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Inspect the same-build implementation and its expressions or provider.", "/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: Merge Append.", "/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": "This extraction does not assign a universal memory limit or spill policy to this node. Inspect the same-build implementation and its expressions or provider.", "/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": "NOTES A MergeAppend node contains a list of one or more subplans. These are each expected to deliver tuples that are sorted according to a common sort key. The MergeAppend node merges these streams to produce output sorted the same way.", "/versions/10/sections/3/paragraphs/1": "MergeAppend nodes don't make use of their left and right subtrees, rather they maintain a list of subplans so a typical MergeAppend node looks like this in the plan tree:", "/versions/10/sections/3/paragraphs/3": "We have one slot for each item in the heap array. We use SlotNumber to store slot indexes. 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"source_hash": "617a30102327f61276ba77fb034f4bf1bbb677d91d4eb5507dc14d740e6394c9", "fragment_sha256": "a7b71780192bea8bfc169883aae459f6d32a71fe928f60388479827c9c8b54bc", "source_revision": "unknown:rendered-translation-baseline", "translation_revision": "snapshot:sha256:ef5c7bc074acae9795db16e6b7482aea3b222bd4bcce0f76831332b97a21e8a1", "translated_from_revision": null}, "body_sha256": "ca0f06d0c0c382b32b29e08db72ef3f7078e0b149a9d9e1ea2c76d54bbd43373", "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\uff1aMerge Append.", "\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": ["\u672c\u6b21\u62bd\u53d6\u4e0d\u4e3a\u6b64\u8282\u70b9\u8bbe\u5b9a\u7edf\u4e00\u7684\u5185\u5b58\u4e0a\u9650\u6216\u843d\u76d8\u7b56\u7565\u3002\u8bf7\u67e5\u770b\u540c\u4e00\u6784\u5efa\u7684\u5b9e\u73b0\u3001\u76f8\u5173\u8868\u8fbe\u5f0f\u6216\u63d0\u4f9b\u65b9\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": "\u6267\u884c\u5668\u5b9e\u73b0\u8bf4\u660e", "paragraphs": ["\u8bf4\u660e\uff1aMergeAppend \u5305\u542b\u4e00\u4e2a\u6216\u591a\u4e2a\u5b50\u8ba1\u5212\uff0c\u8981\u6c42\u5b83\u4eec\u6309\u540c\u4e00\u6392\u5e8f\u952e\u8f93\u51fa\u5143\u7ec4\u3002\u8be5\u8282\u70b9\u5f52\u5e76\u8fd9\u4e9b\u6d41\uff0c\u4ea7\u751f\u6309\u76f8\u540c\u987a\u5e8f\u6392\u5217\u7684\u8f93\u51fa\u3002", "MergeAppend \u8282\u70b9\u4e0d\u4f7f\u7528\u5de6\u53f3\u5b50\u6811\uff0c\u800c\u662f\u7ef4\u62a4\u4e00\u4e2a\u5b50\u8ba1\u5212\u5217\u8868\uff0c\u56e0\u6b64\u5178\u578b\u8282\u70b9\u5728\u8ba1\u5212\u6811\u4e2d\u7684\u5f62\u6001\u5982\u4e0b\uff1a", "... / MergeAppend---+------+------+--- nil / \\ | | | nil nil ... ... ... subplans", "\u5806\u6570\u7ec4\u7684\u6bcf\u4e2a\u5143\u7d20\u5bf9\u5e94\u4e00\u4e2a\u69fd\u4f4d\uff0c\u4f7f\u7528 SlotNumber \u5b58\u50a8\u69fd\u4f4d\u7d22\u5f15\u3002\u8fd9\u5e76\u4e0d\u771f\u6b63\u63d0\u4f9b\u7c7b\u578b\u5b89\u5168\uff0c\u4f46\u80fd\u4f7f\u4ee3\u7801\u542b\u4e49\u66f4\u6e05\u695a\u3002", "\u9501\u5b9a\u6b64\u8282\u70b9\u6240\u63a7\u5236\u5206\u533a\u6811\u4e2d\u7684\u975e\u53f6\u8868\u3002\u5bf9\u4e8e\u975e\u5206\u533a\u7236\u8868\uff0c\u6b64\u64cd\u4f5c\u4e0d\u6267\u884c\u4efb\u4f55\u5de5\u4f5c\u3002"]}, {"code": "case T_MergeAppend:\n\t\t\tpname = sname = \"Merge Append\";\n\t\t\tbreak;", "title": "\u6838\u5fc3\u6e90\u7801\u4e2d\u7684 EXPLAIN \u6807\u8bc6"}], "description_zh": "\u5408\u5e76\u5df2\u6392\u5e8f\u7684\u5b50\u8ba1\u5212\u8f93\u51fa\u5e76\u4fdd\u6301\u6240\u9700\u987a\u5e8f\u3002", "description_zh_html": "\u5408\u5e76\u5df2\u6392\u5e8f\u7684\u5b50\u8ba1\u5212\u8f93\u51fa\u5e76\u4fdd\u6301\u6240\u9700\u987a\u5e8f\u3002
\u6838\u5fc3\u8282\u70b9\u6807\u8bc6\uff1aT_MergeAppend\uff1bEXPLAIN \u540d\u79f0\uff1aMerge Append\u3002
\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
\nPostgreSQL \u4f1a\u4e3a\u6536\u5230\u7684\u6bcf\u4e2a\u67e5\u8be2\u5236\u5b9a\u4e00\u4e2a\u67e5\u8be2\u8ba1\u5212\u3002\u9009\u62e9\u4e0e\u67e5\u8be2\u7ed3\u6784\u548c\u6570\u636e\u7279\u6027\u76f8\u5339\u914d\u7684\u6b63\u786e\u8ba1\u5212\uff0c\u5bf9\u83b7\u5f97\u826f\u597d\u7684\u6027\u80fd\u81f3\u5173\u91cd\u8981\uff0c\u56e0\u6b64\u7cfb\u7edf\u5185\u7f6e\u4e86\u4e00\u4e2a\u590d\u6742\u7684\u89c4\u5212\u5668\u6765\u5c3d\u91cf\u9009\u51fa\u597d\u7684\u8ba1\u5212\u3002\u53ef\u4ee5\u4f7f\u7528 EXPLAIN \u547d\u4ee4\u67e5\u770b\u89c4\u5212\u5668\u4e3a\u4efb\u610f\u67e5\u8be2\u751f\u6210\u7684\u67e5\u8be2\u8ba1\u5212\u3002\u8bfb\u61c2\u8ba1\u5212\u662f\u4e00\u95e8\u9700\u8981\u7ecf\u9a8c\u79ef\u7d2f\u7684\u6280\u80fd\uff0c\u672c\u8282\u5c06\u5c1d\u8bd5\u4ecb\u7ecd\u5176\u4e2d\u7684\u57fa\u7840\u77e5\u8bc6\u3002\n
\n \u672c\u8282\u4e2d\u7684\u793a\u4f8b\u53d6\u81ea\u6267\u884c\u8fc7 VACUUM ANALYZE \u7684\u56de\u5f52\u6d4b\u8bd5\u6570\u636e\u5e93\uff0c\u4f7f\u7528\u7684\u662f 9.3 \u5f00\u53d1\u7248\u672c\u6e90\u7801\u3002\u5982\u679c\u81ea\u884c\u5c1d\u8bd5\u8fd9\u4e9b\u793a\u4f8b\uff0c\u901a\u5e38\u5e94\u5f53\u80fd\u5f97\u5230\u76f8\u8fd1\u7684\u7ed3\u679c\uff0c\u4f46\u4f30\u8ba1\u4ee3\u4ef7\u548c\u884c\u8ba1\u6570\u53ef\u80fd\u7565\u6709\u5dee\u5f02\uff0c\u56e0\u4e3a ANALYZE \u751f\u6210\u7684\u7edf\u8ba1\u4fe1\u606f\u6765\u81ea\u968f\u673a\u91c7\u6837\u800c\u975e\u7cbe\u786e\u8ba1\u6570\uff0c\u800c\u4e14\u4ee3\u4ef7\u672c\u8eab\u5728\u67d0\u79cd\u7a0b\u5ea6\u4e0a\u4e5f\u4f9d\u8d56\u4e8e\u5e73\u53f0\u3002\n
\n \u8fd9\u4e9b\u793a\u4f8b\u4f7f\u7528 EXPLAIN \u9ed8\u8ba4\u7684\u201ctext\u201d\u8f93\u51fa\u683c\u5f0f\uff0c\u5b83\u7d27\u51d1\u4e14\u4fbf\u4e8e\u4eba\u5de5\u9605\u8bfb\u3002\u5982\u679c\u5e0c\u671b\u5c06 EXPLAIN \u7684\u8f93\u51fa\u4ea4\u7ed9\u7a0b\u5e8f\u505a\u8fdb\u4e00\u6b65\u5206\u6790\uff0c\u5219\u5e94\u6539\u7528\u673a\u5668\u53ef\u8bfb\u7684\u8f93\u51fa\u683c\u5f0f\uff08XML\u3001JSON \u6216 YAML\uff09\u3002\n
\u67e5\u770b\u5b8c\u6574\u4e2d\u6587\u624b\u518c\u4e0e\u4e0a\u4e0b\u6587\u3002
\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
"}, "summary": "\u5408\u5e76\u5df2\u6392\u5e8f\u7684\u5b50\u8ba1\u5212\u8f93\u51fa\u5e76\u4fdd\u6301\u6240\u9700\u987a\u5e8f\u3002", "version": "11", "link_map": {"/zh/docs/11/sql-explain.html": "/docs/11/sql-explain.html", "/zh/docs/11/performance-tips.html#USING-EXPLAIN": "/docs/11/performance-tips.html#USING-EXPLAIN"}, "body_html": "\u5408\u5e76\u5df2\u6392\u5e8f\u7684\u5b50\u8ba1\u5212\u8f93\u51fa\u5e76\u4fdd\u6301\u6240\u9700\u987a\u5e8f\u3002
\u6838\u5fc3\u8282\u70b9\u6807\u8bc6\uff1aT_MergeAppend\uff1bEXPLAIN \u540d\u79f0\uff1aMerge Append\u3002
\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
\nPostgreSQL \u4f1a\u4e3a\u6536\u5230\u7684\u6bcf\u4e2a\u67e5\u8be2\u5236\u5b9a\u4e00\u4e2a\u67e5\u8be2\u8ba1\u5212\u3002\u9009\u62e9\u4e0e\u67e5\u8be2\u7ed3\u6784\u548c\u6570\u636e\u7279\u6027\u76f8\u5339\u914d\u7684\u6b63\u786e\u8ba1\u5212\uff0c\u5bf9\u83b7\u5f97\u826f\u597d\u7684\u6027\u80fd\u81f3\u5173\u91cd\u8981\uff0c\u56e0\u6b64\u7cfb\u7edf\u5185\u7f6e\u4e86\u4e00\u4e2a\u590d\u6742\u7684\u89c4\u5212\u5668\u6765\u5c3d\u91cf\u9009\u51fa\u597d\u7684\u8ba1\u5212\u3002\u53ef\u4ee5\u4f7f\u7528 EXPLAIN \u547d\u4ee4\u67e5\u770b\u89c4\u5212\u5668\u4e3a\u4efb\u610f\u67e5\u8be2\u751f\u6210\u7684\u67e5\u8be2\u8ba1\u5212\u3002\u8bfb\u61c2\u8ba1\u5212\u662f\u4e00\u95e8\u9700\u8981\u7ecf\u9a8c\u79ef\u7d2f\u7684\u6280\u80fd\uff0c\u672c\u8282\u5c06\u5c1d\u8bd5\u4ecb\u7ecd\u5176\u4e2d\u7684\u57fa\u7840\u77e5\u8bc6\u3002\n
\n \u672c\u8282\u4e2d\u7684\u793a\u4f8b\u53d6\u81ea\u6267\u884c\u8fc7 VACUUM ANALYZE \u7684\u56de\u5f52\u6d4b\u8bd5\u6570\u636e\u5e93\uff0c\u4f7f\u7528\u7684\u662f 9.3 \u5f00\u53d1\u7248\u672c\u6e90\u7801\u3002\u5982\u679c\u81ea\u884c\u5c1d\u8bd5\u8fd9\u4e9b\u793a\u4f8b\uff0c\u901a\u5e38\u5e94\u5f53\u80fd\u5f97\u5230\u76f8\u8fd1\u7684\u7ed3\u679c\uff0c\u4f46\u4f30\u8ba1\u4ee3\u4ef7\u548c\u884c\u8ba1\u6570\u53ef\u80fd\u7565\u6709\u5dee\u5f02\uff0c\u56e0\u4e3a ANALYZE \u751f\u6210\u7684\u7edf\u8ba1\u4fe1\u606f\u6765\u81ea\u968f\u673a\u91c7\u6837\u800c\u975e\u7cbe\u786e\u8ba1\u6570\uff0c\u800c\u4e14\u4ee3\u4ef7\u672c\u8eab\u5728\u67d0\u79cd\u7a0b\u5ea6\u4e0a\u4e5f\u4f9d\u8d56\u4e8e\u5e73\u53f0\u3002\n
\n \u8fd9\u4e9b\u793a\u4f8b\u4f7f\u7528 EXPLAIN \u9ed8\u8ba4\u7684\u201ctext\u201d\u8f93\u51fa\u683c\u5f0f\uff0c\u5b83\u7d27\u51d1\u4e14\u4fbf\u4e8e\u4eba\u5de5\u9605\u8bfb\u3002\u5982\u679c\u5e0c\u671b\u5c06 EXPLAIN \u7684\u8f93\u51fa\u4ea4\u7ed9\u7a0b\u5e8f\u505a\u8fdb\u4e00\u6b65\u5206\u6790\uff0c\u5219\u5e94\u6539\u7528\u673a\u5668\u53ef\u8bfb\u7684\u8f93\u51fa\u683c\u5f0f\uff08XML\u3001JSON \u6216 YAML\uff09\u3002\n
\u67e5\u770b\u5b8c\u6574\u4e2d\u6587\u624b\u518c\u4e0e\u4e0a\u4e0b\u6587\u3002
\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
", "body_sha256": "311898dba312a7ae286fdc3eff347ad8c286fd570e3080f392c94699295b77e8", "content_hash": "5850a82acc981be232396e598326495000a46657441c1b59399463e90dbd52de", "source_database": "center", "source_revision": "2cb7c97d7a0d7278851bbc9c61f467b69c094c72b81740b751108e7892ebe1f0"}, "tables_zh": [{"key": "explain-labels", "rows": [{"label": "Merge Append", "identity": "Merge Append"}], "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": ["\u5408\u5e76\u5df2\u6392\u5e8f\u7684\u5b50\u8ba1\u5212\u8f93\u51fa\u5e76\u4fdd\u6301\u6240\u9700\u987a\u5e8f\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\uff1aMerge Append.", "\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": ["\u672c\u6b21\u62bd\u53d6\u4e0d\u4e3a\u6b64\u8282\u70b9\u8bbe\u5b9a\u7edf\u4e00\u7684\u5185\u5b58\u4e0a\u9650\u6216\u843d\u76d8\u7b56\u7565\u3002\u8bf7\u67e5\u770b\u540c\u4e00\u6784\u5efa\u7684\u5b9e\u73b0\u3001\u76f8\u5173\u8868\u8fbe\u5f0f\u6216\u63d0\u4f9b\u65b9\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": "\u6267\u884c\u5668\u5b9e\u73b0\u8bf4\u660e", "paragraphs": ["\u8bf4\u660e\uff1aMergeAppend \u5305\u542b\u4e00\u4e2a\u6216\u591a\u4e2a\u5b50\u8ba1\u5212\uff0c\u8981\u6c42\u5b83\u4eec\u6309\u540c\u4e00\u6392\u5e8f\u952e\u8f93\u51fa\u5143\u7ec4\u3002\u8be5\u8282\u70b9\u5f52\u5e76\u8fd9\u4e9b\u6d41\uff0c\u4ea7\u751f\u6309\u76f8\u540c\u987a\u5e8f\u6392\u5217\u7684\u8f93\u51fa\u3002", "MergeAppend \u8282\u70b9\u4e0d\u4f7f\u7528\u5de6\u53f3\u5b50\u6811\uff0c\u800c\u662f\u7ef4\u62a4\u4e00\u4e2a\u5b50\u8ba1\u5212\u5217\u8868\uff0c\u56e0\u6b64\u5178\u578b\u8282\u70b9\u5728\u8ba1\u5212\u6811\u4e2d\u7684\u5f62\u6001\u5982\u4e0b\uff1a", "... / MergeAppend---+------+------+--- nil / \\ | | | nil nil ... ... ... subplans", "\u5806\u6570\u7ec4\u7684\u6bcf\u4e2a\u5143\u7d20\u5bf9\u5e94\u4e00\u4e2a\u69fd\u4f4d\uff0c\u4f7f\u7528 SlotNumber \u5b58\u50a8\u69fd\u4f4d\u7d22\u5f15\u3002\u8fd9\u5e76\u4e0d\u771f\u6b63\u63d0\u4f9b\u7c7b\u578b\u5b89\u5168\uff0c\u4f46\u80fd\u4f7f\u4ee3\u7801\u542b\u4e49\u66f4\u6e05\u695a\u3002", "\u9501\u5b9a\u6b64\u8282\u70b9\u6240\u63a7\u5236\u5206\u533a\u6811\u4e2d\u7684\u975e\u53f6\u8868\u3002\u5bf9\u4e8e\u975e\u5206\u533a\u7236\u8868\uff0c\u6b64\u64cd\u4f5c\u4e0d\u6267\u884c\u4efb\u4f55\u5de5\u4f5c\u3002"]}, {"code": "case T_MergeAppend:\n\t\t\tpname = sname = \"Merge Append\";\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": "Merges sorted child streams while preserving the required ordering.", "/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": "Multiple sorted child plans", "/versions/11/facts/3/label": "Output", "/versions/11/facts/3/value": "Merged ordered tuples", "/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": "Executor implementation notes", "/versions/11/sections/4/title": "EXPLAIN identity in core source", "/versions/11/memory/description": "This extraction does not assign a universal memory limit or spill policy to this node. Inspect the same-build implementation and its expressions or provider.", "/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: Merge Append.", "/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": "This extraction does not assign a universal memory limit or spill policy to this node. Inspect the same-build implementation and its expressions or provider.", "/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": "NOTES A MergeAppend node contains a list of one or more subplans. These are each expected to deliver tuples that are sorted according to a common sort key. The MergeAppend node merges these streams to produce output sorted the same way.", "/versions/11/sections/3/paragraphs/1": "MergeAppend nodes don't make use of their left and right subtrees, rather they maintain a list of subplans so a typical MergeAppend node looks like this in the plan tree:", "/versions/11/sections/3/paragraphs/3": "We have one slot for each item in the heap array. We use SlotNumber to store slot indexes. This doesn't actually provide any formal type-safety, but it makes the code more self-documenting.", "/versions/11/sections/3/paragraphs/4": "Lock the non-leaf tables in the partition tree controlled by this node. It's a no-op for non-partitioned parent tables.", "/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": "edde4067a971dc24d2b45b3ba7806a286902945382aa6865b423f80d05918bfb", "canonical_center_text_hash": "5850a82acc981be232396e598326495000a46657441c1b59399463e90dbd52de"}, "evidence_kind": "source and documentation", "explain_names": ["Merge Append"], "partial_modes": [], "description_zh": "\u5408\u5e76\u5df2\u6392\u5e8f\u7684\u5b50\u8ba1\u5212\u8f93\u51fa\u5e76\u4fdd\u6301\u6240\u9700\u987a\u5e8f\u3002", "comparison_data": {"node_tag": "T_MergeAppend", "strategies": [], "text_names": ["Merge Append"], "initializer": "ExecInitMergeAppend", "partial_modes": [], "memory_mechanism": "unclassified", "parallel_callbacks": []}, "comparison_hash": "5428ffe21c76597da696d12a775fd915b1be22e9ba2d2d5ba3d84704f51ff3d9", "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/nodeMergeAppend.c"}, "parallel_callbacks": [], "description_zh_html": "\u5408\u5e76\u5df2\u6392\u5e8f\u7684\u5b50\u8ba1\u5212\u8f93\u51fa\u5e76\u4fdd\u6301\u6240\u9700\u987a\u5e8f\u3002
