u7528 ExecInitNode\uff0c\u5e76\u5c06\u7ed3\u679c\u4fdd\u5b58\u5230 bitmapplanstates \u6570\u7ec4\u3002", "BitmapOr \u8ba1\u5212\u6ca1\u6709\u8868\u8fbe\u5f0f\u4e0a\u4e0b\u6587\uff0c\u56e0\u4e3a\u5b83\u4eec\u4ece\u4e0d\u8c03\u7528 ExecQual \u6216 ExecProject\uff0c\u4e5f\u4e0d\u9700\u8981\u5143\u7ec4\u69fd\u3002", "\u53ef\u5bf9 BitmapIndexScan \u5b50\u8282\u70b9\u4f5c\u7279\u6b8a\u5904\u7406\uff0c\u907f\u514d\u4e3a\u6bcf\u4e2a\u5b50\u8282\u70b9\u663e\u5f0f\u8c03\u7528 tbm_union\uff1a\u76f4\u63a5\u4e0b\u4f20\u5f53\u524d\u7ed3\u679c\u4f4d\u56fe\uff0c\u8ba9\u5b50\u8282\u70b9\u5c06\u7ed3\u679c\u6309\u4f4d OR \u5408\u5e76\u8fdb\u53bb\u3002", "ExecReScan \u4e0d\u77e5\u9053\u5f53\u524d\u8282\u70b9\u7684\u5b50\u8ba1\u5212\uff0c\u56e0\u6b64\u5fc5\u987b\u81ea\u884c\u901a\u77e5\u5b50\u8ba1\u5212\u54ea\u4e9b\u53c2\u6570\u53d1\u751f\u4e86\u53d8\u5316\u3002"]}, {"code": "case T_BitmapOr:\n\t\t\tpname = sname = \"BitmapOr\";\n\t\t\tbreak;", "title": "\u6838\u5fc3\u6e90\u7801\u4e2d\u7684 EXPLAIN \u6807\u8bc6"}], "localization": {"status": "complete", "sources": [], "language": "zh", "original_text": {"/summary": "Unions bitmaps produced by its child plans.", "/category": "Bitmap", "/versions/20/description/0": "Unions bitmaps produced by its child plans.", "/versions/20/facts/0/label": "Core node tag", "/versions/20/facts/1/label": "Structured EXPLAIN Node Type", "/versions/20/facts/2/label": "Inputs", "/versions/20/facts/2/value": "Bitmap-producing child plans", "/versions/20/facts/3/label": "Output", "/versions/20/facts/3/value": "Tuple-location bitmap, not a tuple stream", "/versions/20/facts/4/label": "Executor initializer", "/versions/20/facts/5/label": "Memory mechanism", "/versions/20/tables/0/title": "EXPLAIN labels in this source build", "/versions/20/related/1/label": "Using EXPLAIN", "/versions/20/related/2/label": "Parallel plans", "/versions/20/sections/0/title": "EXPLAIN names and attributes", "/versions/20/sections/1/title": "Memory and temporary storage", "/versions/20/sections/2/title": "Parallel execution and instrumentation", "/versions/20/sections/3/title": "Same-version manual discussion", "/versions/20/sections/4/title": "Executor implementation notes", "/versions/20/sections/5/title": "EXPLAIN identity in core source", "/versions/20/memory/description": "The node allocates a tuple-location bitmap using a work_mem-derived budget. A bitmap can retain page-level lossy entries instead of every tuple location; heap rechecks then remain necessary.", "/versions/20/sections/0/paragraphs/0": "Structured formats use the Node Type above. Text-format spellings can also include operation, strategy, join type, scan direction or aggregation-stage attributes.", "/versions/20/sections/0/paragraphs/1": "Text names recorded by this source: BitmapOr.", "/versions/20/sections/0/paragraphs/2": "Parallel-aware and parallel-safe are different plan properties. A node running inside a parallel worker is not necessarily a parallel-aware node.", "/versions/20/sections/1/paragraphs/0": "The node allocates a tuple-location bitmap using a work_mem-derived budget. A bitmap can retain page-level lossy entries instead of every tuple location; heap rechecks then remain necessary.", "/versions/20/sections/2/paragraphs/0": "The source callbacks below can coordinate execution or collect worker instrumentation. Their presence is not a blanket claim that this node supports a shared parallel scan or shared state.", "/versions/20/sections/2/paragraphs/1": "Callbacks in this build: none extracted from this node implementation.", "/versions/20/sections/3/paragraphs/0": "BitmapAnd and BitmapOr nodes always report their actual row counts as zero, due to implementation limitations.", "/versions/20/sections/4/paragraphs/0": "NOTES BitmapOr nodes don't make use of their left and right subtrees, rather they maintain a list of subplans, much like Append nodes. The logic is much simpler than Append, however, since we needn't cope with forward/backward execution.", "/versions/20/sections/4/paragraphs/1": "call ExecInitNode on each of the plans to be executed and save the results into the array \"bitmapplanstates\".", "/versions/20/sections/4/paragraphs/2": "BitmapOr plans don't have expression contexts because they never call ExecQual or ExecProject. They don't need any tuple slots either.", "/versions/20/sections/4/paragraphs/3": "We can special-case BitmapIndexScan children to avoid an explicit tbm_union step for each child: just pass down the current result bitmap and let the child OR directly into it.", "/versions/20/sections/4/paragraphs/4": "ExecReScan doesn't know about my subplans, so I have to do changed-parameter signaling myself.", "/versions/20/tables/0/columns/0/label": "Text-format label", "/versions/20/tables/0/columns/1/label": "Structured node identity"}, "fallback_fields": [], "source_language": "en", "original_snapshot_sha256": "533db71211cb4a3802f26248622233ea4941bfa47e622a7d9f6a7d31a0dc96e9", "canonical_center_text_hash": "c78f61d69267940ef957d4f63a855ea00bc519149f009cfed41f462c82cf8efa"}, "evidence_kind": "source and