{"kind": "plan", "major": "18", "item": {"slug": "materialize", "name": "Materialize", "name_zh": "Material", "category": "\u7269\u5316", "summary": "\u5b58\u50a8\u5b50\u8ba1\u5212\u8f93\u51fa\uff0c\u4ee5\u4fbf\u518d\u6b21\u8bfb\u53d6\u8fd9\u4e9b\u884c\u3002", "aliases": ["Material", "Materialize", "T_Material"], "content_hash": "5aa3bdb2e93cf9b134506d3b5857250435a623ad216b8f7bd517d6a6a813c2bd", "versions": {"10": {"facts": [{"label": "\u6838\u5fc3\u8282\u70b9\u6807\u7b7e", "value": "T_Material"}, {"label": "\u7ed3\u6784\u5316 EXPLAIN \u8282\u70b9\u7c7b\u578b", "value": "Materialize"}, {"label": "\u8f93\u5165", "value": "\u4e00\u4e2a\u5b50\u8ba1\u5212"}, {"label": "\u8f93\u51fa", "value": "\u5df2\u7269\u5316\u7684\u5143\u7ec4"}, {"label": "\u6267\u884c\u5668\u521d\u59cb\u5316\u51fd\u6570", "value": "ExecInitMaterial"}, {"label": "\u5185\u5b58\u673a\u5236", "value": "tuplestore"}], "memory": {"evidence": [{"url": "https://ftp.postgresql.org/pub/source/v10.23/postgresql-10.23.tar.bz2", "path": "src/backend/executor/nodeMaterial.c", "label": "src/backend/executor/nodeMaterial.c", "sha256": "8916e4732b1d457926f149b904c2d128c7ba5257382f0ac231c35abb49ad77e7", "archive_sha256": "94a4b2528372458e5662c18d406629266667c437198160a18cdfd2c4a4d6eee9"}, {"url": "https://ftp.postgresql.org/pub/source/v10.23/postgresql-10.23.tar.bz2", "path": "src/backend/utils/sort/tuplestore.c", "label": "src/backend/utils/sort/tuplestore.c", "sha256": "dcf45a15db0b6fce8d77783138557f9fcb956b5c45dceac9ec734c2990f8cb97", "archive_sha256": "94a4b2528372458e5662c18d406629266667c437198160a18cdfd2c4a4d6eee9"}], "mechanism": "tuplestore", "description": "\u6b64\u8282\u70b9\u4f7f\u7528 work_mem \u521b\u5efa tuplestore\u3002tuplestore \u53ef\u4ee5\u5c06\u5b58\u50a8\u7684\u5143\u7ec4\u79fb\u5230\u4e34\u65f6\u6587\u4ef6\uff0c\u4f46\u8fd9\u4e0d\u610f\u5473\u7740 work_mem \u9650\u5236\u4e86\u8282\u70b9\u7684\u5168\u90e8\u5185\u5b58\u5206\u914d\u3002", "source_notes": []}, "tables": [{"key": "explain-labels", "rows": [{"label": "Materialize", "identity": "Materialize"}], "title": "\u672c\u6784\u5efa\u4e2d\u7684 EXPLAIN \u6807\u7b7e", "columns": [{"key": "label", "label": "\u6587\u672c\u683c\u5f0f\u6807\u7b7e"}, {"key": "identity", "label": "\u7ed3\u6784\u5316\u8282\u70b9\u6807\u8bc6"}]}], "related": [{"url": "/wiki/sql/explain/?v=10", "label": "EXPLAIN"}, {"url": "/docs/10/using-explain.html", "label": "\u4f7f\u7528 EXPLAIN"}, {"url": "/docs/10/parallel-plans.html", "label": "\u5e76\u884c\u8ba1\u5212"}, {"url": "/wiki/guc/enable_material/?v=10", "label": "enable_material"}, {"url": "/wiki/guc/work_mem/?v=10", "label": "work_mem"}], "release": {"ref": "PostgreSQL 10.23 source archive", "label": "10.23", "major": "10", "channel": "historical", "revision": "94a4b2528372458e5662c18d406629266667c437198160a18cdfd2c4a4d6eee9", "source_url": "https://ftp.postgresql.org/pub/source/v10.23/postgresql-10.23.tar.bz2", "source_snapshot_utc": ""}, "sources": [{"url": 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"94a4b2528372458e5662c18d406629266667c437198160a18cdfd2c4a4d6eee9"}, {"url": "https://ftp.postgresql.org/pub/source/v10.23/postgresql-10.23.tar.bz2", "path": "src/include/nodes/plannodes.h", "label": "src/include/nodes/plannodes.h", "sha256": "d562c321108844798cd234303fffb618f13d4ee3f3a5ac79bfd963b077e47c22", "archive_sha256": "94a4b2528372458e5662c18d406629266667c437198160a18cdfd2c4a4d6eee9"}, {"url": "https://ftp.postgresql.org/pub/source/v10.23/postgresql-10.23.tar.bz2", "path": "src/backend/utils/sort/tuplestore.c", "label": "src/backend/utils/sort/tuplestore.c", "sha256": "dcf45a15db0b6fce8d77783138557f9fcb956b5c45dceac9ec734c2990f8cb97", "archive_sha256": "94a4b2528372458e5662c18d406629266667c437198160a18cdfd2c4a4d6eee9"}, {"url": "https://pg.center/docs/10/using-explain.html#USING-EXPLAIN-BASICS", "path": "using-explain.html", "label": "PostgreSQL 10.23 \u00b7 using-explain", "sha256": "a4b4304aedb0a2da0145cc7c35b03b319a5c7ee3df35a8ef84ab6d3a610f98f3", "language": "en", "original_url": "/docs/10/using-explain.html#USING-EXPLAIN-BASICS"}], "node_tag": "T_Material", "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\uff1aMaterialize.", "\u5e76\u884c\u611f\u77e5\u4e0e\u5e76\u884c\u5b89\u5168\u662f\u4e0d\u540c\u7684\u8ba1\u5212\u5c5e\u6027\u3002\u5728\u5e76\u884c\u5de5\u4f5c\u8fdb\u7a0b\u5185\u8fd0\u884c\u7684\u8282\u70b9\u4e0d\u4e00\u5b9a\u662f\u5e76\u884c\u611f\u77e5\u8282\u70b9\u3002"]}, {"title": "\u5185\u5b58\u4e0e\u4e34\u65f6\u5b58\u50a8", "paragraphs": ["\u6b64\u8282\u70b9\u4f7f\u7528 work_mem \u521b\u5efa tuplestore\u3002tuplestore \u53ef\u4ee5\u5c06\u5b58\u50a8\u7684\u5143\u7ec4\u79fb\u5230\u4e34\u65f6\u6587\u4ef6\uff0c\u4f46\u8fd9\u4e0d\u610f\u5473\u7740 work_mem \u9650\u5236\u4e86\u8282\u70b9\u7684\u5168\u90e8\u5185\u5b58\u5206\u914d\u3002"]}, {"title": "\u5e76\u884c\u6267\u884c\u4e0e\u8fd0\u884c\u4fe1\u606f\u91c7\u96c6", "paragraphs": ["\u4ee5\u4e0b\u6e90\u7801\u56de\u8c03\u53ef\u4ee5\u534f\u8c03\u6267\u884c\u6216\u6536\u96c6\u5de5\u4f5c\u8fdb\u7a0b\u7684\u6d4b\u91cf\u6570\u636e\u3002\u56de\u8c03\u5b58\u5728\u4e0d\u4ee3\u8868\u8be5\u8282\u70b9\u666e\u904d\u652f\u6301\u5171\u4eab\u5e76\u884c\u626b\u63cf\u6216\u5171\u4eab\u72b6\u6001\u3002", "\u6b64\u6784\u5efa\u7684\u56de\u8c03\uff1anone extracted from this node implementation."]}, {"title": "\u540c\u7248\u672c\u624b\u518c\u8bf4\u660e", "paragraphs": ["\u89c4\u5212\u5668\u5728\u8fde\u63a5\u5185\u4fa7\u5173\u7cfb\u4e4b\u4e0a\u52a0\u5165 Materialize \u8282\u70b9\uff0c\u5c06\u5176\u7269\u5316\u3002\u56e0\u6b64\uff0c\u5c3d\u7ba1\u5d4c\u5957\u5faa\u73af\u8fde\u63a5\u9700\u8981\u4e3a\u5916\u4fa7\u7684\u6bcf\u4e00\u884c\u8bfb\u53d6\u4e00\u6b21\u5185\u4fa7\u6570\u636e\u3001\u5171\u5341\u6b21\uff0ct2 \u7684\u7d22\u5f15\u626b\u63cf\u4e5f\u53ea\u6267\u884c\u4e00\u6b21\u3002Materialize \u5728\u8bfb\u53d6\u65f6\u5c06\u6570\u636e\u4fdd\u5b58\u5728\u5185\u5b58\u4e2d\uff0c\u540e\u7eed\u5404\u8f6e\u76f4\u63a5\u4ece\u5185\u5b58\u8fd4\u56de\u6570\u636e\u3002"]}, {"title": "\u672c\u7248\u624b\u518c\u4e2d\u7684\u793a\u4f8b", "blocks": [{"code": "EXPLAIN SELECT *\nFROM tenk1 t1, tenk2 t2\nWHERE t1.unique1 < 10 AND t2.unique2 < 10 AND t1.hundred < t2.hundred;\n\n                                         QUERY PLAN\n---------------------------------------------------------------------------------------------\n Nested Loop  (cost=4.65..49.46 rows=33 width=488)\n   Join Filter: (t1.hundred < t2.hundred)\n   ->  Bitmap Heap Scan on tenk1 t1  (cost=4.36..39.47 rows=10 width=244)\n         Recheck Cond: (unique1 < 10)\n         ->  Bitmap Index Scan on tenk1_unique1  (cost=0.00..4.36 rows=10 width=0)\n               Index Cond: (unique1 < 10)\n   ->  Materialize  (cost=0.29..8.51 rows=10 width=244)\n         ->  Index Scan using tenk2_unique2 on tenk2 t2  (cost=0.29..8.46 rows=10 width=244)\n               Index Cond: (unique2 < 10)", "source": {"url": "/docs/10/using-explain.html#USING-EXPLAIN-BASICS", "path": "using-explain.html", "label": "PostgreSQL 10.23 \u00b7 using-explain", "sha256": "a4b4304aedb0a2da0145cc7c35b03b319a5c7ee3df35a8ef84ab6d3a610f98f3"}, "paragraphs": ["\u793a\u4f8b\u6458\u81ea PostgreSQL 10.23 \u624b\u518c\uff1b\u672c\u767e\u79d1\u672a\u5b9e\u9645\u6267\u884c\u6b64\u793a\u4f8b\u3002", "\u672c\u4f8b\u4e2d\uff0c\u8fde\u63a5\u7684\u8f93\u51fa\u884c\u6570\u7b49\u4e8e\u4e24\u6b21\u626b\u63cf\u884c\u6570\u7684\u4e58\u79ef\uff0c\u4f46\u5e76\u975e\u603b\u662f\u5982\u6b64\uff1a\u53ef\u80fd\u5b58\u5728\u540c\u65f6\u5f15\u7528\u4e24\u4e2a\u8868\u7684\u989d\u5916 WHERE \u5b50\u53e5\uff0c\u53ea\u80fd\u5728\u8fde\u63a5\u65f6\u5e94\u7528\uff0c\u65e0\u6cd5\u5e94\u7528\u5230\u4efb\u4f55\u5355\u4fa7\u8f93\u5165\u626b\u63cf\u3002\u793a\u4f8b\u5982\u4e0b\uff1a"]}]}, {"title": "\u6267\u884c\u5668\u5b9e\u73b0\u8bf4\u660e", "paragraphs": ["\u53ea\u8981\u5f53\u524d\u4f4d\u4e8e tuplestore \u5df2\u6536\u96c6\u6570\u636e\u7684\u672b\u5c3e\uff0c\u6bcf\u6b21\u8c03\u7528\u5c31\u4ece\u5b50\u8ba1\u5212\u83b7\u53d6\u4e00\u884c\u65b0\u6570\u636e\uff0c\u5728\u8fd4\u56de\u4e4b\u524d\u5c06\u5176\u5b58\u5165 tuplestore\u3002\u53ea\u6709\u8bf7\u6c42\u53cd\u5411\u626b\u63cf\u3001\u91cd\u626b\u6216\u6807\u8bb0\uff0f\u6062\u590d\u65f6\uff0c\u624d\u4ece tuplestore \u8bfb\u53d6\u3002", "\u9996\u6b21\u6267\u884c\u4e14\u9700\u8981\u5143\u7ec4\u5b58\u50a8\u65f6\uff0c\u521d\u59cb\u5316\u5b83\u3002", "\u5206\u914d\u7b2c\u4e8c\u4e2a\u8bfb\u53d6\u6307\u9488\u4f5c\u4e3a\u6807\u8bb0\u3002\u5df2\u77e5\u5176\u7d22\u5f15\u5fc5\u4e3a 1\uff0c\u56e0\u6b64\u65e0\u9700\u53e6\u884c\u4fdd\u5b58\u3002", "\u5982\u679c\u5c1a\u672a\u5230\u8fbe tuplestore \u672b\u5c3e\uff0c\u6216\u6b63\u5728\u53cd\u5411\u626b\u63cf\uff0c\u5219\u5c1d\u8bd5\u4ece tuplestore \u83b7\u53d6\u5143\u7ec4\u3002", "\u5728\u5143\u7ec4\u5b58\u50a8\u672b\u5c3e\u53cd\u8f6c\u626b\u63cf\u65b9\u5411\u65f6\uff0c\u7b2c\u4e00\u6b21 gettupleslot \u4f1a\u53d6\u5f97\u6700\u540e\u6dfb\u52a0\u7684\u5143\u7ec4\uff1b\u4f46\u82e5\u53ef\u80fd\uff0c\u6211\u4eec\u5e0c\u671b\u8fd4\u56de\u5b83\u4e4b\u524d\u7684\u90a3\u4e2a\uff0c\u56e0\u6b64\u989d\u5916\u8bfb\u53d6\u4e00\u6b21\u3002"]}, {"code": "case T_Material:\n\t\t\tpname = sname = \"Materialize\";\n\t\t\tbreak;", "title": "\u6838\u5fc3\u6e90\u7801\u4e2d\u7684 EXPLAIN \u6807\u8bc6"}], "strategies": [], "description": ["\u5b58\u50a8\u5b50\u8ba1\u5212\u8f93\u51fa\uff0c\u4ee5\u4fbf\u518d\u6b21\u8bfb\u53d6\u8fd9\u4e9b\u884c\u3002"], "localization": {"status": "complete", "sources": [], "language": "zh", "original_text": {"/versions/10/description/0": "Stores its child output so the rows can be read again.", "/versions/10/facts/0/label": "Core node tag", "/versions/10/facts/1/label": "Structured EXPLAIN Node Type", "/versions/10/facts/2/label": "Inputs", "/versions/10/facts/2/value": "One child plan", "/versions/10/facts/3/label": "Output", "/versions/10/facts/3/value": "Materialized tuples", "/versions/10/facts/4/label": "Executor initializer", "/versions/10/facts/5/label": "Memory mechanism", "/versions/10/tables/0/title": "EXPLAIN labels in this source build", "/versions/10/related/1/label": "Using EXPLAIN", "/versions/10/related/2/label": "Parallel plans", "/versions/10/sections/0/title": "EXPLAIN names and attributes", "/versions/10/sections/1/title": "Memory and temporary storage", "/versions/10/sections/2/title": "Parallel execution and instrumentation", "/versions/10/sections/3/title": "Same-version manual discussion", "/versions/10/sections/4/title": "Examples from this manual build", "/versions/10/sections/5/title": "Executor implementation notes", "/versions/10/sections/6/title": "EXPLAIN identity in core source", "/versions/10/memory/description": "This node creates a tuplestore with work_mem. The tuplestore can move stored tuples to temporary files; this does not make work_mem a cap on every allocation made by the node.", "/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: Materialize.", "/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 node creates a tuplestore with work_mem. The tuplestore can move stored tuples to temporary files; this does not make work_mem a cap on every allocation made by the node.", "/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": "Notice that here the planner has chosen to \u201c materialize \u201d the inner relation of the join, by putting a Materialize plan node atop it. This means that the t2 index scan will be done just once, even though the nested-loop join node needs to read that data ten times, once for each row from the outer relation. The Materialize node saves the data in memory as it's read, and then returns the data from memory on each subsequent pass.", "/versions/10/sections/5/paragraphs/0": "As long as we are at the end of the data collected in the tuplestore, we collect one new row from the subplan on each call, and stash it aside in the tuplestore before returning it. The tuplestore is only read if we are asked to scan backwards, rescan, or mark/restore.", "/versions/10/sections/5/paragraphs/1": "If first time through, and we need a tuplestore, initialize it.", "/versions/10/sections/5/paragraphs/2": "Allocate a second read pointer to serve as the mark. We know it must have index 1, so needn't store that.", "/versions/10/sections/5/paragraphs/3": "If we are not at the end of the tuplestore, or are going backwards, try to fetch a tuple from tuplestore.", "/versions/10/sections/5/paragraphs/4": "When reversing direction at tuplestore EOF, the first gettupleslot call will fetch the last-added tuple; but we want to return the one before