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\nPostgreSQL \u4f1a\u4e3a\u6536\u5230\u7684\u6bcf\u4e2a\u67e5\u8be2\u5236\u5b9a\u4e00\u4e2a\u67e5\u8be2\u8ba1\u5212\u3002\u9009\u62e9\u4e0e\u67e5\u8be2\u7ed3\u6784\u548c\u6570\u636e\u7279\u6027\u76f8\u5339\u914d\u7684\u6b63\u786e\u8ba1\u5212\uff0c\u5bf9\u83b7\u5f97\u826f\u597d\u7684\u6027\u80fd\u81f3\u5173\u91cd\u8981\uff0c\u56e0\u6b64\u7cfb\u7edf\u5185\u7f6e\u4e86\u4e00\u4e2a\u590d\u6742\u7684\u89c4\u5212\u5668\u6765\u5c3d\u91cf\u9009\u51fa\u597d\u7684\u8ba1\u5212\u3002\u53ef\u4ee5\u4f7f\u7528 EXPLAIN \u547d\u4ee4\u67e5\u770b\u89c4\u5212\u5668\u4e3a\u4efb\u610f\u67e5\u8be2\u751f\u6210\u7684\u67e5\u8be2\u8ba1\u5212\u3002\u8bfb\u61c2\u8ba1\u5212\u662f\u4e00\u95e8\u9700\u8981\u7ecf\u9a8c\u79ef\u7d2f\u7684\u6280\u80fd\uff0c\u672c\u8282\u5c06\u5c1d\u8bd5\u4ecb\u7ecd\u5176\u4e2d\u7684\u57fa\u7840\u77e5\u8bc6\u3002\n
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\n \u8fd9\u4e9b\u793a\u4f8b\u4f7f\u7528 EXPLAIN \u9ed8\u8ba4\u7684\u201ctext\u201d\u8f93\u51fa\u683c\u5f0f\uff0c\u5b83\u7d27\u51d1\u4e14\u4fbf\u4e8e\u4eba\u5de5\u9605\u8bfb\u3002\u5982\u679c\u5e0c\u671b\u5c06 EXPLAIN \u7684\u8f93\u51fa\u4ea4\u7ed9\u7a0b\u5e8f\u505a\u8fdb\u4e00\u6b65\u5206\u6790\uff0c\u5219\u5e94\u6539\u7528\u673a\u5668\u53ef\u8bfb\u7684\u8f93\u51fa\u683c\u5f0f\uff08XML\u3001JSON \u6216 YAML\uff09\u3002\n
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"}, "12": {"facts": [{"label": "\u6838\u5fc3\u8282\u70b9\u6807\u7b7e", "value": "T_MergeAppend"}, {"label": "\u7ed3\u6784\u5316 EXPLAIN \u8282\u70b9\u7c7b\u578b", "value": "Merge Append"}, {"label": "\u8f93\u5165", "value": "\u591a\u4e2a\u5df2\u6392\u5e8f\u7684\u5b50\u8ba1\u5212"}, {"label": "\u8f93\u51fa", "value": "\u6309\u987a\u5e8f\u5f52\u5e76\u7684\u5143\u7ec4"}, {"label": "\u6267\u884c\u5668\u521d\u59cb\u5316\u51fd\u6570", "value": "ExecInitMergeAppend"}, {"label": "\u5185\u5b58\u673a\u5236", "value": "unclassified"}], "memory": {"evidence": [{"url": "https://ftp.postgresql.org/pub/source/v12.22/postgresql-12.22.tar.bz2", "path": "src/backend/executor/nodeMergeAppend.c", "label": "src/backend/executor/nodeMergeAppend.c", "sha256": "6ac00a11383e3122254f4911617f0975954c4171cba11eddb060300bf194e83c", "archive_sha256": "8df3c0474782589d3c6f374b5133b1bd14d168086edbc13c6e72e67dd4527a3b"}], "mechanism": "unclassified", "description": "This extraction does not assign a universal memory limit or spill policy to this node. 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\u6838\u5fc3\u8282\u70b9\u6807\u8bc6\uff1aT_MergeAppend\uff1bEXPLAIN \u540d\u79f0\uff1aMerge Append\u3002
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\nPostgreSQL \u4f1a\u4e3a\u6536\u5230\u7684\u6bcf\u4e2a\u67e5\u8be2\u5236\u5b9a\u4e00\u4e2a\u67e5\u8be2\u8ba1\u5212\u3002\u9009\u62e9\u4e0e\u67e5\u8be2\u7ed3\u6784\u548c\u6570\u636e\u7279\u6027\u76f8\u5339\u914d\u7684\u6b63\u786e\u8ba1\u5212\uff0c\u5bf9\u83b7\u5f97\u826f\u597d\u7684\u6027\u80fd\u81f3\u5173\u91cd\u8981\uff0c\u56e0\u6b64\u7cfb\u7edf\u5185\u7f6e\u4e86\u4e00\u4e2a\u590d\u6742\u7684\u89c4\u5212\u5668\u6765\u5c3d\u91cf\u9009\u51fa\u597d\u7684\u8ba1\u5212\u3002\u53ef\u4ee5\u4f7f\u7528 EXPLAIN \u547d\u4ee4\u67e5\u770b\u89c4\u5212\u5668\u4e3a\u4efb\u610f\u67e5\u8be2\u751f\u6210\u7684\u67e5\u8be2\u8ba1\u5212\u3002\u8bfb\u61c2\u8ba1\u5212\u662f\u4e00\u95e8\u9700\u8981\u7ecf\u9a8c\u79ef\u7d2f\u7684\u6280\u80fd\uff0c\u672c\u8282\u5c06\u5c1d\u8bd5\u4ecb\u7ecd\u5176\u4e2d\u7684\u57fa\u7840\u77e5\u8bc6\u3002\n
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\n \u8fd9\u4e9b\u793a\u4f8b\u4f7f\u7528 EXPLAIN \u9ed8\u8ba4\u7684\u201ctext\u201d\u8f93\u51fa\u683c\u5f0f\uff0c\u5b83\u7d27\u51d1\u4e14\u4fbf\u4e8e\u4eba\u5de5\u9605\u8bfb\u3002\u5982\u679c\u5e0c\u671b\u5c06 EXPLAIN \u7684\u8f93\u51fa\u4ea4\u7ed9\u7a0b\u5e8f\u505a\u8fdb\u4e00\u6b65\u5206\u6790\uff0c\u5219\u5e94\u6539\u7528\u673a\u5668\u53ef\u8bfb\u7684\u8f93\u51fa\u683c\u5f0f\uff08XML\u3001JSON \u6216 YAML\uff09\u3002\n
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\nPostgreSQL \u4f1a\u4e3a\u6536\u5230\u7684\u6bcf\u4e2a\u67e5\u8be2\u5236\u5b9a\u4e00\u4e2a\u67e5\u8be2\u8ba1\u5212\u3002\u9009\u62e9\u4e0e\u67e5\u8be2\u7ed3\u6784\u548c\u6570\u636e\u7279\u6027\u76f8\u5339\u914d\u7684\u6b63\u786e\u8ba1\u5212\uff0c\u5bf9\u83b7\u5f97\u826f\u597d\u7684\u6027\u80fd\u81f3\u5173\u91cd\u8981\uff0c\u56e0\u6b64\u7cfb\u7edf\u5185\u7f6e\u4e86\u4e00\u4e2a\u590d\u6742\u7684\u89c4\u5212\u5668\u6765\u5c3d\u91cf\u9009\u51fa\u597d\u7684\u8ba1\u5212\u3002\u53ef\u4ee5\u4f7f\u7528 EXPLAIN \u547d\u4ee4\u67e5\u770b\u89c4\u5212\u5668\u4e3a\u4efb\u610f\u67e5\u8be2\u751f\u6210\u7684\u67e5\u8be2\u8ba1\u5212\u3002\u8bfb\u61c2\u8ba1\u5212\u662f\u4e00\u95e8\u9700\u8981\u7ecf\u9a8c\u79ef\u7d2f\u7684\u6280\u80fd\uff0c\u672c\u8282\u5c06\u5c1d\u8bd5\u4ecb\u7ecd\u5176\u4e2d\u7684\u57fa\u7840\u77e5\u8bc6\u3002\n
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\n \u8fd9\u4e9b\u793a\u4f8b\u4f7f\u7528 EXPLAIN \u9ed8\u8ba4\u7684\u201ctext\u201d\u8f93\u51fa\u683c\u5f0f\uff0c\u5b83\u7d27\u51d1\u4e14\u4fbf\u4e8e\u4eba\u5de5\u9605\u8bfb\u3002\u5982\u679c\u5e0c\u671b\u5c06 EXPLAIN \u7684\u8f93\u51fa\u4ea4\u7ed9\u7a0b\u5e8f\u505a\u8fdb\u4e00\u6b65\u5206\u6790\uff0c\u5219\u5e94\u6539\u7528\u673a\u5668\u53ef\u8bfb\u7684\u8f93\u51fa\u683c\u5f0f\uff08XML\u3001JSON \u6216 YAML\uff09\u3002\n
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\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
", "body_sha256": "3faab607474f79694a1687214f420496e86dc66a067dd240cc23700c2d155836", "content_hash": "f9ff9401215fdcf134f978ca56fce56b621659e5cfa9c5620a44971b0b766d37", "source_database": "center", "source_revision": "8df3c0474782589d3c6f374b5133b1bd14d168086edbc13c6e72e67dd4527a3b"}, "tables_zh": [{"key": "explain-labels", "rows": [{"label": "Merge Append", "identity": "Merge Append"}], "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": ["\u5408\u5e76\u5df2\u6392\u5e8f\u7684\u5b50\u8ba1\u5212\u8f93\u51fa\u5e76\u4fdd\u6301\u6240\u9700\u987a\u5e8f\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\uff1aMerge Append.", "\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": ["\u672c\u6b21\u62bd\u53d6\u4e0d\u4e3a\u6b64\u8282\u70b9\u8bbe\u5b9a\u7edf\u4e00\u7684\u5185\u5b58\u4e0a\u9650\u6216\u843d\u76d8\u7b56\u7565\u3002\u8bf7\u67e5\u770b\u540c\u4e00\u6784\u5efa\u7684\u5b9e\u73b0\u3001\u76f8\u5173\u8868\u8fbe\u5f0f\u6216\u63d0\u4f9b\u65b9\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": "\u6267\u884c\u5668\u5b9e\u73b0\u8bf4\u660e", "paragraphs": ["\u8bf4\u660e\uff1aMergeAppend \u5305\u542b\u4e00\u4e2a\u6216\u591a\u4e2a\u5b50\u8ba1\u5212\uff0c\u8981\u6c42\u5b83\u4eec\u6309\u540c\u4e00\u6392\u5e8f\u952e\u8f93\u51fa\u5143\u7ec4\u3002\u8be5\u8282\u70b9\u5f52\u5e76\u8fd9\u4e9b\u6d41\uff0c\u4ea7\u751f\u6309\u76f8\u540c\u987a\u5e8f\u6392\u5217\u7684\u8f93\u51fa\u3002", "MergeAppend \u8282\u70b9\u4e0d\u4f7f\u7528\u5de6\u53f3\u5b50\u6811\uff0c\u800c\u662f\u7ef4\u62a4\u4e00\u4e2a\u5b50\u8ba1\u5212\u5217\u8868\uff0c\u56e0\u6b64\u5178\u578b\u8282\u70b9\u5728\u8ba1\u5212\u6811\u4e2d\u7684\u5f62\u6001\u5982\u4e0b\uff1a", "... / MergeAppend---+------+------+--- nil / \\ | | | nil nil ... ... ... subplans", "\u5806\u6570\u7ec4\u7684\u6bcf\u4e2a\u5143\u7d20\u5bf9\u5e94\u4e00\u4e2a\u69fd\u4f4d\uff0c\u4f7f\u7528 SlotNumber \u5b58\u50a8\u69fd\u4f4d\u7d22\u5f15\u3002\u8fd9\u5e76\u4e0d\u771f\u6b63\u63d0\u4f9b\u7c7b\u578b\u5b89\u5168\uff0c\u4f46\u80fd\u4f7f\u4ee3\u7801\u542b\u4e49\u66f4\u6e05\u695a\u3002", "\u82e5\u5df2\u542f\u7528\u8fd0\u884c\u65f6\u5206\u533a\u88c1\u526a\uff0c\u5219\u73b0\u5728\u8fdb\u884c\u76f8\u5e94\u8bbe\u7f6e\u3002"]}, {"code": "case T_MergeAppend:\n\t\t\tpname = sname = \"Merge Append\";\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": "Merges sorted child streams while preserving the required ordering.", "/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": "Multiple sorted child plans", "/versions/12/facts/3/label": "Output", "/versions/12/facts/3/value": "Merged ordered tuples", "/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": "Executor implementation notes", "/versions/12/sections/4/title": "EXPLAIN identity in core source", "/versions/12/memory/description": "This extraction does not assign a universal memory limit or spill policy to this node. Inspect the same-build implementation and its expressions or provider.", "/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: Merge Append.", "/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": "This extraction does not assign a universal memory limit or spill policy to this node. Inspect the same-build implementation and its expressions or provider.", "/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": "NOTES A MergeAppend node contains a list of one or more subplans. These are each expected to deliver tuples that are sorted according to a common sort key. The MergeAppend node merges these streams to produce output sorted the same way.", "/versions/12/sections/3/paragraphs/1": "MergeAppend nodes don't make use of their left and right subtrees, rather they maintain a list of subplans so a typical MergeAppend node looks like this in the plan tree:", "/versions/12/sections/3/paragraphs/3": "We have one slot for each item in the heap array. We use SlotNumber to store slot indexes. 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\u5305\u542b\u4e00\u4e2a\u6216\u591a\u4e2a\u5b50\u8ba1\u5212\uff0c\u8981\u6c42\u5b83\u4eec\u6309\u540c\u4e00\u6392\u5e8f\u952e\u8f93\u51fa\u5143\u7ec4\u3002\u8be5\u8282\u70b9\u5f52\u5e76\u8fd9\u4e9b\u6d41\uff0c\u4ea7\u751f\u6309\u76f8\u540c\u987a\u5e8f\u6392\u5217\u7684\u8f93\u51fa\u3002", "MergeAppend \u8282\u70b9\u4e0d\u4f7f\u7528\u5de6\u53f3\u5b50\u6811\uff0c\u800c\u662f\u7ef4\u62a4\u4e00\u4e2a\u5b50\u8ba1\u5212\u5217\u8868\uff0c\u56e0\u6b64\u5178\u578b\u8282\u70b9\u5728\u8ba1\u5212\u6811\u4e2d\u7684\u5f62\u6001\u5982\u4e0b\uff1a", "... / MergeAppend---+------+------+--- nil / \\ | | | nil nil ... ... ... subplans", "\u5806\u6570\u7ec4\u7684\u6bcf\u4e2a\u5143\u7d20\u5bf9\u5e94\u4e00\u4e2a\u69fd\u4f4d\uff0c\u4f7f\u7528 SlotNumber \u5b58\u50a8\u69fd\u4f4d\u7d22\u5f15\u3002\u8fd9\u5e76\u4e0d\u771f\u6b63\u63d0\u4f9b\u7c7b\u578b\u5b89\u5168\uff0c\u4f46\u80fd\u4f7f\u4ee3\u7801\u542b\u4e49\u66f4\u6e05\u695a\u3002", "\u82e5\u5df2\u542f\u7528\u8fd0\u884c\u65f6\u5206\u533a\u88c1\u526a\uff0c\u5219\u73b0\u5728\u8fdb\u884c\u76f8\u5e94\u8bbe\u7f6e\u3002"]}, {"code": "case T_MergeAppend:\n\t\t\tpname = sname = \"Merge Append\";\n\t\t\tbreak;", "title": "\u6838\u5fc3\u6e90\u7801\u4e2d\u7684 EXPLAIN \u6807\u8bc6"}], "center_zh": {"title": "MergeAppend", "locale": "zh-Hans", "source": {"key": "merge-append", "locale": "zh-Hans", "version": "13", "text_hash": "0ac22f29403151fb8c74b332bd3bca0e77d4d2d4c4439b0f4ba0314a4e214aa8", "collection": "plan", "dataset_hash": "7c31b524dfe136022d39a6ae8dcfac6b3bbd5f8fdaf422536599981252aff0c9", "source_database": "center", "source_revision": "6ec3c82726af92b7dec873fa1cdf881eca92a4219787dfad05acb6b10e041fd6"}, "payload": {"facts": [{"label": "\u6838\u5fc3\u8282\u70b9\u6807\u7b7e", "value": "T_MergeAppend"}, {"label": "\u7ed3\u6784\u5316 EXPLAIN \u8282\u70b9\u7c7b\u578b", "value": "Merge Append"}, {"label": "\u8f93\u5165", "value": "\u591a\u4e2a\u5df2\u6392\u5e8f\u7684\u5b50\u8ba1\u5212"}, {"label": "\u8f93\u51fa", "value": "\u6309\u987a\u5e8f\u5f52\u5e76\u7684\u5143\u7ec4"}, {"label": "\u6267\u884c\u5668\u521d\u59cb\u5316\u51fd\u6570", "value": "ExecInitMergeAppend"}, {"label": "\u5185\u5b58\u673a\u5236", "value": "unclassified"}], "tables": [{"key": "explain-labels", "rows": [{"label": "Merge Append", "identity": "Merge Append"}], "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", "anchor": "USING-EXPLAIN", "locale": "zh-Hans", "version": "13", "build_id": 