documentation", "explain_names": ["BitmapOr"], "partial_modes": [], "description_zh": "\u5bf9\u5404\u5b50\u8ba1\u5212\u751f\u6210\u7684\u4f4d\u56fe\u6c42\u5e76\u96c6\u3002", "comparison_data": {"node_tag": "T_BitmapOr", "strategies": [], "text_names": ["BitmapOr"], "initializer": "ExecInitBitmapOr", "partial_modes": [], "memory_mechanism": "bitmap-lossification", "parallel_callbacks": []}, "comparison_hash": "c0ca503a6029c37ec720213dcdc3094997eb194d4920da68f94a7420d3e8f1d2", "manual_language": "zh", "explain_prefixes": ["Parallel", "Async"], "runtime_verified": false, "source_inventory": {"explain": "src/backend/commands/explain.c", "executor": "src/backend/executor/execProcnode.c", "implementation": "src/backend/executor/nodeBitmapOr.c"}, "parallel_callbacks": [], "description_zh_html": "<p>\u5bf9\u5404\u5b50\u8ba1\u5212\u751f\u6210\u7684\u4f4d\u56fe\u6c42\u5e76\u96c6\u3002</p><p>\u6838\u5fc3\u8282\u70b9\u6807\u8bc6\uff1a<code>T_BitmapOr</code>\uff1bEXPLAIN \u540d\u79f0\uff1a<code>BitmapOr</code>\u3002</p><p>\u672c\u7248\u672c\u6e90\u7801\u4e2d\u7684\u5e76\u884c\u6267\u884c\u6216\u89c2\u6d4b\u56de\u8c03\uff1a\u8be5\u8282\u70b9\u5b9e\u73b0\u4e2d\u672a\u63d0\u53d6\u5230\u6b64\u7c7b\u56de\u8c03\u3002\u56de\u8c03\u7684\u5b58\u5728\u4e0d\u8868\u793a\u8be5\u8282\u70b9\u5fc5\u7136\u652f\u6301\u5171\u4eab\u5e76\u884c\u626b\u63cf\uff1b\u5728\u5e76\u884c\u5de5\u4f5c\u8fdb\u7a0b\u4e2d\u6267\u884c\u4e5f\u4e0d\u7b49\u4e8e\u5177\u6709\u5e76\u884c\u611f\u77e5\u80fd\u529b\u3002</p><h3>\u540c\u7248\u672c\u4e2d\u6587\u624b\u518c\u8282\u9009</h3><p>\n<code>EXPLAIN ANALYZE</code> \u6d4b\u5f97\u7684\u8fd0\u884c\u65f6\u95f4\uff0c\u53ef\u80fd\u4ee5\u4e24\u79cd\u91cd\u8981\u65b9\u5f0f\u504f\u79bb\u540c\u4e00\u67e5\u8be2\u7684\u6b63\u5e38\u6267\u884c\u65f6\u95f4\u3002\u7b2c\u4e00\uff0c\u7531\u4e8e\u4e0d\u4f1a\u5411\u5ba2\u6237\u7aef\u4f20\u9012\u4efb\u4f55\u8f93\u51fa\u884c\uff0c\u56e0\u6b64\u7f51\u7edc\u4f20\u8f93\u5f00\u9500\u4e0d\u4f1a\u88ab\u8ba1\u5165\u3002\u9664\u975e\u6307\u5b9a\u4e86 <code>SERIALIZE</code>\uff0cI/O \u8f6c\u6362\u5f00\u9500\u540c\u6837\u4e5f\u4e0d\u4f1a\u88ab\u8ba1\u5165\u3002\u7b2c\u4e8c\uff0c<code>EXPLAIN ANALYZE</code> \u9644\u52a0\u7684\u6d4b\u91cf\u5f00\u9500\u672c\u8eab\u53ef\u80fd\u76f8\u5f53\u53ef\u89c2\uff0c\u5c24\u5176\u662f\u5728\u64cd\u4f5c\u7cfb\u7edf\u8c03\u7528 <code>gettimeofday()</code> \u8f83\u6162\u7684\u673a\u5668\u4e0a\u3002\u53ef\u4ee5\u4f7f\u7528 <a href=\"/zh/docs/devel/pgtesttiming.html\" rel=\"nofollow\"><span><span>pg_test_timing</span></span></a> \u5de5\u5177\u6765\u6d4b\u91cf\u7cfb\u7edf\u4e0a\u7684\u8ba1\u65f6\u5f00\u9500\u3002\n   </p><p>\n    \u4e0d\u5e94\u5c06 <code>EXPLAIN</code> \u7ed3\u679c\u5916\u63a8\u5230\u4e0e\u5b9e\u9645\u6d4b\u8bd5\u573a\u666f\u5dee\u5f02\u5f88\u5927\u7684\u60c5\u51b5\u3002\u4f8b\u5982\uff0c\u5728\u4e00\u4e2a\u5f88\u5c0f\u7684\u8868\u4e0a\u5f97\u5230\u7684\u7ed3\u679c\uff0c\u4e0d\u80fd\u5047\u5b9a\u4e5f\u9002\u7528\u4e8e\u5927\u578b\u8868\u3002\u89c4\u5212\u5668\u7684\u4ee3\u4ef7\u4f30\u8ba1\u4e0d\u662f\u7ebf\u6027\u7684\uff0c\u56e0\u6b64\u5b83\u53ef\u80fd\u4f1a\u4e3a\u66f4\u5927\u6216\u66f4\u5c0f\u7684\u8868\u9009\u62e9\u4e0d\u540c\u7684\u8ba1\u5212\u3002\u4e00\u4e2a\u6781\u7aef\u793a\u4f8b\u662f\uff1a\u5bf9\u4e8e\u53ea\u5360\u7528\u4e00\u4e2a\u78c1\u76d8\u9875\u7684\u8868\uff0c\u65e0\u8bba\u7d22\u5f15\u662f\u5426\u53ef\u7528\uff0c\u51e0\u4e4e\u603b\u4f1a\u5f97\u5230\u987a\u5e8f\u626b\u63cf\u8ba1\u5212\u3002\u89c4\u5212\u5668\u8ba4\u8bc6\u5230\uff0c\u65e0\u8bba\u5982\u4f55\u5904\u7406\u8be5\u8868\u90fd\u9700\u8981\u4e00\u6b21\u78c1\u76d8\u9875\u8bfb\u53d6\uff0c\u56e0\u6b64\u518d\u989d\u5916\u8bfb\u53d6\u9875\u9762\u53bb\u67e5\u770b\u7d22\u5f15\u5e76\u6ca1\u6709\u4ef7\u503c\u3002\uff08\u524d\u9762\u7684 <code>polygon_tbl</code> \u793a\u4f8b\u5df2\u7ecf\u5c55\u793a\u8fc7\u8fd9\u79cd\u60c5\u51b5\u3002\uff09\n   </p><p>\n    \u5728\u67d0\u4e9b\u60c5\u51b5\u4e0b\uff0c\u5b9e\u9645\u503c\u548c\u4f30\u8ba1\u503c\u4e0d\u4f1a\u5f88\u597d\u5730\u5bf9\u5e94\uff0c\u4f46\u8fd9\u5e76\u4e0d\u8868\u793a\u51fa\u73b0\u4e86\u95ee\u9898\u3002\u5176\u4e2d\u4e00\u79cd\u60c5\u51b5\u662f\uff0c\u8ba1\u5212\u8282\u70b9\u7684\u6267\u884c\u4f1a\u88ab <code>LIMIT</code> \u6216\u7c7b\u4f3c\u6548\u679c\u63d0\u524d\u622a\u65ad\u3002\u4f8b\u5982\uff0c\u5728\u524d\u9762\u7528\u8fc7\u7684 <code>LIMIT</code> \u67e5\u8be2\u4e2d\uff1a\n\n</p><p>\n\n    Index Scan \u8282\u70b9\u7684\u4f30\u8ba1\u4ee3\u4ef7\u548c\u884c\u8ba1\u6570\u663e\u793a\u5f97\u50cf\u662f\u5b83\u4f1a\u8fd0\u884c\u5230\u7ed3\u675f\u4e00\u6837\u3002\u4f46\u5b9e\u9645\u4e0a\uff0cLimit \u8282\u70b9\u5728\u62ff\u5230\u4e24\u884c\u4e4b\u540e\u5c31\u505c\u6b62\u8bf7\u6c42\u66f4\u591a\u884c\uff0c\u56e0\u6b64\u5b9e\u9645\u884c\u8ba1\u6570\u53ea\u6709 2\uff0c\u8fd0\u884c\u65f6\u95f4\u4e5f\u4f4e\u4e8e\u4ee3\u4ef7\u4f30\u8ba1\u6240\u6697\u793a\u7684\u6c34\u5e73\u3002\u8fd9\u5e76\u4e0d\u662f\u4f30\u8ba1\u9519\u8bef\uff0c\u53ea\u662f\u4f30\u8ba1\u503c\u4e0e\u771f\u5b9e\u503c\u7684\u663e\u793a\u65b9\u5f0f\u4e0d\u540c\u800c\u5df2\u3002\n   </p><p><a href=\"/zh/docs/devel/using-explain.html#USING-EXPLAIN-CAVEATS\" rel=\"nofollow\">\u67e5\u770b\u5b8c\u6574\u4e2d\u6587\u624b\u518c\u4e0e\u4e0a\u4e0b\u6587</a>\u3002</p><p>\u672c\u9875\u5f00\u5934\u7684\u4e2d\u6587\u8bf4\u660e\u4e3a PG.CENTER \u5bf9\u7f16\u8f91\u8bf4\u660e\u7684\u7ffb\u8bd1\uff1b\u624b\u518c\u8282\u9009\u4fdd\u7559\u5bf9\u5e94\u7248\u672c\u4e2d\u6587\u6587\u6863\u539f\u6587\u3002\u6e90\u7801\u4fe1\u606f\u53ca\u624b\u518c\u793a\u4f8b\u4e0d\u4ee3\u8868\u91cd\u65b0\u8fdb\u884c\u8fc7\u8fd0\u884c\u6d4b\u8bd5\u3002</p>", "source_revalidation": {"kind": "static-same-version-source-and-manual-replay", "audit": "wiki-audit-20261023", "runtime_rerun": false, "compared_fields": "entity membership and source-derived facts; presentation markup