that, if possible. So do an extra fetch.", "/versions/10/tables/0/columns/0/label": "Text-format label", "/versions/10/tables/0/columns/1/label": "Structured node identity", "/versions/10/sections/4/blocks/0/paragraphs/0": "Example copied from the PostgreSQL 10.23 manual; it was not executed for this collection.", "/versions/10/sections/4/blocks/0/paragraphs/1": "In this example the join's output row count is the same as the product of the two scans' row counts, but that's not true in all cases because there can be additional WHERE clauses that mention both tables and so can only be applied at the join point, not to either input scan. Here's an example:"}, "fallback_fields": [], "source_language": "en", "original_snapshot_sha256": "e9bf0e113e77cd96c51eefadc05badcec8331707b1b66618b55e2f76efa95e26"}, "evidence_kind": "source and documentation", "explain_names": ["Materialize"], "partial_modes": [], "comparison_data": {"node_tag": "T_Material", "strategies": [], "text_names": ["Materialize"], "initializer": "ExecInitMaterial", "partial_modes": [], "memory_mechanism": "tuplestore", "parallel_callbacks": []}, "comparison_hash": "c1d37bf334409fe6ded8ce560fe45fd495ff89ceda2808b6f5ef18daca520393", "explain_prefixes": ["Parallel"], "runtime_verified": false, "source_inventory": {"explain": "src/backend/commands/explain.c", "executor": "src/backend/executor/execProcnode.c", "implementation": "src/backend/executor/nodeMaterial.c"}, "parallel_callbacks": []}, "11": {"facts": [{"label": "\u6838\u5fc3\u8282\u70b9\u6807\u7b7e", "value": "T_Material"}, {"label": "\u7ed3\u6784\u5316 EXPLAIN \u8282\u70b9\u7c7b\u578b", "value": "Materialize"}, {"label": "\u8f93\u5165", "value": "\u4e00\u4e2a\u5b50\u8ba1\u5212"}, {"label": "\u8f93\u51fa", "value": "\u5df2\u7269\u5316\u7684\u5143\u7ec4"}, {"label": "\u6267\u884c\u5668\u521d\u59cb\u5316\u51fd\u6570", "value": "ExecInitMaterial"}, {"label": "\u5185\u5b58\u673a\u5236", "value": "tuplestore"}], "memory": {"evidence": [{"url": "https://ftp.postgresql.org/pub/source/v11.22/postgresql-11.22.tar.bz2", "path": "src/backend/executor/nodeMaterial.c", "label": "src/backend/executor/nodeMaterial.c", "sha256": "15a29388c6c88781d0ea650b1bc3494343a889c3127d02a0bb1fe79514110276", "archive_sha256": "2cb7c97d7a0d7278851bbc9c61f467b69c094c72b81740b751108e7892ebe1f0"}, {"url": "https://ftp.postgresql.org/pub/source/v11.22/postgresql-11.22.tar.bz2", "path": "src/backend/utils/sort/tuplestore.c", "label": "src/backend/utils/sort/tuplestore.c", "sha256": "2891704a2b38e4f4c52cce4604f1cad8b83781217697c4cddd6d3d99ddc14fce", "archive_sha256": 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"/wiki/guc/enable_material/?v=11", "label": "enable_material"}, {"url": "/wiki/guc/work_mem/?v=11", "label": "work_mem"}], "release": {"ref": "PostgreSQL 11.22 source archive", "label": "11.22", "major": "11", "channel": "historical", "revision": "2cb7c97d7a0d7278851bbc9c61f467b69c094c72b81740b751108e7892ebe1f0", "source_url": "https://ftp.postgresql.org/pub/source/v11.22/postgresql-11.22.tar.bz2", "source_snapshot_utc": ""}, "sources": [{"url": "https://ftp.postgresql.org/pub/source/v11.22/postgresql-11.22.tar.bz2", "line": 1138, "path": "src/backend/commands/explain.c", "label": "src/backend/commands/explain.c:1138", "sha256": "9df8400c1a4377179572ceb916d6020fca4e2760f74bf416d77ed97476523bbd", "archive_sha256": "2cb7c97d7a0d7278851bbc9c61f467b69c094c72b81740b751108e7892ebe1f0"}, {"url": "https://ftp.postgresql.org/pub/source/v11.22/postgresql-11.22.tar.bz2", "line": 308, "path": "src/backend/executor/execProcnode.c", "label": "src/backend/executor/execProcnode.c:308", "sha256": 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"sha256": "2891704a2b38e4f4c52cce4604f1cad8b83781217697c4cddd6d3d99ddc14fce", "archive_sha256": "2cb7c97d7a0d7278851bbc9c61f467b69c094c72b81740b751108e7892ebe1f0"}, {"url": "https://pg.center/docs/11/using-explain.html#USING-EXPLAIN-BASICS", "path": "using-explain.html", "label": "PostgreSQL 11.22 \u00b7 using-explain", "sha256": "8411bc78085d4737e32d7cca103d859da6c6539e33ec5e2fba46e74c6f199d8a", "language": "en", "original_url": "/docs/11/using-explain.html#USING-EXPLAIN-BASICS"}], "node_tag": "T_Material", "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\uff1aMaterialize.", "\u5e76\u884c\u611f\u77e5\u4e0e\u5e76\u884c\u5b89\u5168\u662f\u4e0d\u540c\u7684\u8ba1\u5212\u5c5e\u6027\u3002\u5728\u5e76\u884c\u5de5\u4f5c\u8fdb\u7a0b\u5185\u8fd0\u884c\u7684\u8282\u70b9\u4e0d\u4e00\u5b9a\u662f\u5e76\u884c\u611f\u77e5\u8282\u70b9\u3002"]}, {"title": "\u5185\u5b58\u4e0e\u4e34\u65f6\u5b58\u50a8", "paragraphs": ["\u6b64\u8282\u70b9\u4f7f\u7528 work_mem \u521b\u5efa tuplestore\u3002tuplestore \u53ef\u4ee5\u5c06\u5b58\u50a8\u7684\u5143\u7ec4\u79fb\u5230\u4e34\u65f6\u6587\u4ef6\uff0c\u4f46\u8fd9\u4e0d\u610f\u5473\u7740 work_mem \u9650\u5236\u4e86\u8282\u70b9\u7684\u5168\u90e8\u5185\u5b58\u5206\u914d\u3002"]}, {"title": "\u5e76\u884c\u6267\u884c\u4e0e\u8fd0\u884c\u4fe1\u606f\u91c7\u96c6", "paragraphs": ["\u4ee5\u4e0b\u6e90\u7801\u56de\u8c03\u53ef\u4ee5\u534f\u8c03\u6267\u884c\u6216\u6536\u96c6\u5de5\u4f5c\u8fdb\u7a0b\u7684\u6d4b\u91cf\u6570\u636e\u3002\u56de\u8c03\u5b58\u5728\u4e0d\u4ee3\u8868\u8be5\u8282\u70b9\u666e\u904d\u652f\u6301\u5171\u4eab\u5e76\u884c\u626b\u63cf\u6216\u5171\u4eab\u72b6\u6001\u3002", "\u6b64\u6784\u5efa\u7684\u56de\u8c03\uff1anone extracted from this node implementation."]}, {"title": "\u540c\u7248\u672c\u624b\u518c\u8bf4\u660e", "paragraphs": ["\u89c4\u5212\u5668\u5728\u8fde\u63a5\u5185\u4fa7\u5173\u7cfb\u4e4b\u4e0a\u52a0\u5165 Materialize \u8282\u70b9\uff0c\u5c06\u5176\u7269\u5316\u3002\u56e0\u6b64\uff0c\u5c3d\u7ba1\u5d4c\u5957\u5faa\u73af\u8fde\u63a5\u9700\u8981\u4e3a\u5916\u4fa7\u7684\u6bcf\u4e00\u884c\u8bfb\u53d6\u4e00\u6b21\u5185\u4fa7\u6570\u636e\u3001\u5171\u5341\u6b21\uff0ct2 \u7684\u7d22\u5f15\u626b\u63cf\u4e5f\u53ea\u6267\u884c\u4e00\u6b21\u3002Materialize \u5728\u8bfb\u53d6\u65f6\u5c06\u6570\u636e\u4fdd\u5b58\u5728\u5185\u5b58\u4e2d\uff0c\u540e\u7eed\u5404\u8f6e\u76f4\u63a5\u4ece\u5185\u5b58\u8fd4\u56de\u6570\u636e\u3002"]}, {"title": "\u672c\u7248\u624b\u518c\u4e2d\u7684\u793a\u4f8b", "blocks": [{"code": "EXPLAIN SELECT *\nFROM tenk1 t1, tenk2 t2\nWHERE t1.unique1 < 10 AND t2.unique2 < 10 AND t1.hundred < t2.hundred;\n\n                                         QUERY PLAN\n---------------------------------------------------------------------------------------------\n Nested Loop  (cost=4.65..49.46 rows=33 width=488)\n   Join Filter: (t1.hundred < t2.hundred)\n   ->  Bitmap Heap Scan on tenk1 t1  (cost=4.36..39.47 rows=10 width=244)\n         Recheck Cond: (unique1 < 10)\n         ->  Bitmap Index Scan on tenk1_unique1  (cost=0.00..4.36 rows=10 width=0)\n               Index Cond: (unique1 < 10)\n   ->  Materialize  (cost=0.29..8.51 rows=10 width=244)\n         ->  Index Scan using tenk2_unique2 on tenk2 t2  (cost=0.29..8.46 rows=10 width=244)\n               Index Cond: (unique2 < 10)", "source": {"url": "/docs/11/using-explain.html#USING-EXPLAIN-BASICS", "path": "using-explain.html", "label": "PostgreSQL 11.22 \u00b7 using-explain", "sha256": "8411bc78085d4737e32d7cca103d859da6c6539e33ec5e2fba46e74c6f199d8a"}, "paragraphs": ["\u793a\u4f8b\u6458\u81ea PostgreSQL 11.22 \u624b\u518c\uff1b\u672c\u767e\u79d1\u672a\u5b9e\u9645\u6267\u884c\u6b64\u793a\u4f8b\u3002", "\u672c\u4f8b\u4e2d\uff0c\u8fde\u63a5\u7684\u8f93\u51fa\u884c\u6570\u7b49\u4e8e\u4e24\u6b21\u626b\u63cf\u884c\u6570\u7684\u4e58\u79ef\uff0c\u4f46\u5e76\u975e\u603b\u662f\u5982\u6b64\uff1a\u53ef\u80fd\u5b58\u5728\u540c\u65f6\u5f15\u7528\u4e24\u4e2a\u8868\u7684\u989d\u5916 WHERE \u5b50\u53e5\uff0c\u53ea\u80fd\u5728\u8fde\u63a5\u65f6\u5e94\u7528\uff0c\u65e0\u6cd5\u5e94\u7528\u5230\u4efb\u4f55\u5355\u4fa7\u8f93\u5165\u626b\u63cf\u3002\u793a\u4f8b\u5982\u4e0b\uff1a"]}]}, {"title": "\u6267\u884c\u5668\u5b9e\u73b0\u8bf4\u660e", "paragraphs": ["\u53ea\u8981\u5f53\u524d\u4f4d\u4e8e tuplestore \u5df2\u6536\u96c6\u6570\u636e\u7684\u672b\u5c3e\uff0c\u6bcf\u6b21\u8c03\u7528\u5c31\u4ece\u5b50\u8ba1\u5212\u83b7\u53d6\u4e00\u884c\u65b0\u6570\u636e\uff0c\u5728\u8fd4\u56de\u4e4b\u524d\u5c06\u5176\u5b58\u5165 tuplestore\u3002\u53ea\u6709\u8bf7\u6c42\u53cd\u5411\u626b\u63cf\u3001\u91cd\u626b\u6216\u6807\u8bb0\uff0f\u6062\u590d\u65f6\uff0c\u624d\u4ece tuplestore \u8bfb\u53d6\u3002", "\u9996\u6b21\u6267\u884c\u4e14\u9700\u8981\u5143\u7ec4\u5b58\u50a8\u65f6\uff0c\u521d\u59cb\u5316\u5b83\u3002", "\u5206\u914d\u7b2c\u4e8c\u4e2a\u8bfb\u53d6\u6307\u9488\u4f5c\u4e3a\u6807\u8bb0\u3002\u5df2\u77e5\u5176\u7d22\u5f15\u5fc5\u4e3a 1\uff0c\u56e0\u6b64\u65e0\u9700\u53e6\u884c\u4fdd\u5b58\u3002", "\u5982\u679c\u5c1a\u672a\u5230\u8fbe tuplestore \u672b\u5c3e\uff0c\u6216\u6b63\u5728\u53cd\u5411\u626b\u63cf\uff0c\u5219\u5c1d\u8bd5\u4ece tuplestore \u83b7\u53d6\u5143\u7ec4\u3002", "\u5728\u5143\u7ec4\u5b58\u50a8\u672b\u5c3e\u53cd\u8f6c\u626b\u63cf\u65b9\u5411\u65f6\uff0c\u7b2c\u4e00\u6b21 gettupleslot \u4f1a\u53d6\u5f97\u6700\u540e\u6dfb\u52a0\u7684\u5143\u7ec4\uff1b\u4f46\u82e5\u53ef\u80fd\uff0c\u6211\u4eec\u5e0c\u671b\u8fd4\u56de\u5b83\u4e4b\u524d\u7684\u90a3\u4e2a\uff0c\u56e0\u6b64\u989d\u5916\u8bfb\u53d6\u4e00\u6b21\u3002"]}, {"code": "case T_Material:\n\t\t\tpname = sname = \"Materialize\";\n\t\t\tbreak;", "title": "\u6838\u5fc3\u6e90\u7801\u4e2d\u7684 EXPLAIN \u6807\u8bc6"}], "strategies": [], "description": ["\u5b58\u50a8\u5b50\u8ba1\u5212\u8f93\u51fa\uff0c\u4ee5\u4fbf\u518d\u6b21\u8bfb\u53d6\u8fd9\u4e9b\u884c\u3002"], "localization": {"status": "complete", "sources": [], "language": "zh", "original_text": {"/versions/11/description/0": "Stores its child output so the rows can be read again.", "/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": "One child plan", "/versions/11/facts/3/label": "Output", "/versions/11/facts/3/value": "Materialized 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": "Same-version manual discussion", "/versions/11/sections/4/title": "Examples from this manual build", "/versions/11/sections/5/title": "Executor implementation notes", "/versions/11/sections/6/title": "EXPLAIN identity in core source", "/versions/11/memory/description": "This node creates a tuplestore with work_mem. The tuplestore can move stored tuples to temporary files; this does not make work_mem a cap on every allocation made by the node.", "/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: Materialize.", "/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 node creates a tuplestore with work_mem. The tuplestore can move stored tuples to temporary files; this does not make work_mem a cap on every allocation made by the node.", "/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": "Notice that here the planner has chosen to \u201c materialize \u201d the inner relation of the join, by putting a Materialize plan node atop it. This means that the t2 index scan will be done just once, even though the nested-loop join node needs to read that data ten times, once for each row from the outer relation. The Materialize node saves the data in memory as it's read, and then returns the data from memory on each subsequent pass.", "/versions/11/sections/5/paragraphs/0": "As long as we are at the end of the data collected in the tuplestore, we collect one new row from the subplan on each call, and stash it aside in the tuplestore before returning it. The tuplestore is only read if we are asked to scan backwards, rescan, or mark/restore.", "/versions/11/sections/5/paragraphs/1": "If first time through, and we need a tuplestore, initialize it.", "/versions/11/sections/5/paragraphs/2": "Allocate a second read pointer to serve as the mark. We know it must have index 1, so needn't store that.", "/versions/11/sections/5/paragraphs/3": "If we are not at the end of the tuplestore, or are going backwards, try to fetch a tuple from tuplestore.", "/versions/11/sections/5/paragraphs/4": "When reversing direction at tuplestore EOF, the first gettupleslot call will fetch the last-added tuple; but we want to return the one before that, if possible. So do an extra fetch.", "/versions/11/tables/0/columns/0/label": "Text-format label", "/versions/11/tables/0/columns/1/label": "Structured node identity", "/versions/11/sections/4/blocks/0/paragraphs/0": "Example copied from the PostgreSQL 11.22 manual; it was not executed for this collection.", "/versions/11/sections/4/blocks/0/paragraphs/1": "In this example the join's output row count is the same as the product of the two scans' row counts, but that's