66, "page_key": "performance-tips.html", "extraction": "concept-introduction", "source_hash": "d7400476f3cf658423dd2d2f64b6b6b0e53d8fdc8692b9e93a05587095d469e1", "fragment_sha256": "9385d1b095126378694216a1f9cb95d249ccc7fab5ffa3f65cf08679fe2b14c3", "source_revision": "unknown:rendered-translation-baseline", "translation_revision": "snapshot:sha256:a13a825c39f0268ef1cfe9137e283e38d0da73b2d7894f0733c7b26372a4f6a4", "translated_from_revision": null}, "body_sha256": "1d28217cbc4fd03782a1a3ab49f90378c8f1013ae7da64436e2b11b1dd0a1582", "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\uff1aMerge Append.", "\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": ["\u672c\u6b21\u62bd\u53d6\u4e0d\u4e3a\u6b64\u8282\u70b9\u8bbe\u5b9a\u7edf\u4e00\u7684\u5185\u5b58\u4e0a\u9650\u6216\u843d\u76d8\u7b56\u7565\u3002\u8bf7\u67e5\u770b\u540c\u4e00\u6784\u5efa\u7684\u5b9e\u73b0\u3001\u76f8\u5173\u8868\u8fbe\u5f0f\u6216\u63d0\u4f9b\u65b9\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": "\u6267\u884c\u5668\u5b9e\u73b0\u8bf4\u660e", "paragraphs": ["\u8bf4\u660e\uff1aMergeAppend \u5305\u542b\u4e00\u4e2a\u6216\u591a\u4e2a\u5b50\u8ba1\u5212\uff0c\u8981\u6c42\u5b83\u4eec\u6309\u540c\u4e00\u6392\u5e8f\u952e\u8f93\u51fa\u5143\u7ec4\u3002\u8be5\u8282\u70b9\u5f52\u5e76\u8fd9\u4e9b\u6d41\uff0c\u4ea7\u751f\u6309\u76f8\u540c\u987a\u5e8f\u6392\u5217\u7684\u8f93\u51fa\u3002", "MergeAppend \u8282\u70b9\u4e0d\u4f7f\u7528\u5de6\u53f3\u5b50\u6811\uff0c\u800c\u662f\u7ef4\u62a4\u4e00\u4e2a\u5b50\u8ba1\u5212\u5217\u8868\uff0c\u56e0\u6b64\u5178\u578b\u8282\u70b9\u5728\u8ba1\u5212\u6811\u4e2d\u7684\u5f62\u6001\u5982\u4e0b\uff1a", "... / MergeAppend---+------+------+--- nil / \\ | | | nil nil ... ... ... subplans", "\u5806\u6570\u7ec4\u7684\u6bcf\u4e2a\u5143\u7d20\u5bf9\u5e94\u4e00\u4e2a\u69fd\u4f4d\uff0c\u4f7f\u7528 SlotNumber \u5b58\u50a8\u69fd\u4f4d\u7d22\u5f15\u3002\u8fd9\u5e76\u4e0d\u771f\u6b63\u63d0\u4f9b\u7c7b\u578b\u5b89\u5168\uff0c\u4f46\u80fd\u4f7f\u4ee3\u7801\u542b\u4e49\u66f4\u6e05\u695a\u3002", "\u82e5\u5df2\u542f\u7528\u8fd0\u884c\u65f6\u5206\u533a\u88c1\u526a\uff0c\u5219\u73b0\u5728\u8fdb\u884c\u76f8\u5e94\u8bbe\u7f6e\u3002"]}, {"code": "case T_MergeAppend:\n\t\t\tpname = sname = \"Merge Append\";\n\t\t\tbreak;", "title": "\u6838\u5fc3\u6e90\u7801\u4e2d\u7684 EXPLAIN \u6807\u8bc6"}], "description_zh": "\u5408\u5e76\u5df2\u6392\u5e8f\u7684\u5b50\u8ba1\u5212\u8f93\u51fa\u5e76\u4fdd\u6301\u6240\u9700\u987a\u5e8f\u3002", "description_zh_html": "\u5408\u5e76\u5df2\u6392\u5e8f\u7684\u5b50\u8ba1\u5212\u8f93\u51fa\u5e76\u4fdd\u6301\u6240\u9700\u987a\u5e8f\u3002
\u6838\u5fc3\u8282\u70b9\u6807\u8bc6\uff1aT_MergeAppend\uff1bEXPLAIN \u540d\u79f0\uff1aMerge Append\u3002
\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
\nPostgreSQL \u4f1a\u4e3a\u6536\u5230\u7684\u6bcf\u4e2a\u67e5\u8be2\u5236\u5b9a\u4e00\u4e2a\u67e5\u8be2\u8ba1\u5212\u3002\u9009\u62e9\u4e0e\u67e5\u8be2\u7ed3\u6784\u548c\u6570\u636e\u7279\u6027\u76f8\u5339\u914d\u7684\u6b63\u786e\u8ba1\u5212\uff0c\u5bf9\u83b7\u5f97\u826f\u597d\u7684\u6027\u80fd\u81f3\u5173\u91cd\u8981\uff0c\u56e0\u6b64\u7cfb\u7edf\u5185\u7f6e\u4e86\u4e00\u4e2a\u590d\u6742\u7684\u89c4\u5212\u5668\u6765\u5c3d\u91cf\u9009\u51fa\u597d\u7684\u8ba1\u5212\u3002\u53ef\u4ee5\u4f7f\u7528 EXPLAIN \u547d\u4ee4\u67e5\u770b\u89c4\u5212\u5668\u4e3a\u4efb\u610f\u67e5\u8be2\u751f\u6210\u7684\u67e5\u8be2\u8ba1\u5212\u3002\u8bfb\u61c2\u8ba1\u5212\u662f\u4e00\u95e8\u9700\u8981\u7ecf\u9a8c\u79ef\u7d2f\u7684\u6280\u80fd\uff0c\u672c\u8282\u5c06\u5c1d\u8bd5\u4ecb\u7ecd\u5176\u4e2d\u7684\u57fa\u7840\u77e5\u8bc6\u3002\n
\n \u672c\u8282\u4e2d\u7684\u793a\u4f8b\u53d6\u81ea\u6267\u884c\u8fc7 VACUUM ANALYZE \u7684\u56de\u5f52\u6d4b\u8bd5\u6570\u636e\u5e93\uff0c\u4f7f\u7528\u7684\u662f 9.3 \u5f00\u53d1\u7248\u672c\u6e90\u7801\u3002\u5982\u679c\u81ea\u884c\u5c1d\u8bd5\u8fd9\u4e9b\u793a\u4f8b\uff0c\u901a\u5e38\u5e94\u5f53\u80fd\u5f97\u5230\u76f8\u8fd1\u7684\u7ed3\u679c\uff0c\u4f46\u4f30\u8ba1\u4ee3\u4ef7\u548c\u884c\u8ba1\u6570\u53ef\u80fd\u7565\u6709\u5dee\u5f02\uff0c\u56e0\u4e3a ANALYZE \u751f\u6210\u7684\u7edf\u8ba1\u4fe1\u606f\u6765\u81ea\u968f\u673a\u91c7\u6837\u800c\u975e\u7cbe\u786e\u8ba1\u6570\uff0c\u800c\u4e14\u4ee3\u4ef7\u672c\u8eab\u5728\u67d0\u79cd\u7a0b\u5ea6\u4e0a\u4e5f\u4f9d\u8d56\u4e8e\u5e73\u53f0\u3002\n
\n \u8fd9\u4e9b\u793a\u4f8b\u4f7f\u7528 EXPLAIN \u9ed8\u8ba4\u7684\u201ctext\u201d\u8f93\u51fa\u683c\u5f0f\uff0c\u5b83\u7d27\u51d1\u4e14\u4fbf\u4e8e\u4eba\u5de5\u9605\u8bfb\u3002\u5982\u679c\u5e0c\u671b\u5c06 EXPLAIN \u7684\u8f93\u51fa\u4ea4\u7ed9\u7a0b\u5e8f\u505a\u8fdb\u4e00\u6b65\u5206\u6790\uff0c\u5219\u5e94\u6539\u7528\u673a\u5668\u53ef\u8bfb\u7684\u8f93\u51fa\u683c\u5f0f\uff08XML\u3001JSON \u6216 YAML\uff09\u3002\n
\u67e5\u770b\u5b8c\u6574\u4e2d\u6587\u624b\u518c\u4e0e\u4e0a\u4e0b\u6587\u3002
\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
"}, "summary": "\u5408\u5e76\u5df2\u6392\u5e8f\u7684\u5b50\u8ba1\u5212\u8f93\u51fa\u5e76\u4fdd\u6301\u6240\u9700\u987a\u5e8f\u3002", "version": "13", "link_map": {"/zh/docs/13/sql-explain.html": "/docs/13/sql-explain.html", "/zh/docs/13/performance-tips.html#USING-EXPLAIN": "/docs/13/performance-tips.html#USING-EXPLAIN"}, "body_html": "\u5408\u5e76\u5df2\u6392\u5e8f\u7684\u5b50\u8ba1\u5212\u8f93\u51fa\u5e76\u4fdd\u6301\u6240\u9700\u987a\u5e8f\u3002
\u6838\u5fc3\u8282\u70b9\u6807\u8bc6\uff1aT_MergeAppend\uff1bEXPLAIN \u540d\u79f0\uff1aMerge Append\u3002
\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
\nPostgreSQL \u4f1a\u4e3a\u6536\u5230\u7684\u6bcf\u4e2a\u67e5\u8be2\u5236\u5b9a\u4e00\u4e2a\u67e5\u8be2\u8ba1\u5212\u3002\u9009\u62e9\u4e0e\u67e5\u8be2\u7ed3\u6784\u548c\u6570\u636e\u7279\u6027\u76f8\u5339\u914d\u7684\u6b63\u786e\u8ba1\u5212\uff0c\u5bf9\u83b7\u5f97\u826f\u597d\u7684\u6027\u80fd\u81f3\u5173\u91cd\u8981\uff0c\u56e0\u6b64\u7cfb\u7edf\u5185\u7f6e\u4e86\u4e00\u4e2a\u590d\u6742\u7684\u89c4\u5212\u5668\u6765\u5c3d\u91cf\u9009\u51fa\u597d\u7684\u8ba1\u5212\u3002\u53ef\u4ee5\u4f7f\u7528 EXPLAIN \u547d\u4ee4\u67e5\u770b\u89c4\u5212\u5668\u4e3a\u4efb\u610f\u67e5\u8be2\u751f\u6210\u7684\u67e5\u8be2\u8ba1\u5212\u3002\u8bfb\u61c2\u8ba1\u5212\u662f\u4e00\u95e8\u9700\u8981\u7ecf\u9a8c\u79ef\u7d2f\u7684\u6280\u80fd\uff0c\u672c\u8282\u5c06\u5c1d\u8bd5\u4ecb\u7ecd\u5176\u4e2d\u7684\u57fa\u7840\u77e5\u8bc6\u3002\n
\n \u672c\u8282\u4e2d\u7684\u793a\u4f8b\u53d6\u81ea\u6267\u884c\u8fc7 VACUUM ANALYZE \u7684\u56de\u5f52\u6d4b\u8bd5\u6570\u636e\u5e93\uff0c\u4f7f\u7528\u7684\u662f 9.3 \u5f00\u53d1\u7248\u672c\u6e90\u7801\u3002\u5982\u679c\u81ea\u884c\u5c1d\u8bd5\u8fd9\u4e9b\u793a\u4f8b\uff0c\u901a\u5e38\u5e94\u5f53\u80fd\u5f97\u5230\u76f8\u8fd1\u7684\u7ed3\u679c\uff0c\u4f46\u4f30\u8ba1\u4ee3\u4ef7\u548c\u884c\u8ba1\u6570\u53ef\u80fd\u7565\u6709\u5dee\u5f02\uff0c\u56e0\u4e3a ANALYZE \u751f\u6210\u7684\u7edf\u8ba1\u4fe1\u606f\u6765\u81ea\u968f\u673a\u91c7\u6837\u800c\u975e\u7cbe\u786e\u8ba1\u6570\uff0c\u800c\u4e14\u4ee3\u4ef7\u672c\u8eab\u5728\u67d0\u79cd\u7a0b\u5ea6\u4e0a\u4e5f\u4f9d\u8d56\u4e8e\u5e73\u53f0\u3002\n
\n \u8fd9\u4e9b\u793a\u4f8b\u4f7f\u7528 EXPLAIN \u9ed8\u8ba4\u7684\u201ctext\u201d\u8f93\u51fa\u683c\u5f0f\uff0c\u5b83\u7d27\u51d1\u4e14\u4fbf\u4e8e\u4eba\u5de5\u9605\u8bfb\u3002\u5982\u679c\u5e0c\u671b\u5c06 EXPLAIN \u7684\u8f93\u51fa\u4ea4\u7ed9\u7a0b\u5e8f\u505a\u8fdb\u4e00\u6b65\u5206\u6790\uff0c\u5219\u5e94\u6539\u7528\u673a\u5668\u53ef\u8bfb\u7684\u8f93\u51fa\u683c\u5f0f\uff08XML\u3001JSON \u6216 YAML\uff09\u3002\n
\u67e5\u770b\u5b8c\u6574\u4e2d\u6587\u624b\u518c\u4e0e\u4e0a\u4e0b\u6587\u3002
\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
", "body_sha256": "f40dd93944380cf33dce3ecfebb96a5295ae04ce4a94e0a4471b309cc24ac42d", "content_hash": "0ac22f29403151fb8c74b332bd3bca0e77d4d2d4c4439b0f4ba0314a4e214aa8", "source_database": "center", "source_revision": "6ec3c82726af92b7dec873fa1cdf881eca92a4219787dfad05acb6b10e041fd6"}, "tables_zh": [{"key": "explain-labels", "rows": [{"label": "Merge Append", "identity": "Merge Append"}], "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": ["\u5408\u5e76\u5df2\u6392\u5e8f\u7684\u5b50\u8ba1\u5212\u8f93\u51fa\u5e76\u4fdd\u6301\u6240\u9700\u987a\u5e8f\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\uff1aMerge Append.", "\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": ["\u672c\u6b21\u62bd\u53d6\u4e0d\u4e3a\u6b64\u8282\u70b9\u8bbe\u5b9a\u7edf\u4e00\u7684\u5185\u5b58\u4e0a\u9650\u6216\u843d\u76d8\u7b56\u7565\u3002\u8bf7\u67e5\u770b\u540c\u4e00\u6784\u5efa\u7684\u5b9e\u73b0\u3001\u76f8\u5173\u8868\u8fbe\u5f0f\u6216\u63d0\u4f9b\u65b9\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": "\u6267\u884c\u5668\u5b9e\u73b0\u8bf4\u660e", "paragraphs": ["\u8bf4\u660e\uff1aMergeAppend \u5305\u542b\u4e00\u4e2a\u6216\u591a\u4e2a\u5b50\u8ba1\u5212\uff0c\u8981\u6c42\u5b83\u4eec\u6309\u540c\u4e00\u6392\u5e8f\u952e\u8f93\u51fa\u5143\u7ec4\u3002\u8be5\u8282\u70b9\u5f52\u5e76\u8fd9\u4e9b\u6d41\uff0c\u4ea7\u751f\u6309\u76f8\u540c\u987a\u5e8f\u6392\u5217\u7684\u8f93\u51fa\u3002", "MergeAppend \u8282\u70b9\u4e0d\u4f7f\u7528\u5de6\u53f3\u5b50\u6811\uff0c\u800c\u662f\u7ef4\u62a4\u4e00\u4e2a\u5b50\u8ba1\u5212\u5217\u8868\uff0c\u56e0\u6b64\u5178\u578b\u8282\u70b9\u5728\u8ba1\u5212\u6811\u4e2d\u7684\u5f62\u6001\u5982\u4e0b\uff1a", "... / MergeAppend---+------+------+--- nil / \\ | | | nil nil ... ... ... subplans", "\u5806\u6570\u7ec4\u7684\u6bcf\u4e2a\u5143\u7d20\u5bf9\u5e94\u4e00\u4e2a\u69fd\u4f4d\uff0c\u4f7f\u7528 SlotNumber \u5b58\u50a8\u69fd\u4f4d\u7d22\u5f15\u3002\u8fd9\u5e76\u4e0d\u771f\u6b63\u63d0\u4f9b\u7c7b\u578b\u5b89\u5168\uff0c\u4f46\u80fd\u4f7f\u4ee3\u7801\u542b\u4e49\u66f4\u6e05\u695a\u3002", "\u82e5\u5df2\u542f\u7528\u8fd0\u884c\u65f6\u5206\u533a\u88c1\u526a\uff0c\u5219\u73b0\u5728\u8fdb\u884c\u76f8\u5e94\u8bbe\u7f6e\u3002"]}, {"code": "case T_MergeAppend:\n\t\t\tpname = sname = \"Merge Append\";\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": "Merges sorted child streams while preserving the required ordering.", "/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": "Multiple sorted child plans", "/versions/13/facts/3/label": "Output", "/versions/13/facts/3/value": "Merged ordered tuples", "/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": "Executor implementation notes", "/versions/13/sections/4/title": "EXPLAIN identity in core source", "/versions/13/memory/description": "This extraction does not assign a universal memory limit or spill policy to this node. Inspect the same-build implementation and its expressions or provider.", "/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: Merge Append.", "/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": "This extraction does not assign a universal memory limit or spill policy to this node. Inspect the same-build implementation and its expressions or provider.", "/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": "NOTES A MergeAppend node contains a list of one or more subplans. These are each expected to deliver tuples that are sorted according to a common sort key. The MergeAppend node merges these streams to produce output sorted the same way.", "/versions/13/sections/3/paragraphs/1": "MergeAppend nodes don't make use of their left and right subtrees, rather they maintain a list of subplans so a typical MergeAppend node looks like this in the plan tree:", "/versions/13/sections/3/paragraphs/3": "We have one slot for each item in the heap array. We use SlotNumber to store slot indexes. This doesn't actually provide any formal type-safety, but it makes the code more self-documenting.", "/versions/13/sections/3/paragraphs/4": "If run-time partition pruning is enabled, then set that up now", "/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": "d8266d87c0edb3ff74a24a72cf28127c4d300d19acc75a25b84234d853b15753", "canonical_center_text_hash": "0ac22f29403151fb8c74b332bd3bca0e77d4d2d4c4439b0f4ba0314a4e214aa8"}, "evidence_kind": "source and documentation", "explain_names": ["Merge Append"], "partial_modes": [], "description_zh": "\u5408\u5e76\u5df2\u6392\u5e8f\u7684\u5b50\u8ba1\u5212\u8f93\u51fa\u5e76\u4fdd\u6301\u6240\u9700\u987a\u5e8f\u3002", "comparison_data": {"node_tag": "T_MergeAppend", "strategies": [], "text_names": ["Merge Append"], "initializer": "ExecInitMergeAppend", "partial_modes": [], "memory_mechanism": "unclassified", "parallel_callbacks": []}, "comparison_hash": "5428ffe21c76597da696d12a775fd915b1be22e9ba2d2d5ba3d84704f51ff3d9", "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/nodeMergeAppend.c"}, "parallel_callbacks": [], "description_zh_html": "\u5408\u5e76\u5df2\u6392\u5e8f\u7684\u5b50\u8ba1\u5212\u8f93\u51fa\u5e76\u4fdd\u6301\u6240\u9700\u987a\u5e8f\u3002
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\nPostgreSQL \u4f1a\u4e3a\u6536\u5230\u7684\u6bcf\u4e2a\u67e5\u8be2\u5236\u5b9a\u4e00\u4e2a\u67e5\u8be2\u8ba1\u5212\u3002\u9009\u62e9\u4e0e\u67e5\u8be2\u7ed3\u6784\u548c\u6570\u636e\u7279\u6027\u76f8\u5339\u914d\u7684\u6b63\u786e\u8ba1\u5212\uff0c\u5bf9\u83b7\u5f97\u826f\u597d\u7684\u6027\u80fd\u81f3\u5173\u91cd\u8981\uff0c\u56e0\u6b64\u7cfb\u7edf\u5185\u7f6e\u4e86\u4e00\u4e2a\u590d\u6742\u7684\u89c4\u5212\u5668\u6765\u5c3d\u91cf\u9009\u51fa\u597d\u7684\u8ba1\u5212\u3002\u53ef\u4ee5\u4f7f\u7528 EXPLAIN \u547d\u4ee4\u67e5\u770b\u89c4\u5212\u5668\u4e3a\u4efb\u610f\u67e5\u8be2\u751f\u6210\u7684\u67e5\u8be2\u8ba1\u5212\u3002\u8bfb\u61c2\u8ba1\u5212\u662f\u4e00\u95e8\u9700\u8981\u7ecf\u9a8c\u79ef\u7d2f\u7684\u6280\u80fd\uff0c\u672c\u8282\u5c06\u5c1d\u8bd5\u4ecb\u7ecd\u5176\u4e2d\u7684\u57fa\u7840\u77e5\u8bc6\u3002\n