normalized", "source_revision": "49c73aa4c9cacef8ca979276a28ac416c08e9e54c9baee4ae5fd116a35fa13ac", "previous_source_revision": "4d3346909b201ac1648232cf290462a7070c119326f56196f1f0253ed80fae41"}}}}, "snapshot": {"facts": [{"label": "\u6838\u5fc3\u8282\u70b9\u6807\u7b7e", "value": "T_BitmapOr"}, {"label": "\u7ed3\u6784\u5316 EXPLAIN \u8282\u70b9\u7c7b\u578b", "value": "BitmapOr"}, {"label": "\u8f93\u5165", "value": "\u4ea7\u751f\u4f4d\u56fe\u7684\u5b50\u8ba1\u5212"}, {"label": "\u8f93\u51fa", "value": "\u5143\u7ec4\u4f4d\u7f6e\u4f4d\u56fe\uff0c\u4e0d\u662f\u5143\u7ec4\u6d41"}, {"label": "\u6267\u884c\u5668\u521d\u59cb\u5316\u51fd\u6570", "value": "ExecInitBitmapOr"}, {"label": "\u5185\u5b58\u673a\u5236", "value": "bitmap-lossification"}], "memory": {"evidence": [{"url": "https://ftp.postgresql.org/pub/source/v18.6/postgresql-18.6.tar.bz2", "path": "src/backend/executor/nodeBitmapOr.c", "label": "src/backend/executor/nodeBitmapOr.c", "sha256": "81e2aeb0cc0d4cece84b7514385636cd11ea0e1faab93c721d4c3b86c20c9104", "archive_sha256": "555610c24d53e4316da5b7d3fc25c279d96856d5e0e23ee308c328c5fa881d9f"}, {"url": "https://ftp.postgresql.org/pub/source/v18.6/postgresql-18.6.tar.bz2", "path": "src/backend/nodes/tidbitmap.c", "label": "src/backend/nodes/tidbitmap.c", "sha256": "e2453b7155d55db8c3a59bc929362f01d3f9692b0a483e5aa81a7b6c50db6102", "archive_sha256": "555610c24d53e4316da5b7d3fc25c279d96856d5e0e23ee308c328c5fa881d9f"}], "mechanism": "bitmap-lossification", "description": "The node allocates a tuple-location bitmap using a work_mem-derived budget. A bitmap can retain page-level lossy entries instead of every tuple location; heap rechecks then remain necessary.", "source_notes": []}, "tables": [{"key": "explain-labels", "rows": [{"label": "BitmapOr", "identity": "BitmapOr"}], "title": "\u672c\u6784\u5efa\u4e2d\u7684 EXPLAIN \u6807\u7b7e", "columns": [{"key": "label", "label": "\u6587\u672c\u683c\u5f0f\u6807\u7b7e"}, {"key": "identity", "label": "\u7ed3\u6784\u5316\u8282\u70b9\u6807\u8bc6"}]}], "related": [{"url": "/wiki/sql/explain/?v=18", "label": "EXPLAIN"}, {"url": "/docs/18/using-explain.html", "label": "\u4f7f\u7528 EXPLAIN"}, {"url": "/docs/18/parallel-plans.html", "label": "\u5e76\u884c\u8ba1\u5212"}, {"url": "/wiki/guc/work_mem/?v=18", "label": "work_mem"}], "release": {"ref": "PostgreSQL 18.6 source archive", "label": "18.6", "major": "18", "channel": "stable", "revision": "555610c24d53e4316da5b7d3fc25c279d96856d5e0e23ee308c328c5fa881d9f", "source_url": 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"\u5e76\u884c\u6267\u884c\u4e0e\u8fd0\u884c\u4fe1\u606f\u91c7\u96c6", "paragraphs": ["\u4ee5\u4e0b\u6e90\u7801\u56de\u8c03\u53ef\u4ee5\u534f\u8c03\u6267\u884c\u6216\u6536\u96c6\u5de5\u4f5c\u8fdb\u7a0b\u7684\u6d4b\u91cf\u6570\u636e\u3002\u56de\u8c03\u5b58\u5728\u4e0d\u4ee3\u8868\u8be5\u8282\u70b9\u666e\u904d\u652f\u6301\u5171\u4eab\u5e76\u884c\u626b\u63cf\u6216\u5171\u4eab\u72b6\u6001\u3002", "\u6b64\u6784\u5efa\u7684\u56de\u8c03\uff1anone extracted from this node implementation."]}, {"title": "\u540c\u7248\u672c\u624b\u518c\u8bf4\u660e", "paragraphs": ["\u7531\u4e8e\u5b9e\u73b0\u4e0a\u7684\u9650\u5236\uff0cBitmapAnd \u548c BitmapOr \u8282\u70b9\u62a5\u544a\u7684\u5b9e\u9645\u884c\u6570\u59cb\u7ec8\u4e3a\u96f6\u3002"]}, {"title": "\u6267\u884c\u5668\u5b9e\u73b0\u8bf4\u660e", "paragraphs": ["\u8bf4\u660e\uff1aBitmapOr \u4e0d\u4f7f\u7528\u5de6\u53f3\u5b50\u6811\uff0c\u800c\u50cf Append \u4e00\u6837\u7ef4\u62a4\u5b50\u8ba1\u5212\u5217\u8868\u3002\u4e0d\u8fc7\u5176\u903b\u8f91\u6bd4 Append \u7b80\u5355\u5f97\u591a\uff0c\u56e0\u4e3a\u65e0\u9700\u5904\u7406\u6b63\u5411\u6216\u53cd\u5411\u6267\u884c\u3002", "\u5bf9\u6bcf\u4e2a\u5f85\u6267\u884c\u8ba1\u5212\u8c03\u7528 ExecInitNode\uff0c\u5e76\u5c06\u7ed3\u679c\u4fdd\u5b58\u5230 bitmapplanstates \u6570\u7ec4\u3002", "BitmapOr \u8ba1\u5212\u6ca1\u6709\u8868\u8fbe\u5f0f\u4e0a\u4e0b\u6587\uff0c\u56e0\u4e3a\u5b83\u4eec\u4ece\u4e0d\u8c03\u7528 ExecQual \u6216 ExecProject\uff0c\u4e5f\u4e0d\u9700\u8981\u5143\u7ec4\u69fd\u3002", "\u53ef\u5bf9 BitmapIndexScan \u5b50\u8282\u70b9\u4f5c\u7279\u6b8a\u5904\u7406\uff0c\u907f\u514d\u4e3a\u6bcf\u4e2a\u5b50\u8282\u70b9\u663e\u5f0f\u8c03\u7528 tbm_union\uff1a\u76f4\u63a5\u4e0b\u4f20\u5f53\u524d\u7ed3\u679c\u4f4d\u56fe\uff0c\u8ba9\u5b50\u8282\u70b9\u5c06\u7ed3\u679c\u6309\u4f4d OR \u5408\u5e76\u8fdb\u53bb\u3002", "ExecReScan \u4e0d\u77e5\u9053\u5f53\u524d\u8282\u70b9\u7684\u5b50\u8ba1\u5212\uff0c\u56e0\u6b64\u5fc5\u987b\u81ea\u884c\u901a\u77e5\u5b50\u8ba1\u5212\u54ea\u4e9b\u53c2\u6570\u53d1\u751f\u4e86\u53d8\u5316\u3002"]}, {"code": "case T_BitmapOr:\n\t\t\tpname = sname = \"BitmapOr\";\n\t\t\tbreak;", "title": "\u6838\u5fc3\u6e90\u7801\u4e2d\u7684 EXPLAIN \u6807\u8bc6"}], "description_zh": "\u5bf9\u5404\u5b50\u8ba1\u5212\u751f\u6210\u7684\u4f4d\u56fe\u6c42\u5e76\u96c6\u3002", "description_zh_html": "<p>\u5bf9\u5404\u5b50\u8ba1\u5212\u751f\u6210\u7684\u4f4d\u56fe\u6c42\u5e76\u96c6\u3002</p><p>\u6838\u5fc3\u8282\u70b9\u6807\u8bc6\uff1a<code>T_BitmapOr</code>\uff1bEXPLAIN \u540d\u79f0\uff1a<code>BitmapOr</code>\u3002</p><p>\u672c\u7248\u672c\u6e90\u7801\u4e2d\u7684\u5e76\u884c\u6267\u884c\u6216\u89c2\u6d4b\u56de\u8c03\uff1a\u8be5\u8282\u70b9\u5b9e\u73b0\u4e2d\u672a\u63d0\u53d6\u5230\u6b64\u7c7b\u56de\u8c03\u3002\u56de\u8c03\u7684\u5b58\u5728\u4e0d\u8868\u793a\u8be5\u8282\u70b9\u5fc5\u7136\u652f\u6301\u5171\u4eab\u5e76\u884c\u626b\u63cf\uff1b\u5728\u5e76\u884c\u5de5\u4f5c\u8fdb\u7a0b\u4e2d\u6267\u884c\u4e5f\u4e0d\u7b49\u4e8e\u5177\u6709\u5e76\u884c\u611f\u77e5\u80fd\u529b\u3002</p><h3>\u540c\u7248\u672c\u4e2d\u6587\u624b\u518c\u8282\u9009</h3><p>\n<code class=\"command\">EXPLAIN