not true in all cases because there can be additional WHERE clauses that mention both tables and so can only be applied at the join point, not to either input scan. Here's an example:"}, "fallback_fields": [], "source_language": "en", "original_snapshot_sha256": "63087d7175e3441d4b9a7fc517fbab67cebc479c5831e7c39a18d73df657ba45"}, "evidence_kind": "source and documentation", "explain_names": ["Materialize"], "partial_modes": [], "comparison_data": {"node_tag": "T_Material", "strategies": [], "text_names": ["Materialize"], "initializer": "ExecInitMaterial", "partial_modes": [], "memory_mechanism": "tuplestore", "parallel_callbacks": []}, "comparison_hash": "c1d37bf334409fe6ded8ce560fe45fd495ff89ceda2808b6f5ef18daca520393", "explain_prefixes": ["Parallel"], "runtime_verified": false, "source_inventory": {"explain": "src/backend/commands/explain.c", "executor": "src/backend/executor/execProcnode.c", "implementation": "src/backend/executor/nodeMaterial.c"}, "parallel_callbacks": []}, "12": {"facts": [{"label": "\u6838\u5fc3\u8282\u70b9\u6807\u7b7e", "value": "T_Material"}, {"label": "\u7ed3\u6784\u5316 EXPLAIN \u8282\u70b9\u7c7b\u578b", "value": "Materialize"}, {"label": "\u8f93\u5165", "value": "\u4e00\u4e2a\u5b50\u8ba1\u5212"}, {"label": "\u8f93\u51fa", "value": "\u5df2\u7269\u5316\u7684\u5143\u7ec4"}, {"label": "\u6267\u884c\u5668\u521d\u59cb\u5316\u51fd\u6570", "value": "ExecInitMaterial"}, {"label": "\u5185\u5b58\u673a\u5236", "value": "tuplestore"}], "memory": {"evidence": [{"url": "https://ftp.postgresql.org/pub/source/v12.22/postgresql-12.22.tar.bz2", "path": "src/backend/executor/nodeMaterial.c", "label": "src/backend/executor/nodeMaterial.c", "sha256": "b6ff5cdf699143bf2c94d9182574d1f9ad846bc272e4fe4039dcadd7e0c3af00", "archive_sha256": "8df3c0474782589d3c6f374b5133b1bd14d168086edbc13c6e72e67dd4527a3b"}, {"url": "https://ftp.postgresql.org/pub/source/v12.22/postgresql-12.22.tar.bz2", "path": "src/backend/utils/sort/tuplestore.c", "label": "src/backend/utils/sort/tuplestore.c", "sha256": "44cccd98d659272f5c8f3ff6adffb1f6cc911acd13a3cfafc74cc7841318f929", "archive_sha256": 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"/wiki/guc/enable_material/?v=12", "label": "enable_material"}, {"url": "/wiki/guc/work_mem/?v=12", "label": "work_mem"}], "release": {"ref": "PostgreSQL 12.22 source archive", "label": "12.22", "major": "12", "channel": "historical", "revision": "8df3c0474782589d3c6f374b5133b1bd14d168086edbc13c6e72e67dd4527a3b", "source_url": "https://ftp.postgresql.org/pub/source/v12.22/postgresql-12.22.tar.bz2", "source_snapshot_utc": ""}, "sources": [{"url": "https://ftp.postgresql.org/pub/source/v12.22/postgresql-12.22.tar.bz2", "line": 1209, "path": "src/backend/commands/explain.c", "label": "src/backend/commands/explain.c:1209", "sha256": "d02ea84fdaa201de5d9360645a9f24bfbd2c31f7d45a639e09560ac0e6b6471d", "archive_sha256": "8df3c0474782589d3c6f374b5133b1bd14d168086edbc13c6e72e67dd4527a3b"}, {"url": "https://ftp.postgresql.org/pub/source/v12.22/postgresql-12.22.tar.bz2", "line": 308, "path": "src/backend/executor/execProcnode.c", "label": "src/backend/executor/execProcnode.c:308", "sha256": 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"sha256": "44cccd98d659272f5c8f3ff6adffb1f6cc911acd13a3cfafc74cc7841318f929", "archive_sha256": "8df3c0474782589d3c6f374b5133b1bd14d168086edbc13c6e72e67dd4527a3b"}, {"url": "https://pg.center/docs/12/using-explain.html#USING-EXPLAIN-BASICS", "path": "using-explain.html", "label": "PostgreSQL 12.22 \u00b7 using-explain", "sha256": "06297525f2180b07e752837a3351be9c871b56559f535bcd0a67dec9baac10c0", "language": "en", "original_url": "/docs/12/using-explain.html#USING-EXPLAIN-BASICS"}], "node_tag": "T_Material", "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\uff1aMaterialize.", "\u5e76\u884c\u611f\u77e5\u4e0e\u5e76\u884c\u5b89\u5168\u662f\u4e0d\u540c\u7684\u8ba1\u5212\u5c5e\u6027\u3002\u5728\u5e76\u884c\u5de5\u4f5c\u8fdb\u7a0b\u5185\u8fd0\u884c\u7684\u8282\u70b9\u4e0d\u4e00\u5b9a\u662f\u5e76\u884c\u611f\u77e5\u8282\u70b9\u3002"]}, {"title": "\u5185\u5b58\u4e0e\u4e34\u65f6\u5b58\u50a8", "paragraphs": ["\u6b64\u8282\u70b9\u4f7f\u7528 work_mem \u521b\u5efa tuplestore\u3002tuplestore \u53ef\u4ee5\u5c06\u5b58\u50a8\u7684\u5143\u7ec4\u79fb\u5230\u4e34\u65f6\u6587\u4ef6\uff0c\u4f46\u8fd9\u4e0d\u610f\u5473\u7740 work_mem \u9650\u5236\u4e86\u8282\u70b9\u7684\u5168\u90e8\u5185\u5b58\u5206\u914d\u3002"]}, {"title": "\u5e76\u884c\u6267\u884c\u4e0e\u8fd0\u884c\u4fe1\u606f\u91c7\u96c6", "paragraphs": ["\u4ee5\u4e0b\u6e90\u7801\u56de\u8c03\u53ef\u4ee5\u534f\u8c03\u6267\u884c\u6216\u6536\u96c6\u5de5\u4f5c\u8fdb\u7a0b\u7684\u6d4b\u91cf\u6570\u636e\u3002\u56de\u8c03\u5b58\u5728\u4e0d\u4ee3\u8868\u8be5\u8282\u70b9\u666e\u904d\u652f\u6301\u5171\u4eab\u5e76\u884c\u626b\u63cf\u6216\u5171\u4eab\u72b6\u6001\u3002", "\u6b64\u6784\u5efa\u7684\u56de\u8c03\uff1anone extracted from this node implementation."]}, {"title": "\u540c\u7248\u672c\u624b\u518c\u8bf4\u660e", "paragraphs": ["\u89c4\u5212\u5668\u5728\u8fde\u63a5\u5185\u4fa7\u5173\u7cfb\u4e4b\u4e0a\u52a0\u5165 Materialize \u8282\u70b9\uff0c\u5c06\u5176\u7269\u5316\u3002\u56e0\u6b64\uff0c\u5c3d\u7ba1\u5d4c\u5957\u5faa\u73af\u8fde\u63a5\u9700\u8981\u4e3a\u5916\u4fa7\u7684\u6bcf\u4e00\u884c\u8bfb\u53d6\u4e00\u6b21\u5185\u4fa7\u6570\u636e\u3001\u5171\u5341\u6b21\uff0ct2 \u7684\u7d22\u5f15\u626b\u63cf\u4e5f\u53ea\u6267\u884c\u4e00\u6b21\u3002Materialize \u5728\u8bfb\u53d6\u65f6\u5c06\u6570\u636e\u4fdd\u5b58\u5728\u5185\u5b58\u4e2d\uff0c\u540e\u7eed\u5404\u8f6e\u76f4\u63a5\u4ece\u5185\u5b58\u8fd4\u56de\u6570\u636e\u3002"]}, {"title": "\u672c\u7248\u624b\u518c\u4e2d\u7684\u793a\u4f8b", "blocks": [{"code": "EXPLAIN SELECT *\nFROM tenk1 t1, tenk2 t2\nWHERE t1.unique1 < 10 AND t2.unique2 < 10 AND t1.hundred < t2.hundred;\n\n                                         QUERY PLAN\n---------------------------------------------------------------------------------------------\n Nested Loop  (cost=4.65..49.46 rows=33 width=488)\n   Join Filter: (t1.hundred < t2.hundred)\n   ->  Bitmap Heap Scan on tenk1 t1  (cost=4.36..39.47 rows=10 width=244)\n         Recheck Cond: (unique1 < 10)\n         ->  Bitmap Index Scan on tenk1_unique1  (cost=0.00..4.36 rows=10 width=0)\n               Index Cond: (unique1 < 10)\n   ->  Materialize  (cost=0.29..8.51 rows=10 width=244)\n         ->  Index Scan using tenk2_unique2 on tenk2 t2  (cost=0.29..8.46 rows=10 width=244)\n               Index Cond: (unique2 < 10)", "source": {"url": "/docs/12/using-explain.html#USING-EXPLAIN-BASICS", "path": "using-explain.html", "label": "PostgreSQL 12.22 \u00b7 using-explain", "sha256": "06297525f2180b07e752837a3351be9c871b56559f535bcd0a67dec9baac10c0"}, "paragraphs": ["\u793a\u4f8b\u6458\u81ea PostgreSQL 12.22 \u624b\u518c\uff1b\u672c\u767e\u79d1\u672a\u5b9e\u9645\u6267\u884c\u6b64\u793a\u4f8b\u3002", "\u672c\u4f8b\u4e2d\uff0c\u8fde\u63a5\u7684\u8f93\u51fa\u884c\u6570\u7b49\u4e8e\u4e24\u6b21\u626b\u63cf\u884c\u6570\u7684\u4e58\u79ef\uff0c\u4f46\u5e76\u975e\u603b\u662f\u5982\u6b64\uff1a\u53ef\u80fd\u5b58\u5728\u540c\u65f6\u5f15\u7528\u4e24\u4e2a\u8868\u7684\u989d\u5916 WHERE \u5b50\u53e5\uff0c\u53ea\u80fd\u5728\u8fde\u63a5\u65f6\u5e94\u7528\uff0c\u65e0\u6cd5\u5e94\u7528\u5230\u4efb\u4f55\u5355\u4fa7\u8f93\u5165\u626b\u63cf\u3002\u793a\u4f8b\u5982\u4e0b\uff1a"]}]}, {"title": "\u6267\u884c\u5668\u5b9e\u73b0\u8bf4\u660e", "paragraphs": ["\u53ea\u8981\u5f53\u524d\u4f4d\u4e8e tuplestore \u5df2\u6536\u96c6\u6570\u636e\u7684\u672b\u5c3e\uff0c\u6bcf\u6b21\u8c03\u7528\u5c31\u4ece\u5b50\u8ba1\u5212\u83b7\u53d6\u4e00\u884c\u65b0\u6570\u636e\uff0c\u5728\u8fd4\u56de\u4e4b\u524d\u5c06\u5176\u5b58\u5165 tuplestore\u3002\u53ea\u6709\u8bf7\u6c42\u53cd\u5411\u626b\u63cf\u3001\u91cd\u626b\u6216\u6807\u8bb0\uff0f\u6062\u590d\u65f6\uff0c\u624d\u4ece tuplestore \u8bfb\u53d6\u3002", "\u9996\u6b21\u6267\u884c\u4e14\u9700\u8981\u5143\u7ec4\u5b58\u50a8\u65f6\uff0c\u521d\u59cb\u5316\u5b83\u3002", "\u5206\u914d\u7b2c\u4e8c\u4e2a\u8bfb\u53d6\u6307\u9488\u4f5c\u4e3a\u6807\u8bb0\u3002\u5df2\u77e5\u5176\u7d22\u5f15\u5fc5\u4e3a 1\uff0c\u56e0\u6b64\u65e0\u9700\u53e6\u884c\u4fdd\u5b58\u3002", "\u5982\u679c\u5c1a\u672a\u5230\u8fbe tuplestore \u672b\u5c3e\uff0c\u6216\u6b63\u5728\u53cd\u5411\u626b\u63cf\uff0c\u5219\u5c1d\u8bd5\u4ece tuplestore \u83b7\u53d6\u5143\u7ec4\u3002", "\u5728\u5143\u7ec4\u5b58\u50a8\u672b\u5c3e\u53cd\u8f6c\u626b\u63cf\u65b9\u5411\u65f6\uff0c\u7b2c\u4e00\u6b21 gettupleslot \u4f1a\u53d6\u5f97\u6700\u540e\u6dfb\u52a0\u7684\u5143\u7ec4\uff1b\u4f46\u82e5\u53ef\u80fd\uff0c\u6211\u4eec\u5e0c\u671b\u8fd4\u56de\u5b83\u4e4b\u524d\u7684\u90a3\u4e2a\uff0c\u56e0\u6b64\u989d\u5916\u8bfb\u53d6\u4e00\u6b21\u3002"]}, {"code": "case T_Material:\n\t\t\tpname = sname = \"Materialize\";\n\t\t\tbreak;", "title": "\u6838\u5fc3\u6e90\u7801\u4e2d\u7684 EXPLAIN \u6807\u8bc6"}], "strategies": [], "description": ["\u5b58\u50a8\u5b50\u8ba1\u5212\u8f93\u51fa\uff0c\u4ee5\u4fbf\u518d\u6b21\u8bfb\u53d6\u8fd9\u4e9b\u884c\u3002"], "localization": {"status": "complete", "sources": [], "language": "zh", "original_text": {"/versions/12/description/0": "Stores its child output so the rows can be read again.", "/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": "One child plan", "/versions/12/facts/3/label": "Output", "/versions/12/facts/3/value": "Materialized 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": "Same-version manual discussion", "/versions/12/sections/4/title": "Examples from this manual build", "/versions/12/sections/5/title": "Executor implementation notes", "/versions/12/sections/6/title": "EXPLAIN identity in core source", "/versions/12/memory/description": "This node creates a tuplestore with work_mem. The tuplestore can move stored tuples to temporary files; this does not make work_mem a cap on every allocation made by the node.", "/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: Materialize.", "/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 node creates a tuplestore with work_mem. The tuplestore can move stored tuples to temporary files; this does not make work_mem a cap on every allocation made by the node.", "/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": "Notice that here the planner has chosen to \u201c materialize \u201d the inner relation of the join, by putting a Materialize plan node atop it. This means that the t2 index scan will be done just once, even though the nested-loop join node needs to read that data ten times, once for each row from the outer relation. The Materialize node saves the data in memory as it's read, and then returns the data from memory on each subsequent pass.", "/versions/12/sections/5/paragraphs/0": "As long as we are at the end of the data collected in the tuplestore, we collect one new row from the subplan on each call, and stash it aside in the tuplestore before returning it. The tuplestore is only read if we are asked to scan backwards, rescan, or mark/restore.", "/versions/12/sections/5/paragraphs/1": "If first time through, and we need a tuplestore, initialize it.", "/versions/12/sections/5/paragraphs/2": "Allocate a second read pointer to serve as the mark. We know it must have index 1, so needn't store that.", "/versions/12/sections/5/paragraphs/3": "If we are not at the end of the tuplestore, or are going backwards, try to fetch a tuple from tuplestore.", "/versions/12/sections/5/paragraphs/4": "When reversing direction at tuplestore EOF, the first gettupleslot call will fetch the last-added tuple; but we want to return the one before that, if possible. So do an extra fetch.", "/versions/12/tables/0/columns/0/label": "Text-format label", "/versions/12/tables/0/columns/1/label": "Structured node identity", "/versions/12/sections/4/blocks/0/paragraphs/0": "Example copied from the PostgreSQL 12.22 manual; it was not executed for this collection.", "/versions/12/sections/4/blocks/0/paragraphs/1": "In this example the join's output row count is the same as the product of the two scans' row counts, but that's not true in all cases because there can be additional WHERE clauses that mention both tables and so can only be applied at the join point, not to either input scan. Here's an example:"}, "fallback_fields": [], "source_language": "en", "original_snapshot_sha256": "c0e98912e5b23e229291074b7f9433f833492560955f333e0cc319763371da59"}, "evidence_kind": "source and