\n \u672c\u8282\u4e2d\u7684\u793a\u4f8b\u53d6\u81ea\u6267\u884c\u8fc7 VACUUM ANALYZE \u7684\u56de\u5f52\u6d4b\u8bd5\u6570\u636e\u5e93\uff0c\u4f7f\u7528\u7684\u662f 9.3 \u5f00\u53d1\u7248\u672c\u6e90\u7801\u3002\u5982\u679c\u81ea\u884c\u5c1d\u8bd5\u8fd9\u4e9b\u793a\u4f8b\uff0c\u901a\u5e38\u5e94\u5f53\u80fd\u5f97\u5230\u76f8\u8fd1\u7684\u7ed3\u679c\uff0c\u4f46\u4f30\u8ba1\u4ee3\u4ef7\u548c\u884c\u8ba1\u6570\u53ef\u80fd\u7565\u6709\u5dee\u5f02\uff0c\u56e0\u4e3a ANALYZE \u751f\u6210\u7684\u7edf\u8ba1\u4fe1\u606f\u6765\u81ea\u968f\u673a\u91c7\u6837\u800c\u975e\u7cbe\u786e\u8ba1\u6570\uff0c\u800c\u4e14\u4ee3\u4ef7\u672c\u8eab\u5728\u67d0\u79cd\u7a0b\u5ea6\u4e0a\u4e5f\u4f9d\u8d56\u4e8e\u5e73\u53f0\u3002\n
\n \u8fd9\u4e9b\u793a\u4f8b\u4f7f\u7528 EXPLAIN \u9ed8\u8ba4\u7684\u201ctext\u201d\u8f93\u51fa\u683c\u5f0f\uff0c\u5b83\u7d27\u51d1\u4e14\u4fbf\u4e8e\u4eba\u5de5\u9605\u8bfb\u3002\u5982\u679c\u5e0c\u671b\u5c06 EXPLAIN \u7684\u8f93\u51fa\u4ea4\u7ed9\u7a0b\u5e8f\u505a\u8fdb\u4e00\u6b65\u5206\u6790\uff0c\u5219\u5e94\u6539\u7528\u673a\u5668\u53ef\u8bfb\u7684\u8f93\u51fa\u683c\u5f0f\uff08XML\u3001JSON \u6216 YAML\uff09\u3002\n
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\u6838\u5fc3\u8282\u70b9\u6807\u8bc6\uff1aT_MergeAppend\uff1bEXPLAIN \u540d\u79f0\uff1aMerge Append\u3002
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\nPostgreSQL \u4f1a\u4e3a\u6536\u5230\u7684\u6bcf\u4e2a\u67e5\u8be2\u5236\u5b9a\u4e00\u4e2a\u67e5\u8be2\u8ba1\u5212\u3002\u9009\u62e9\u4e0e\u67e5\u8be2\u7ed3\u6784\u548c\u6570\u636e\u7279\u6027\u76f8\u5339\u914d\u7684\u6b63\u786e\u8ba1\u5212\uff0c\u5bf9\u83b7\u5f97\u826f\u597d\u7684\u6027\u80fd\u81f3\u5173\u91cd\u8981\uff0c\u56e0\u6b64\u7cfb\u7edf\u5185\u7f6e\u4e86\u4e00\u4e2a\u590d\u6742\u7684\u89c4\u5212\u5668\u6765\u5c3d\u91cf\u9009\u51fa\u597d\u7684\u8ba1\u5212\u3002\u53ef\u4ee5\u4f7f\u7528 EXPLAIN \u547d\u4ee4\u67e5\u770b\u89c4\u5212\u5668\u4e3a\u4efb\u610f\u67e5\u8be2\u751f\u6210\u7684\u67e5\u8be2\u8ba1\u5212\u3002\u8bfb\u61c2\u8ba1\u5212\u662f\u4e00\u95e8\u9700\u8981\u7ecf\u9a8c\u79ef\u7d2f\u7684\u6280\u80fd\uff0c\u672c\u8282\u5c06\u5c1d\u8bd5\u4ecb\u7ecd\u5176\u4e2d\u7684\u57fa\u7840\u77e5\u8bc6\u3002\n
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\n \u8fd9\u4e9b\u793a\u4f8b\u4f7f\u7528 EXPLAIN \u9ed8\u8ba4\u7684\u201ctext\u201d\u8f93\u51fa\u683c\u5f0f\uff0c\u5b83\u7d27\u51d1\u4e14\u4fbf\u4e8e\u4eba\u5de5\u9605\u8bfb\u3002\u5982\u679c\u5e0c\u671b\u5c06 EXPLAIN \u7684\u8f93\u51fa\u4ea4\u7ed9\u7a0b\u5e8f\u505a\u8fdb\u4e00\u6b65\u5206\u6790\uff0c\u5219\u5e94\u6539\u7528\u673a\u5668\u53ef\u8bfb\u7684\u8f93\u51fa\u683c\u5f0f\uff08XML\u3001JSON \u6216 YAML\uff09\u3002\n
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\nPostgreSQL \u4f1a\u4e3a\u6536\u5230\u7684\u6bcf\u4e2a\u67e5\u8be2\u5236\u5b9a\u4e00\u4e2a\u67e5\u8be2\u8ba1\u5212\u3002\u9009\u62e9\u4e0e\u67e5\u8be2\u7ed3\u6784\u548c\u6570\u636e\u7279\u6027\u76f8\u5339\u914d\u7684\u6b63\u786e\u8ba1\u5212\uff0c\u5bf9\u83b7\u5f97\u826f\u597d\u7684\u6027\u80fd\u81f3\u5173\u91cd\u8981\uff0c\u56e0\u6b64\u7cfb\u7edf\u5185\u7f6e\u4e86\u4e00\u4e2a\u590d\u6742\u7684\u89c4\u5212\u5668\u6765\u5c3d\u91cf\u9009\u51fa\u597d\u7684\u8ba1\u5212\u3002\u53ef\u4ee5\u4f7f\u7528 EXPLAIN \u547d\u4ee4\u67e5\u770b\u89c4\u5212\u5668\u4e3a\u4efb\u610f\u67e5\u8be2\u751f\u6210\u7684\u67e5\u8be2\u8ba1\u5212\u3002\u8bfb\u61c2\u8ba1\u5212\u662f\u4e00\u95e8\u9700\u8981\u7ecf\u9a8c\u79ef\u7d2f\u7684\u6280\u80fd\uff0c\u672c\u8282\u5c06\u5c1d\u8bd5\u4ecb\u7ecd\u5176\u4e2d\u7684\u57fa\u7840\u77e5\u8bc6\u3002\n
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\n \u8fd9\u4e9b\u793a\u4f8b\u4f7f\u7528 EXPLAIN \u9ed8\u8ba4\u7684\u201ctext\u201d\u8f93\u51fa\u683c\u5f0f\uff0c\u5b83\u7d27\u51d1\u4e14\u4fbf\u4e8e\u4eba\u5de5\u9605\u8bfb\u3002\u5982\u679c\u5e0c\u671b\u5c06 EXPLAIN \u7684\u8f93\u51fa\u4ea4\u7ed9\u7a0b\u5e8f\u505a\u8fdb\u4e00\u6b65\u5206\u6790\uff0c\u5219\u5e94\u6539\u7528\u673a\u5668\u53ef\u8bfb\u7684\u8f93\u51fa\u683c\u5f0f\uff08XML\u3001JSON \u6216 YAML\uff09\u3002\n
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Inspect the same-build implementation and its expressions or provider.", "/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: Merge Append.", "/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": "This extraction does not assign a universal memory limit or spill policy to this node. Inspect the same-build implementation and its expressions or provider.", "/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": "NOTES A MergeAppend node contains a list of one or more subplans. These are each expected to deliver tuples that are sorted according to a common sort key. The MergeAppend node merges these streams to produce output sorted the same way.", "/versions/14/sections/3/paragraphs/1": "MergeAppend nodes don't make use of their left and right subtrees, rather they maintain a list of subplans so a typical MergeAppend node looks like this in the plan tree:", "/versions/14/sections/3/paragraphs/3": "We have one slot for each item in the heap array. We use SlotNumber to store slot indexes. 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\u5305\u542b\u4e00\u4e2a\u6216\u591a\u4e2a\u5b50\u8ba1\u5212\uff0c\u8981\u6c42\u5b83\u4eec\u6309\u540c\u4e00\u6392\u5e8f\u952e\u8f93\u51fa\u5143\u7ec4\u3002\u8be5\u8282\u70b9\u5f52\u5e76\u8fd9\u4e9b\u6d41\uff0c\u4ea7\u751f\u6309\u76f8\u540c\u987a\u5e8f\u6392\u5217\u7684\u8f93\u51fa\u3002", "MergeAppend \u8282\u70b9\u4e0d\u4f7f\u7528\u5de6\u53f3\u5b50\u6811\uff0c\u800c\u662f\u7ef4\u62a4\u4e00\u4e2a\u5b50\u8ba1\u5212\u5217\u8868\uff0c\u56e0\u6b64\u5178\u578b\u8282\u70b9\u5728\u8ba1\u5212\u6811\u4e2d\u7684\u5f62\u6001\u5982\u4e0b\uff1a", "... / MergeAppend---+------+------+--- nil / \\ | | | nil nil ... ... ... subplans", "\u5806\u6570\u7ec4\u7684\u6bcf\u4e2a\u5143\u7d20\u5bf9\u5e94\u4e00\u4e2a\u69fd\u4f4d\uff0c\u4f7f\u7528 SlotNumber \u5b58\u50a8\u69fd\u4f4d\u7d22\u5f15\u3002\u8fd9\u5e76\u4e0d\u771f\u6b63\u63d0\u4f9b\u7c7b\u578b\u5b89\u5168\uff0c\u4f46\u80fd\u4f7f\u4ee3\u7801\u542b\u4e49\u66f4\u6e05\u695a\u3002", 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"\u591a\u4e2a\u5df2\u6392\u5e8f\u7684\u5b50\u8ba1\u5212"}, {"label": "\u8f93\u51fa", "value": "\u6309\u987a\u5e8f\u5f52\u5e76\u7684\u5143\u7ec4"}, {"label": "\u6267\u884c\u5668\u521d\u59cb\u5316\u51fd\u6570", "value": "ExecInitMergeAppend"}, {"label": "\u5185\u5b58\u673a\u5236", "value": "unclassified"}], "tables": [{"key": "explain-labels", "rows": [{"label": "Merge Append", "identity": "Merge Append"}], "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/15/performance-tips.html#USING-EXPLAIN", "anchor": "USING-EXPLAIN", "locale": "zh-Hans", "version": "15", "build_id": 101, "page_key": "performance-tips.html", "extraction": "concept-introduction", "source_hash": "d842974e11d60f39bee19269d456c1cf6a01bc6c2c3ac27d8d1e7966ef5f46b9", "fragment_sha256": "16561716621b0c2403eaa78c0cd62211754eaec8fd5716f685f693e1deb3a07b", "source_revision": "unknown:rendered-translation-baseline", "translation_revision": "git:b1b500221dbe5437cfca004d6b04d3f6e422765d;html-sha256:6bce1a2df9170cb1146a1411c5547190856638221a6539e618ee1016c9f493ad", "translated_from_revision": null}, "body_sha256": "094edad43823979b768dc729c4e65c5861743f9a0aede6bc289ed805f61ebf2e", "runtime_rerun": false, "authored_translation": "authored-translation-of-reviewed-guidance", "source_facts_revision": "e1a64a87a46b825b88c082e4518161a47aab53c45694964f8ba1df28f7859f89"}, "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\uff1aMerge Append.", "\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": ["\u672c\u6b21\u62bd\u53d6\u4e0d\u4e3a\u6b64\u8282\u70b9\u8bbe\u5b9a\u7edf\u4e00\u7684\u5185\u5b58\u4e0a\u9650\u6216\u843d\u76d8\u7b56\u7565\u3002\u8bf7\u67e5\u770b\u540c\u4e00\u6784\u5efa\u7684\u5b9e\u73b0\u3001\u76f8\u5173\u8868\u8fbe\u5f0f\u6216\u63d0\u4f9b\u65b9\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": "\u6267\u884c\u5668\u5b9e\u73b0\u8bf4\u660e", "paragraphs": ["\u8bf4\u660e\uff1aMergeAppend \u5305\u542b\u4e00\u4e2a\u6216\u591a\u4e2a\u5b50\u8ba1\u5212\uff0c\u8981\u6c42\u5b83\u4eec\u6309\u540c\u4e00\u6392\u5e8f\u952e\u8f93\u51fa\u5143\u7ec4\u3002\u8be5\u8282\u70b9\u5f52\u5e76\u8fd9\u4e9b\u6d41\uff0c\u4ea7\u751f\u6309\u76f8\u540c\u987a\u5e8f\u6392\u5217\u7684\u8f93\u51fa\u3002", "MergeAppend \u8282\u70b9\u4e0d\u4f7f\u7528\u5de6\u53f3\u5b50\u6811\uff0c\u800c\u662f\u7ef4\u62a4\u4e00\u4e2a\u5b50\u8ba1\u5212\u5217\u8868\uff0c\u56e0\u6b64\u5178\u578b\u8282\u70b9\u5728\u8ba1\u5212\u6811\u4e2d\u7684\u5f62\u6001\u5982\u4e0b\uff1a", "... / MergeAppend---+------+------+--- nil / \\ | | | nil nil ... ... ... subplans", "\u5806\u6570\u7ec4\u7684\u6bcf\u4e2a\u5143\u7d20\u5bf9\u5e94\u4e00\u4e2a\u69fd\u4f4d\uff0c\u4f7f\u7528 SlotNumber \u5b58\u50a8\u69fd\u4f4d\u7d22\u5f15\u3002\u8fd9\u5e76\u4e0d\u771f\u6b63\u63d0\u4f9b\u7c7b\u578b\u5b89\u5168\uff0c\u4f46\u80fd\u4f7f\u4ee3\u7801\u542b\u4e49\u66f4\u6e05\u695a\u3002", "\u82e5\u5df2\u542f\u7528\u8fd0\u884c\u65f6\u5206\u533a\u88c1\u526a\uff0c\u5219\u73b0\u5728\u8fdb\u884c\u76f8\u5e94\u8bbe\u7f6e\u3002"]}, {"code": "case T_MergeAppend:\n\t\t\tpname = sname = \"Merge Append\";\n\t\t\tbreak;", "title": "\u6838\u5fc3\u6e90\u7801\u4e2d\u7684 EXPLAIN \u6807\u8bc6"}], "description_zh": "\u5408\u5e76\u5df2\u6392\u5e8f\u7684\u5b50\u8ba1\u5212\u8f93\u51fa\u5e76\u4fdd\u6301\u6240\u9700\u987a\u5e8f\u3002", "description_zh_html": "\u5408\u5e76\u5df2\u6392\u5e8f\u7684\u5b50\u8ba1\u5212\u8f93\u51fa\u5e76\u4fdd\u6301\u6240\u9700\u987a\u5e8f\u3002
\u6838\u5fc3\u8282\u70b9\u6807\u8bc6\uff1aT_MergeAppend\uff1bEXPLAIN \u540d\u79f0\uff1aMerge Append\u3002
\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
\nPostgreSQL \u4f1a\u4e3a\u6536\u5230\u7684\u6bcf\u4e2a\u67e5\u8be2\u5236\u5b9a\u4e00\u4e2a\u67e5\u8be2\u8ba1\u5212\u3002\u9009\u62e9\u4e0e\u67e5\u8be2\u7ed3\u6784\u548c\u6570\u636e\u7279\u6027\u76f8\u5339\u914d\u7684\u6b63\u786e\u8ba1\u5212\uff0c\u5bf9\u83b7\u5f97\u826f\u597d\u7684\u6027\u80fd\u81f3\u5173\u91cd\u8981\uff0c\u56e0\u6b64\u7cfb\u7edf\u5185\u7f6e\u4e86\u4e00\u4e2a\u590d\u6742\u7684\u89c4\u5212\u5668\u6765\u5c3d\u91cf\u9009\u51fa\u597d\u7684\u8ba1\u5212\u3002\u53ef\u4ee5\u4f7f\u7528 EXPLAIN \u547d\u4ee4\u67e5\u770b\u89c4\u5212\u5668\u4e3a\u4efb\u610f\u67e5\u8be2\u751f\u6210\u7684\u67e5\u8be2\u8ba1\u5212\u3002\u8bfb\u61c2\u8ba1\u5212\u662f\u4e00\u95e8\u9700\u8981\u7ecf\u9a8c\u79ef\u7d2f\u7684\u6280\u80fd\uff0c\u672c\u8282\u5c06\u5c1d\u8bd5\u4ecb\u7ecd\u5176\u4e2d\u7684\u57fa\u7840\u77e5\u8bc6\u3002\n
\n \u672c\u8282\u4e2d\u7684\u793a\u4f8b\u53d6\u81ea\u6267\u884c\u8fc7 VACUUM ANALYZE \u7684\u56de\u5f52\u6d4b\u8bd5\u6570\u636e\u5e93\uff0c\u4f7f\u7528\u7684\u662f 9.3 \u5f00\u53d1\u7248\u672c\u6e90\u7801\u3002\u5982\u679c\u81ea\u884c\u5c1d\u8bd5\u8fd9\u4e9b\u793a\u4f8b\uff0c\u901a\u5e38\u5e94\u5f53\u80fd\u5f97\u5230\u76f8\u8fd1\u7684\u7ed3\u679c\uff0c\u4f46\u4f30\u8ba1\u4ee3\u4ef7\u548c\u884c\u8ba1\u6570\u53ef\u80fd\u7565\u6709\u5dee\u5f02\uff0c\u56e0\u4e3a ANALYZE \u751f\u6210\u7684\u7edf\u8ba1\u4fe1\u606f\u6765\u81ea\u968f\u673a\u91c7\u6837\u800c\u975e\u7cbe\u786e\u8ba1\u6570\uff0c\u800c\u4e14\u4ee3\u4ef7\u672c\u8eab\u5728\u67d0\u79cd\u7a0b\u5ea6\u4e0a\u4e5f\u4f9d\u8d56\u4e8e\u5e73\u53f0\u3002\n
\n \u8fd9\u4e9b\u793a\u4f8b\u4f7f\u7528 EXPLAIN \u9ed8\u8ba4\u7684\u201ctext\u201d\u8f93\u51fa\u683c\u5f0f\uff0c\u5b83\u7d27\u51d1\u4e14\u4fbf\u4e8e\u4eba\u5de5\u9605\u8bfb\u3002\u5982\u679c\u5e0c\u671b\u5c06 EXPLAIN \u7684\u8f93\u51fa\u4ea4\u7ed9\u7a0b\u5e8f\u505a\u8fdb\u4e00\u6b65\u5206\u6790\uff0c\u5219\u5e94\u6539\u7528\u673a\u5668\u53ef\u8bfb\u7684\u8f93\u51fa\u683c\u5f0f\uff08XML\u3001JSON \u6216 YAML\uff09\u3002\n
\u67e5\u770b\u5b8c\u6574\u4e2d\u6587\u624b\u518c\u4e0e\u4e0a\u4e0b\u6587\u3002
\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
"}, "summary": "\u5408\u5e76\u5df2\u6392\u5e8f\u7684\u5b50\u8ba1\u5212\u8f93\u51fa\u5e76\u4fdd\u6301\u6240\u9700\u987a\u5e8f\u3002", "version": "15", "link_map": {"/zh/docs/15/sql-explain.html": "/docs/15/sql-explain.html", "/zh/docs/15/performance-tips.html#USING-EXPLAIN": "/docs/15/performance-tips.html#USING-EXPLAIN"}, "body_html": "\u5408\u5e76\u5df2\u6392\u5e8f\u7684\u5b50\u8ba1\u5212\u8f93\u51fa\u5e76\u4fdd\u6301\u6240\u9700\u987a\u5e8f\u3002
\u6838\u5fc3\u8282\u70b9\u6807\u8bc6\uff1aT_MergeAppend\uff1bEXPLAIN \u540d\u79f0\uff1aMerge Append\u3002
\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