ANALYZE</code> \u6d4b\u5f97\u7684\u8fd0\u884c\u65f6\u95f4\uff0c\u53ef\u80fd\u4ee5\u4e24\u79cd\u91cd\u8981\u65b9\u5f0f\u504f\u79bb\u540c\u4e00\u67e5\u8be2\u7684\u6b63\u5e38\u6267\u884c\u65f6\u95f4\u3002\u7b2c\u4e00\uff0c\u7531\u4e8e\u4e0d\u4f1a\u5411\u5ba2\u6237\u7aef\u4f20\u9012\u4efb\u4f55\u8f93\u51fa\u884c\uff0c\u56e0\u6b64\u7f51\u7edc\u4f20\u8f93\u5f00\u9500\u4e0d\u4f1a\u88ab\u8ba1\u5165\u3002\u9664\u975e\u6307\u5b9a\u4e86 <code class=\"literal\">SERIALIZE</code>\uff0cI/O \u8f6c\u6362\u5f00\u9500\u540c\u6837\u4e5f\u4e0d\u4f1a\u88ab\u8ba1\u5165\u3002\u7b2c\u4e8c\uff0c<code class=\"command\">EXPLAIN ANALYZE</code> \u9644\u52a0\u7684\u6d4b\u91cf\u5f00\u9500\u672c\u8eab\u53ef\u80fd\u76f8\u5f53\u53ef\u89c2\uff0c\u5c24\u5176\u662f\u5728\u64cd\u4f5c\u7cfb\u7edf\u8c03\u7528 <code class=\"function\">gettimeofday()</code> \u8f83\u6162\u7684\u673a\u5668\u4e0a\u3002\u53ef\u4ee5\u4f7f\u7528 <a class=\"xref\" href=\"/zh/docs/18/pgtesttiming.html\"><span class=\"refentrytitle\"><span class=\"application\">pg_test_timing</span></span></a> \u5de5\u5177\u6765\u6d4b\u91cf\u7cfb\u7edf\u4e0a\u7684\u8ba1\u65f6\u5f00\u9500\u3002\n   </p><p>\n    \u4e0d\u5e94\u5c06 <code class=\"command\">EXPLAIN</code> \u7ed3\u679c\u5916\u63a8\u5230\u4e0e\u5b9e\u9645\u6d4b\u8bd5\u573a\u666f\u5dee\u5f02\u5f88\u5927\u7684\u60c5\u51b5\u3002\u4f8b\u5982\uff0c\u5728\u4e00\u4e2a\u5f88\u5c0f\u7684\u8868\u4e0a\u5f97\u5230\u7684\u7ed3\u679c\uff0c\u4e0d\u80fd\u5047\u5b9a\u4e5f\u9002\u7528\u4e8e\u5927\u578b\u8868\u3002\u89c4\u5212\u5668\u7684\u4ee3\u4ef7\u4f30\u8ba1\u4e0d\u662f\u7ebf\u6027\u7684\uff0c\u56e0\u6b64\u5b83\u53ef\u80fd\u4f1a\u4e3a\u66f4\u5927\u6216\u66f4\u5c0f\u7684\u8868\u9009\u62e9\u4e0d\u540c\u7684\u8ba1\u5212\u3002\u4e00\u4e2a\u6781\u7aef\u793a\u4f8b\u662f\uff1a\u5bf9\u4e8e\u53ea\u5360\u7528\u4e00\u4e2a\u78c1\u76d8\u9875\u7684\u8868\uff0c\u65e0\u8bba\u7d22\u5f15\u662f\u5426\u53ef\u7528\uff0c\u51e0\u4e4e\u603b\u4f1a\u5f97\u5230\u987a\u5e8f\u626b\u63cf\u8ba1\u5212\u3002\u89c4\u5212\u5668\u8ba4\u8bc6\u5230\uff0c\u65e0\u8bba\u5982\u4f55\u5904\u7406\u8be5\u8868\u90fd\u9700\u8981\u4e00\u6b21\u78c1\u76d8\u9875\u8bfb\u53d6\uff0c\u56e0\u6b64\u518d\u989d\u5916\u8bfb\u53d6\u9875\u9762\u53bb\u67e5\u770b\u7d22\u5f15\u5e76\u6ca1\u6709\u4ef7\u503c\u3002\uff08\u524d\u9762\u7684 <code class=\"literal\">polygon_tbl</code> \u793a\u4f8b\u5df2\u7ecf\u5c55\u793a\u8fc7\u8fd9\u79cd\u60c5\u51b5\u3002\uff09\n   </p><p>\n    \u5728\u67d0\u4e9b\u60c5\u51b5\u4e0b\uff0c\u5b9e\u9645\u503c\u548c\u4f30\u8ba1\u503c\u4e0d\u4f1a\u5f88\u597d\u5730\u5bf9\u5e94\uff0c\u4f46\u8fd9\u5e76\u4e0d\u8868\u793a\u51fa\u73b0\u4e86\u95ee\u9898\u3002\u5176\u4e2d\u4e00\u79cd\u60c5\u51b5\u662f\uff0c\u8ba1\u5212\u8282\u70b9\u7684\u6267\u884c\u4f1a\u88ab <code class=\"literal\">LIMIT</code> \u6216\u7c7b\u4f3c\u6548\u679c\u63d0\u524d\u622a\u65ad\u3002\u4f8b\u5982\uff0c\u5728\u524d\u9762\u7528\u8fc7\u7684 <code class=\"literal\">LIMIT</code> \u67e5\u8be2\u4e2d\uff1a\n\n</p><p>\n\n    Index Scan \u8282\u70b9\u7684\u4f30\u8ba1\u4ee3\u4ef7\u548c\u884c\u8ba1\u6570\u663e\u793a\u5f97\u50cf\u662f\u5b83\u4f1a\u8fd0\u884c\u5230\u7ed3\u675f\u4e00\u6837\u3002\u4f46\u5b9e\u9645\u4e0a\uff0cLimit \u8282\u70b9\u5728\u62ff\u5230\u4e24\u884c\u4e4b\u540e\u5c31\u505c\u6b62\u8bf7\u6c42\u66f4\u591a\u884c\uff0c\u56e0\u6b64\u5b9e\u9645\u884c\u8ba1\u6570\u53ea\u6709 2\uff0c\u8fd0\u884c\u65f6\u95f4\u4e5f\u4f4e\u4e8e\u4ee3\u4ef7\u4f30\u8ba1\u6240\u6697\u793a\u7684\u6c34\u5e73\u3002\u8fd9\u5e76\u4e0d\u662f\u4f30\u8ba1\u9519\u8bef\uff0c\u53ea\u662f\u4f30\u8ba1\u503c\u4e0e\u771f\u5b9e\u503c\u7684\u663e\u793a\u65b9\u5f0f\u4e0d\u540c\u800c\u5df2\u3002\n   </p><p><a href=\"/zh/docs/18/using-explain.html#USING-EXPLAIN-CAVEATS\">\u67e5\u770b\u5b8c\u6574\u4e2d\u6587\u624b\u518c\u4e0e\u4e0a\u4e0b\u6587</a>\u3002</p><p>\u672c\u9875\u5f00\u5934\u7684\u4e2d\u6587\u8bf4\u660e\u4e3a PG.CENTER \u5bf9\u7f16\u8f91\u8bf4\u660e\u7684\u7ffb\u8bd1\uff1b\u624b\u518c\u8282\u9009\u4fdd\u7559\u5bf9\u5e94\u7248\u672c\u4e2d\u6587\u6587\u6863\u539f\u6587\u3002\u6e90\u7801\u4fe1\u606f\u53ca\u624b\u518c\u793a\u4f8b\u4e0d\u4ee3\u8868\u91cd\u65b0\u8fdb\u884c\u8fc7\u8fd0\u884c\u6d4b\u8bd5\u3002</p>"}, "summary": "\u5bf9\u5404\u5b50\u8ba1\u5212\u751f\u6210\u7684\u4f4d\u56fe\u6c42\u5e76\u96c6\u3002", "version": "18", "link_map": {"/zh/docs/18/pgtesttiming.html": "/docs/18/pgtesttiming.html", "/zh/docs/18/using-explain.html#USING-EXPLAIN-CAVEATS": "/docs/18/using-explain.html#USING-EXPLAIN-CAVEATS"}, "body_html": "<p>\u5bf9\u5404\u5b50\u8ba1\u5212\u751f\u6210\u7684\u4f4d\u56fe\u6c42\u5e76\u96c6\u3002</p><p>\u6838\u5fc3\u8282\u70b9\u6807\u8bc6\uff1a<code>T_BitmapOr</code>\uff1bEXPLAIN \u540d\u79f0\uff1a<code>BitmapOr</code>\u3002</p><p>\u672c\u7248\u672c\u6e90\u7801\u4e2d\u7684\u5e76\u884c\u6267\u884c\u6216\u89c2\u6d4b\u56de\u8c03\uff1a\u8be5\u8282\u70b9\u5b9e\u73b0\u4e2d\u672a\u63d0\u53d6\u5230\u6b64\u7c7b\u56de\u8c03\u3002\u56de\u8c03\u7684\u5b58\u5728\u4e0d\u8868\u793a\u8be5\u8282\u70b9\u5fc5\u7136\u652f\u6301\u5171\u4eab\u5e76\u884c\u626b\u63cf\uff1b\u5728\u5e76\u884c\u5de5\u4f5c\u8fdb\u7a0b\u4e2d\u6267\u884c\u4e5f\u4e0d\u7b49\u4e8e\u5177\u6709\u5e76\u884c\u611f\u77e5\u80fd\u529b\u3002</p><h3>\u540c\u7248\u672c\u4e2d\u6587\u624b\u518c\u8282\u9009</h3><p>\n<code>EXPLAIN ANALYZE</code> \u6d4b\u5f97\u7684\u8fd0\u884c\u65f6\u95f4\uff0c\u53ef\u80fd\u4ee5\u4e24\u79cd\u91cd\u8981\u65b9\u5f0f\u504f\u79bb\u540c\u4e00\u67e5\u8be2\u7684\u6b63\u5e38\u6267\u884c\u65f6\u95f4\u3002\u7b2c\u4e00\uff0c\u7531\u4e8e\u4e0d\u4f1a\u5411\u5ba2\u6237\u7aef\u4f20\u9012\u4efb\u4f55\u8f93\u51fa\u884c\uff0c\u56e0\u6b64\u7f51\u7edc\u4f20\u8f93\u5f00\u9500\u4e0d\u4f1a\u88ab\u8ba1\u5165\u3002\u9664\u975e\u6307\u5b9a\u4e86 <code>SERIALIZE</code>\uff0cI/O \u8f6c\u6362\u5f00\u9500\u540c\u6837\u4e5f\u4e0d\u4f1a\u88ab\u8ba1\u5165\u3002\u7b2c\u4e8c\uff0c<code>EXPLAIN ANALYZE</code> \u9644\u52a0\u7684\u6d4b\u91cf\u5f00\u9500\u672c\u8eab\u53ef\u80fd\u76f8\u5f53\u53ef\u89c2\uff0c\u5c24\u5176\u662f\u5728\u64cd\u4f5c\u7cfb\u7edf\u8c03\u7528 <code>gettimeofday()</code> \u8f83\u6162\u7684\u673a\u5668\u4e0a\u3002\u53ef\u4ee5\u4f7f\u7528 <a href=\"/zh/docs/18/pgtesttiming.html\" rel=\"nofollow\"><span><span>pg_test_timing</span></span></a> \u5de5\u5177\u6765\u6d4b\u91cf\u7cfb\u7edf\u4e0a\u7684\u8ba1\u65f6\u5f00\u9500\u3002\n   </p><p>\n    \u4e0d\u5e94\u5c06 <code>EXPLAIN</code> \u7ed3\u679c\u5916\u63a8\u5230\u4e0e\u5b9e\u9645\u6d4b\u8bd5\u573a\u666f\u5dee\u5f02\u5f88\u5927\u7684\u60c5\u51b5\u3002\u4f8b\u5982\uff0c\u5728\u4e00\u4e2a\u5f88\u5c0f\u7684\u8868\u4e0a\u5f97\u5230\u7684\u7ed3\u679c\uff0c\u4e0d\u80fd\u5047\u5b9a\u4e5f\u9002\u7528\u4e8e\u5927\u578b\u8868\u3002\u89c4\u5212\u5668\u7684\u4ee3\u4ef7\u4f30\u8ba1\u4e0d\u662f\u7ebf\u6027\u7684\uff0c\u56e0\u6b64\u5b83\u53ef\u80fd\u4f1a\u4e3a\u66f4\u5927\u6216\u66f4\u5c0f\u7684\u8868\u9009\u62e9\u4e0d\u540c\u7684\u8ba1\u5212\u3002\u4e00\u4e2a\u6781\u7aef\u793a\u4f8b\u662f\uff1a\u5bf9\u4e8e\u53ea\u5360\u7528\u4e00\u4e2a\u78c1\u76d8\u9875\u7684\u8868\uff0c\u65e0\u8bba\u7d22\u5f15\u662f\u5426\u53ef\u7528\uff0c\u51e0\u4e4e\u603b\u4f1a\u5f97\u5230\u987a\u5e8f\u626b\u63cf\u8ba1\u5212\u3002\u89c4\u5212\u5668\u8ba4\u8bc6\u5230\uff0c\u65e0\u8bba\u5982\u4f55\u5904\u7406\u8be5\u8868\u90fd\u9700\u8981\u4e00\u6b21\u78c1\u76d8\u9875\u8bfb\u53d6\uff0c\u56e0\u6b64\u518d\u989d\u5916\u8bfb\u53d6\u9875\u9762\u53bb\u67e5\u770b\u7d22\u5f15\u5e76\u6ca1\u6709\u4ef7\u503c\u3002\uff08\u524d\u9762\u7684 <code>polygon_tbl</code> \u793a\u4f8b\u5df2\u7ecf\u5c55\u793a\u8fc7\u8fd9\u79cd\u60c5\u51b5\u3002\uff09\n   </p><p>\n    \u5728\u67d0\u4e9b\u60c5\u51b5\u4e0b\uff0c\u5b9e\u9645\u503c\u548c\u4f30\u8ba1\u503c\u4e0d\u4f1a\u5f88\u597d\u5730\u5bf9\u5e94\uff0c\u4f46\u8fd9\u5e76\u4e0d\u8868\u793a\u51fa\u73b0\u4e86\u95ee\u9898\u3002\u5176\u4e2d\u4e00\u79cd\u60c5\u51b5\u662f\uff0c\u8ba1\u5212\u8282\u70b9\u7684\u6267\u884c\u4f1a\u88ab <code>LIMIT</code> \u6216\u7c7b\u4f3c\u6548\u679c\u63d0\u524d\u622a\u65ad\u3002\u4f8b\u5982\uff0c\u5728\u524d\u9762\u7528\u8fc7\u7684 <code>LIMIT</code> \u67e5\u8be2\u4e2d\uff1a\n\n</p><p>\n\n    Index Scan \u8282\u70b9\u7684\u4f30\u8ba1\u4ee3\u4ef7\u548c\u884c\u8ba1\u6570\u663e\u793a\u5f97\u50cf\u662f\u5b83\u4f1a\u8fd0\u884c\u5230\u7ed3\u675f\u4e00\u6837\u3002\u4f46\u5b9e\u9645\u4e0a\uff0cLimit \u8282\u70b9\u5728\u62ff\u5230\u4e24\u884c\u4e4b\u540e\u5c31\u505c\u6b62\u8bf7\u6c42\u66f4\u591a\u884c\uff0c\u56e0\u6b64\u5b9e\u9645\u884c\u8ba1\u6570\u53ea\u6709 2\uff0c\u8fd0\u884c\u65f6\u95f4\u4e5f\u4f4e\u4e8e\u4ee3\u4ef7\u4f30\u8ba1\u6240\u6697\u793a\u7684\u6c34\u5e73\u3002\u8fd9\u5e76\u4e0d\u662f\u4f30\u8ba1\u9519\u8bef\uff0c\u53ea\u662f\u4f30\u8ba1\u503c\u4e0e\u771f\u5b9e\u503c\u7684\u663e\u793a\u65b9\u5f0f\u4e0d\u540c\u800c\u5df2\u3002\n   </p><p><a href=\"/zh/docs/18/using-explain.html#USING-EXPLAIN-CAVEATS\" rel=\"nofollow\">\u67e5\u770b\u5b8c\u6574\u4e2d\u6587\u624b\u518c\u4e0e\u4e0a\u4e0b\u6587</a>\u3002</p><p>\u672c\u9875\u5f00\u5934\u7684\u4e2d\u6587\u8bf4\u660e\u4e3a PG.CENTER \u5bf9\u7f16\u8f91\u8bf4\u660e\u7684\u7ffb\u8bd1\uff1b\u624b\u518c\u8282\u9009\u4fdd\u7559\u5bf9\u5e94\u7248\u672c\u4e2d\u6587\u6587\u6863\u539f\u6587\u3002\u6e90\u7801\u4fe1\u606f\u53ca\u624b\u518c\u793a\u4f8b\u4e0d\u4ee3\u8868\u91cd\u65b0\u8fdb\u884c\u8fc7\u8fd0\u884c\u6d4b\u8bd5\u3002</p>", "body_sha256": "a85c98c108dd0a6d20ad2a0cc957445b7b345e7b52b6abc55c73b047fc6bd771", "content_hash": "f8d78c3bdfda27d2cc2ca9143972699fbb0d6b91be2489b419984d0e16d7a1ba", "source_database": "center", "source_revision": "555610c24d53e4316da5b7d3fc25c279d96856d5e0e23ee308c328c5fa881d9f"}, "tables_zh": [{"key": "explain-labels", "rows": [{"label": "BitmapOr", "identity": "BitmapOr"}], "title": "\u672c\u6784\u5efa\u4e2d\u7684 EXPLAIN \u6807\u7b7e", "columns": [{"key": "label", "label": "\u6587\u672c\u683c\u5f0f\u6807\u7b7e"}, {"key": "identity", "label": "\u7ed3\u6784\u5316\u8282\u70b9\u6807\u8bc6"}]}], "strategies": [], "description": ["\u5bf9\u5404\u5b50\u8ba1\u5212\u751f\u6210\u7684\u4f4d\u56fe\u6c42\u5e76\u96c6\u3002"], "sections_zh": [{"title": "EXPLAIN \u540d\u79f0\u4e0e\u5c5e\u6027", "paragraphs": ["\u7ed3\u6784\u5316\u683c\u5f0f\u4f7f\u7528\u4e0a\u8ff0 Node Type\u3002\u6587\u672c\u683c\u5f0f\u540d\u79f0\u8fd8\u53ef\u80fd\u5305\u542b\u64cd\u4f5c\u3001\u7b56\u7565\u3001\u8fde\u63a5\u7c7b\u578b\u3001\u626b\u63cf\u65b9\u5411\u6216\u805a\u5408\u9636\u6bb5\u5c5e\u6027\u3002", "\u6b64\u6e90\u7801\u8bb0\u5f55\u7684\u6587\u672c\u540d\u79f0\uff1aBitmapOr.", "\u5e76\u884c\u611f\u77e5\u4e0e\u5e76\u884c\u5b89\u5168\u662f\u4e0d\u540c\u7684\u8ba1\u5212\u5c5e\u6027\u3002\u5728\u5e76\u884c\u5de5\u4f5c\u8fdb\u7a0b\u5185\u8fd0\u884c\u7684\u8282\u70b9\u4e0d\u4e00\u5b9a\u662f\u5e76\u884c\u611f\u77e5\u8282\u70b9\u3002"]}, {"title": "\u5185\u5b58\u4e0e\u4e34\u65f6\u5b58\u50a8", "paragraphs": ["\u6b64\u8282\u70b9\u6309\u57fa\u4e8e work_mem \u7684\u9884\u7b97\u5206\u914d\u5143\u7ec4\u4f4d\u7f6e\u4f4d\u56fe\u3002\u4f4d\u56fe\u53ef\u4ee5\u4fdd\u7559\u9875\u7ea7\u6709\u635f\u6761\u76ee\uff0c\u800c\u4e0d\u8bb0\u5f55\u6bcf\u4e2a\u5143\u7ec4\u4f4d\u7f6e\uff0c\u56e0\u6b64\u4ecd\u53ef\u80fd\u9700\u8981\u5806\u91cd\u68c0\u3002"]}, {"title": "\u5e76\u884c\u6267\u884c\u4e0e\u8fd0\u884c\u4fe1\u606f\u91c7\u96c6", "paragraphs": ["\u4ee5\u4e0b\u6e90\u7801\u56de\u8c03\u53ef\u4ee5\u534f\u8c03\u6267\u884c\u6216\u6536\u96c6\u5de5\u4f5c\u8fdb\u7a0b\u7684\u6d4b\u91cf\u6570\u636e\u3002\u56de\u8c03\u5b58\u5728\u4e0d\u4ee3\u8868\u8be5\u8282\u70b9\u666e\u904d\u652f\u6301\u5171\u4eab\u5e76\u884c\u626b\u63cf\u6216\u5171\u4eab\u72b6\u6001\u3002", "\u6b64\u6784\u5efa\u7684\u56de\u8c03\uff1anone extracted from this node implementation."]