documentation", "explain_names": ["Materialize"], "partial_modes": [], "comparison_data": {"node_tag": "T_Material", "strategies": [], "text_names": ["Materialize"], "initializer": "ExecInitMaterial", "partial_modes": [], "memory_mechanism": "tuplestore", "parallel_callbacks": []}, "comparison_hash": "c1d37bf334409fe6ded8ce560fe45fd495ff89ceda2808b6f5ef18daca520393", "explain_prefixes": ["Parallel"], "runtime_verified": false, "source_inventory": {"explain": "src/backend/commands/explain.c", "executor": "src/backend/executor/execProcnode.c", "implementation": "src/backend/executor/nodeMaterial.c"}, "parallel_callbacks": []}, "13": {"facts": [{"label": "\u6838\u5fc3\u8282\u70b9\u6807\u7b7e", "value": "T_Material"}, {"label": "\u7ed3\u6784\u5316 EXPLAIN \u8282\u70b9\u7c7b\u578b", "value": "Materialize"}, {"label": "\u8f93\u5165", "value": "\u4e00\u4e2a\u5b50\u8ba1\u5212"}, {"label": "\u8f93\u51fa", "value": "\u5df2\u7269\u5316\u7684\u5143\u7ec4"}, {"label": "\u6267\u884c\u5668\u521d\u59cb\u5316\u51fd\u6570", "value": "ExecInitMaterial"}, {"label": "\u5185\u5b58\u673a\u5236", "value": "tuplestore"}], "memory": {"evidence": [{"url": "https://ftp.postgresql.org/pub/source/v13.23/postgresql-13.23.tar.bz2", "path": "src/backend/executor/nodeMaterial.c", "label": "src/backend/executor/nodeMaterial.c", "sha256": "4fa900bee651a37e89526526d333bb1c2697f5ee4073be32d3233493b3d23f6d", "archive_sha256": "6ec3c82726af92b7dec873fa1cdf881eca92a4219787dfad05acb6b10e041fd6"}, {"url": "https://ftp.postgresql.org/pub/source/v13.23/postgresql-13.23.tar.bz2", "path": "src/backend/utils/sort/tuplestore.c", "label": "src/backend/utils/sort/tuplestore.c", "sha256": "4cba6490949d7dd9338b8499fcbb489e84cfd6cda9b98599512eb40bfbde6f9d", "archive_sha256": 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"/wiki/guc/enable_material/?v=13", "label": "enable_material"}, {"url": "/wiki/guc/work_mem/?v=13", "label": "work_mem"}], "release": {"ref": "PostgreSQL 13.23 source archive", "label": "13.23", "major": "13", "channel": "historical", "revision": "6ec3c82726af92b7dec873fa1cdf881eca92a4219787dfad05acb6b10e041fd6", "source_url": "https://ftp.postgresql.org/pub/source/v13.23/postgresql-13.23.tar.bz2", "source_snapshot_utc": ""}, "sources": [{"url": "https://ftp.postgresql.org/pub/source/v13.23/postgresql-13.23.tar.bz2", "line": 1267, "path": "src/backend/commands/explain.c", "label": "src/backend/commands/explain.c:1267", "sha256": "541713e0e7f1c9cc352c2b6028964d440c19d2678a4463000094c24a88c1e730", "archive_sha256": "6ec3c82726af92b7dec873fa1cdf881eca92a4219787dfad05acb6b10e041fd6"}, {"url": "https://ftp.postgresql.org/pub/source/v13.23/postgresql-13.23.tar.bz2", "line": 308, "path": "src/backend/executor/execProcnode.c", "label": "src/backend/executor/execProcnode.c:308", "sha256": 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"sha256": "4cba6490949d7dd9338b8499fcbb489e84cfd6cda9b98599512eb40bfbde6f9d", "archive_sha256": "6ec3c82726af92b7dec873fa1cdf881eca92a4219787dfad05acb6b10e041fd6"}, {"url": "https://pg.center/docs/13/using-explain.html#USING-EXPLAIN-BASICS", "path": "using-explain.html", "label": "PostgreSQL 13.23 \u00b7 using-explain", "sha256": "650fd8629382d5dc8f9f8412c50ec5f32442a9ad2f98ca88e5348a7c2bd0ac7a", "language": "en", "original_url": "/docs/13/using-explain.html#USING-EXPLAIN-BASICS"}], "node_tag": "T_Material", "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\uff1aMaterialize.", "\u5e76\u884c\u611f\u77e5\u4e0e\u5e76\u884c\u5b89\u5168\u662f\u4e0d\u540c\u7684\u8ba1\u5212\u5c5e\u6027\u3002\u5728\u5e76\u884c\u5de5\u4f5c\u8fdb\u7a0b\u5185\u8fd0\u884c\u7684\u8282\u70b9\u4e0d\u4e00\u5b9a\u662f\u5e76\u884c\u611f\u77e5\u8282\u70b9\u3002"]}, {"title": "\u5185\u5b58\u4e0e\u4e34\u65f6\u5b58\u50a8", "paragraphs": ["\u6b64\u8282\u70b9\u4f7f\u7528 work_mem \u521b\u5efa tuplestore\u3002tuplestore \u53ef\u4ee5\u5c06\u5b58\u50a8\u7684\u5143\u7ec4\u79fb\u5230\u4e34\u65f6\u6587\u4ef6\uff0c\u4f46\u8fd9\u4e0d\u610f\u5473\u7740 work_mem \u9650\u5236\u4e86\u8282\u70b9\u7684\u5168\u90e8\u5185\u5b58\u5206\u914d\u3002"]}, {"title": "\u5e76\u884c\u6267\u884c\u4e0e\u8fd0\u884c\u4fe1\u606f\u91c7\u96c6", "paragraphs": ["\u4ee5\u4e0b\u6e90\u7801\u56de\u8c03\u53ef\u4ee5\u534f\u8c03\u6267\u884c\u6216\u6536\u96c6\u5de5\u4f5c\u8fdb\u7a0b\u7684\u6d4b\u91cf\u6570\u636e\u3002\u56de\u8c03\u5b58\u5728\u4e0d\u4ee3\u8868\u8be5\u8282\u70b9\u666e\u904d\u652f\u6301\u5171\u4eab\u5e76\u884c\u626b\u63cf\u6216\u5171\u4eab\u72b6\u6001\u3002", "\u6b64\u6784\u5efa\u7684\u56de\u8c03\uff1anone extracted from this node implementation."]}, {"title": "\u540c\u7248\u672c\u624b\u518c\u8bf4\u660e", "paragraphs": ["\u89c4\u5212\u5668\u5728\u8fde\u63a5\u5185\u4fa7\u5173\u7cfb\u4e4b\u4e0a\u52a0\u5165 Materialize \u8282\u70b9\uff0c\u5c06\u5176\u7269\u5316\u3002\u56e0\u6b64\uff0c\u5c3d\u7ba1\u5d4c\u5957\u5faa\u73af\u8fde\u63a5\u9700\u8981\u4e3a\u5916\u4fa7\u7684\u6bcf\u4e00\u884c\u8bfb\u53d6\u4e00\u6b21\u5185\u4fa7\u6570\u636e\u3001\u5171\u5341\u6b21\uff0ct2 \u7684\u7d22\u5f15\u626b\u63cf\u4e5f\u53ea\u6267\u884c\u4e00\u6b21\u3002Materialize \u5728\u8bfb\u53d6\u65f6\u5c06\u6570\u636e\u4fdd\u5b58\u5728\u5185\u5b58\u4e2d\uff0c\u540e\u7eed\u5404\u8f6e\u76f4\u63a5\u4ece\u5185\u5b58\u8fd4\u56de\u6570\u636e\u3002"]}, {"title": "\u672c\u7248\u624b\u518c\u4e2d\u7684\u793a\u4f8b", "blocks": [{"code": "EXPLAIN SELECT *\nFROM tenk1 t1, tenk2 t2\nWHERE t1.unique1 < 10 AND t2.unique2 < 10 AND t1.hundred < t2.hundred;\n\n                                         QUERY PLAN\n---------------------------------------------------------------------------------------------\n Nested Loop  (cost=4.65..49.46 rows=33 width=488)\n   Join Filter: (t1.hundred < t2.hundred)\n   ->  Bitmap Heap Scan on tenk1 t1  (cost=4.36..39.47 rows=10 width=244)\n         Recheck Cond: (unique1 < 10)\n         ->  Bitmap Index Scan on tenk1_unique1  (cost=0.00..4.36 rows=10 width=0)\n               Index Cond: (unique1 < 10)\n   ->  Materialize  (cost=0.29..8.51 rows=10 width=244)\n         ->  Index Scan using tenk2_unique2 on tenk2 t2  (cost=0.29..8.46 rows=10 width=244)\n               Index Cond: (unique2 < 10)", "source": {"url": "/docs/13/using-explain.html#USING-EXPLAIN-BASICS", "path": "using-explain.html", "label": "PostgreSQL 13.23 \u00b7 using-explain", "sha256": "650fd8629382d5dc8f9f8412c50ec5f32442a9ad2f98ca88e5348a7c2bd0ac7a"}, "paragraphs": ["\u793a\u4f8b\u6458\u81ea PostgreSQL 13.23 \u624b\u518c\uff1b\u672c\u767e\u79d1\u672a\u5b9e\u9645\u6267\u884c\u6b64\u793a\u4f8b\u3002", "\u672c\u4f8b\u4e2d\uff0c\u8fde\u63a5\u7684\u8f93\u51fa\u884c\u6570\u7b49\u4e8e\u4e24\u6b21\u626b\u63cf\u884c\u6570\u7684\u4e58\u79ef\uff0c\u4f46\u5e76\u975e\u603b\u662f\u5982\u6b64\uff1a\u53ef\u80fd\u5b58\u5728\u540c\u65f6\u5f15\u7528\u4e24\u4e2a\u8868\u7684\u989d\u5916 WHERE \u5b50\u53e5\uff0c\u53ea\u80fd\u5728\u8fde\u63a5\u65f6\u5e94\u7528\uff0c\u65e0\u6cd5\u5e94\u7528\u5230\u4efb\u4f55\u5355\u4fa7\u8f93\u5165\u626b\u63cf\u3002\u793a\u4f8b\u5982\u4e0b\uff1a"]}]}, {"title": "\u6267\u884c\u5668\u5b9e\u73b0\u8bf4\u660e", "paragraphs": ["\u53ea\u8981\u5f53\u524d\u4f4d\u4e8e tuplestore \u5df2\u6536\u96c6\u6570\u636e\u7684\u672b\u5c3e\uff0c\u6bcf\u6b21\u8c03\u7528\u5c31\u4ece\u5b50\u8ba1\u5212\u83b7\u53d6\u4e00\u884c\u65b0\u6570\u636e\uff0c\u5728\u8fd4\u56de\u4e4b\u524d\u5c06\u5176\u5b58\u5165 tuplestore\u3002\u53ea\u6709\u8bf7\u6c42\u53cd\u5411\u626b\u63cf\u3001\u91cd\u626b\u6216\u6807\u8bb0\uff0f\u6062\u590d\u65f6\uff0c\u624d\u4ece tuplestore \u8bfb\u53d6\u3002", "\u9996\u6b21\u6267\u884c\u4e14\u9700\u8981\u5143\u7ec4\u5b58\u50a8\u65f6\uff0c\u521d\u59cb\u5316\u5b83\u3002", "\u5206\u914d\u7b2c\u4e8c\u4e2a\u8bfb\u53d6\u6307\u9488\u4f5c\u4e3a\u6807\u8bb0\u3002\u5df2\u77e5\u5176\u7d22\u5f15\u5fc5\u4e3a 1\uff0c\u56e0\u6b64\u65e0\u9700\u53e6\u884c\u4fdd\u5b58\u3002", "\u5982\u679c\u5c1a\u672a\u5230\u8fbe tuplestore \u672b\u5c3e\uff0c\u6216\u6b63\u5728\u53cd\u5411\u626b\u63cf\uff0c\u5219\u5c1d\u8bd5\u4ece tuplestore \u83b7\u53d6\u5143\u7ec4\u3002", "\u5728\u5143\u7ec4\u5b58\u50a8\u672b\u5c3e\u53cd\u8f6c\u626b\u63cf\u65b9\u5411\u65f6\uff0c\u7b2c\u4e00\u6b21 gettupleslot \u4f1a\u53d6\u5f97\u6700\u540e\u6dfb\u52a0\u7684\u5143\u7ec4\uff1b\u4f46\u82e5\u53ef\u80fd\uff0c\u6211\u4eec\u5e0c\u671b\u8fd4\u56de\u5b83\u4e4b\u524d\u7684\u90a3\u4e2a\uff0c\u56e0\u6b64\u989d\u5916\u8bfb\u53d6\u4e00\u6b21\u3002"]}, {"code": "case T_Material:\n\t\t\tpname = sname = \"Materialize\";\n\t\t\tbreak;", "title": "\u6838\u5fc3\u6e90\u7801\u4e2d\u7684 EXPLAIN \u6807\u8bc6"}], "strategies": [], "description": ["\u5b58\u50a8\u5b50\u8ba1\u5212\u8f93\u51fa\uff0c\u4ee5\u4fbf\u518d\u6b21\u8bfb\u53d6\u8fd9\u4e9b\u884c\u3002"], "localization": {"status": "complete", "sources": [], "language": "zh", "original_text": {"/versions/13/description/0": "Stores its child output so the rows can be read again.", "/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": "One child plan", "/versions/13/facts/3/label": "Output", "/versions/13/facts/3/value": "Materialized 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": "Same-version manual discussion", "/versions/13/sections/4/title": "Examples from this manual build", "/versions/13/sections/5/title": "Executor implementation notes", "/versions/13/sections/6/title": "EXPLAIN identity in core source", "/versions/13/memory/description": "This node creates a tuplestore with work_mem. The tuplestore can move stored tuples to temporary files; this does not make work_mem a cap on every allocation made by the node.", "/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: Materialize.", "/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 node creates a tuplestore with work_mem. The tuplestore can move stored tuples to temporary files; this does not make work_mem a cap on every allocation made by the node.", "/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": "Notice that here the planner has chosen to \u201c materialize \u201d the inner relation of the join, by putting a Materialize plan node atop it. This means that the t2 index scan will be done just once, even though the nested-loop join node needs to read that data ten times, once for each row from the outer relation. The Materialize node saves the data in memory as it's read, and then returns the data from memory on each subsequent pass.", "/versions/13/sections/5/paragraphs/0": "As long as we are at the end of the data collected in the tuplestore, we collect one new row from the subplan on each call, and stash it aside in the tuplestore before returning it. The tuplestore is only read if we are asked to scan backwards, rescan, or mark/restore.", "/versions/13/sections/5/paragraphs/1": "If first time through, and we need a tuplestore, initialize it.", "/versions/13/sections/5/paragraphs/2": "Allocate a second read pointer to serve as the mark. We know it must have index 1, so needn't store that.", "/versions/13/sections/5/paragraphs/3": "If we are not at the end of the tuplestore, or are going backwards, try to fetch a tuple from tuplestore.", "/versions/13/sections/5/paragraphs/4": "When reversing direction at tuplestore EOF, the first gettupleslot call will fetch the last-added tuple; but we want to return the one before that, if possible. So do an extra fetch.", "/versions/13/tables/0/columns/0/label": "Text-format label", "/versions/13/tables/0/columns/1/label": "Structured node identity", "/versions/13/sections/4/blocks/0/paragraphs/0": "Example copied from the PostgreSQL 13.23 manual; it was not executed for this collection.", "/versions/13/sections/4/blocks/0/paragraphs/1": "In this example the join's output row count is the same as the product of the two scans' row counts, but that's not true in all cases because there can be additional WHERE clauses that mention both tables and so can only be applied at the join point, not to either input scan. Here's an example:"}, "fallback_fields": [], "source_language": "en", "original_snapshot_sha256": "8893b5e26ee10da58e1f7fa027f8d26648495c7dcbad2f18e5f235546189c7f1"}, "evidence_kind": "source and documentation", "explain_names": ["Materialize"], "partial_modes": [], "comparison_data": {"node_tag": "T_Material", "strategies": [], "text_names": ["Materialize"], "initializer": "ExecInitMaterial", "partial_modes": [], "memory_mechanism": "tuplestore", "parallel_callbacks": []}, "comparison_hash": "c1d37bf334409fe6ded8ce560fe45fd495ff89ceda2808b6f5ef18daca520393", "explain_prefixes": ["Parallel"], "runtime_verified": false, "source_inventory": {"explain": "src/backend/commands/explain.c", "executor": "src/backend/executor/execProcnode.c", "implementation": "src/backend/executor/nodeMaterial.c"}, "parallel_callbacks": []}, "14": {"facts": [{"label": "\u6838\u5fc3\u8282\u70b9\u6807\u7b7e", "value": "T_Material"}, {"label": "\u7ed3\u6784\u5316 