\nPostgreSQL \u4f1a\u4e3a\u6536\u5230\u7684\u6bcf\u4e2a\u67e5\u8be2\u5236\u5b9a\u4e00\u4e2a\u67e5\u8be2\u8ba1\u5212\u3002\u9009\u62e9\u4e0e\u67e5\u8be2\u7ed3\u6784\u548c\u6570\u636e\u7279\u6027\u76f8\u5339\u914d\u7684\u6b63\u786e\u8ba1\u5212\uff0c\u5bf9\u83b7\u5f97\u826f\u597d\u7684\u6027\u80fd\u81f3\u5173\u91cd\u8981\uff0c\u56e0\u6b64\u7cfb\u7edf\u5185\u7f6e\u4e86\u4e00\u4e2a\u590d\u6742\u7684\u89c4\u5212\u5668\u6765\u5c3d\u91cf\u9009\u51fa\u597d\u7684\u8ba1\u5212\u3002\u53ef\u4ee5\u4f7f\u7528 EXPLAIN \u547d\u4ee4\u67e5\u770b\u89c4\u5212\u5668\u4e3a\u4efb\u610f\u67e5\u8be2\u751f\u6210\u7684\u67e5\u8be2\u8ba1\u5212\u3002\u8bfb\u61c2\u8ba1\u5212\u662f\u4e00\u95e8\u9700\u8981\u7ecf\u9a8c\u79ef\u7d2f\u7684\u6280\u80fd\uff0c\u672c\u8282\u5c06\u5c1d\u8bd5\u4ecb\u7ecd\u5176\u4e2d\u7684\u57fa\u7840\u77e5\u8bc6\u3002\n
\n \u672c\u8282\u4e2d\u7684\u793a\u4f8b\u53d6\u81ea\u6267\u884c\u8fc7 VACUUM ANALYZE \u7684\u56de\u5f52\u6d4b\u8bd5\u6570\u636e\u5e93\uff0c\u4f7f\u7528\u7684\u662f 9.3 \u5f00\u53d1\u7248\u672c\u6e90\u7801\u3002\u5982\u679c\u81ea\u884c\u5c1d\u8bd5\u8fd9\u4e9b\u793a\u4f8b\uff0c\u901a\u5e38\u5e94\u5f53\u80fd\u5f97\u5230\u76f8\u8fd1\u7684\u7ed3\u679c\uff0c\u4f46\u4f30\u8ba1\u4ee3\u4ef7\u548c\u884c\u8ba1\u6570\u53ef\u80fd\u7565\u6709\u5dee\u5f02\uff0c\u56e0\u4e3a ANALYZE \u751f\u6210\u7684\u7edf\u8ba1\u4fe1\u606f\u6765\u81ea\u968f\u673a\u91c7\u6837\u800c\u975e\u7cbe\u786e\u8ba1\u6570\uff0c\u800c\u4e14\u4ee3\u4ef7\u672c\u8eab\u5728\u67d0\u79cd\u7a0b\u5ea6\u4e0a\u4e5f\u4f9d\u8d56\u4e8e\u5e73\u53f0\u3002\n
\n \u8fd9\u4e9b\u793a\u4f8b\u4f7f\u7528 EXPLAIN \u9ed8\u8ba4\u7684\u201ctext\u201d\u8f93\u51fa\u683c\u5f0f\uff0c\u5b83\u7d27\u51d1\u4e14\u4fbf\u4e8e\u4eba\u5de5\u9605\u8bfb\u3002\u5982\u679c\u5e0c\u671b\u5c06 EXPLAIN \u7684\u8f93\u51fa\u4ea4\u7ed9\u7a0b\u5e8f\u505a\u8fdb\u4e00\u6b65\u5206\u6790\uff0c\u5219\u5e94\u6539\u7528\u673a\u5668\u53ef\u8bfb\u7684\u8f93\u51fa\u683c\u5f0f\uff08XML\u3001JSON \u6216 YAML\uff09\u3002\n
\u67e5\u770b\u5b8c\u6574\u4e2d\u6587\u624b\u518c\u4e0e\u4e0a\u4e0b\u6587\u3002
\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
", "body_sha256": "5a84799ca0917fc4076be4736b53c7083a0821087857da6d1e43642588a4b6a9", "content_hash": "ac8f52305529e551d98d076f54e718c5ff4bff7dbbb2b926800c9cab8c2ac453", "source_database": "center", "source_revision": "e1a64a87a46b825b88c082e4518161a47aab53c45694964f8ba1df28f7859f89"}, "tables_zh": [{"key": "explain-labels", "rows": [{"label": "Merge Append", "identity": "Merge Append"}], "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": ["\u5408\u5e76\u5df2\u6392\u5e8f\u7684\u5b50\u8ba1\u5212\u8f93\u51fa\u5e76\u4fdd\u6301\u6240\u9700\u987a\u5e8f\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\uff1aMerge Append.", "\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": ["\u672c\u6b21\u62bd\u53d6\u4e0d\u4e3a\u6b64\u8282\u70b9\u8bbe\u5b9a\u7edf\u4e00\u7684\u5185\u5b58\u4e0a\u9650\u6216\u843d\u76d8\u7b56\u7565\u3002\u8bf7\u67e5\u770b\u540c\u4e00\u6784\u5efa\u7684\u5b9e\u73b0\u3001\u76f8\u5173\u8868\u8fbe\u5f0f\u6216\u63d0\u4f9b\u65b9\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": "\u6267\u884c\u5668\u5b9e\u73b0\u8bf4\u660e", "paragraphs": ["\u8bf4\u660e\uff1aMergeAppend \u5305\u542b\u4e00\u4e2a\u6216\u591a\u4e2a\u5b50\u8ba1\u5212\uff0c\u8981\u6c42\u5b83\u4eec\u6309\u540c\u4e00\u6392\u5e8f\u952e\u8f93\u51fa\u5143\u7ec4\u3002\u8be5\u8282\u70b9\u5f52\u5e76\u8fd9\u4e9b\u6d41\uff0c\u4ea7\u751f\u6309\u76f8\u540c\u987a\u5e8f\u6392\u5217\u7684\u8f93\u51fa\u3002", "MergeAppend \u8282\u70b9\u4e0d\u4f7f\u7528\u5de6\u53f3\u5b50\u6811\uff0c\u800c\u662f\u7ef4\u62a4\u4e00\u4e2a\u5b50\u8ba1\u5212\u5217\u8868\uff0c\u56e0\u6b64\u5178\u578b\u8282\u70b9\u5728\u8ba1\u5212\u6811\u4e2d\u7684\u5f62\u6001\u5982\u4e0b\uff1a", "... / MergeAppend---+------+------+--- nil / \\ | | | nil nil ... ... ... subplans", "\u5806\u6570\u7ec4\u7684\u6bcf\u4e2a\u5143\u7d20\u5bf9\u5e94\u4e00\u4e2a\u69fd\u4f4d\uff0c\u4f7f\u7528 SlotNumber \u5b58\u50a8\u69fd\u4f4d\u7d22\u5f15\u3002\u8fd9\u5e76\u4e0d\u771f\u6b63\u63d0\u4f9b\u7c7b\u578b\u5b89\u5168\uff0c\u4f46\u80fd\u4f7f\u4ee3\u7801\u542b\u4e49\u66f4\u6e05\u695a\u3002", "\u82e5\u5df2\u542f\u7528\u8fd0\u884c\u65f6\u5206\u533a\u88c1\u526a\uff0c\u5219\u73b0\u5728\u8fdb\u884c\u76f8\u5e94\u8bbe\u7f6e\u3002"]}, {"code": "case T_MergeAppend:\n\t\t\tpname = sname = \"Merge Append\";\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": "Merges sorted child streams while preserving the required ordering.", "/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": "Multiple sorted child plans", "/versions/15/facts/3/label": "Output", "/versions/15/facts/3/value": "Merged ordered tuples", "/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": "Executor implementation notes", "/versions/15/sections/4/title": "EXPLAIN identity in core source", "/versions/15/memory/description": "This extraction does not assign a universal memory limit or spill policy to this node. Inspect the same-build implementation and its expressions or provider.", "/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: Merge Append.", "/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": "This extraction does not assign a universal memory limit or spill policy to this node. Inspect the same-build implementation and its expressions or provider.", "/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": "NOTES A MergeAppend node contains a list of one or more subplans. These are each expected to deliver tuples that are sorted according to a common sort key. The MergeAppend node merges these streams to produce output sorted the same way.", "/versions/15/sections/3/paragraphs/1": "MergeAppend nodes don't make use of their left and right subtrees, rather they maintain a list of subplans so a typical MergeAppend node looks like this in the plan tree:", "/versions/15/sections/3/paragraphs/3": "We have one slot for each item in the heap array. We use SlotNumber to store slot indexes. This doesn't actually provide any formal type-safety, but it makes the code more self-documenting.", "/versions/15/sections/3/paragraphs/4": "If run-time partition pruning is enabled, then set that up now", "/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": "ffc55827573cd662ee76f59ca8bc50498d72eec027cf3f430ed8a5a531efacb8", "canonical_center_text_hash": "ac8f52305529e551d98d076f54e718c5ff4bff7dbbb2b926800c9cab8c2ac453"}, "evidence_kind": "source and documentation", "explain_names": ["Merge Append"], "partial_modes": [], "description_zh": "\u5408\u5e76\u5df2\u6392\u5e8f\u7684\u5b50\u8ba1\u5212\u8f93\u51fa\u5e76\u4fdd\u6301\u6240\u9700\u987a\u5e8f\u3002", "comparison_data": {"node_tag": "T_MergeAppend", "strategies": [], "text_names": ["Merge Append"], "initializer": "ExecInitMergeAppend", "partial_modes": [], "memory_mechanism": "unclassified", "parallel_callbacks": []}, "comparison_hash": "5428ffe21c76597da696d12a775fd915b1be22e9ba2d2d5ba3d84704f51ff3d9", "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/nodeMergeAppend.c"}, "parallel_callbacks": [], "description_zh_html": "\u5408\u5e76\u5df2\u6392\u5e8f\u7684\u5b50\u8ba1\u5212\u8f93\u51fa\u5e76\u4fdd\u6301\u6240\u9700\u987a\u5e8f\u3002
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\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
\nPostgreSQL \u4f1a\u4e3a\u6536\u5230\u7684\u6bcf\u4e2a\u67e5\u8be2\u5236\u5b9a\u4e00\u4e2a\u67e5\u8be2\u8ba1\u5212\u3002\u9009\u62e9\u4e0e\u67e5\u8be2\u7ed3\u6784\u548c\u6570\u636e\u7279\u6027\u76f8\u5339\u914d\u7684\u6b63\u786e\u8ba1\u5212\uff0c\u5bf9\u83b7\u5f97\u826f\u597d\u7684\u6027\u80fd\u81f3\u5173\u91cd\u8981\uff0c\u56e0\u6b64\u7cfb\u7edf\u5185\u7f6e\u4e86\u4e00\u4e2a\u590d\u6742\u7684\u89c4\u5212\u5668\u6765\u5c3d\u91cf\u9009\u51fa\u597d\u7684\u8ba1\u5212\u3002\u53ef\u4ee5\u4f7f\u7528 EXPLAIN \u547d\u4ee4\u67e5\u770b\u89c4\u5212\u5668\u4e3a\u4efb\u610f\u67e5\u8be2\u751f\u6210\u7684\u67e5\u8be2\u8ba1\u5212\u3002\u8bfb\u61c2\u8ba1\u5212\u662f\u4e00\u95e8\u9700\u8981\u7ecf\u9a8c\u79ef\u7d2f\u7684\u6280\u80fd\uff0c\u672c\u8282\u5c06\u5c1d\u8bd5\u4ecb\u7ecd\u5176\u4e2d\u7684\u57fa\u7840\u77e5\u8bc6\u3002\n
\n \u672c\u8282\u4e2d\u7684\u793a\u4f8b\u53d6\u81ea\u6267\u884c\u8fc7 VACUUM ANALYZE \u7684\u56de\u5f52\u6d4b\u8bd5\u6570\u636e\u5e93\uff0c\u4f7f\u7528\u7684\u662f 9.3 \u5f00\u53d1\u7248\u672c\u6e90\u7801\u3002\u5982\u679c\u81ea\u884c\u5c1d\u8bd5\u8fd9\u4e9b\u793a\u4f8b\uff0c\u901a\u5e38\u5e94\u5f53\u80fd\u5f97\u5230\u76f8\u8fd1\u7684\u7ed3\u679c\uff0c\u4f46\u4f30\u8ba1\u4ee3\u4ef7\u548c\u884c\u8ba1\u6570\u53ef\u80fd\u7565\u6709\u5dee\u5f02\uff0c\u56e0\u4e3a ANALYZE \u751f\u6210\u7684\u7edf\u8ba1\u4fe1\u606f\u6765\u81ea\u968f\u673a\u91c7\u6837\u800c\u975e\u7cbe\u786e\u8ba1\u6570\uff0c\u800c\u4e14\u4ee3\u4ef7\u672c\u8eab\u5728\u67d0\u79cd\u7a0b\u5ea6\u4e0a\u4e5f\u4f9d\u8d56\u4e8e\u5e73\u53f0\u3002\n
\n \u8fd9\u4e9b\u793a\u4f8b\u4f7f\u7528 EXPLAIN \u9ed8\u8ba4\u7684\u201ctext\u201d\u8f93\u51fa\u683c\u5f0f\uff0c\u5b83\u7d27\u51d1\u4e14\u4fbf\u4e8e\u4eba\u5de5\u9605\u8bfb\u3002\u5982\u679c\u5e0c\u671b\u5c06 EXPLAIN \u7684\u8f93\u51fa\u4ea4\u7ed9\u7a0b\u5e8f\u505a\u8fdb\u4e00\u6b65\u5206\u6790\uff0c\u5219\u5e94\u6539\u7528\u673a\u5668\u53ef\u8bfb\u7684\u8f93\u51fa\u683c\u5f0f\uff08XML\u3001JSON \u6216 YAML\uff09\u3002\n
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["\u672c\u6b21\u62bd\u53d6\u4e0d\u4e3a\u6b64\u8282\u70b9\u8bbe\u5b9a\u7edf\u4e00\u7684\u5185\u5b58\u4e0a\u9650\u6216\u843d\u76d8\u7b56\u7565\u3002\u8bf7\u67e5\u770b\u540c\u4e00\u6784\u5efa\u7684\u5b9e\u73b0\u3001\u76f8\u5173\u8868\u8fbe\u5f0f\u6216\u63d0\u4f9b\u65b9\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": "\u6267\u884c\u5668\u5b9e\u73b0\u8bf4\u660e", "paragraphs": ["\u8bf4\u660e\uff1aMergeAppend 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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\uff1aMerge Append.", "\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": ["\u672c\u6b21\u62bd\u53d6\u4e0d\u4e3a\u6b64\u8282\u70b9\u8bbe\u5b9a\u7edf\u4e00\u7684\u5185\u5b58\u4e0a\u9650\u6216\u843d\u76d8\u7b56\u7565\u3002\u8bf7\u67e5\u770b\u540c\u4e00\u6784\u5efa\u7684\u5b9e\u73b0\u3001\u76f8\u5173\u8868\u8fbe\u5f0f\u6216\u63d0\u4f9b\u65b9\u3002"]}, {"title": "\u5e76\u884c\u6267\u884c\u4e0e\u8fd0\u884c\u4fe1\u606f\u91c7\u96c6", "paragraphs": 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\u6838\u5fc3\u8282\u70b9\u6807\u8bc6\uff1aT_MergeAppend\uff1bEXPLAIN \u540d\u79f0\uff1aMerge Append\u3002
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\nPostgreSQL \u4f1a\u4e3a\u6536\u5230\u7684\u6bcf\u4e2a\u67e5\u8be2\u5236\u5b9a\u4e00\u4e2a\u67e5\u8be2\u8ba1\u5212\u3002\u9009\u62e9\u4e0e\u67e5\u8be2\u7ed3\u6784\u548c\u6570\u636e\u7279\u6027\u76f8\u5339\u914d\u7684\u6b63\u786e\u8ba1\u5212\uff0c\u5bf9\u83b7\u5f97\u826f\u597d\u7684\u6027\u80fd\u81f3\u5173\u91cd\u8981\uff0c\u56e0\u6b64\u7cfb\u7edf\u5185\u7f6e\u4e86\u4e00\u4e2a\u590d\u6742\u7684\u89c4\u5212\u5668\u6765\u5c3d\u91cf\u9009\u51fa\u597d\u7684\u8ba1\u5212\u3002\u53ef\u4ee5\u4f7f\u7528 EXPLAIN \u547d\u4ee4\u67e5\u770b\u89c4\u5212\u5668\u4e3a\u4efb\u610f\u67e5\u8be2\u751f\u6210\u7684\u67e5\u8be2\u8ba1\u5212\u3002\u8bfb\u61c2\u8ba1\u5212\u662f\u4e00\u95e8\u9700\u8981\u7ecf\u9a8c\u79ef\u7d2f\u7684\u6280\u80fd\uff0c\u672c\u8282\u5c06\u5c1d\u8bd5\u4ecb\u7ecd\u5176\u4e2d\u7684\u57fa\u7840\u77e5\u8bc6\u3002\n
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\n \u8fd9\u4e9b\u793a\u4f8b\u4f7f\u7528 EXPLAIN \u9ed8\u8ba4\u7684\u201ctext\u201d\u8f93\u51fa\u683c\u5f0f\uff0c\u5b83\u7d27\u51d1\u4e14\u4fbf\u4e8e\u4eba\u5de5\u9605\u8bfb\u3002\u5982\u679c\u5e0c\u671b\u5c06 EXPLAIN \u7684\u8f93\u51fa\u4ea4\u7ed9\u7a0b\u5e8f\u505a\u8fdb\u4e00\u6b65\u5206\u6790\uff0c\u5219\u5e94\u6539\u7528\u673a\u5668\u53ef\u8bfb\u7684\u8f93\u51fa\u683c\u5f0f\uff08XML\u3001JSON \u6216 YAML\uff09\u3002\n