}, {"title": "\u540c\u7248\u672c\u624b\u518c\u8bf4\u660e", "paragraphs": ["\u7531\u4e8e\u5b9e\u73b0\u4e0a\u7684\u9650\u5236\uff0cBitmapAnd \u548c BitmapOr \u8282\u70b9\u62a5\u544a\u7684\u5b9e\u9645\u884c\u6570\u59cb\u7ec8\u4e3a\u96f6\u3002"]}, {"title": "\u6267\u884c\u5668\u5b9e\u73b0\u8bf4\u660e", "paragraphs": ["\u8bf4\u660e\uff1aBitmapOr \u4e0d\u4f7f\u7528\u5de6\u53f3\u5b50\u6811\uff0c\u800c\u50cf Append \u4e00\u6837\u7ef4\u62a4\u5b50\u8ba1\u5212\u5217\u8868\u3002\u4e0d\u8fc7\u5176\u903b\u8f91\u6bd4 Append \u7b80\u5355\u5f97\u591a\uff0c\u56e0\u4e3a\u65e0\u9700\u5904\u7406\u6b63\u5411\u6216\u53cd\u5411\u6267\u884c\u3002", "\u5bf9\u6bcf\u4e2a\u5f85\u6267\u884c\u8ba1\u5212\u8c03\u7528 ExecInitNode\uff0c\u5e76\u5c06\u7ed3\u679c\u4fdd\u5b58\u5230 bitmapplanstates \u6570\u7ec4\u3002", "BitmapOr \u8ba1\u5212\u6ca1\u6709\u8868\u8fbe\u5f0f\u4e0a\u4e0b\u6587\uff0c\u56e0\u4e3a\u5b83\u4eec\u4ece\u4e0d\u8c03\u7528 ExecQual \u6216 ExecProject\uff0c\u4e5f\u4e0d\u9700\u8981\u5143\u7ec4\u69fd\u3002", "\u53ef\u5bf9 BitmapIndexScan \u5b50\u8282\u70b9\u4f5c\u7279\u6b8a\u5904\u7406\uff0c\u907f\u514d\u4e3a\u6bcf\u4e2a\u5b50\u8282\u70b9\u663e\u5f0f\u8c03\u7528 tbm_union\uff1a\u76f4\u63a5\u4e0b\u4f20\u5f53\u524d\u7ed3\u679c\u4f4d\u56fe\uff0c\u8ba9\u5b50\u8282\u70b9\u5c06\u7ed3\u679c\u6309\u4f4d OR \u5408\u5e76\u8fdb\u53bb\u3002", "ExecReScan \u4e0d\u77e5\u9053\u5f53\u524d\u8282\u70b9\u7684\u5b50\u8ba1\u5212\uff0c\u56e0\u6b64\u5fc5\u987b\u81ea\u884c\u901a\u77e5\u5b50\u8ba1\u5212\u54ea\u4e9b\u53c2\u6570\u53d1\u751f\u4e86\u53d8\u5316\u3002"]}, {"code": "case T_BitmapOr:\n\t\t\tpname = sname = \"BitmapOr\";\n\t\t\tbreak;", "title": "\u6838\u5fc3\u6e90\u7801\u4e2d\u7684 EXPLAIN \u6807\u8bc6"}], "localization": {"status": "complete", "sources": [], "language": "zh", "original_text": {"/versions/18/description/0": "Unions bitmaps produced by its child plans.", "/versions/18/facts/0/label": "Core node tag", "/versions/18/facts/1/label": "Structured EXPLAIN Node Type", "/versions/18/facts/2/label": "Inputs", "/versions/18/facts/2/value": "Bitmap-producing child plans", "/versions/18/facts/3/label": "Output", "/versions/18/facts/3/value": "Tuple-location bitmap, not a tuple stream", "/versions/18/facts/4/label": "Executor initializer", "/versions/18/facts/5/label": "Memory mechanism", "/versions/18/tables/0/title": "EXPLAIN labels in this source build", "/versions/18/related/1/label": "Using EXPLAIN", "/versions/18/related/2/label": "Parallel plans", "/versions/18/sections/0/title": "EXPLAIN names and attributes", "/versions/18/sections/1/title": "Memory and temporary storage", "/versions/18/sections/2/title": "Parallel execution and instrumentation", "/versions/18/sections/3/title": "Same-version manual discussion", "/versions/18/sections/4/title": "Executor implementation notes", "/versions/18/sections/5/title": "EXPLAIN identity in core source", "/versions/18/memory/description": "The node allocates a tuple-location bitmap using a work_mem-derived budget. A bitmap can retain page-level lossy entries instead of every tuple location; heap rechecks then remain necessary.", "/versions/18/sections/0/paragraphs/0": "Structured formats use the Node Type above. Text-format spellings can also include operation, strategy, join type, scan direction or aggregation-stage attributes.", "/versions/18/sections/0/paragraphs/1": "Text names recorded by this source: BitmapOr.", "/versions/18/sections/0/paragraphs/2": "Parallel-aware and parallel-safe are different plan properties. A node running inside a parallel worker is not necessarily a parallel-aware node.", "/versions/18/sections/1/paragraphs/0": "The node allocates a tuple-location bitmap using a work_mem-derived budget. A bitmap can retain page-level lossy entries instead of every tuple location; heap rechecks then remain necessary.", "/versions/18/sections/2/paragraphs/0": "The source callbacks below can coordinate execution or collect worker instrumentation. Their presence is not a blanket claim that this node supports a shared parallel scan or shared state.", "/versions/18/sections/2/paragraphs/1": "Callbacks in this build: none extracted from this node implementation.", "/versions/18/sections/3/paragraphs/0": "BitmapAnd and BitmapOr nodes always report their actual row counts as zero, due to implementation limitations.", "/versions/18/sections/4/paragraphs/0": "NOTES BitmapOr nodes don't make use of their left and right subtrees, rather they maintain a list of subplans, much like Append nodes. The logic is much simpler than Append, however, since we needn't cope with forward/backward execution.", "/versions/18/sections/4/paragraphs/1": "call ExecInitNode on each of the plans to be executed and save the results into the array \"bitmapplanstates\".", "/versions/18/sections/4/paragraphs/2": "BitmapOr plans don't have expression contexts because they never call ExecQual or ExecProject. They don't need any tuple slots either.", "/versions/18/sections/4/paragraphs/3": "We can special-case BitmapIndexScan children to avoid an