EXPLAIN \u8282\u70b9\u7c7b\u578b", "value": "Materialize"}, {"label": "\u8f93\u5165", "value": "\u4e00\u4e2a\u5b50\u8ba1\u5212"}, {"label": "\u8f93\u51fa", "value": "\u5df2\u7269\u5316\u7684\u5143\u7ec4"}, {"label": "\u6267\u884c\u5668\u521d\u59cb\u5316\u51fd\u6570", "value": "ExecInitMaterial"}, {"label": "\u5185\u5b58\u673a\u5236", "value": "tuplestore"}], "memory": {"evidence": [{"url": "https://ftp.postgresql.org/pub/source/v14.24/postgresql-14.24.tar.bz2", "path": "src/backend/executor/nodeMaterial.c", "label": "src/backend/executor/nodeMaterial.c", "sha256": "7ed98002a97fbd0a47432a5c02fd65ed2ecb3898c903d1a54db4c22f13e16291", "archive_sha256": "a7fa7ed3d558172355f51406097a7bd4f6b473be80f311ef7cda96bf383d8897"}, {"url": "https://ftp.postgresql.org/pub/source/v14.24/postgresql-14.24.tar.bz2", "path": "src/backend/utils/sort/tuplestore.c", "label": "src/backend/utils/sort/tuplestore.c", "sha256": "833cff27e0a2c863b9e897cd3bf4127df1b3e3a9b976694f3323a1c1a466d9b2", "archive_sha256": 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"/wiki/guc/enable_material/?v=14", "label": "enable_material"}, {"url": "/wiki/guc/work_mem/?v=14", "label": "work_mem"}], "release": {"ref": "PostgreSQL 14.24 source archive", "label": "14.24", "major": "14", "channel": "stable", "revision": "a7fa7ed3d558172355f51406097a7bd4f6b473be80f311ef7cda96bf383d8897", "source_url": "https://ftp.postgresql.org/pub/source/v14.24/postgresql-14.24.tar.bz2", "source_snapshot_utc": ""}, "sources": [{"url": "https://ftp.postgresql.org/pub/source/v14.24/postgresql-14.24.tar.bz2", "line": 1306, "path": "src/backend/commands/explain.c", "label": "src/backend/commands/explain.c:1306", "sha256": "e091be4e2a083b8dea39ccd09beedede22c1716ef974da66c214a44f48be8c41", "archive_sha256": "a7fa7ed3d558172355f51406097a7bd4f6b473be80f311ef7cda96bf383d8897"}, {"url": "https://ftp.postgresql.org/pub/source/v14.24/postgresql-14.24.tar.bz2", "line": 315, "path": "src/backend/executor/execProcnode.c", "label": "src/backend/executor/execProcnode.c:315", "sha256": 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"sha256": "833cff27e0a2c863b9e897cd3bf4127df1b3e3a9b976694f3323a1c1a466d9b2", "archive_sha256": "a7fa7ed3d558172355f51406097a7bd4f6b473be80f311ef7cda96bf383d8897"}, {"url": "https://pg.center/docs/14/using-explain.html#USING-EXPLAIN-BASICS", "path": "using-explain.html", "label": "PostgreSQL 14.24 \u00b7 using-explain", "sha256": "7f5ab59cb21a035ada45ea3426c5d1cca3f781273483677f73fdd76753555206", "language": "en", "original_url": "/docs/14/using-explain.html#USING-EXPLAIN-BASICS"}], "node_tag": "T_Material", "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\uff1aMaterialize.", "\u5e76\u884c\u611f\u77e5\u4e0e\u5e76\u884c\u5b89\u5168\u662f\u4e0d\u540c\u7684\u8ba1\u5212\u5c5e\u6027\u3002\u5728\u5e76\u884c\u5de5\u4f5c\u8fdb\u7a0b\u5185\u8fd0\u884c\u7684\u8282\u70b9\u4e0d\u4e00\u5b9a\u662f\u5e76\u884c\u611f\u77e5\u8282\u70b9\u3002"]}, {"title": "\u5185\u5b58\u4e0e\u4e34\u65f6\u5b58\u50a8", "paragraphs": ["\u6b64\u8282\u70b9\u4f7f\u7528 work_mem \u521b\u5efa tuplestore\u3002tuplestore \u53ef\u4ee5\u5c06\u5b58\u50a8\u7684\u5143\u7ec4\u79fb\u5230\u4e34\u65f6\u6587\u4ef6\uff0c\u4f46\u8fd9\u4e0d\u610f\u5473\u7740 work_mem \u9650\u5236\u4e86\u8282\u70b9\u7684\u5168\u90e8\u5185\u5b58\u5206\u914d\u3002"]}, {"title": "\u5e76\u884c\u6267\u884c\u4e0e\u8fd0\u884c\u4fe1\u606f\u91c7\u96c6", "paragraphs": ["\u4ee5\u4e0b\u6e90\u7801\u56de\u8c03\u53ef\u4ee5\u534f\u8c03\u6267\u884c\u6216\u6536\u96c6\u5de5\u4f5c\u8fdb\u7a0b\u7684\u6d4b\u91cf\u6570\u636e\u3002\u56de\u8c03\u5b58\u5728\u4e0d\u4ee3\u8868\u8be5\u8282\u70b9\u666e\u904d\u652f\u6301\u5171\u4eab\u5e76\u884c\u626b\u63cf\u6216\u5171\u4eab\u72b6\u6001\u3002", "\u6b64\u6784\u5efa\u7684\u56de\u8c03\uff1anone extracted from this node implementation."]}, {"title": "\u540c\u7248\u672c\u624b\u518c\u8bf4\u660e", "paragraphs": ["\u89c4\u5212\u5668\u5728\u8fde\u63a5\u5185\u4fa7\u5173\u7cfb\u4e4b\u4e0a\u52a0\u5165 Materialize \u8282\u70b9\uff0c\u5c06\u5176\u7269\u5316\u3002\u56e0\u6b64\uff0c\u5c3d\u7ba1\u5d4c\u5957\u5faa\u73af\u8fde\u63a5\u9700\u8981\u4e3a\u5916\u4fa7\u7684\u6bcf\u4e00\u884c\u8bfb\u53d6\u4e00\u6b21\u5185\u4fa7\u6570\u636e\u3001\u5171\u5341\u6b21\uff0ct2 \u7684\u7d22\u5f15\u626b\u63cf\u4e5f\u53ea\u6267\u884c\u4e00\u6b21\u3002Materialize \u5728\u8bfb\u53d6\u65f6\u5c06\u6570\u636e\u4fdd\u5b58\u5728\u5185\u5b58\u4e2d\uff0c\u540e\u7eed\u5404\u8f6e\u76f4\u63a5\u4ece\u5185\u5b58\u8fd4\u56de\u6570\u636e\u3002"]}, {"title": "\u672c\u7248\u624b\u518c\u4e2d\u7684\u793a\u4f8b", "blocks": [{"code": "EXPLAIN SELECT *\nFROM tenk1 t1, tenk2 t2\nWHERE t1.unique1 < 10 AND t2.unique2 < 10 AND t1.hundred < t2.hundred;\n\n                                         QUERY PLAN\n---------------------------------------------------------------------------------------------\n Nested Loop  (cost=4.65..49.46 rows=33 width=488)\n   Join Filter: (t1.hundred < t2.hundred)\n   ->  Bitmap Heap Scan on tenk1 t1  (cost=4.36..39.47 rows=10 width=244)\n         Recheck Cond: (unique1 < 10)\n         ->  Bitmap Index Scan on tenk1_unique1  (cost=0.00..4.36 rows=10 width=0)\n               Index Cond: (unique1 < 10)\n   ->  Materialize  (cost=0.29..8.51 rows=10 width=244)\n         ->  Index Scan using tenk2_unique2 on tenk2 t2  (cost=0.29..8.46 rows=10 width=244)\n               Index Cond: (unique2 < 10)", "source": {"url": "/docs/14/using-explain.html#USING-EXPLAIN-BASICS", "path": "using-explain.html", "label": "PostgreSQL 14.24 \u00b7 using-explain", "sha256": "7f5ab59cb21a035ada45ea3426c5d1cca3f781273483677f73fdd76753555206"}, "paragraphs": ["\u793a\u4f8b\u6458\u81ea PostgreSQL 14.24 \u624b\u518c\uff1b\u672c\u767e\u79d1\u672a\u5b9e\u9645\u6267\u884c\u6b64\u793a\u4f8b\u3002", "\u672c\u4f8b\u4e2d\uff0c\u8fde\u63a5\u7684\u8f93\u51fa\u884c\u6570\u7b49\u4e8e\u4e24\u6b21\u626b\u63cf\u884c\u6570\u7684\u4e58\u79ef\uff0c\u4f46\u5e76\u975e\u603b\u662f\u5982\u6b64\uff1a\u53ef\u80fd\u5b58\u5728\u540c\u65f6\u5f15\u7528\u4e24\u4e2a\u8868\u7684\u989d\u5916 WHERE \u5b50\u53e5\uff0c\u53ea\u80fd\u5728\u8fde\u63a5\u65f6\u5e94\u7528\uff0c\u65e0\u6cd5\u5e94\u7528\u5230\u4efb\u4f55\u5355\u4fa7\u8f93\u5165\u626b\u63cf\u3002\u793a\u4f8b\u5982\u4e0b\uff1a"]}]}, {"title": "\u6267\u884c\u5668\u5b9e\u73b0\u8bf4\u660e", "paragraphs": ["\u53ea\u8981\u5f53\u524d\u4f4d\u4e8e tuplestore \u5df2\u6536\u96c6\u6570\u636e\u7684\u672b\u5c3e\uff0c\u6bcf\u6b21\u8c03\u7528\u5c31\u4ece\u5b50\u8ba1\u5212\u83b7\u53d6\u4e00\u884c\u65b0\u6570\u636e\uff0c\u5728\u8fd4\u56de\u4e4b\u524d\u5c06\u5176\u5b58\u5165 tuplestore\u3002\u53ea\u6709\u8bf7\u6c42\u53cd\u5411\u626b\u63cf\u3001\u91cd\u626b\u6216\u6807\u8bb0\uff0f\u6062\u590d\u65f6\uff0c\u624d\u4ece tuplestore \u8bfb\u53d6\u3002", "\u9996\u6b21\u6267\u884c\u4e14\u9700\u8981\u5143\u7ec4\u5b58\u50a8\u65f6\uff0c\u521d\u59cb\u5316\u5b83\u3002", "\u5206\u914d\u7b2c\u4e8c\u4e2a\u8bfb\u53d6\u6307\u9488\u4f5c\u4e3a\u6807\u8bb0\u3002\u5df2\u77e5\u5176\u7d22\u5f15\u5fc5\u4e3a 1\uff0c\u56e0\u6b64\u65e0\u9700\u53e6\u884c\u4fdd\u5b58\u3002", "\u5982\u679c\u5c1a\u672a\u5230\u8fbe tuplestore \u672b\u5c3e\uff0c\u6216\u6b63\u5728\u53cd\u5411\u626b\u63cf\uff0c\u5219\u5c1d\u8bd5\u4ece tuplestore \u83b7\u53d6\u5143\u7ec4\u3002", "\u5728\u5143\u7ec4\u5b58\u50a8\u672b\u5c3e\u53cd\u8f6c\u626b\u63cf\u65b9\u5411\u65f6\uff0c\u7b2c\u4e00\u6b21 gettupleslot \u4f1a\u53d6\u5f97\u6700\u540e\u6dfb\u52a0\u7684\u5143\u7ec4\uff1b\u4f46\u82e5\u53ef\u80fd\uff0c\u6211\u4eec\u5e0c\u671b\u8fd4\u56de\u5b83\u4e4b\u524d\u7684\u90a3\u4e2a\uff0c\u56e0\u6b64\u989d\u5916\u8bfb\u53d6\u4e00\u6b21\u3002"]}, {"code": "case T_Material:\n\t\t\tpname = sname = \"Materialize\";\n\t\t\tbreak;", "title": "\u6838\u5fc3\u6e90\u7801\u4e2d\u7684 EXPLAIN \u6807\u8bc6"}], "strategies": [], "description": ["\u5b58\u50a8\u5b50\u8ba1\u5212\u8f93\u51fa\uff0c\u4ee5\u4fbf\u518d\u6b21\u8bfb\u53d6\u8fd9\u4e9b\u884c\u3002"], "localization": {"status": "complete", "sources": [], "language": "zh", "original_text": {"/versions/14/description/0": "Stores its child output so the rows can be read again.", "/versions/14/facts/0/label": "Core node tag", "/versions/14/facts/1/label": "Structured EXPLAIN Node Type", "/versions/14/facts/2/label": "Inputs", "/versions/14/facts/2/value": "One child plan", "/versions/14/facts/3/label": "Output", "/versions/14/facts/3/value": "Materialized tuples", "/versions/14/facts/4/label": "Executor initializer", "/versions/14/facts/5/label": "Memory mechanism", "/versions/14/tables/0/title": "EXPLAIN labels in this source build", "/versions/14/related/1/label": "Using EXPLAIN", "/versions/14/related/2/label": "Parallel plans", "/versions/14/sections/0/title": "EXPLAIN names and attributes", "/versions/14/sections/1/title": "Memory and temporary storage", "/versions/14/sections/2/title": "Parallel execution and instrumentation", "/versions/14/sections/3/title": "Same-version manual discussion", "/versions/14/sections/4/title": "Examples from this manual build", "/versions/14/sections/5/title": "Executor implementation notes", "/versions/14/sections/6/title": "EXPLAIN identity in core source", "/versions/14/memory/description": "This node creates a tuplestore with work_mem. The tuplestore can move stored tuples to temporary files; this does not make work_mem a cap on every allocation made by the node.", "/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: Materialize.", "/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 node creates a tuplestore with work_mem. The tuplestore can move stored tuples to temporary files; this does not make work_mem a cap on every allocation made by the node.", "/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": "Notice that here the planner has chosen to \u201c materialize \u201d the inner relation of the join, by putting a Materialize plan node atop it. This means that the t2 index scan will be done just once, even though the nested-loop join node needs to read that data ten times, once for each row from the outer relation. The Materialize node saves the data in memory as it's read, and then returns the data from memory on each subsequent pass.", "/versions/14/sections/5/paragraphs/0": "As long as we are at the end of the data collected in the tuplestore, we collect one new row from the subplan on each call, and stash it aside in the tuplestore before returning it. The tuplestore is only read if we are asked to scan backwards, rescan, or mark/restore.", "/versions/14/sections/5/paragraphs/1": "If first time through, and we need a tuplestore, initialize it.", "/versions/14/sections/5/paragraphs/2": "Allocate a second read pointer to serve as the mark. We know it must have index 1, so needn't store that.", "/versions/14/sections/5/paragraphs/3": "If we are not at the end of the tuplestore, or are going backwards, try to fetch a tuple from tuplestore.", "/versions/14/sections/5/paragraphs/4": "When reversing direction at tuplestore EOF, the first gettupleslot call will fetch the last-added tuple; but we want to return the one before that, if possible. So do an extra fetch.", "/versions/14/tables/0/columns/0/label": "Text-format label", "/versions/14/tables/0/columns/1/label": "Structured node identity", "/versions/14/sections/4/blocks/0/paragraphs/0": "Example copied from the PostgreSQL 14.24 manual; it was not executed for this collection.", "/versions/14/sections/4/blocks/0/paragraphs/1": "In this example the join's output row count is the same as the product of the two scans' row counts, but that's not true in all cases because there can be additional WHERE clauses that mention both tables and so can only be applied at the join point, not to either input scan. Here's an example:"}, "fallback_fields": [], "source_language": "en", "original_snapshot_sha256": "54ec1d48cbe1217b5c27e0387caec87b55d15bb03405217fbe8b26f9b1d5e5c7"}, "evidence_kind": "source and documentation", "explain_names": ["Materialize"], "partial_modes": [], "comparison_data": {"node_tag": "T_Material", "strategies": [], "text_names": ["Materialize"], "initializer": "ExecInitMaterial", "partial_modes": [], "memory_mechanism": "tuplestore", "parallel_callbacks": []}, "comparison_hash": "c1d37bf334409fe6ded8ce560fe45fd495ff89ceda2808b6f5ef18daca520393", "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/nodeMaterial.c"}, "parallel_callbacks": []}, "15": {"facts": [{"label": "\u6838\u5fc3\u8282\u70b9\u6807\u7b7e", "value": "T_Material"}, {"label": "\u7ed3\u6784\u5316 