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Inspect the same-build implementation and its expressions or provider.", "/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: Merge Append.", "/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": "This extraction does not assign a universal memory limit or spill policy to this node. Inspect the same-build implementation and its expressions or provider.", "/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": "NOTES A MergeAppend node contains a list of one or more subplans. These are each expected to deliver tuples that are sorted according to a common sort key. The MergeAppend node merges these streams to produce output sorted the same way.", "/versions/16/sections/3/paragraphs/1": "MergeAppend nodes don't make use of their left and right subtrees, rather they maintain a list of subplans so a typical MergeAppend node looks like this in the plan tree:", "/versions/16/sections/3/paragraphs/3": "We have one slot for each item in the heap array. We use SlotNumber to store slot indexes. 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\u5305\u542b\u4e00\u4e2a\u6216\u591a\u4e2a\u5b50\u8ba1\u5212\uff0c\u8981\u6c42\u5b83\u4eec\u6309\u540c\u4e00\u6392\u5e8f\u952e\u8f93\u51fa\u5143\u7ec4\u3002\u8be5\u8282\u70b9\u5f52\u5e76\u8fd9\u4e9b\u6d41\uff0c\u4ea7\u751f\u6309\u76f8\u540c\u987a\u5e8f\u6392\u5217\u7684\u8f93\u51fa\u3002", "MergeAppend \u8282\u70b9\u4e0d\u4f7f\u7528\u5de6\u53f3\u5b50\u6811\uff0c\u800c\u662f\u7ef4\u62a4\u4e00\u4e2a\u5b50\u8ba1\u5212\u5217\u8868\uff0c\u56e0\u6b64\u5178\u578b\u8282\u70b9\u5728\u8ba1\u5212\u6811\u4e2d\u7684\u5f62\u6001\u5982\u4e0b\uff1a", "... / MergeAppend---+------+------+--- nil / \\ | | | nil nil ... ... ... subplans", "\u5806\u6570\u7ec4\u7684\u6bcf\u4e2a\u5143\u7d20\u5bf9\u5e94\u4e00\u4e2a\u69fd\u4f4d\uff0c\u4f7f\u7528 SlotNumber \u5b58\u50a8\u69fd\u4f4d\u7d22\u5f15\u3002\u8fd9\u5e76\u4e0d\u771f\u6b63\u63d0\u4f9b\u7c7b\u578b\u5b89\u5168\uff0c\u4f46\u80fd\u4f7f\u4ee3\u7801\u542b\u4e49\u66f4\u6e05\u695a\u3002", "\u82e5\u5df2\u542f\u7528\u8fd0\u884c\u65f6\u5206\u533a\u88c1\u526a\uff0c\u5219\u73b0\u5728\u8fdb\u884c\u76f8\u5e94\u8bbe\u7f6e\u3002"]}, {"code": "case T_MergeAppend:\n\t\t\tpname = sname = \"Merge Append\";\n\t\t\tbreak;", "title": "\u6838\u5fc3\u6e90\u7801\u4e2d\u7684 EXPLAIN \u6807\u8bc6"}], "center_zh": {"title": "MergeAppend", "locale": "zh-Hans", "source": {"key": "merge-append", "locale": "zh-Hans", "version": "17", "text_hash": "b3867e173250de62e6b55cdcdbea9a63d9f45b4cb779ff903a8379ed571ba7d0", "collection": "plan", "dataset_hash": "7c31b524dfe136022d39a6ae8dcfac6b3bbd5f8fdaf422536599981252aff0c9", "source_database": "center", "source_revision": "dd27f2b3c59e73ed14aa3324901242bf69a032a6347805f274e6260322d42979"}, "payload": {"facts": [{"label": "\u6838\u5fc3\u8282\u70b9\u6807\u7b7e", "value": "T_MergeAppend"}, {"label": "\u7ed3\u6784\u5316 EXPLAIN \u8282\u70b9\u7c7b\u578b", "value": "Merge Append"}, {"label": "\u8f93\u5165", "value": "\u591a\u4e2a\u5df2\u6392\u5e8f\u7684\u5b50\u8ba1\u5212"}, {"label": "\u8f93\u51fa", "value": "\u6309\u987a\u5e8f\u5f52\u5e76\u7684\u5143\u7ec4"}, {"label": "\u6267\u884c\u5668\u521d\u59cb\u5316\u51fd\u6570", "value": "ExecInitMergeAppend"}, {"label": "\u5185\u5b58\u673a\u5236", "value": "unclassified"}], "tables": [{"key": "explain-labels", "rows": [{"label": "Merge Append", "identity": "Merge Append"}], "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", "anchor": "", "locale": "zh-Hans", "version": "17", "build_id": 105, "page_key": "using-explain.html", "extraction": "concept-introduction", "source_hash": "b1252952c6d796f5e38c223b74ff667f2d19d677dcf85fe5269b782b830e5013", "fragment_sha256": "8f5243c368dfae57e826af49b7461d37d7f4d97207bd5f540aebe6b10a61f883", "source_revision": "unknown:rendered-translation-baseline", "translation_revision": "git:b1b500221dbe5437cfca004d6b04d3f6e422765d;html-sha256:7340767258d21c21b36f373f1fff6bab2be18e0daca13a865129db6105c09efd", "translated_from_revision": null}, "body_sha256": "db3f9a437897d0d02d62bf6c96bddac590c98b51d172e90b508360163cbb755f", "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\uff1aMerge Append.", "\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": ["\u672c\u6b21\u62bd\u53d6\u4e0d\u4e3a\u6b64\u8282\u70b9\u8bbe\u5b9a\u7edf\u4e00\u7684\u5185\u5b58\u4e0a\u9650\u6216\u843d\u76d8\u7b56\u7565\u3002\u8bf7\u67e5\u770b\u540c\u4e00\u6784\u5efa\u7684\u5b9e\u73b0\u3001\u76f8\u5173\u8868\u8fbe\u5f0f\u6216\u63d0\u4f9b\u65b9\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": "\u6267\u884c\u5668\u5b9e\u73b0\u8bf4\u660e", "paragraphs": ["\u8bf4\u660e\uff1aMergeAppend \u5305\u542b\u4e00\u4e2a\u6216\u591a\u4e2a\u5b50\u8ba1\u5212\uff0c\u8981\u6c42\u5b83\u4eec\u6309\u540c\u4e00\u6392\u5e8f\u952e\u8f93\u51fa\u5143\u7ec4\u3002\u8be5\u8282\u70b9\u5f52\u5e76\u8fd9\u4e9b\u6d41\uff0c\u4ea7\u751f\u6309\u76f8\u540c\u987a\u5e8f\u6392\u5217\u7684\u8f93\u51fa\u3002", "MergeAppend \u8282\u70b9\u4e0d\u4f7f\u7528\u5de6\u53f3\u5b50\u6811\uff0c\u800c\u662f\u7ef4\u62a4\u4e00\u4e2a\u5b50\u8ba1\u5212\u5217\u8868\uff0c\u56e0\u6b64\u5178\u578b\u8282\u70b9\u5728\u8ba1\u5212\u6811\u4e2d\u7684\u5f62\u6001\u5982\u4e0b\uff1a", "... / MergeAppend---+------+------+--- nil / \\ | | | nil nil ... ... ... subplans", "\u5806\u6570\u7ec4\u7684\u6bcf\u4e2a\u5143\u7d20\u5bf9\u5e94\u4e00\u4e2a\u69fd\u4f4d\uff0c\u4f7f\u7528 SlotNumber \u5b58\u50a8\u69fd\u4f4d\u7d22\u5f15\u3002\u8fd9\u5e76\u4e0d\u771f\u6b63\u63d0\u4f9b\u7c7b\u578b\u5b89\u5168\uff0c\u4f46\u80fd\u4f7f\u4ee3\u7801\u542b\u4e49\u66f4\u6e05\u695a\u3002", "\u82e5\u5df2\u542f\u7528\u8fd0\u884c\u65f6\u5206\u533a\u88c1\u526a\uff0c\u5219\u73b0\u5728\u8fdb\u884c\u76f8\u5e94\u8bbe\u7f6e\u3002"]}, {"code": "case T_MergeAppend:\n\t\t\tpname = sname = \"Merge Append\";\n\t\t\tbreak;", "title": "\u6838\u5fc3\u6e90\u7801\u4e2d\u7684 EXPLAIN \u6807\u8bc6"}], "description_zh": "\u5408\u5e76\u5df2\u6392\u5e8f\u7684\u5b50\u8ba1\u5212\u8f93\u51fa\u5e76\u4fdd\u6301\u6240\u9700\u987a\u5e8f\u3002", "description_zh_html": "\u5408\u5e76\u5df2\u6392\u5e8f\u7684\u5b50\u8ba1\u5212\u8f93\u51fa\u5e76\u4fdd\u6301\u6240\u9700\u987a\u5e8f\u3002
\u6838\u5fc3\u8282\u70b9\u6807\u8bc6\uff1aT_MergeAppend\uff1bEXPLAIN \u540d\u79f0\uff1aMerge Append\u3002
\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
\nPostgreSQL \u4f1a\u4e3a\u6536\u5230\u7684\u6bcf\u4e2a\u67e5\u8be2\u5236\u5b9a\u4e00\u4e2a\u67e5\u8be2\u8ba1\u5212\u3002\u9009\u62e9\u4e0e\u67e5\u8be2\u7ed3\u6784\u548c\u6570\u636e\u7279\u6027\u76f8\u5339\u914d\u7684\u6b63\u786e\u8ba1\u5212\uff0c\u5bf9\u83b7\u5f97\u826f\u597d\u7684\u6027\u80fd\u81f3\u5173\u91cd\u8981\uff0c\u56e0\u6b64\u7cfb\u7edf\u5185\u7f6e\u4e86\u4e00\u4e2a\u590d\u6742\u7684\u89c4\u5212\u5668\u6765\u5c3d\u91cf\u9009\u51fa\u597d\u7684\u8ba1\u5212\u3002\u53ef\u4ee5\u4f7f\u7528 EXPLAIN \u547d\u4ee4\u67e5\u770b\u89c4\u5212\u5668\u4e3a\u4efb\u610f\u67e5\u8be2\u751f\u6210\u7684\u67e5\u8be2\u8ba1\u5212\u3002\u8bfb\u61c2\u8ba1\u5212\u662f\u4e00\u95e8\u9700\u8981\u7ecf\u9a8c\u79ef\u7d2f\u7684\u6280\u80fd\uff0c\u672c\u8282\u5c06\u5c1d\u8bd5\u4ecb\u7ecd\u5176\u4e2d\u7684\u57fa\u7840\u77e5\u8bc6\u3002\n
\n \u672c\u8282\u4e2d\u7684\u793a\u4f8b\u53d6\u81ea\u6267\u884c\u8fc7 VACUUM ANALYZE \u7684\u56de\u5f52\u6d4b\u8bd5\u6570\u636e\u5e93\uff0c\u4f7f\u7528\u7684\u662f v17 \u5f00\u53d1\u7248\u672c\u6e90\u7801\u3002\u5982\u679c\u81ea\u884c\u5c1d\u8bd5\u8fd9\u4e9b\u793a\u4f8b\uff0c\u901a\u5e38\u5e94\u5f53\u80fd\u5f97\u5230\u76f8\u8fd1\u7684\u7ed3\u679c\uff0c\u4f46\u4f30\u8ba1\u4ee3\u4ef7\u548c\u884c\u8ba1\u6570\u53ef\u80fd\u7565\u6709\u5dee\u5f02\uff0c\u56e0\u4e3a ANALYZE \u751f\u6210\u7684\u7edf\u8ba1\u4fe1\u606f\u6765\u81ea\u968f\u673a\u91c7\u6837\u800c\u975e\u7cbe\u786e\u8ba1\u6570\uff0c\u800c\u4e14\u4ee3\u4ef7\u672c\u8eab\u5728\u67d0\u79cd\u7a0b\u5ea6\u4e0a\u4e5f\u4f9d\u8d56\u4e8e\u5e73\u53f0\u3002\n
\n \u8fd9\u4e9b\u793a\u4f8b\u4f7f\u7528 EXPLAIN \u9ed8\u8ba4\u7684\u201ctext\u201d\u8f93\u51fa\u683c\u5f0f\uff0c\u5b83\u7d27\u51d1\u4e14\u4fbf\u4e8e\u4eba\u5de5\u9605\u8bfb\u3002\u5982\u679c\u5e0c\u671b\u5c06 EXPLAIN \u7684\u8f93\u51fa\u4ea4\u7ed9\u7a0b\u5e8f\u505a\u8fdb\u4e00\u6b65\u5206\u6790\uff0c\u5219\u5e94\u6539\u7528\u673a\u5668\u53ef\u8bfb\u7684\u8f93\u51fa\u683c\u5f0f\uff08XML\u3001JSON \u6216 YAML\uff09\u3002\n
\u67e5\u770b\u5b8c\u6574\u4e2d\u6587\u624b\u518c\u4e0e\u4e0a\u4e0b\u6587\u3002
\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
"}, "summary": "\u5408\u5e76\u5df2\u6392\u5e8f\u7684\u5b50\u8ba1\u5212\u8f93\u51fa\u5e76\u4fdd\u6301\u6240\u9700\u987a\u5e8f\u3002", "version": "17", "link_map": {"/zh/docs/17/sql-explain.html": "/docs/17/sql-explain.html", "/zh/docs/17/using-explain.html": "/docs/17/using-explain.html"}, "body_html": "\u5408\u5e76\u5df2\u6392\u5e8f\u7684\u5b50\u8ba1\u5212\u8f93\u51fa\u5e76\u4fdd\u6301\u6240\u9700\u987a\u5e8f\u3002
\u6838\u5fc3\u8282\u70b9\u6807\u8bc6\uff1aT_MergeAppend\uff1bEXPLAIN \u540d\u79f0\uff1aMerge Append\u3002
\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
\nPostgreSQL \u4f1a\u4e3a\u6536\u5230\u7684\u6bcf\u4e2a\u67e5\u8be2\u5236\u5b9a\u4e00\u4e2a\u67e5\u8be2\u8ba1\u5212\u3002\u9009\u62e9\u4e0e\u67e5\u8be2\u7ed3\u6784\u548c\u6570\u636e\u7279\u6027\u76f8\u5339\u914d\u7684\u6b63\u786e\u8ba1\u5212\uff0c\u5bf9\u83b7\u5f97\u826f\u597d\u7684\u6027\u80fd\u81f3\u5173\u91cd\u8981\uff0c\u56e0\u6b64\u7cfb\u7edf\u5185\u7f6e\u4e86\u4e00\u4e2a\u590d\u6742\u7684\u89c4\u5212\u5668\u6765\u5c3d\u91cf\u9009\u51fa\u597d\u7684\u8ba1\u5212\u3002\u53ef\u4ee5\u4f7f\u7528 EXPLAIN \u547d\u4ee4\u67e5\u770b\u89c4\u5212\u5668\u4e3a\u4efb\u610f\u67e5\u8be2\u751f\u6210\u7684\u67e5\u8be2\u8ba1\u5212\u3002\u8bfb\u61c2\u8ba1\u5212\u662f\u4e00\u95e8\u9700\u8981\u7ecf\u9a8c\u79ef\u7d2f\u7684\u6280\u80fd\uff0c\u672c\u8282\u5c06\u5c1d\u8bd5\u4ecb\u7ecd\u5176\u4e2d\u7684\u57fa\u7840\u77e5\u8bc6\u3002\n
\n \u672c\u8282\u4e2d\u7684\u793a\u4f8b\u53d6\u81ea\u6267\u884c\u8fc7 VACUUM ANALYZE \u7684\u56de\u5f52\u6d4b\u8bd5\u6570\u636e\u5e93\uff0c\u4f7f\u7528\u7684\u662f v17 \u5f00\u53d1\u7248\u672c\u6e90\u7801\u3002\u5982\u679c\u81ea\u884c\u5c1d\u8bd5\u8fd9\u4e9b\u793a\u4f8b\uff0c\u901a\u5e38\u5e94\u5f53\u80fd\u5f97\u5230\u76f8\u8fd1\u7684\u7ed3\u679c\uff0c\u4f46\u4f30\u8ba1\u4ee3\u4ef7\u548c\u884c\u8ba1\u6570\u53ef\u80fd\u7565\u6709\u5dee\u5f02\uff0c\u56e0\u4e3a ANALYZE \u751f\u6210\u7684\u7edf\u8ba1\u4fe1\u606f\u6765\u81ea\u968f\u673a\u91c7\u6837\u800c\u975e\u7cbe\u786e\u8ba1\u6570\uff0c\u800c\u4e14\u4ee3\u4ef7\u672c\u8eab\u5728\u67d0\u79cd\u7a0b\u5ea6\u4e0a\u4e5f\u4f9d\u8d56\u4e8e\u5e73\u53f0\u3002\n
\n \u8fd9\u4e9b\u793a\u4f8b\u4f7f\u7528 EXPLAIN \u9ed8\u8ba4\u7684\u201ctext\u201d\u8f93\u51fa\u683c\u5f0f\uff0c\u5b83\u7d27\u51d1\u4e14\u4fbf\u4e8e\u4eba\u5de5\u9605\u8bfb\u3002\u5982\u679c\u5e0c\u671b\u5c06 EXPLAIN \u7684\u8f93\u51fa\u4ea4\u7ed9\u7a0b\u5e8f\u505a\u8fdb\u4e00\u6b65\u5206\u6790\uff0c\u5219\u5e94\u6539\u7528\u673a\u5668\u53ef\u8bfb\u7684\u8f93\u51fa\u683c\u5f0f\uff08XML\u3001JSON \u6216 YAML\uff09\u3002\n
\u67e5\u770b\u5b8c\u6574\u4e2d\u6587\u624b\u518c\u4e0e\u4e0a\u4e0b\u6587\u3002
\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
", "body_sha256": "97b1ccf60be846991fe04c16cccc27fe4c7639f48a85bf5651dcedbe3d715097", "content_hash": "b3867e173250de62e6b55cdcdbea9a63d9f45b4cb779ff903a8379ed571ba7d0", "source_database": "center", "source_revision": "dd27f2b3c59e73ed14aa3324901242bf69a032a6347805f274e6260322d42979"}, "tables_zh": [{"key": "explain-labels", "rows": [{"label": "Merge Append", "identity": "Merge Append"}], "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": ["\u5408\u5e76\u5df2\u6392\u5e8f\u7684\u5b50\u8ba1\u5212\u8f93\u51fa\u5e76\u4fdd\u6301\u6240\u9700\u987a\u5e8f\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\uff1aMerge Append.", "\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": ["\u672c\u6b21\u62bd\u53d6\u4e0d\u4e3a\u6b64\u8282\u70b9\u8bbe\u5b9a\u7edf\u4e00\u7684\u5185\u5b58\u4e0a\u9650\u6216\u843d\u76d8\u7b56\u7565\u3002\u8bf7\u67e5\u770b\u540c\u4e00\u6784\u5efa\u7684\u5b9e\u73b0\u3001\u76f8\u5173\u8868\u8fbe\u5f0f\u6216\u63d0\u4f9b\u65b9\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": "\u6267\u884c\u5668\u5b9e\u73b0\u8bf4\u660e", "paragraphs": ["\u8bf4\u660e\uff1aMergeAppend \u5305\u542b\u4e00\u4e2a\u6216\u591a\u4e2a\u5b50\u8ba1\u5212\uff0c\u8981\u6c42\u5b83\u4eec\u6309\u540c\u4e00\u6392\u5e8f\u952e\u8f93\u51fa\u5143\u7ec4\u3002\u8be5\u8282\u70b9\u5f52\u5e76\u8fd9\u4e9b\u6d41\uff0c\u4ea7\u751f\u6309\u76f8\u540c\u987a\u5e8f\u6392\u5217\u7684\u8f93\u51fa\u3002", "MergeAppend \u8282\u70b9\u4e0d\u4f7f\u7528\u5de6\u53f3\u5b50\u6811\uff0c\u800c\u662f\u7ef4\u62a4\u4e00\u4e2a\u5b50\u8ba1\u5212\u5217\u8868\uff0c\u56e0\u6b64\u5178\u578b\u8282\u70b9\u5728\u8ba1\u5212\u6811\u4e2d\u7684\u5f62\u6001\u5982\u4e0b\uff1a", "... / MergeAppend---+------+------+--- nil / \\ | | | nil nil ... ... ... subplans", "\u5806\u6570\u7ec4\u7684\u6bcf\u4e2a\u5143\u7d20\u5bf9\u5e94\u4e00\u4e2a\u69fd\u4f4d\uff0c\u4f7f\u7528 SlotNumber \u5b58\u50a8\u69fd\u4f4d\u7d22\u5f15\u3002\u8fd9\u5e76\u4e0d\u771f\u6b63\u63d0\u4f9b\u7c7b\u578b\u5b89\u5168\uff0c\u4f46\u80fd\u4f7f\u4ee3\u7801\u542b\u4e49\u66f4\u6e05\u695a\u3002", "\u82e5\u5df2\u542f\u7528\u8fd0\u884c\u65f6\u5206\u533a\u88c1\u526a\uff0c\u5219\u73b0\u5728\u8fdb\u884c\u76f8\u5e94\u8bbe\u7f6e\u3002"]}, {"code": "case T_MergeAppend:\n\t\t\tpname = sname = \"Merge Append\";\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": "Merges sorted child streams while preserving the required ordering.", "/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": "Multiple sorted child plans", "/versions/17/facts/3/label": "Output", "/versions/17/facts/3/value": "Merged ordered tuples", "/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": "Executor implementation notes", "/versions/17/sections/4/title": "EXPLAIN identity in core source", "/versions/17/memory/description": "This extraction does not assign a universal memory limit or spill policy to this node. Inspect the same-build implementation and its expressions or provider.", "/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: Merge Append.", "/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": "This extraction does not