explicit tbm_union step for each child: just pass down the current result bitmap and let the child OR directly into it.", "/versions/18/sections/4/paragraphs/4": "ExecReScan doesn't know about my subplans, so I have to do changed-parameter signaling myself.", "/versions/18/tables/0/columns/0/label": "Text-format label", "/versions/18/tables/0/columns/1/label": "Structured node identity"}, "fallback_fields": [], "source_language": "en", "original_snapshot_sha256": "6555fae880f7d80cecb472ac63d57e5c11bc60d158b34b99d1d8c4be9c3c8829", "canonical_center_text_hash": "f8d78c3bdfda27d2cc2ca9143972699fbb0d6b91be2489b419984d0e16d7a1ba"}, "evidence_kind": "source and documentation", "explain_names": ["BitmapOr"], "partial_modes": [], "description_zh": "\u5bf9\u5404\u5b50\u8ba1\u5212\u751f\u6210\u7684\u4f4d\u56fe\u6c42\u5e76\u96c6\u3002", "comparison_data": {"node_tag": "T_BitmapOr", "strategies": [], "text_names": ["BitmapOr"], "initializer": "ExecInitBitmapOr", "partial_modes": [], "memory_mechanism": "bitmap-lossification", "parallel_callbacks": []}, "comparison_hash": "c0ca503a6029c37ec720213dcdc3094997eb194d4920da68f94a7420d3e8f1d2", "manual_language": "zh", "explain_prefixes": ["Parallel", "Async"], "runtime_verified": false, "source_inventory": {"explain": "src/backend/commands/explain.c", "executor": "src/backend/executor/execProcnode.c", "implementation": "src/backend/executor/nodeBitmapOr.c"}, "parallel_callbacks": [], "description_zh_html": "<p>\u5bf9\u5404\u5b50\u8ba1\u5212\u751f\u6210\u7684\u4f4d\u56fe\u6c42\u5e76\u96c6\u3002</p><p>\u6838\u5fc3\u8282\u70b9\u6807\u8bc6\uff1a<code>T_BitmapOr</code>\uff1bEXPLAIN \u540d\u79f0\uff1a<code>BitmapOr</code>\u3002</p><p>\u672c\u7248\u672c\u6e90\u7801\u4e2d\u7684\u5e76\u884c\u6267\u884c\u6216\u89c2\u6d4b\u56de\u8c03\uff1a\u8be5\u8282\u70b9\u5b9e\u73b0\u4e2d\u672a\u63d0\u53d6\u5230\u6b64\u7c7b\u56de\u8c03\u3002\u56de\u8c03\u7684\u5b58\u5728\u4e0d\u8868\u793a\u8be5\u8282\u70b9\u5fc5\u7136\u652f\u6301\u5171\u4eab\u5e76\u884c\u626b\u63cf\uff1b\u5728\u5e76\u884c\u5de5\u4f5c\u8fdb\u7a0b\u4e2d\u6267\u884c\u4e5f\u4e0d\u7b49\u4e8e\u5177\u6709\u5e76\u884c\u611f\u77e5\u80fd\u529b\u3002</p><h3>\u540c\u7248\u672c\u4e2d\u6587\u624b\u518c\u8282\u9009</h3><p>\n<code>EXPLAIN ANALYZE</code> \u6d4b\u5f97\u7684\u8fd0\u884c\u65f6\u95f4\uff0c\u53ef\u80fd\u4ee5\u4e24\u79cd\u91cd\u8981\u65b9\u5f0f\u504f\u79bb\u540c\u4e00\u67e5\u8be2\u7684\u6b63\u5e38\u6267\u884c\u65f6\u95f4\u3002\u7b2c\u4e00\uff0c\u7531\u4e8e\u4e0d\u4f1a\u5411\u5ba2\u6237\u7aef\u4f20\u9012\u4efb\u4f55\u8f93\u51fa\u884c\uff0c\u56e0\u6b64\u7f51\u7edc\u4f20\u8f93\u5f00\u9500\u4e0d\u4f1a\u88ab\u8ba1\u5165\u3002\u9664\u975e\u6307\u5b9a\u4e86 <code>SERIALIZE</code>\uff0cI/O \u8f6c\u6362\u5f00\u9500\u540c\u6837\u4e5f\u4e0d\u4f1a\u88ab\u8ba1\u5165\u3002\u7b2c\u4e8c\uff0c<code>EXPLAIN ANALYZE</code> \u9644\u52a0\u7684\u6d4b\u91cf\u5f00\u9500\u672c\u8eab\u53ef\u80fd\u76f8\u5f53\u53ef\u89c2\uff0c\u5c24\u5176\u662f\u5728\u64cd\u4f5c\u7cfb\u7edf\u8c03\u7528 <code>gettimeofday()</code> \u8f83\u6162\u7684\u673a\u5668\u4e0a\u3002\u53ef\u4ee5\u4f7f\u7528 <a href=\"/zh/docs/18/pgtesttiming.html\" rel=\"nofollow\"><span><span>pg_test_timing</span></span></a> \u5de5\u5177\u6765\u6d4b\u91cf\u7cfb\u7edf\u4e0a\u7684\u8ba1\u65f6\u5f00\u9500\u3002\n   </p><p>\n    \u4e0d\u5e94\u5c06 <code>EXPLAIN</code> \u7ed3\u679c\u5916\u63a8\u5230\u4e0e\u5b9e\u9645\u6d4b\u8bd5\u573a\u666f\u5dee\u5f02\u5f88\u5927\u7684\u60c5\u51b5\u3002\u4f8b\u5982\uff0c\u5728\u4e00\u4e2a\u5f88\u5c0f\u7684\u8868\u4e0a\u5f97\u5230\u7684\u7ed3\u679c\uff0c\u4e0d\u80fd\u5047\u5b9a\u4e5f\u9002\u7528\u4e8e\u5927\u578b\u8868\u3002\u89c4\u5212\u5668\u7684\u4ee3\u4ef7\u4f30\u8ba1\u4e0d\u662f\u7ebf\u6027\u7684\uff0c\u56e0\u6b64\u5b83\u53ef\u80fd\u4f1a\u4e3a\u66f4\u5927\u6216\u66f4\u5c0f\u7684\u8868\u9009\u62e9\u4e0d\u540c\u7684\u8ba1\u5212\u3002\u4e00\u4e2a\u6781\u7aef\u793a\u4f8b\u662f\uff1a\u5bf9\u4e8e\u53ea\u5360\u7528\u4e00\u4e2a\u78c1\u76d8\u9875\u7684\u8868\uff0c\u65e0\u8bba\u7d22\u5f15\u662f\u5426\u53ef\u7528\uff0c\u51e0\u4e4e\u603b\u4f1a\u5f97\u5230\u987a\u5e8f\u626b\u63cf\u8ba1\u5212\u3002\u89c4\u5212\u5668\u8ba4\u8bc6\u5230\uff0c\u65e0\u8bba\u5982\u4f55\u5904\u7406\u8be5\u8868\u90fd\u9700\u8981\u4e00\u6b21\u78c1\u76d8\u9875\u8bfb\u53d6\uff0c\u56e0\u6b64\u518d\u989d\u5916\u8bfb\u53d6\u9875\u9762\u53bb\u67e5\u770b\u7d22\u5f15\u5e76\u6ca1\u6709\u4ef7\u503c\u3002\uff08\u524d\u9762\u7684 <code>polygon_tbl</code> \u793a\u4f8b\u5df2\u7ecf\u5c55\u793a\u8fc7\u8fd9\u79cd\u60c5\u51b5\u3002\uff09\n   </p><p>\n    \u5728\u67d0\u4e9b\u60c5\u51b5\u4e0b\uff0c\u5b9e\u9645\u503c\u548c\u4f30\u8ba1\u503c\u4e0d\u4f1a\u5f88\u597d\u5730\u5bf9\u5e94\uff0c\u4f46\u8fd9\u5e76\u4e0d\u8868\u793a\u51fa\u73b0\u4e86\u95ee\u9898\u3002\u5176\u4e2d\u4e00\u79cd\u60c5\u51b5\u662f\uff0c\u8ba1\u5212\u8282\u70b9\u7684\u6267\u884c\u4f1a\u88ab <code>LIMIT</code> \u6216\u7c7b\u4f3c\u6548\u679c\u63d0\u524d\u622a\u65ad\u3002\u4f8b\u5982\uff0c\u5728\u524d\u9762\u7528\u8fc7\u7684 <code>LIMIT</code> \u67e5\u8be2\u4e2d\uff1a\n\n</p><p>\n\n    Index Scan \u8282\u70b9\u7684\u4f30\u8ba1\u4ee3\u4ef7\u548c\u884c\u8ba1\u6570\u663e\u793a\u5f97\u50cf\u662f\u5b83\u4f1a\u8fd0\u884c\u5230\u7ed3\u675f\u4e00\u6837\u3002\u4f46\u5b9e\u9645\u4e0a\uff0cLimit \u8282\u70b9\u5728\u62ff\u5230\u4e24\u884c\u4e4b\u540e\u5c31\u505c\u6b62\u8bf7\u6c42\u66f4\u591a\u884c\uff0c\u56e0\u6b64\u5b9e\u9645\u884c\u8ba1\u6570\u53ea\u6709 