EXPLAIN \u8282\u70b9\u7c7b\u578b", "value": "Materialize"}, {"label": "\u8f93\u5165", "value": "\u4e00\u4e2a\u5b50\u8ba1\u5212"}, {"label": "\u8f93\u51fa", "value": "\u5df2\u7269\u5316\u7684\u5143\u7ec4"}, {"label": "\u6267\u884c\u5668\u521d\u59cb\u5316\u51fd\u6570", "value": "ExecInitMaterial"}, {"label": "\u5185\u5b58\u673a\u5236", "value": "tuplestore"}], "memory": {"evidence": [{"url": "https://ftp.postgresql.org/pub/source/v15.19/postgresql-15.19.tar.bz2", "path": "src/backend/executor/nodeMaterial.c", "label": "src/backend/executor/nodeMaterial.c", "sha256": "d4c6f075095bba6a1b82766d9d8e43995af4641a5b3a969616e1e543e84a62da", "archive_sha256": "e1a64a87a46b825b88c082e4518161a47aab53c45694964f8ba1df28f7859f89"}, {"url": "https://ftp.postgresql.org/pub/source/v15.19/postgresql-15.19.tar.bz2", "path": "src/backend/utils/sort/tuplestore.c", "label": "src/backend/utils/sort/tuplestore.c", "sha256": "37be0ffb18c97558ea6fe6e1e0072564026b231edb9edf0a29faf27f13827aab", "archive_sha256": 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"/wiki/guc/enable_material/?v=15", "label": "enable_material"}, {"url": "/wiki/guc/work_mem/?v=15", "label": "work_mem"}], "release": {"ref": "PostgreSQL 15.19 source archive", "label": "15.19", "major": "15", "channel": "stable", "revision": "e1a64a87a46b825b88c082e4518161a47aab53c45694964f8ba1df28f7859f89", "source_url": "https://ftp.postgresql.org/pub/source/v15.19/postgresql-15.19.tar.bz2", "source_snapshot_utc": ""}, "sources": [{"url": "https://ftp.postgresql.org/pub/source/v15.19/postgresql-15.19.tar.bz2", "line": 1309, "path": "src/backend/commands/explain.c", "label": "src/backend/commands/explain.c:1309", "sha256": "bb3b442d0f1b098aa8707335250102f027a596cd94117308bd16d1d36b258f5c", "archive_sha256": "e1a64a87a46b825b88c082e4518161a47aab53c45694964f8ba1df28f7859f89"}, {"url": "https://ftp.postgresql.org/pub/source/v15.19/postgresql-15.19.tar.bz2", "line": 315, "path": "src/backend/executor/execProcnode.c", "label": "src/backend/executor/execProcnode.c:315", "sha256": 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"sha256": "37be0ffb18c97558ea6fe6e1e0072564026b231edb9edf0a29faf27f13827aab", "archive_sha256": "e1a64a87a46b825b88c082e4518161a47aab53c45694964f8ba1df28f7859f89"}, {"url": "https://pg.center/docs/15/using-explain.html#USING-EXPLAIN-BASICS", "path": "using-explain.html", "label": "PostgreSQL 15.19 \u00b7 using-explain", "sha256": "d1f509457c647da453d2575c772d91022a0f115dd84f9a3b20f5ff25a243648f", "language": "en", "original_url": "/docs/15/using-explain.html#USING-EXPLAIN-BASICS"}], "node_tag": "T_Material", "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\uff1aMaterialize.", "\u5e76\u884c\u611f\u77e5\u4e0e\u5e76\u884c\u5b89\u5168\u662f\u4e0d\u540c\u7684\u8ba1\u5212\u5c5e\u6027\u3002\u5728\u5e76\u884c\u5de5\u4f5c\u8fdb\u7a0b\u5185\u8fd0\u884c\u7684\u8282\u70b9\u4e0d\u4e00\u5b9a\u662f\u5e76\u884c\u611f\u77e5\u8282\u70b9\u3002"]}, {"title": "\u5185\u5b58\u4e0e\u4e34\u65f6\u5b58\u50a8", "paragraphs": ["\u6b64\u8282\u70b9\u4f7f\u7528 work_mem \u521b\u5efa tuplestore\u3002tuplestore \u53ef\u4ee5\u5c06\u5b58\u50a8\u7684\u5143\u7ec4\u79fb\u5230\u4e34\u65f6\u6587\u4ef6\uff0c\u4f46\u8fd9\u4e0d\u610f\u5473\u7740 work_mem \u9650\u5236\u4e86\u8282\u70b9\u7684\u5168\u90e8\u5185\u5b58\u5206\u914d\u3002"]}, {"title": "\u5e76\u884c\u6267\u884c\u4e0e\u8fd0\u884c\u4fe1\u606f\u91c7\u96c6", "paragraphs": ["\u4ee5\u4e0b\u6e90\u7801\u56de\u8c03\u53ef\u4ee5\u534f\u8c03\u6267\u884c\u6216\u6536\u96c6\u5de5\u4f5c\u8fdb\u7a0b\u7684\u6d4b\u91cf\u6570\u636e\u3002\u56de\u8c03\u5b58\u5728\u4e0d\u4ee3\u8868\u8be5\u8282\u70b9\u666e\u904d\u652f\u6301\u5171\u4eab\u5e76\u884c\u626b\u63cf\u6216\u5171\u4eab\u72b6\u6001\u3002", "\u6b64\u6784\u5efa\u7684\u56de\u8c03\uff1anone extracted from this node implementation."]}, {"title": "\u540c\u7248\u672c\u624b\u518c\u8bf4\u660e", "paragraphs": ["\u89c4\u5212\u5668\u5728\u8fde\u63a5\u5185\u4fa7\u5173\u7cfb\u4e4b\u4e0a\u52a0\u5165 Materialize \u8282\u70b9\uff0c\u5c06\u5176\u7269\u5316\u3002\u56e0\u6b64\uff0c\u5c3d\u7ba1\u5d4c\u5957\u5faa\u73af\u8fde\u63a5\u9700\u8981\u4e3a\u5916\u4fa7\u7684\u6bcf\u4e00\u884c\u8bfb\u53d6\u4e00\u6b21\u5185\u4fa7\u6570\u636e\u3001\u5171\u5341\u6b21\uff0ct2 \u7684\u7d22\u5f15\u626b\u63cf\u4e5f\u53ea\u6267\u884c\u4e00\u6b21\u3002Materialize \u5728\u8bfb\u53d6\u65f6\u5c06\u6570\u636e\u4fdd\u5b58\u5728\u5185\u5b58\u4e2d\uff0c\u540e\u7eed\u5404\u8f6e\u76f4\u63a5\u4ece\u5185\u5b58\u8fd4\u56de\u6570\u636e\u3002"]}, {"title": "\u672c\u7248\u624b\u518c\u4e2d\u7684\u793a\u4f8b", "blocks": [{"code": "EXPLAIN SELECT *\nFROM tenk1 t1, tenk2 t2\nWHERE t1.unique1 < 10 AND t2.unique2 < 10 AND t1.hundred < t2.hundred;\n\n                                         QUERY PLAN\n---------------------------------------------------------------------------------------------\n Nested Loop  (cost=4.65..49.46 rows=33 width=488)\n   Join Filter: (t1.hundred < t2.hundred)\n   ->  Bitmap Heap Scan on tenk1 t1  (cost=4.36..39.47 rows=10 width=244)\n         Recheck Cond: (unique1 < 10)\n         ->  Bitmap Index Scan on tenk1_unique1  (cost=0.00..4.36 rows=10 width=0)\n               Index Cond: (unique1 < 10)\n   ->  Materialize  (cost=0.29..8.51 rows=10 width=244)\n         ->  Index Scan using tenk2_unique2 on tenk2 t2  (cost=0.29..8.46 rows=10 width=244)\n               Index Cond: (unique2 < 10)", "source": {"url": "/docs/15/using-explain.html#USING-EXPLAIN-BASICS", "path": "using-explain.html", "label": "PostgreSQL 15.19 \u00b7 using-explain", "sha256": "d1f509457c647da453d2575c772d91022a0f115dd84f9a3b20f5ff25a243648f"}, "paragraphs": ["\u793a\u4f8b\u6458\u81ea PostgreSQL 15.19 \u624b\u518c\uff1b\u672c\u767e\u79d1\u672a\u5b9e\u9645\u6267\u884c\u6b64\u793a\u4f8b\u3002", "\u672c\u4f8b\u4e2d\uff0c\u8fde\u63a5\u7684\u8f93\u51fa\u884c\u6570\u7b49\u4e8e\u4e24\u6b21\u626b\u63cf\u884c\u6570\u7684\u4e58\u79ef\uff0c\u4f46\u5e76\u975e\u603b\u662f\u5982\u6b64\uff1a\u53ef\u80fd\u5b58\u5728\u540c\u65f6\u5f15\u7528\u4e24\u4e2a\u8868\u7684\u989d\u5916 WHERE \u5b50\u53e5\uff0c\u53ea\u80fd\u5728\u8fde\u63a5\u65f6\u5e94\u7528\uff0c\u65e0\u6cd5\u5e94\u7528\u5230\u4efb\u4f55\u5355\u4fa7\u8f93\u5165\u626b\u63cf\u3002\u793a\u4f8b\u5982\u4e0b\uff1a"]}]}, {"title": "\u6267\u884c\u5668\u5b9e\u73b0\u8bf4\u660e", "paragraphs": ["\u53ea\u8981\u5f53\u524d\u4f4d\u4e8e tuplestore \u5df2\u6536\u96c6\u6570\u636e\u7684\u672b\u5c3e\uff0c\u6bcf\u6b21\u8c03\u7528\u5c31\u4ece\u5b50\u8ba1\u5212\u83b7\u53d6\u4e00\u884c\u65b0\u6570\u636e\uff0c\u5728\u8fd4\u56de\u4e4b\u524d\u5c06\u5176\u5b58\u5165 tuplestore\u3002\u53ea\u6709\u8bf7\u6c42\u53cd\u5411\u626b\u63cf\u3001\u91cd\u626b\u6216\u6807\u8bb0\uff0f\u6062\u590d\u65f6\uff0c\u624d\u4ece tuplestore \u8bfb\u53d6\u3002", "\u9996\u6b21\u6267\u884c\u4e14\u9700\u8981\u5143\u7ec4\u5b58\u50a8\u65f6\uff0c\u521d\u59cb\u5316\u5b83\u3002", "\u5206\u914d\u7b2c\u4e8c\u4e2a\u8bfb\u53d6\u6307\u9488\u4f5c\u4e3a\u6807\u8bb0\u3002\u5df2\u77e5\u5176\u7d22\u5f15\u5fc5\u4e3a 1\uff0c\u56e0\u6b64\u65e0\u9700\u53e6\u884c\u4fdd\u5b58\u3002", "\u5982\u679c\u5c1a\u672a\u5230\u8fbe tuplestore \u672b\u5c3e\uff0c\u6216\u6b63\u5728\u53cd\u5411\u626b\u63cf\uff0c\u5219\u5c1d\u8bd5\u4ece tuplestore \u83b7\u53d6\u5143\u7ec4\u3002", "\u5728\u5143\u7ec4\u5b58\u50a8\u672b\u5c3e\u53cd\u8f6c\u626b\u63cf\u65b9\u5411\u65f6\uff0c\u7b2c\u4e00\u6b21 gettupleslot \u4f1a\u53d6\u5f97\u6700\u540e\u6dfb\u52a0\u7684\u5143\u7ec4\uff1b\u4f46\u82e5\u53ef\u80fd\uff0c\u6211\u4eec\u5e0c\u671b\u8fd4\u56de\u5b83\u4e4b\u524d\u7684\u90a3\u4e2a\uff0c\u56e0\u6b64\u989d\u5916\u8bfb\u53d6\u4e00\u6b21\u3002"]}, {"code": "case T_Material:\n\t\t\tpname = sname = \"Materialize\";\n\t\t\tbreak;", "title": "\u6838\u5fc3\u6e90\u7801\u4e2d\u7684 EXPLAIN \u6807\u8bc6"}], "strategies": [], "description": ["\u5b58\u50a8\u5b50\u8ba1\u5212\u8f93\u51fa\uff0c\u4ee5\u4fbf\u518d\u6b21\u8bfb\u53d6\u8fd9\u4e9b\u884c\u3002"], "localization": {"status": "complete", "sources": [], "language": "zh", "original_text": {"/versions/15/description/0": "Stores its child output so the rows can be read again.", "/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": "One child plan", "/versions/15/facts/3/label": "Output", "/versions/15/facts/3/value": "Materialized 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": "Same-version manual discussion", "/versions/15/sections/4/title": "Examples from this manual build", "/versions/15/sections/5/title": "Executor implementation notes", "/versions/15/sections/6/title": "EXPLAIN identity in core source", "/versions/15/memory/description": "This node creates a tuplestore with work_mem. The tuplestore can move stored tuples to temporary files; this does not make work_mem a cap on every allocation made by the node.", "/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: Materialize.", "/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 node creates a tuplestore with work_mem. The tuplestore can move stored tuples to temporary files; this does not make work_mem a cap on every allocation made by the node.", "/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": "Notice that here the planner has chosen to \u201c materialize \u201d the inner relation of the join, by putting a Materialize plan node atop it. This means that the t2 index scan will be done just once, even though the nested-loop join node needs to read that data ten times, once for each row from the outer relation. The Materialize node saves the data in memory as it's read, and then returns the data from memory on each subsequent pass.", "/versions/15/sections/5/paragraphs/0": "As long as we are at the end of the data collected in the tuplestore, we collect one new row from the subplan on each call, and stash it aside in the tuplestore before returning it. The tuplestore is only read if we are asked to scan backwards, rescan, or mark/restore.", "/versions/15/sections/5/paragraphs/1": "If first time through, and we need a tuplestore, initialize it.", "/versions/15/sections/5/paragraphs/2": "Allocate a second read pointer to serve as the mark. We know it must have index 1, so needn't store that.", "/versions/15/sections/5/paragraphs/3": "If we are not at the end of the tuplestore, or are going backwards, try to fetch a tuple from tuplestore.", "/versions/15/sections/5/paragraphs/4": "When reversing direction at tuplestore EOF, the first gettupleslot call will fetch the last-added tuple; but we want to return the one before that, if possible. So do an extra fetch.", "/versions/15/tables/0/columns/0/label": "Text-format label", "/versions/15/tables/0/columns/1/label": "Structured node identity", "/versions/15/sections/4/blocks/0/paragraphs/0": "Example copied from the PostgreSQL 15.19 manual; it was not executed for this collection.", "/versions/15/sections/4/blocks/0/paragraphs/1": "In this example the join's output row count is the same as the product of the two scans' row counts, but that's not true in all cases because there can be additional WHERE clauses that mention both tables and so can only be applied at the join point, not to either input scan. Here's an example:"}, "fallback_fields": [], "source_language": "en", "original_snapshot_sha256": "ddbc137aab060afdb492d8dc41a94c3b759ef536e2a0f43146099032857679a6"}, "evidence_kind": "source and documentation", "explain_names": ["Materialize"], "partial_modes": [], "comparison_data": {"node_tag": "T_Material", "strategies": [], "text_names": ["Materialize"], "initializer": "ExecInitMaterial", "partial_modes": [], "memory_mechanism": "tuplestore", "parallel_callbacks": []}, "comparison_hash": "c1d37bf334409fe6ded8ce560fe45fd495ff89ceda2808b6f5ef18daca520393", "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/nodeMaterial.c"}, "parallel_callbacks": []}, "16": {"facts": [{"label": "\u6838\u5fc3\u8282\u70b9\u6807\u7b7e", "value": "T_Material"}, {"label": "\u7ed3\u6784\u5316 EXPLAIN \u8282\u70b9\u7c7b\u578b", "value": "Materialize"}, {"label": "\u8f93\u5165", "value": "\u4e00\u4e2a\u5b50\u8ba1\u5212"}, {"label": "\u8f93\u51fa", "value": "\u5df2\u7269\u5316\u7684\u5143\u7ec4"}, {"label": "\u6267\u884c\u5668\u521d\u59cb\u5316\u51fd\u6570", "value": "ExecInitMaterial"}, {"label": "\u5185\u5b58\u673a\u5236", "value": "tuplestore"}], "memory": {"evidence": [{"url": "https://ftp.postgresql.org/pub/source/v16.15/postgresql-16.15.tar.bz2", "path": "src/backend/executor/nodeMaterial.c", "label": "src/backend/executor/nodeMaterial.c", "sha256": "0560d2ada70d5e580b4b2a047a88f13a47397f470980ce415e9c0f05439b4553", "archive_sha256": "c1575341fa7bd40f5274ea465b34390f4dc64cdd0770af327005caaeb9f6b7ed"}, {"url": "https://ftp.postgresql.org/pub/source/v16.15/postgresql-16.15.tar.bz2", "path": "src/backend/utils/sort/tuplestore.c", "label": "src/backend/utils/sort/tuplestore.c", "sha256": "a990669858f1847ac83b5e1e65cf5515fe05ea0ad45ff64dd9347ba4f2110e62", "archive_sha256": 