assign a universal memory limit or spill policy to this node. Inspect the same-build implementation and its expressions or provider.", "/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": "NOTES A MergeAppend node contains a list of one or more subplans. These are each expected to deliver tuples that are sorted according to a common sort key. The MergeAppend node merges these streams to produce output sorted the same way.", "/versions/17/sections/3/paragraphs/1": "MergeAppend nodes don't make use of their left and right subtrees, rather they maintain a list of subplans so a typical MergeAppend node looks like this in the plan tree:", "/versions/17/sections/3/paragraphs/3": "We have one slot for each item in the heap array. We use SlotNumber to store slot indexes. This doesn't actually provide any formal type-safety, but it makes the code more self-documenting.", "/versions/17/sections/3/paragraphs/4": "If run-time partition pruning is enabled, then set that up now", "/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": "62f9d60f17913eb9f032615bb1c567bd51e29196c05049e502eeea9f22f64778", "canonical_center_text_hash": "b3867e173250de62e6b55cdcdbea9a63d9f45b4cb779ff903a8379ed571ba7d0"}, "evidence_kind": "source and documentation", "explain_names": ["Merge Append"], "partial_modes": [], "description_zh": "\u5408\u5e76\u5df2\u6392\u5e8f\u7684\u5b50\u8ba1\u5212\u8f93\u51fa\u5e76\u4fdd\u6301\u6240\u9700\u987a\u5e8f\u3002", "comparison_data": {"node_tag": "T_MergeAppend", "strategies": [], "text_names": ["Merge Append"], "initializer": "ExecInitMergeAppend", "partial_modes": [], "memory_mechanism": "unclassified", "parallel_callbacks": []}, "comparison_hash": "5428ffe21c76597da696d12a775fd915b1be22e9ba2d2d5ba3d84704f51ff3d9", "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/nodeMergeAppend.c"}, "parallel_callbacks": [], "description_zh_html": "\u5408\u5e76\u5df2\u6392\u5e8f\u7684\u5b50\u8ba1\u5212\u8f93\u51fa\u5e76\u4fdd\u6301\u6240\u9700\u987a\u5e8f\u3002
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\nPostgreSQL \u4f1a\u4e3a\u6536\u5230\u7684\u6bcf\u4e2a\u67e5\u8be2\u5236\u5b9a\u4e00\u4e2a\u67e5\u8be2\u8ba1\u5212\u3002\u9009\u62e9\u4e0e\u67e5\u8be2\u7ed3\u6784\u548c\u6570\u636e\u7279\u6027\u76f8\u5339\u914d\u7684\u6b63\u786e\u8ba1\u5212\uff0c\u5bf9\u83b7\u5f97\u826f\u597d\u7684\u6027\u80fd\u81f3\u5173\u91cd\u8981\uff0c\u56e0\u6b64\u7cfb\u7edf\u5185\u7f6e\u4e86\u4e00\u4e2a\u590d\u6742\u7684\u89c4\u5212\u5668\u6765\u5c3d\u91cf\u9009\u51fa\u597d\u7684\u8ba1\u5212\u3002\u53ef\u4ee5\u4f7f\u7528 EXPLAIN \u547d\u4ee4\u67e5\u770b\u89c4\u5212\u5668\u4e3a\u4efb\u610f\u67e5\u8be2\u751f\u6210\u7684\u67e5\u8be2\u8ba1\u5212\u3002\u8bfb\u61c2\u8ba1\u5212\u662f\u4e00\u95e8\u9700\u8981\u7ecf\u9a8c\u79ef\u7d2f\u7684\u6280\u80fd\uff0c\u672c\u8282\u5c06\u5c1d\u8bd5\u4ecb\u7ecd\u5176\u4e2d\u7684\u57fa\u7840\u77e5\u8bc6\u3002\n
\n \u672c\u8282\u4e2d\u7684\u793a\u4f8b\u53d6\u81ea\u6267\u884c\u8fc7 VACUUM ANALYZE \u7684\u56de\u5f52\u6d4b\u8bd5\u6570\u636e\u5e93\uff0c\u4f7f\u7528\u7684\u662f v17 \u5f00\u53d1\u7248\u672c\u6e90\u7801\u3002\u5982\u679c\u81ea\u884c\u5c1d\u8bd5\u8fd9\u4e9b\u793a\u4f8b\uff0c\u901a\u5e38\u5e94\u5f53\u80fd\u5f97\u5230\u76f8\u8fd1\u7684\u7ed3\u679c\uff0c\u4f46\u4f30\u8ba1\u4ee3\u4ef7\u548c\u884c\u8ba1\u6570\u53ef\u80fd\u7565\u6709\u5dee\u5f02\uff0c\u56e0\u4e3a ANALYZE \u751f\u6210\u7684\u7edf\u8ba1\u4fe1\u606f\u6765\u81ea\u968f\u673a\u91c7\u6837\u800c\u975e\u7cbe\u786e\u8ba1\u6570\uff0c\u800c\u4e14\u4ee3\u4ef7\u672c\u8eab\u5728\u67d0\u79cd\u7a0b\u5ea6\u4e0a\u4e5f\u4f9d\u8d56\u4e8e\u5e73\u53f0\u3002\n
\n \u8fd9\u4e9b\u793a\u4f8b\u4f7f\u7528 EXPLAIN \u9ed8\u8ba4\u7684\u201ctext\u201d\u8f93\u51fa\u683c\u5f0f\uff0c\u5b83\u7d27\u51d1\u4e14\u4fbf\u4e8e\u4eba\u5de5\u9605\u8bfb\u3002\u5982\u679c\u5e0c\u671b\u5c06 EXPLAIN \u7684\u8f93\u51fa\u4ea4\u7ed9\u7a0b\u5e8f\u505a\u8fdb\u4e00\u6b65\u5206\u6790\uff0c\u5219\u5e94\u6539\u7528\u673a\u5668\u53ef\u8bfb\u7684\u8f93\u51fa\u683c\u5f0f\uff08XML\u3001JSON \u6216 YAML\uff09\u3002\n
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\nPostgreSQL \u4f1a\u4e3a\u6536\u5230\u7684\u6bcf\u4e2a\u67e5\u8be2\u5236\u5b9a\u4e00\u4e2a\u67e5\u8be2\u8ba1\u5212\u3002\u9009\u62e9\u4e0e\u67e5\u8be2\u7ed3\u6784\u548c\u6570\u636e\u7279\u6027\u76f8\u5339\u914d\u7684\u6b63\u786e\u8ba1\u5212\uff0c\u5bf9\u83b7\u5f97\u826f\u597d\u7684\u6027\u80fd\u81f3\u5173\u91cd\u8981\uff0c\u56e0\u6b64\u7cfb\u7edf\u5185\u7f6e\u4e86\u4e00\u4e2a\u590d\u6742\u7684\u89c4\u5212\u5668\u6765\u5c3d\u91cf\u9009\u51fa\u597d\u7684\u8ba1\u5212\u3002\u53ef\u4ee5\u4f7f\u7528 EXPLAIN \u547d\u4ee4\u67e5\u770b\u89c4\u5212\u5668\u4e3a\u4efb\u610f\u67e5\u8be2\u751f\u6210\u7684\u67e5\u8be2\u8ba1\u5212\u3002\u8bfb\u61c2\u8ba1\u5212\u662f\u4e00\u95e8\u9700\u8981\u7ecf\u9a8c\u79ef\u7d2f\u7684\u6280\u80fd\uff0c\u672c\u8282\u5c06\u5c1d\u8bd5\u4ecb\u7ecd\u5176\u4e2d\u7684\u57fa\u7840\u77e5\u8bc6\u3002\n
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\n \u8fd9\u4e9b\u793a\u4f8b\u4f7f\u7528 EXPLAIN \u9ed8\u8ba4\u7684\u201ctext\u201d\u8f93\u51fa\u683c\u5f0f\uff0c\u5b83\u7d27\u51d1\u4e14\u4fbf\u4e8e\u4eba\u5de5\u9605\u8bfb\u3002\u5982\u679c\u5e0c\u671b\u5c06 EXPLAIN \u7684\u8f93\u51fa\u4ea4\u7ed9\u7a0b\u5e8f\u505a\u8fdb\u4e00\u6b65\u5206\u6790\uff0c\u5219\u5e94\u6539\u7528\u673a\u5668\u53ef\u8bfb\u7684\u8f93\u51fa\u683c\u5f0f\uff08XML\u3001JSON \u6216 YAML\uff09\u3002\n
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Inspect the same-build implementation and its expressions or provider.", "/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: Merge Append.", "/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": "This extraction does not assign a universal memory limit or spill policy to this node. Inspect the same-build implementation and its expressions or provider.", "/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": "NOTES A MergeAppend node contains a list of one or more subplans. These are each expected to deliver tuples that are sorted according to a common sort key. The MergeAppend node merges these streams to produce output sorted the same way.", "/versions/18/sections/3/paragraphs/1": "MergeAppend nodes don't make use of their left and right subtrees, rather they maintain a list of subplans so a typical MergeAppend node looks like this in the plan tree:", "/versions/18/sections/3/paragraphs/3": "We have one slot for each item in the heap array. We use SlotNumber to store slot indexes. 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["\u672c\u6b21\u62bd\u53d6\u4e0d\u4e3a\u6b64\u8282\u70b9\u8bbe\u5b9a\u7edf\u4e00\u7684\u5185\u5b58\u4e0a\u9650\u6216\u843d\u76d8\u7b56\u7565\u3002\u8bf7\u67e5\u770b\u540c\u4e00\u6784\u5efa\u7684\u5b9e\u73b0\u3001\u76f8\u5173\u8868\u8fbe\u5f0f\u6216\u63d0\u4f9b\u65b9\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": "\u6267\u884c\u5668\u5b9e\u73b0\u8bf4\u660e", "paragraphs": ["\u8bf4\u660e\uff1aMergeAppend 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\u6838\u5fc3\u8282\u70b9\u6807\u8bc6\uff1aT_MergeAppend\uff1bEXPLAIN \u540d\u79f0\uff1aMerge Append\u3002
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Inspect the same-build implementation and its expressions or provider.", "/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: Merge Append.", "/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": "This extraction does not assign a universal memory limit or spill policy to this node. Inspect the same-build implementation and its expressions or provider.", "/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": "NOTES A MergeAppend node contains a list of one or more subplans. These are each expected to deliver tuples that are sorted according to a common sort key. The MergeAppend node merges these streams to produce output sorted the same way.", "/versions/19/sections/3/paragraphs/1": "MergeAppend nodes don't make use of their left and right subtrees, rather they maintain a list of subplans so a typical MergeAppend node looks like this in the plan tree:", "/versions/19/sections/3/paragraphs/3": "We have one slot for each item in the heap array. We use SlotNumber to store slot indexes. 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"436517563e51b6d851ef143e70d01f5f68fe0a01e00a0d507e7bd79d7570aa25", "fragment_sha256": "f2d2c226e0479b8d931accead1f2cf7c1b8646afa24d8025ea5d5bcab837f779", "source_revision": "sha256:49c73aa4c9cacef8ca979276a28ac416c08e9e54c9baee4ae5fd116a35fa13ac", "translation_revision": "git:b1b500221dbe5437cfca004d6b04d3f6e422765d;html-sha256:98c980963b401d40bd50df72b909e7523e3148b8fdb48edd897de2efb67e5235", "translated_from_revision": "sha256:49c73aa4c9cacef8ca979276a28ac416c08e9e54c9baee4ae5fd116a35fa13ac"}, "body_sha256": "409b8b0973d54fd3b1479bfb179332fed62b2a30f336413bc74d4fd310762204", "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\uff1aMerge Append.", "\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": ["\u672c\u6b21\u62bd\u53d6\u4e0d\u4e3a\u6b64\u8282\u70b9\u8bbe\u5b9a\u7edf\u4e00\u7684\u5185\u5b58\u4e0a\u9650\u6216\u843d\u76d8\u7b56\u7565\u3002\u8bf7\u67e5\u770b\u540c\u4e00\u6784\u5efa\u7684\u5b9e\u73b0\u3001\u76f8\u5173\u8868\u8fbe\u5f0f\u6216\u63d0\u4f9b\u65b9\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": "\u6267\u884c\u5668\u5b9e\u73b0\u8bf4\u660e", "paragraphs": ["\u8bf4\u660e\uff1aMergeAppend \u5305\u542b\u4e00\u4e2a\u6216\u591a\u4e2a\u5b50\u8ba1\u5212\uff0c\u8981\u6c42\u5b83\u4eec\u6309\u540c\u4e00\u6392\u5e8f\u952e\u8f93\u51fa\u5143\u7ec4\u3002\u8be5\u8282\u70b9\u5f52\u5e76\u8fd9\u4e9b\u6d41\uff0c\u4ea7\u751f\u6309\u76f8\u540c\u987a\u5e8f\u6392\u5217\u7684\u8f93\u51fa\u3002", "MergeAppend \u8282\u70b9\u4e0d\u4f7f\u7528\u5de6\u53f3\u5b50\u6811\uff0c\u800c\u662f\u7ef4\u62a4\u4e00\u4e2a\u5b50\u8ba1\u5212\u5217\u8868\uff0c\u56e0\u6b64\u5178\u578b\u8282\u70b9\u5728\u8ba1\u5212\u6811\u4e2d\u7684\u5f62\u6001\u5982\u4e0b\uff1a", "... / MergeAppend---+------+------+--- nil / \\ | | | nil nil ... ... ... subplans", "\u5806\u6570\u7ec4\u7684\u6bcf\u4e2a\u5143\u7d20\u5bf9\u5e94\u4e00\u4e2a\u69fd\u4f4d\uff0c\u4f7f\u7528 SlotNumber \u5b58\u50a8\u69fd\u4f4d\u7d22\u5f15\u3002\u8fd9\u5e76\u4e0d\u771f\u6b63\u63d0\u4f9b\u7c7b\u578b\u5b89\u5168\uff0c\u4f46\u80fd\u4f7f\u4ee3\u7801\u542b\u4e49\u66f4\u6e05\u695a\u3002", "\u82e5\u5df2\u542f\u7528\u8fd0\u884c\u65f6\u5206\u533a\u88c1\u526a\uff0c\u5219\u73b0\u5728\u8fdb\u884c\u76f8\u5e94\u8bbe\u7f6e\u3002"]}, {"code": "case T_MergeAppend:\n\t\t\tpname = sname = \"Merge Append\";\n\t\t\tbreak;", "title": "\u6838\u5fc3\u6e90\u7801\u4e2d\u7684 EXPLAIN \u6807\u8bc6"}], "description_zh": "\u5408\u5e76\u5df2\u6392\u5e8f\u7684\u5b50\u8ba1\u5212\u8f93\u51fa\u5e76\u4fdd\u6301\u6240\u9700\u987a\u5e8f\u3002", "description_zh_html": "\u5408\u5e76\u5df2\u6392\u5e8f\u7684\u5b50\u8ba1\u5212\u8f93\u51fa\u5e76\u4fdd\u6301\u6240\u9700\u987a\u5e8f\u3002
\u6838\u5fc3\u8282\u70b9\u6807\u8bc6\uff1aT_MergeAppend\uff1bEXPLAIN \u540d\u79f0\uff1aMerge Append\u3002
\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
\nPostgreSQL \u4f1a\u4e3a\u6536\u5230\u7684\u6bcf\u4e2a\u67e5\u8be2\u5236\u5b9a\u4e00\u4e2a\u67e5\u8be2\u8ba1\u5212\u3002\u9009\u62e9\u4e0e\u67e5\u8be2\u7ed3\u6784\u548c\u6570\u636e\u7279\u6027\u76f8\u5339\u914d\u7684\u6b63\u786e\u8ba1\u5212\uff0c\u5bf9\u83b7\u5f97\u826f\u597d\u7684\u6027\u80fd\u81f3\u5173\u91cd\u8981\uff0c\u56e0\u6b64\u7cfb\u7edf\u5185\u7f6e\u4e86\u4e00\u4e2a\u590d\u6742\u7684\u89c4\u5212\u5668\u6765\u5c3d\u91cf\u9009\u51fa\u597d\u7684\u8ba1\u5212\u3002\u53ef\u4ee5\u4f7f\u7528 EXPLAIN \u547d\u4ee4\u67e5\u770b\u89c4\u5212\u5668\u4e3a\u4efb\u610f\u67e5\u8be2\u751f\u6210\u7684\u67e5\u8be2\u8ba1\u5212\u3002\u8bfb\u61c2\u8ba1\u5212\u662f\u4e00\u95e8\u9700\u8981\u7ecf\u9a8c\u79ef\u7d2f\u7684\u6280\u80fd\uff0c\u672c\u8282\u5c06\u5c1d\u8bd5\u4ecb\u7ecd\u5176\u4e2d\u7684\u57fa\u7840\u77e5\u8bc6\u3002\n
\n \u672c\u8282\u4e2d\u7684\u793a\u4f8b\u53d6\u81ea\u6267\u884c\u8fc7 VACUUM ANALYZE \u7684\u56de\u5f52\u6d4b\u8bd5\u6570\u636e\u5e93\uff0c\u4f7f\u7528\u7684\u662f v18 \u5f00\u53d1\u7248\u672c\u6e90\u7801\u3002\u5982\u679c\u81ea\u884c\u5c1d\u8bd5\u8fd9\u4e9b\u793a\u4f8b\uff0c\u901a\u5e38\u5e94\u5f53\u80fd\u5f97\u5230\u76f8\u8fd1\u7684\u7ed3\u679c\uff0c\u4f46\u4f30\u8ba1\u4ee3\u4ef7\u548c\u884c\u8ba1\u6570\u53ef\u80fd\u7565\u6709\u5dee\u5f02\uff0c\u56e0\u4e3a ANALYZE \u751f\u6210\u7684\u7edf\u8ba1\u4fe1\u606f\u6765\u81ea\u968f\u673a\u91c7\u6837\u800c\u975e\u7cbe\u786e\u8ba1\u6570\uff0c\u800c\u4e14\u4ee3\u4ef7\u672c\u8eab\u5728\u67d0\u79cd\u7a0b\u5ea6\u4e0a\u4e5f\u4f9d\u8d56\u4e8e\u5e73\u53f0\u3002\n
\n \u8fd9\u4e9b\u793a\u4f8b\u4f7f\u7528 EXPLAIN \u9ed8\u8ba4\u7684\u201ctext\u201d\u8f93\u51fa\u683c\u5f0f\uff0c\u5b83\u7d27\u51d1\u4e14\u4fbf\u4e8e\u4eba\u5de5\u9605\u8bfb\u3002\u5982\u679c\u5e0c\u671b\u5c06 EXPLAIN \u7684\u8f93\u51fa\u4ea4\u7ed9\u7a0b\u5e8f\u505a\u8fdb\u4e00\u6b65\u5206\u6790\uff0c\u5219\u5e94\u6539\u7528\u673a\u5668\u53ef\u8bfb\u7684\u8f93\u51fa\u683c\u5f0f\uff08XML\u3001JSON \u6216 YAML\uff09\u3002\n