2\uff0c\u8fd0\u884c\u65f6\u95f4\u4e5f\u4f4e\u4e8e\u4ee3\u4ef7\u4f30\u8ba1\u6240\u6697\u793a\u7684\u6c34\u5e73\u3002\u8fd9\u5e76\u4e0d\u662f\u4f30\u8ba1\u9519\u8bef\uff0c\u53ea\u662f\u4f30\u8ba1\u503c\u4e0e\u771f\u5b9e\u503c\u7684\u663e\u793a\u65b9\u5f0f\u4e0d\u540c\u800c\u5df2\u3002\n   </p><p><a href=\"/zh/docs/18/using-explain.html#USING-EXPLAIN-CAVEATS\" rel=\"nofollow\">\u67e5\u770b\u5b8c\u6574\u4e2d\u6587\u624b\u518c\u4e0e\u4e0a\u4e0b\u6587</a>\u3002</p><p>\u672c\u9875\u5f00\u5934\u7684\u4e2d\u6587\u8bf4\u660e\u4e3a PG.CENTER \u5bf9\u7f16\u8f91\u8bf4\u660e\u7684\u7ffb\u8bd1\uff1b\u624b\u518c\u8282\u9009\u4fdd\u7559\u5bf9\u5e94\u7248\u672c\u4e2d\u6587\u6587\u6863\u539f\u6587\u3002\u6e90\u7801\u4fe1\u606f\u53ca\u624b\u518c\u793a\u4f8b\u4e0d\u4ee3\u8868\u91cd\u65b0\u8fdb\u884c\u8fc7\u8fd0\u884c\u6d4b\u8bd5\u3002</p>", "center_zh_rendered": "<p>\u5bf9\u5404\u5b50\u8ba1\u5212\u751f\u6210\u7684\u4f4d\u56fe\u6c42\u5e76\u96c6\u3002</p><p>\u6838\u5fc3\u8282\u70b9\u6807\u8bc6\uff1a<code>T_BitmapOr</code>\uff1bEXPLAIN \u540d\u79f0\uff1a<code>BitmapOr</code>\u3002</p><p>\u672c\u7248\u672c\u6e90\u7801\u4e2d\u7684\u5e76\u884c\u6267\u884c\u6216\u89c2\u6d4b\u56de\u8c03\uff1a\u8be5\u8282\u70b9\u5b9e\u73b0\u4e2d\u672a\u63d0\u53d6\u5230\u6b64\u7c7b\u56de\u8c03\u3002\u56de\u8c03\u7684\u5b58\u5728\u4e0d\u8868\u793a\u8be5\u8282\u70b9\u5fc5\u7136\u652f\u6301\u5171\u4eab\u5e76\u884c\u626b\u63cf\uff1b\u5728\u5e76\u884c\u5de5\u4f5c\u8fdb\u7a0b\u4e2d\u6267\u884c\u4e5f\u4e0d\u7b49\u4e8e\u5177\u6709\u5e76\u884c\u611f\u77e5\u80fd\u529b\u3002</p><h3>\u540c\u7248\u672c\u4e2d\u6587\u624b\u518c\u8282\u9009</h3><p>\n<code>EXPLAIN ANALYZE</code> \u6d4b\u5f97\u7684\u8fd0\u884c\u65f6\u95f4\uff0c\u53ef\u80fd\u4ee5\u4e24\u79cd\u91cd\u8981\u65b9\u5f0f\u504f\u79bb\u540c\u4e00\u67e5\u8be2\u7684\u6b63\u5e38\u6267\u884c\u65f6\u95f4\u3002\u7b2c\u4e00\uff0c\u7531\u4e8e\u4e0d\u4f1a\u5411\u5ba2\u6237\u7aef\u4f20\u9012\u4efb\u4f55\u8f93\u51fa\u884c\uff0c\u56e0\u6b64\u7f51\u7edc\u4f20\u8f93\u5f00\u9500\u4e0d\u4f1a\u88ab\u8ba1\u5165\u3002\u9664\u975e\u6307\u5b9a\u4e86 <code>SERIALIZE</code>\uff0cI/O \u8f6c\u6362\u5f00\u9500\u540c\u6837\u4e5f\u4e0d\u4f1a\u88ab\u8ba1\u5165\u3002\u7b2c\u4e8c\uff0c<code>EXPLAIN ANALYZE</code> \u9644\u52a0\u7684\u6d4b\u91cf\u5f00\u9500\u672c\u8eab\u53ef\u80fd\u76f8\u5f53\u53ef\u89c2\uff0c\u5c24\u5176\u662f\u5728\u64cd\u4f5c\u7cfb\u7edf\u8c03\u7528 <code>gettimeofday()</code> \u8f83\u6162\u7684\u673a\u5668\u4e0a\u3002\u53ef\u4ee5\u4f7f\u7528 <a href=\"/docs/18/pgtesttiming.html\"><span><span>pg_test_timing</span></span></a> \u5de5\u5177\u6765\u6d4b\u91cf\u7cfb\u7edf\u4e0a\u7684\u8ba1\u65f6\u5f00\u9500\u3002\n   </p><p>\n    \u4e0d\u5e94\u5c06 <code>EXPLAIN</code> \u7ed3\u679c\u5916\u63a8\u5230\u4e0e\u5b9e\u9645\u6d4b\u8bd5\u573a\u666f\u5dee\u5f02\u5f88\u5927\u7684\u60c5\u51b5\u3002\u4f8b\u5982\uff0c\u5728\u4e00\u4e2a\u5f88\u5c0f\u7684\u8868\u4e0a\u5f97\u5230\u7684\u7ed3\u679c\uff0c\u4e0d\u80fd\u5047\u5b9a\u4e5f\u9002\u7528\u4e8e\u5927\u578b\u8868\u3002\u89c4\u5212\u5668\u7684\u4ee3\u4ef7\u4f30\u8ba1\u4e0d\u662f\u7ebf\u6027\u7684\uff0c\u56e0\u6b64\u5b83\u53ef\u80fd\u4f1a\u4e3a\u66f4\u5927\u6216\u66f4\u5c0f\u7684\u8868\u9009\u62e9\u4e0d\u540c\u7684\u8ba1\u5212\u3002\u4e00\u4e2a\u6781\u7aef\u793a\u4f8b\u662f\uff1a\u5bf9\u4e8e\u53ea\u5360\u7528\u4e00\u4e2a\u78c1\u76d8\u9875\u7684\u8868\uff0c\u65e0\u8bba\u7d22\u5f15\u662f\u5426\u53ef\u7528\uff0c\u51e0\u4e4e\u603b\u4f1a\u5f97\u5230\u987a\u5e8f\u626b\u63cf\u8ba1\u5212\u3002\u89c4\u5212\u5668\u8ba4\u8bc6\u5230\uff0c\u65e0\u8bba\u5982\u4f55\u5904\u7406\u8be5\u8868\u90fd\u9700\u8981\u4e00\u6b21\u78c1\u76d8\u9875\u8bfb\u53d6\uff0c\u56e0\u6b64\u518d\u989d\u5916\u8bfb\u53d6\u9875\u9762\u53bb\u67e5\u770b\u7d22\u5f15\u5e76\u6ca1\u6709\u4ef7\u503c\u3002\uff08\u524d\u9762\u7684 <code>polygon_tbl</code> \u793a\u4f8b\u5df2\u7ecf\u5c55\u793a\u8fc7\u8fd9\u79cd\u60c5\u51b5\u3002\uff09\n   </p><p>\n    \u5728\u67d0\u4e9b\u60c5\u51b5\u4e0b\uff0c\u5b9e\u9645\u503c\u548c\u4f30\u8ba1\u503c\u4e0d\u4f1a\u5f88\u597d\u5730\u5bf9\u5e94\uff0c\u4f46\u8fd9\u5e76\u4e0d\u8868\u793a\u51fa\u73b0\u4e86\u95ee\u9898\u3002\u5176\u4e2d\u4e00\u79cd\u60c5\u51b5\u662f\uff0c\u8ba1\u5212\u8282\u70b9\u7684\u6267\u884c\u4f1a\u88ab <code>LIMIT</code> \u6216\u7c7b\u4f3c\u6548\u679c\u63d0\u524d\u622a\u65ad\u3002\u4f8b\u5982\uff0c\u5728\u524d\u9762\u7528\u8fc7\u7684 <code>LIMIT</code> \u67e5\u8be2\u4e2d\uff1a\n\n</p><p>\n\n    Index Scan \u8282\u70b9\u7684\u4f30\u8ba1\u4ee3\u4ef7\u548c\u884c\u8ba1\u6570\u663e\u793a\u5f97\u50cf\u662f\u5b83\u4f1a\u8fd0\u884c\u5230\u7ed3\u675f\u4e00\u6837\u3002\u4f46\u5b9e\u9645\u4e0a\uff0cLimit \u8282\u70b9\u5728\u62ff\u5230\u4e24\u884c\u4e4b\u540e\u5c31\u505c\u6b62\u8bf7\u6c42\u66f4\u591a\u884c\uff0c\u56e0\u6b64\u5b9e\u9645\u884c\u8ba1\u6570\u53ea\u6709 2\uff0c\u8fd0\u884c\u65f6\u95f4\u4e5f\u4f4e\u4e8e\u4ee3\u4ef7\u4f30\u8ba1\u6240\u6697\u793a\u7684\u6c34\u5e73\u3002\u8fd9\u5e76\u4e0d\u662f\u4f30\u8ba1\u9519\u8bef\uff0c\u53ea\u662f\u4f30\u8ba1\u503c\u4e0e\u771f\u5b9e\u503c\u7684\u663e\u793a\u65b9\u5f0f\u4e0d\u540c\u800c\u5df2\u3002\n   </p><p><a href=\"/docs/18/using-explain.html#USING-EXPLAIN-CAVEATS\">\u67e5\u770b\u5b8c\u6574\u4e2d\u6587\u624b\u518c\u4e0e\u4e0a\u4e0b\u6587</a>\u3002</p><p>\u672c\u9875\u5f00\u5934\u7684\u4e2d\u6587\u8bf4\u660e\u4e3a PG.CENTER \u5bf9\u7f16\u8f91\u8bf4\u660e\u7684\u7ffb\u8bd1\uff1b\u624b\u518c\u8282\u9009\u4fdd\u7559\u5bf9\u5e94\u7248\u672c\u4e2d\u6587\u6587\u6863\u539f\u6587\u3002\u6e90\u7801\u4fe1\u606f\u53ca\u624b\u518c\u793a\u4f8b\u4e0d\u4ee3\u8868\u91cd\u65b0\u8fdb\u884c\u8fc7\u8fd0\u884c\u6d4b\u8bd5\u3002</p>"}, "comparison": {"left": "17", "right": "18", "status": "unchanged", "diff": ""}}