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"/wiki/guc/enable_material/?v=16", "label": "enable_material"}, {"url": "/wiki/guc/work_mem/?v=16", "label": "work_mem"}], "release": {"ref": "PostgreSQL 16.15 source archive", "label": "16.15", "major": "16", "channel": "stable", "revision": "c1575341fa7bd40f5274ea465b34390f4dc64cdd0770af327005caaeb9f6b7ed", "source_url": "https://ftp.postgresql.org/pub/source/v16.15/postgresql-16.15.tar.bz2", "source_snapshot_utc": ""}, "sources": [{"url": "https://ftp.postgresql.org/pub/source/v16.15/postgresql-16.15.tar.bz2", "line": 1342, "path": "src/backend/commands/explain.c", "label": "src/backend/commands/explain.c:1342", "sha256": "8e017f0116dbea471339b40c37a667cc9f95039e7e0329c783e5e8ce194de7e1", "archive_sha256": "c1575341fa7bd40f5274ea465b34390f4dc64cdd0770af327005caaeb9f6b7ed"}, {"url": "https://ftp.postgresql.org/pub/source/v16.15/postgresql-16.15.tar.bz2", "line": 315, "path": "src/backend/executor/execProcnode.c", "label": "src/backend/executor/execProcnode.c:315", "sha256": 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"sha256": "a990669858f1847ac83b5e1e65cf5515fe05ea0ad45ff64dd9347ba4f2110e62", "archive_sha256": "c1575341fa7bd40f5274ea465b34390f4dc64cdd0770af327005caaeb9f6b7ed"}, {"url": "https://pg.center/docs/16/using-explain.html#USING-EXPLAIN-BASICS", "path": "using-explain.html", "label": "PostgreSQL 16.15 \u00b7 using-explain", "sha256": "bd8b86e5281cf0e52ad6e0e4bb8b6ff6510dac61982b44f0c1dd07d54012db3c", "language": "en", "original_url": "/docs/16/using-explain.html#USING-EXPLAIN-BASICS"}], "node_tag": "T_Material", "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\uff1aMaterialize.", "\u5e76\u884c\u611f\u77e5\u4e0e\u5e76\u884c\u5b89\u5168\u662f\u4e0d\u540c\u7684\u8ba1\u5212\u5c5e\u6027\u3002\u5728\u5e76\u884c\u5de5\u4f5c\u8fdb\u7a0b\u5185\u8fd0\u884c\u7684\u8282\u70b9\u4e0d\u4e00\u5b9a\u662f\u5e76\u884c\u611f\u77e5\u8282\u70b9\u3002"]}, {"title": "\u5185\u5b58\u4e0e\u4e34\u65f6\u5b58\u50a8", "paragraphs": ["\u6b64\u8282\u70b9\u4f7f\u7528 work_mem \u521b\u5efa tuplestore\u3002tuplestore \u53ef\u4ee5\u5c06\u5b58\u50a8\u7684\u5143\u7ec4\u79fb\u5230\u4e34\u65f6\u6587\u4ef6\uff0c\u4f46\u8fd9\u4e0d\u610f\u5473\u7740 work_mem \u9650\u5236\u4e86\u8282\u70b9\u7684\u5168\u90e8\u5185\u5b58\u5206\u914d\u3002"]}, {"title": "\u5e76\u884c\u6267\u884c\u4e0e\u8fd0\u884c\u4fe1\u606f\u91c7\u96c6", "paragraphs": ["\u4ee5\u4e0b\u6e90\u7801\u56de\u8c03\u53ef\u4ee5\u534f\u8c03\u6267\u884c\u6216\u6536\u96c6\u5de5\u4f5c\u8fdb\u7a0b\u7684\u6d4b\u91cf\u6570\u636e\u3002\u56de\u8c03\u5b58\u5728\u4e0d\u4ee3\u8868\u8be5\u8282\u70b9\u666e\u904d\u652f\u6301\u5171\u4eab\u5e76\u884c\u626b\u63cf\u6216\u5171\u4eab\u72b6\u6001\u3002", "\u6b64\u6784\u5efa\u7684\u56de\u8c03\uff1anone extracted from this node implementation."]}, {"title": "\u540c\u7248\u672c\u624b\u518c\u8bf4\u660e", "paragraphs": ["\u89c4\u5212\u5668\u5728\u8fde\u63a5\u5185\u4fa7\u5173\u7cfb\u4e4b\u4e0a\u52a0\u5165 Materialize \u8282\u70b9\uff0c\u5c06\u5176\u7269\u5316\u3002\u56e0\u6b64\uff0c\u5c3d\u7ba1\u5d4c\u5957\u5faa\u73af\u8fde\u63a5\u9700\u8981\u4e3a\u5916\u4fa7\u7684\u6bcf\u4e00\u884c\u8bfb\u53d6\u4e00\u6b21\u5185\u4fa7\u6570\u636e\u3001\u5171\u5341\u6b21\uff0ct2 \u7684\u7d22\u5f15\u626b\u63cf\u4e5f\u53ea\u6267\u884c\u4e00\u6b21\u3002Materialize \u5728\u8bfb\u53d6\u65f6\u5c06\u6570\u636e\u4fdd\u5b58\u5728\u5185\u5b58\u4e2d\uff0c\u540e\u7eed\u5404\u8f6e\u76f4\u63a5\u4ece\u5185\u5b58\u8fd4\u56de\u6570\u636e\u3002"]}, {"title": "\u672c\u7248\u624b\u518c\u4e2d\u7684\u793a\u4f8b", "blocks": [{"code": "EXPLAIN SELECT *\nFROM tenk1 t1, tenk2 t2\nWHERE t1.unique1 < 10 AND t2.unique2 < 10 AND t1.hundred < t2.hundred;\n\n                                         QUERY PLAN\n---------------------------------------------------------------------------------------------\n Nested Loop  (cost=4.65..49.46 rows=33 width=488)\n   Join Filter: (t1.hundred < t2.hundred)\n   ->  Bitmap Heap Scan on tenk1 t1  (cost=4.36..39.47 rows=10 width=244)\n         Recheck Cond: (unique1 < 10)\n         ->  Bitmap Index Scan on tenk1_unique1  (cost=0.00..4.36 rows=10 width=0)\n               Index Cond: (unique1 < 10)\n   ->  Materialize  (cost=0.29..8.51 rows=10 width=244)\n         ->  Index Scan using tenk2_unique2 on tenk2 t2  (cost=0.29..8.46 rows=10 width=244)\n               Index Cond: (unique2 < 10)", "source": {"url": "/docs/16/using-explain.html#USING-EXPLAIN-BASICS", "path": "using-explain.html", "label": "PostgreSQL 16.15 \u00b7 using-explain", "sha256": "bd8b86e5281cf0e52ad6e0e4bb8b6ff6510dac61982b44f0c1dd07d54012db3c"}, "paragraphs": ["\u793a\u4f8b\u6458\u81ea PostgreSQL 16.15 \u624b\u518c\uff1b\u672c\u767e\u79d1\u672a\u5b9e\u9645\u6267\u884c\u6b64\u793a\u4f8b\u3002", "\u672c\u4f8b\u4e2d\uff0c\u8fde\u63a5\u7684\u8f93\u51fa\u884c\u6570\u7b49\u4e8e\u4e24\u6b21\u626b\u63cf\u884c\u6570\u7684\u4e58\u79ef\uff0c\u4f46\u5e76\u975e\u603b\u662f\u5982\u6b64\uff1a\u53ef\u80fd\u5b58\u5728\u540c\u65f6\u5f15\u7528\u4e24\u4e2a\u8868\u7684\u989d\u5916 WHERE \u5b50\u53e5\uff0c\u53ea\u80fd\u5728\u8fde\u63a5\u65f6\u5e94\u7528\uff0c\u65e0\u6cd5\u5e94\u7528\u5230\u4efb\u4f55\u5355\u4fa7\u8f93\u5165\u626b\u63cf\u3002\u793a\u4f8b\u5982\u4e0b\uff1a"]}]}, {"title": "\u6267\u884c\u5668\u5b9e\u73b0\u8bf4\u660e", "paragraphs": ["\u53ea\u8981\u5f53\u524d\u4f4d\u4e8e tuplestore \u5df2\u6536\u96c6\u6570\u636e\u7684\u672b\u5c3e\uff0c\u6bcf\u6b21\u8c03\u7528\u5c31\u4ece\u5b50\u8ba1\u5212\u83b7\u53d6\u4e00\u884c\u65b0\u6570\u636e\uff0c\u5728\u8fd4\u56de\u4e4b\u524d\u5c06\u5176\u5b58\u5165 tuplestore\u3002\u53ea\u6709\u8bf7\u6c42\u53cd\u5411\u626b\u63cf\u3001\u91cd\u626b\u6216\u6807\u8bb0\uff0f\u6062\u590d\u65f6\uff0c\u624d\u4ece tuplestore \u8bfb\u53d6\u3002", "\u9996\u6b21\u6267\u884c\u4e14\u9700\u8981\u5143\u7ec4\u5b58\u50a8\u65f6\uff0c\u521d\u59cb\u5316\u5b83\u3002", "\u5206\u914d\u7b2c\u4e8c\u4e2a\u8bfb\u53d6\u6307\u9488\u4f5c\u4e3a\u6807\u8bb0\u3002\u5df2\u77e5\u5176\u7d22\u5f15\u5fc5\u4e3a 1\uff0c\u56e0\u6b64\u65e0\u9700\u53e6\u884c\u4fdd\u5b58\u3002", "\u5982\u679c\u5c1a\u672a\u5230\u8fbe tuplestore \u672b\u5c3e\uff0c\u6216\u6b63\u5728\u53cd\u5411\u626b\u63cf\uff0c\u5219\u5c1d\u8bd5\u4ece tuplestore \u83b7\u53d6\u5143\u7ec4\u3002", "\u5728\u5143\u7ec4\u5b58\u50a8\u672b\u5c3e\u53cd\u8f6c\u626b\u63cf\u65b9\u5411\u65f6\uff0c\u7b2c\u4e00\u6b21 gettupleslot \u4f1a\u53d6\u5f97\u6700\u540e\u6dfb\u52a0\u7684\u5143\u7ec4\uff1b\u4f46\u82e5\u53ef\u80fd\uff0c\u6211\u4eec\u5e0c\u671b\u8fd4\u56de\u5b83\u4e4b\u524d\u7684\u90a3\u4e2a\uff0c\u56e0\u6b64\u989d\u5916\u8bfb\u53d6\u4e00\u6b21\u3002"]}, {"code": "case T_Material:\n\t\t\tpname = sname = \"Materialize\";\n\t\t\tbreak;", "title": "\u6838\u5fc3\u6e90\u7801\u4e2d\u7684 EXPLAIN \u6807\u8bc6"}], "strategies": [], "description": ["\u5b58\u50a8\u5b50\u8ba1\u5212\u8f93\u51fa\uff0c\u4ee5\u4fbf\u518d\u6b21\u8bfb\u53d6\u8fd9\u4e9b\u884c\u3002"], "localization": {"status": "complete", "sources": [], "language": "zh", "original_text": {"/versions/16/description/0": "Stores its child output so the rows can be read again.", "/versions/16/facts/0/label": "Core node tag", "/versions/16/facts/1/label": "Structured EXPLAIN Node Type", "/versions/16/facts/2/label": "Inputs", "/versions/16/facts/2/value": "One child plan", "/versions/16/facts/3/label": "Output", "/versions/16/facts/3/value": "Materialized tuples", "/versions/16/facts/4/label": "Executor initializer", "/versions/16/facts/5/label": "Memory mechanism", "/versions/16/tables/0/title": "EXPLAIN labels in this source build", "/versions/16/related/1/label": "Using EXPLAIN", "/versions/16/related/2/label": "Parallel plans", "/versions/16/sections/0/title": "EXPLAIN names and attributes", "/versions/16/sections/1/title": "Memory and temporary storage", "/versions/16/sections/2/title": "Parallel execution and instrumentation", "/versions/16/sections/3/title": "Same-version manual discussion", "/versions/16/sections/4/title": "Examples from this manual build", "/versions/16/sections/5/title": "Executor implementation notes", "/versions/16/sections/6/title": "EXPLAIN identity in core source", "/versions/16/memory/description": "This node creates a tuplestore with work_mem. The tuplestore can move stored tuples to temporary files; this does not make work_mem a cap on every allocation made by the node.", "/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: Materialize.", "/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 node creates a tuplestore with work_mem. The tuplestore can move stored tuples to temporary files; this does not make work_mem a cap on every allocation made by the node.", "/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": "Notice that here the planner has chosen to \u201c materialize \u201d the inner relation of the join, by putting a Materialize plan node atop it. This means that the t2 index scan will be done just once, even though the nested-loop join node needs to read that data ten times, once for each row from the outer relation. The Materialize node saves the data in memory as it's read, and then returns the data from memory on each subsequent pass.", "/versions/16/sections/5/paragraphs/0": "As long as we are at the end of the data collected in the tuplestore, we collect one new row from the subplan on each call, and stash it aside in the tuplestore before returning it. The tuplestore is only read if we are asked to scan backwards, rescan, or mark/restore.", "/versions/16/sections/5/paragraphs/1": "If first time through, and we need a tuplestore, initialize it.", "/versions/16/sections/5/paragraphs/2": "Allocate a second read pointer to serve as the mark. We know it must have index 1, so needn't store that.", "/versions/16/sections/5/paragraphs/3": "If we are not at the end of the tuplestore, or are going backwards, try to fetch a tuple from tuplestore.", "/versions/16/sections/5/paragraphs/4": "When reversing direction at tuplestore EOF, the first gettupleslot call will fetch the last-added tuple; but we want to return the one before that, if possible. So do an extra fetch.", "/versions/16/tables/0/columns/0/label": "Text-format label", "/versions/16/tables/0/columns/1/label": "Structured node identity", "/versions/16/sections/4/blocks/0/paragraphs/0": "Example copied from the PostgreSQL 16.15 manual; it was not executed for this collection.", "/versions/16/sections/4/blocks/0/paragraphs/1": "In this example the join's output row count is the same as the product of the two scans' row counts, but that's not true in all cases because there can be additional WHERE clauses that mention both tables and so can only be applied at the join point, not to either input scan. Here's an example:"}, "fallback_fields": [], "source_language": "en", "original_snapshot_sha256": "7e5a8dfd16e4a3dc1388a9e0e456011bd164cb4b0288d95a4faba8ad64b42fea"}, "evidence_kind": "source and documentation", "explain_names": ["Materialize"], "partial_modes": [], "comparison_data": {"node_tag": "T_Material", "strategies": [], "text_names": ["Materialize"], "initializer": "ExecInitMaterial", "partial_modes": [], "memory_mechanism": "tuplestore", "parallel_callbacks": []}, "comparison_hash": "c1d37bf334409fe6ded8ce560fe45fd495ff89ceda2808b6f5ef18daca520393", "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/nodeMaterial.c"}, "parallel_callbacks": []}, "17": {"facts": [{"label": "\u6838\u5fc3\u8282\u70b9\u6807\u7b7e", "value": "T_Material"}, {"label": "\u7ed3\u6784\u5316 EXPLAIN \u8282\u70b9\u7c7b\u578b", "value": "Materialize"}, {"label": "\u8f93\u5165", "value": "\u4e00\u4e2a\u5b50\u8ba1\u5212"}, {"label": "\u8f93\u51fa", "value": "\u5df2\u7269\u5316\u7684\u5143\u7ec4"}, {"label": "\u6267\u884c\u5668\u521d\u59cb\u5316\u51fd\u6570", "value": "ExecInitMaterial"}, {"label": "\u5185\u5b58\u673a\u5236", "value": "tuplestore"}], "memory": {"evidence": [{"url": "https://ftp.postgresql.org/pub/source/v17.11/postgresql-17.11.tar.bz2", "path": "src/backend/executor/nodeMaterial.c", "label": "src/backend/executor/nodeMaterial.c", "sha256": "516a8b4d4c886136b82c48c65ee59f5a38f86845270666fd65868562df0e14f5", "archive_sha256": "dd27f2b3c59e73ed14aa3324901242bf69a032a6347805f274e6260322d42979"}, {"url": "https://ftp.postgresql.org/pub/source/v17.11/postgresql-17.11.tar.bz2", "path": "src/backend/utils/sort/tuplestore.c", "label": "src/backend/utils/sort/tuplestore.c", "sha256": "0d4316ed2d09288c2e3be15be1ce01b88622354bcd571ac7ebc45aa9319b90e7", "archive_sha256": 