\u67e5\u770b\u5b8c\u6574\u4e2d\u6587\u624b\u518c\u4e0e\u4e0a\u4e0b\u6587\u3002
\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
"}, "summary": "\u5408\u5e76\u5df2\u6392\u5e8f\u7684\u5b50\u8ba1\u5212\u8f93\u51fa\u5e76\u4fdd\u6301\u6240\u9700\u987a\u5e8f\u3002", "version": "20", "link_map": {"/zh/docs/devel/sql-explain.html": "/docs/devel/sql-explain.html", "/zh/docs/devel/using-explain.html": "/docs/devel/using-explain.html"}, "body_html": "\u5408\u5e76\u5df2\u6392\u5e8f\u7684\u5b50\u8ba1\u5212\u8f93\u51fa\u5e76\u4fdd\u6301\u6240\u9700\u987a\u5e8f\u3002
\u6838\u5fc3\u8282\u70b9\u6807\u8bc6\uff1aT_MergeAppend\uff1bEXPLAIN \u540d\u79f0\uff1aMerge Append\u3002
\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
\nPostgreSQL \u4f1a\u4e3a\u6536\u5230\u7684\u6bcf\u4e2a\u67e5\u8be2\u5236\u5b9a\u4e00\u4e2a\u67e5\u8be2\u8ba1\u5212\u3002\u9009\u62e9\u4e0e\u67e5\u8be2\u7ed3\u6784\u548c\u6570\u636e\u7279\u6027\u76f8\u5339\u914d\u7684\u6b63\u786e\u8ba1\u5212\uff0c\u5bf9\u83b7\u5f97\u826f\u597d\u7684\u6027\u80fd\u81f3\u5173\u91cd\u8981\uff0c\u56e0\u6b64\u7cfb\u7edf\u5185\u7f6e\u4e86\u4e00\u4e2a\u590d\u6742\u7684\u89c4\u5212\u5668\u6765\u5c3d\u91cf\u9009\u51fa\u597d\u7684\u8ba1\u5212\u3002\u53ef\u4ee5\u4f7f\u7528 EXPLAIN \u547d\u4ee4\u67e5\u770b\u89c4\u5212\u5668\u4e3a\u4efb\u610f\u67e5\u8be2\u751f\u6210\u7684\u67e5\u8be2\u8ba1\u5212\u3002\u8bfb\u61c2\u8ba1\u5212\u662f\u4e00\u95e8\u9700\u8981\u7ecf\u9a8c\u79ef\u7d2f\u7684\u6280\u80fd\uff0c\u672c\u8282\u5c06\u5c1d\u8bd5\u4ecb\u7ecd\u5176\u4e2d\u7684\u57fa\u7840\u77e5\u8bc6\u3002\n
\n \u672c\u8282\u4e2d\u7684\u793a\u4f8b\u53d6\u81ea\u6267\u884c\u8fc7 VACUUM ANALYZE \u7684\u56de\u5f52\u6d4b\u8bd5\u6570\u636e\u5e93\uff0c\u4f7f\u7528\u7684\u662f v18 \u5f00\u53d1\u7248\u672c\u6e90\u7801\u3002\u5982\u679c\u81ea\u884c\u5c1d\u8bd5\u8fd9\u4e9b\u793a\u4f8b\uff0c\u901a\u5e38\u5e94\u5f53\u80fd\u5f97\u5230\u76f8\u8fd1\u7684\u7ed3\u679c\uff0c\u4f46\u4f30\u8ba1\u4ee3\u4ef7\u548c\u884c\u8ba1\u6570\u53ef\u80fd\u7565\u6709\u5dee\u5f02\uff0c\u56e0\u4e3a ANALYZE \u751f\u6210\u7684\u7edf\u8ba1\u4fe1\u606f\u6765\u81ea\u968f\u673a\u91c7\u6837\u800c\u975e\u7cbe\u786e\u8ba1\u6570\uff0c\u800c\u4e14\u4ee3\u4ef7\u672c\u8eab\u5728\u67d0\u79cd\u7a0b\u5ea6\u4e0a\u4e5f\u4f9d\u8d56\u4e8e\u5e73\u53f0\u3002\n
\n \u8fd9\u4e9b\u793a\u4f8b\u4f7f\u7528 EXPLAIN \u9ed8\u8ba4\u7684\u201ctext\u201d\u8f93\u51fa\u683c\u5f0f\uff0c\u5b83\u7d27\u51d1\u4e14\u4fbf\u4e8e\u4eba\u5de5\u9605\u8bfb\u3002\u5982\u679c\u5e0c\u671b\u5c06 EXPLAIN \u7684\u8f93\u51fa\u4ea4\u7ed9\u7a0b\u5e8f\u505a\u8fdb\u4e00\u6b65\u5206\u6790\uff0c\u5219\u5e94\u6539\u7528\u673a\u5668\u53ef\u8bfb\u7684\u8f93\u51fa\u683c\u5f0f\uff08XML\u3001JSON \u6216 YAML\uff09\u3002\n
\u67e5\u770b\u5b8c\u6574\u4e2d\u6587\u624b\u518c\u4e0e\u4e0a\u4e0b\u6587\u3002
\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
", "body_sha256": "54b083ba2f37ea30cd3ac69243a8cdbefe0d8b7dd591b1fed361b94f69ddb19f", "content_hash": "0ce6dffd6e15229acc1070718afb326801de424fbc70e957a7a51049489ff313", "source_database": "center", "source_revision": "49c73aa4c9cacef8ca979276a28ac416c08e9e54c9baee4ae5fd116a35fa13ac"}, "tables_zh": [{"key": "explain-labels", "rows": [{"label": "Merge Append", "identity": "Merge Append"}], "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": ["\u5408\u5e76\u5df2\u6392\u5e8f\u7684\u5b50\u8ba1\u5212\u8f93\u51fa\u5e76\u4fdd\u6301\u6240\u9700\u987a\u5e8f\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\uff1aMerge Append.", "\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": ["\u672c\u6b21\u62bd\u53d6\u4e0d\u4e3a\u6b64\u8282\u70b9\u8bbe\u5b9a\u7edf\u4e00\u7684\u5185\u5b58\u4e0a\u9650\u6216\u843d\u76d8\u7b56\u7565\u3002\u8bf7\u67e5\u770b\u540c\u4e00\u6784\u5efa\u7684\u5b9e\u73b0\u3001\u76f8\u5173\u8868\u8fbe\u5f0f\u6216\u63d0\u4f9b\u65b9\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": "\u6267\u884c\u5668\u5b9e\u73b0\u8bf4\u660e", "paragraphs": ["\u8bf4\u660e\uff1aMergeAppend \u5305\u542b\u4e00\u4e2a\u6216\u591a\u4e2a\u5b50\u8ba1\u5212\uff0c\u8981\u6c42\u5b83\u4eec\u6309\u540c\u4e00\u6392\u5e8f\u952e\u8f93\u51fa\u5143\u7ec4\u3002\u8be5\u8282\u70b9\u5f52\u5e76\u8fd9\u4e9b\u6d41\uff0c\u4ea7\u751f\u6309\u76f8\u540c\u987a\u5e8f\u6392\u5217\u7684\u8f93\u51fa\u3002", "MergeAppend \u8282\u70b9\u4e0d\u4f7f\u7528\u5de6\u53f3\u5b50\u6811\uff0c\u800c\u662f\u7ef4\u62a4\u4e00\u4e2a\u5b50\u8ba1\u5212\u5217\u8868\uff0c\u56e0\u6b64\u5178\u578b\u8282\u70b9\u5728\u8ba1\u5212\u6811\u4e2d\u7684\u5f62\u6001\u5982\u4e0b\uff1a", "... / MergeAppend---+------+------+--- nil / \\ | | | nil nil ... ... ... subplans", "\u5806\u6570\u7ec4\u7684\u6bcf\u4e2a\u5143\u7d20\u5bf9\u5e94\u4e00\u4e2a\u69fd\u4f4d\uff0c\u4f7f\u7528 SlotNumber \u5b58\u50a8\u69fd\u4f4d\u7d22\u5f15\u3002\u8fd9\u5e76\u4e0d\u771f\u6b63\u63d0\u4f9b\u7c7b\u578b\u5b89\u5168\uff0c\u4f46\u80fd\u4f7f\u4ee3\u7801\u542b\u4e49\u66f4\u6e05\u695a\u3002", "\u82e5\u5df2\u542f\u7528\u8fd0\u884c\u65f6\u5206\u533a\u88c1\u526a\uff0c\u5219\u73b0\u5728\u8fdb\u884c\u76f8\u5e94\u8bbe\u7f6e\u3002"]}, {"code": "case T_MergeAppend:\n\t\t\tpname = sname = \"Merge Append\";\n\t\t\tbreak;", "title": "\u6838\u5fc3\u6e90\u7801\u4e2d\u7684 EXPLAIN \u6807\u8bc6"}], "localization": {"status": "complete", "sources": [], "language": "zh", "original_text": {"/summary": "Merges sorted child streams while preserving the required ordering.", "/category": "Combination", "/versions/20/description/0": "Merges sorted child streams while preserving the required ordering.", "/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": "Multiple sorted child plans", "/versions/20/facts/3/label": "Output", "/versions/20/facts/3/value": "Merged ordered tuples", "/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": "Executor implementation notes", "/versions/20/sections/4/title": "EXPLAIN identity in core source", "/versions/20/memory/description": "This extraction does not assign a universal memory limit or spill policy to this node. Inspect the same-build implementation and its expressions or provider.", "/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: Merge Append.", "/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": "This extraction does not assign a universal memory limit or spill policy to this node. Inspect the same-build implementation and its expressions or provider.", "/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": "NOTES A MergeAppend node contains a list of one or more subplans. These are each expected to deliver tuples that are sorted according to a common sort key. The MergeAppend node merges these streams to produce output sorted the same way.", "/versions/20/sections/3/paragraphs/1": "MergeAppend nodes don't make use of their left and right subtrees, rather they maintain a list of subplans so a typical MergeAppend node looks like this in the plan tree:", "/versions/20/sections/3/paragraphs/3": "We have one slot for each item in the heap array. We use SlotNumber to store slot indexes. This doesn't actually provide any formal type-safety, but it makes the code more self-documenting.", "/versions/20/sections/3/paragraphs/4": "If run-time partition pruning is enabled, then set that up now", "/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": "deb1217eb806d8baebde9041aefcc6f9276214f03331dd5ebecb1a192b6cfc11", "canonical_center_text_hash": "0ce6dffd6e15229acc1070718afb326801de424fbc70e957a7a51049489ff313"}, "evidence_kind": "source and documentation", "explain_names": ["Merge Append"], "partial_modes": [], "description_zh": "\u5408\u5e76\u5df2\u6392\u5e8f\u7684\u5b50\u8ba1\u5212\u8f93\u51fa\u5e76\u4fdd\u6301\u6240\u9700\u987a\u5e8f\u3002", "comparison_data": {"node_tag": "T_MergeAppend", "strategies": [], "text_names": ["Merge Append"], "initializer": "ExecInitMergeAppend", "partial_modes": [], "memory_mechanism": "unclassified", "parallel_callbacks": []}, "comparison_hash": "5428ffe21c76597da696d12a775fd915b1be22e9ba2d2d5ba3d84704f51ff3d9", "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/nodeMergeAppend.c"}, "parallel_callbacks": [], "description_zh_html": "\u5408\u5e76\u5df2\u6392\u5e8f\u7684\u5b50\u8ba1\u5212\u8f93\u51fa\u5e76\u4fdd\u6301\u6240\u9700\u987a\u5e8f\u3002
\u6838\u5fc3\u8282\u70b9\u6807\u8bc6\uff1aT_MergeAppend\uff1bEXPLAIN \u540d\u79f0\uff1aMerge Append\u3002
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\nPostgreSQL \u4f1a\u4e3a\u6536\u5230\u7684\u6bcf\u4e2a\u67e5\u8be2\u5236\u5b9a\u4e00\u4e2a\u67e5\u8be2\u8ba1\u5212\u3002\u9009\u62e9\u4e0e\u67e5\u8be2\u7ed3\u6784\u548c\u6570\u636e\u7279\u6027\u76f8\u5339\u914d\u7684\u6b63\u786e\u8ba1\u5212\uff0c\u5bf9\u83b7\u5f97\u826f\u597d\u7684\u6027\u80fd\u81f3\u5173\u91cd\u8981\uff0c\u56e0\u6b64\u7cfb\u7edf\u5185\u7f6e\u4e86\u4e00\u4e2a\u590d\u6742\u7684\u89c4\u5212\u5668\u6765\u5c3d\u91cf\u9009\u51fa\u597d\u7684\u8ba1\u5212\u3002\u53ef\u4ee5\u4f7f\u7528 EXPLAIN \u547d\u4ee4\u67e5\u770b\u89c4\u5212\u5668\u4e3a\u4efb\u610f\u67e5\u8be2\u751f\u6210\u7684\u67e5\u8be2\u8ba1\u5212\u3002\u8bfb\u61c2\u8ba1\u5212\u662f\u4e00\u95e8\u9700\u8981\u7ecf\u9a8c\u79ef\u7d2f\u7684\u6280\u80fd\uff0c\u672c\u8282\u5c06\u5c1d\u8bd5\u4ecb\u7ecd\u5176\u4e2d\u7684\u57fa\u7840\u77e5\u8bc6\u3002\n
\n \u672c\u8282\u4e2d\u7684\u793a\u4f8b\u53d6\u81ea\u6267\u884c\u8fc7 VACUUM ANALYZE \u7684\u56de\u5f52\u6d4b\u8bd5\u6570\u636e\u5e93\uff0c\u4f7f\u7528\u7684\u662f v18 \u5f00\u53d1\u7248\u672c\u6e90\u7801\u3002\u5982\u679c\u81ea\u884c\u5c1d\u8bd5\u8fd9\u4e9b\u793a\u4f8b\uff0c\u901a\u5e38\u5e94\u5f53\u80fd\u5f97\u5230\u76f8\u8fd1\u7684\u7ed3\u679c\uff0c\u4f46\u4f30\u8ba1\u4ee3\u4ef7\u548c\u884c\u8ba1\u6570\u53ef\u80fd\u7565\u6709\u5dee\u5f02\uff0c\u56e0\u4e3a ANALYZE \u751f\u6210\u7684\u7edf\u8ba1\u4fe1\u606f\u6765\u81ea\u968f\u673a\u91c7\u6837\u800c\u975e\u7cbe\u786e\u8ba1\u6570\uff0c\u800c\u4e14\u4ee3\u4ef7\u672c\u8eab\u5728\u67d0\u79cd\u7a0b\u5ea6\u4e0a\u4e5f\u4f9d\u8d56\u4e8e\u5e73\u53f0\u3002\n
\n \u8fd9\u4e9b\u793a\u4f8b\u4f7f\u7528 EXPLAIN \u9ed8\u8ba4\u7684\u201ctext\u201d\u8f93\u51fa\u683c\u5f0f\uff0c\u5b83\u7d27\u51d1\u4e14\u4fbf\u4e8e\u4eba\u5de5\u9605\u8bfb\u3002\u5982\u679c\u5e0c\u671b\u5c06 EXPLAIN \u7684\u8f93\u51fa\u4ea4\u7ed9\u7a0b\u5e8f\u505a\u8fdb\u4e00\u6b65\u5206\u6790\uff0c\u5219\u5e94\u6539\u7528\u673a\u5668\u53ef\u8bfb\u7684\u8f93\u51fa\u683c\u5f0f\uff08XML\u3001JSON \u6216 YAML\uff09\u3002\n
\u67e5\u770b\u5b8c\u6574\u4e2d\u6587\u624b\u518c\u4e0e\u4e0a\u4e0b\u6587\u3002
\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
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\nPostgreSQL \u4f1a\u4e3a\u6536\u5230\u7684\u6bcf\u4e2a\u67e5\u8be2\u5236\u5b9a\u4e00\u4e2a\u67e5\u8be2\u8ba1\u5212\u3002\u9009\u62e9\u4e0e\u67e5\u8be2\u7ed3\u6784\u548c\u6570\u636e\u7279\u6027\u76f8\u5339\u914d\u7684\u6b63\u786e\u8ba1\u5212\uff0c\u5bf9\u83b7\u5f97\u826f\u597d\u7684\u6027\u80fd\u81f3\u5173\u91cd\u8981\uff0c\u56e0\u6b64\u7cfb\u7edf\u5185\u7f6e\u4e86\u4e00\u4e2a\u590d\u6742\u7684\u89c4\u5212\u5668\u6765\u5c3d\u91cf\u9009\u51fa\u597d\u7684\u8ba1\u5212\u3002\u53ef\u4ee5\u4f7f\u7528 EXPLAIN \u547d\u4ee4\u67e5\u770b\u89c4\u5212\u5668\u4e3a\u4efb\u610f\u67e5\u8be2\u751f\u6210\u7684\u67e5\u8be2\u8ba1\u5212\u3002\u8bfb\u61c2\u8ba1\u5212\u662f\u4e00\u95e8\u9700\u8981\u7ecf\u9a8c\u79ef\u7d2f\u7684\u6280\u80fd\uff0c\u672c\u8282\u5c06\u5c1d\u8bd5\u4ecb\u7ecd\u5176\u4e2d\u7684\u57fa\u7840\u77e5\u8bc6\u3002\n
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\n \u8fd9\u4e9b\u793a\u4f8b\u4f7f\u7528 EXPLAIN \u9ed8\u8ba4\u7684\u201ctext\u201d\u8f93\u51fa\u683c\u5f0f\uff0c\u5b83\u7d27\u51d1\u4e14\u4fbf\u4e8e\u4eba\u5de5\u9605\u8bfb\u3002\u5982\u679c\u5e0c\u671b\u5c06 EXPLAIN \u7684\u8f93\u51fa\u4ea4\u7ed9\u7a0b\u5e8f\u505a\u8fdb\u4e00\u6b65\u5206\u6790\uff0c\u5219\u5e94\u6539\u7528\u673a\u5668\u53ef\u8bfb\u7684\u8f93\u51fa\u683c\u5f0f\uff08XML\u3001JSON \u6216 YAML\uff09\u3002\n
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Inspect the same-build implementation and its expressions or provider.", "/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: Merge Append.", "/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": "This extraction does not assign a universal memory limit or spill policy to this node. Inspect the same-build implementation and its expressions or provider.", "/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": "NOTES A MergeAppend node contains a list of one or more subplans. These are each expected to deliver tuples that are sorted according to a common sort key. The MergeAppend node merges these streams to produce output sorted the same way.", "/versions/18/sections/3/paragraphs/1": "MergeAppend nodes don't make use of their left and right subtrees, rather they maintain a list of subplans so a typical MergeAppend node looks like this in the plan tree:", "/versions/18/sections/3/paragraphs/3": "We have one slot for each item in the heap array. We use SlotNumber to store slot indexes. 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