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"/wiki/guc/enable_material/?v=17", "label": "enable_material"}, {"url": "/wiki/guc/work_mem/?v=17", "label": "work_mem"}], "release": {"ref": "PostgreSQL 17.11 source archive", "label": "17.11", "major": "17", "channel": "stable", "revision": "dd27f2b3c59e73ed14aa3324901242bf69a032a6347805f274e6260322d42979", "source_url": "https://ftp.postgresql.org/pub/source/v17.11/postgresql-17.11.tar.bz2", "source_snapshot_utc": ""}, "sources": [{"url": "https://ftp.postgresql.org/pub/source/v17.11/postgresql-17.11.tar.bz2", "line": 1531, "path": "src/backend/commands/explain.c", "label": "src/backend/commands/explain.c:1531", "sha256": "741251b1a3b6d269a52a673d42eb63b02e13a5872db7b359b137086ab21b63c8", "archive_sha256": "dd27f2b3c59e73ed14aa3324901242bf69a032a6347805f274e6260322d42979"}, {"url": "https://ftp.postgresql.org/pub/source/v17.11/postgresql-17.11.tar.bz2", "line": 315, "path": "src/backend/executor/execProcnode.c", "label": "src/backend/executor/execProcnode.c:315", "sha256": 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"sha256": "0d4316ed2d09288c2e3be15be1ce01b88622354bcd571ac7ebc45aa9319b90e7", "archive_sha256": "dd27f2b3c59e73ed14aa3324901242bf69a032a6347805f274e6260322d42979"}, {"url": "https://pg.center/docs/17/using-explain.html#USING-EXPLAIN-BASICS", "path": "using-explain.html", "label": "PostgreSQL 17.11 \u00b7 using-explain", "sha256": "8e3422c77496cc53bfc225ccadda3e82eb23c8c362b8eb95e7fb02cdb315ea78", "language": "en", "original_url": "/docs/17/using-explain.html#USING-EXPLAIN-BASICS"}], "node_tag": "T_Material", "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\uff1aMaterialize.", "\u5e76\u884c\u611f\u77e5\u4e0e\u5e76\u884c\u5b89\u5168\u662f\u4e0d\u540c\u7684\u8ba1\u5212\u5c5e\u6027\u3002\u5728\u5e76\u884c\u5de5\u4f5c\u8fdb\u7a0b\u5185\u8fd0\u884c\u7684\u8282\u70b9\u4e0d\u4e00\u5b9a\u662f\u5e76\u884c\u611f\u77e5\u8282\u70b9\u3002"]}, {"title": "\u5185\u5b58\u4e0e\u4e34\u65f6\u5b58\u50a8", "paragraphs": ["\u6b64\u8282\u70b9\u4f7f\u7528 work_mem \u521b\u5efa tuplestore\u3002tuplestore \u53ef\u4ee5\u5c06\u5b58\u50a8\u7684\u5143\u7ec4\u79fb\u5230\u4e34\u65f6\u6587\u4ef6\uff0c\u4f46\u8fd9\u4e0d\u610f\u5473\u7740 work_mem \u9650\u5236\u4e86\u8282\u70b9\u7684\u5168\u90e8\u5185\u5b58\u5206\u914d\u3002"]}, {"title": "\u5e76\u884c\u6267\u884c\u4e0e\u8fd0\u884c\u4fe1\u606f\u91c7\u96c6", "paragraphs": ["\u4ee5\u4e0b\u6e90\u7801\u56de\u8c03\u53ef\u4ee5\u534f\u8c03\u6267\u884c\u6216\u6536\u96c6\u5de5\u4f5c\u8fdb\u7a0b\u7684\u6d4b\u91cf\u6570\u636e\u3002\u56de\u8c03\u5b58\u5728\u4e0d\u4ee3\u8868\u8be5\u8282\u70b9\u666e\u904d\u652f\u6301\u5171\u4eab\u5e76\u884c\u626b\u63cf\u6216\u5171\u4eab\u72b6\u6001\u3002", "\u6b64\u6784\u5efa\u7684\u56de\u8c03\uff1anone extracted from this node implementation."]}, {"title": "\u540c\u7248\u672c\u624b\u518c\u8bf4\u660e", "paragraphs": ["\u89c4\u5212\u5668\u5728\u8fde\u63a5\u5185\u4fa7\u5173\u7cfb\u4e4b\u4e0a\u52a0\u5165 Materialize \u8282\u70b9\uff0c\u5c06\u5176\u7269\u5316\u3002\u56e0\u6b64\uff0c\u5c3d\u7ba1\u5d4c\u5957\u5faa\u73af\u8fde\u63a5\u9700\u8981\u4e3a\u5916\u4fa7\u7684\u6bcf\u4e00\u884c\u8bfb\u53d6\u4e00\u6b21\u5185\u4fa7\u6570\u636e\u3001\u5171\u5341\u6b21\uff0ct2 \u7684\u7d22\u5f15\u626b\u63cf\u4e5f\u53ea\u6267\u884c\u4e00\u6b21\u3002Materialize \u5728\u8bfb\u53d6\u65f6\u5c06\u6570\u636e\u4fdd\u5b58\u5728\u5185\u5b58\u4e2d\uff0c\u540e\u7eed\u5404\u8f6e\u76f4\u63a5\u4ece\u5185\u5b58\u8fd4\u56de\u6570\u636e\u3002"]}, {"title": "\u672c\u7248\u624b\u518c\u4e2d\u7684\u793a\u4f8b", "blocks": [{"code": "EXPLAIN SELECT *\nFROM tenk1 t1, tenk2 t2\nWHERE t1.unique1 < 10 AND t2.unique2 < 10 AND t1.hundred < t2.hundred;\n\n                                         QUERY PLAN\n---------------------------------------------------------------------------------------------\n Nested Loop  (cost=4.65..49.36 rows=33 width=488)\n   Join Filter: (t1.hundred < t2.hundred)\n   ->  Bitmap Heap Scan on tenk1 t1  (cost=4.36..39.38 rows=10 width=244)\n         Recheck Cond: (unique1 < 10)\n         ->  Bitmap Index Scan on tenk1_unique1  (cost=0.00..4.36 rows=10 width=0)\n               Index Cond: (unique1 < 10)\n   ->  Materialize  (cost=0.29..8.51 rows=10 width=244)\n         ->  Index Scan using tenk2_unique2 on tenk2 t2  (cost=0.29..8.46 rows=10 width=244)\n               Index Cond: (unique2 < 10)", "source": {"url": "/docs/17/using-explain.html#USING-EXPLAIN-BASICS", "path": "using-explain.html", "label": "PostgreSQL 17.11 \u00b7 using-explain", "sha256": "8e3422c77496cc53bfc225ccadda3e82eb23c8c362b8eb95e7fb02cdb315ea78"}, "paragraphs": ["\u793a\u4f8b\u6458\u81ea PostgreSQL 17.11 \u624b\u518c\uff1b\u672c\u767e\u79d1\u672a\u5b9e\u9645\u6267\u884c\u6b64\u793a\u4f8b\u3002", "\u672c\u4f8b\u4e2d\uff0c\u8fde\u63a5\u7684\u8f93\u51fa\u884c\u6570\u7b49\u4e8e\u4e24\u6b21\u626b\u63cf\u884c\u6570\u7684\u4e58\u79ef\uff0c\u4f46\u5e76\u975e\u603b\u662f\u5982\u6b64\uff1a\u53ef\u80fd\u5b58\u5728\u540c\u65f6\u5f15\u7528\u4e24\u4e2a\u8868\u7684\u989d\u5916 WHERE \u5b50\u53e5\uff0c\u53ea\u80fd\u5728\u8fde\u63a5\u65f6\u5e94\u7528\uff0c\u65e0\u6cd5\u5e94\u7528\u5230\u4efb\u4f55\u5355\u4fa7\u8f93\u5165\u626b\u63cf\u3002\u793a\u4f8b\u5982\u4e0b\uff1a"]}]}, {"title": "\u6267\u884c\u5668\u5b9e\u73b0\u8bf4\u660e", "paragraphs": ["\u53ea\u8981\u5f53\u524d\u4f4d\u4e8e tuplestore \u5df2\u6536\u96c6\u6570\u636e\u7684\u672b\u5c3e\uff0c\u6bcf\u6b21\u8c03\u7528\u5c31\u4ece\u5b50\u8ba1\u5212\u83b7\u53d6\u4e00\u884c\u65b0\u6570\u636e\uff0c\u5728\u8fd4\u56de\u4e4b\u524d\u5c06\u5176\u5b58\u5165 tuplestore\u3002\u53ea\u6709\u8bf7\u6c42\u53cd\u5411\u626b\u63cf\u3001\u91cd\u626b\u6216\u6807\u8bb0\uff0f\u6062\u590d\u65f6\uff0c\u624d\u4ece tuplestore \u8bfb\u53d6\u3002", "\u9996\u6b21\u6267\u884c\u4e14\u9700\u8981\u5143\u7ec4\u5b58\u50a8\u65f6\uff0c\u521d\u59cb\u5316\u5b83\u3002", "\u5206\u914d\u7b2c\u4e8c\u4e2a\u8bfb\u53d6\u6307\u9488\u4f5c\u4e3a\u6807\u8bb0\u3002\u5df2\u77e5\u5176\u7d22\u5f15\u5fc5\u4e3a 1\uff0c\u56e0\u6b64\u65e0\u9700\u53e6\u884c\u4fdd\u5b58\u3002", "\u5982\u679c\u5c1a\u672a\u5230\u8fbe tuplestore \u672b\u5c3e\uff0c\u6216\u6b63\u5728\u53cd\u5411\u626b\u63cf\uff0c\u5219\u5c1d\u8bd5\u4ece tuplestore \u83b7\u53d6\u5143\u7ec4\u3002", "\u5728\u5143\u7ec4\u5b58\u50a8\u672b\u5c3e\u53cd\u8f6c\u626b\u63cf\u65b9\u5411\u65f6\uff0c\u7b2c\u4e00\u6b21 gettupleslot \u4f1a\u53d6\u5f97\u6700\u540e\u6dfb\u52a0\u7684\u5143\u7ec4\uff1b\u4f46\u82e5\u53ef\u80fd\uff0c\u6211\u4eec\u5e0c\u671b\u8fd4\u56de\u5b83\u4e4b\u524d\u7684\u90a3\u4e2a\uff0c\u56e0\u6b64\u989d\u5916\u8bfb\u53d6\u4e00\u6b21\u3002"]}, {"code": "case T_Material:\n\t\t\tpname = sname = \"Materialize\";\n\t\t\tbreak;", "title": "\u6838\u5fc3\u6e90\u7801\u4e2d\u7684 EXPLAIN \u6807\u8bc6"}], "strategies": [], "description": ["\u5b58\u50a8\u5b50\u8ba1\u5212\u8f93\u51fa\uff0c\u4ee5\u4fbf\u518d\u6b21\u8bfb\u53d6\u8fd9\u4e9b\u884c\u3002"], "localization": {"status": "complete", "sources": [], "language": "zh", "original_text": {"/versions/17/description/0": "Stores its child output so the rows can be read again.", "/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": "One child plan", "/versions/17/facts/3/label": "Output", "/versions/17/facts/3/value": "Materialized 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": "Same-version manual discussion", "/versions/17/sections/4/title": "Examples from this manual build", "/versions/17/sections/5/title": "Executor implementation notes", "/versions/17/sections/6/title": "EXPLAIN identity in core source", "/versions/17/memory/description": "This node creates a tuplestore with work_mem. The tuplestore can move stored tuples to temporary files; this does not make work_mem a cap on every allocation made by the node.", "/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: Materialize.", "/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 node creates a tuplestore with work_mem. The tuplestore can move stored tuples to temporary files; this does not make work_mem a cap on every allocation made by the node.", "/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": "Notice that here the planner has chosen to \u201c materialize \u201d the inner relation of the join, by putting a Materialize plan node atop it. This means that the t2 index scan will be done just once, even though the nested-loop join node needs to read that data ten times, once for each row from the outer relation. The Materialize node saves the data in memory as it's read, and then returns the data from memory on each subsequent pass.", "/versions/17/sections/5/paragraphs/0": "As long as we are at the end of the data collected in the tuplestore, we collect one new row from the subplan on each call, and stash it aside in the tuplestore before returning it. The tuplestore is only read if we are asked to scan backwards, rescan, or mark/restore.", "/versions/17/sections/5/paragraphs/1": "If first time through, and we need a tuplestore, initialize it.", "/versions/17/sections/5/paragraphs/2": "Allocate a second read pointer to serve as the mark. We know it must have index 1, so needn't store that.", "/versions/17/sections/5/paragraphs/3": "If we are not at the end of the tuplestore, or are going backwards, try to fetch a tuple from tuplestore.", "/versions/17/sections/5/paragraphs/4": "When reversing direction at tuplestore EOF, the first gettupleslot call will fetch the last-added tuple; but we want to return the one before that, if possible. So do an extra fetch.", "/versions/17/tables/0/columns/0/label": "Text-format label", "/versions/17/tables/0/columns/1/label": "Structured node identity", "/versions/17/sections/4/blocks/0/paragraphs/0": "Example copied from the PostgreSQL 17.11 manual; it was not executed for this collection.", "/versions/17/sections/4/blocks/0/paragraphs/1": "In this example the join's output row count is the same as the product of the two scans' row counts, but that's not true in all cases because there can be additional WHERE clauses that mention both tables and so can only be applied at the join point, not to either input scan. Here's an example:"}, "fallback_fields": [], "source_language": "en", "original_snapshot_sha256": "2094f3025d1e8b41e1e49c0bb81ee9b47f91ba8d91c930a627f9ca155137bd99"}, "evidence_kind": "source and documentation", "explain_names": ["Materialize"], "partial_modes": [], "comparison_data": {"node_tag": "T_Material", "strategies": [], "text_names": ["Materialize"], "initializer": "ExecInitMaterial", "partial_modes": [], "memory_mechanism": "tuplestore", "parallel_callbacks": []}, "comparison_hash": "c1d37bf334409fe6ded8ce560fe45fd495ff89ceda2808b6f5ef18daca520393", "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/nodeMaterial.c"}, "parallel_callbacks": []}, "18": {"facts": [{"label": "\u6838\u5fc3\u8282\u70b9\u6807\u7b7e", "value": "T_Material"}, {"label": "\u7ed3\u6784\u5316 EXPLAIN \u8282\u70b9\u7c7b\u578b", "value": "Materialize"}, {"label": "\u8f93\u5165", "value": "\u4e00\u4e2a\u5b50\u8ba1\u5212"}, {"label": "\u8f93\u51fa", "value": "\u5df2\u7269\u5316\u7684\u5143\u7ec4"}, {"label": "\u6267\u884c\u5668\u521d\u59cb\u5316\u51fd\u6570", "value": "ExecInitMaterial"}, {"label": "\u5185\u5b58\u673a\u5236", "value": "tuplestore"}], "memory": {"evidence": [{"url": "https://ftp.postgresql.org/pub/source/v18.6/postgresql-18.6.tar.bz2", "path": "src/backend/executor/nodeMaterial.c", "label": "src/backend/executor/nodeMaterial.c", "sha256": "410b7129ca7e86ce3cf59ed7afed813fc6a47d68f5195e14df36559c75c7ef91", "archive_sha256": "555610c24d53e4316da5b7d3fc25c279d96856d5e0e23ee308c328c5fa881d9f"}, {"url": "https://ftp.postgresql.org/pub/source/v18.6/postgresql-18.6.tar.bz2", "path": "src/backend/utils/sort/tuplestore.c", "label": "src/backend/utils/sort/tuplestore.c", "sha256": "27a85416bafed557006c705ab5d0c5dce3d3c1702812bb54d136f2ac4c41055a", "archive_sha256": 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"/wiki/guc/enable_material/?v=18", "label": "enable_material"}, {"url": "/wiki/guc/work_mem/?v=18", "label": "work_mem"}], "release": {"ref": "PostgreSQL 18.6 source archive", "label": "18.6", "major": "18", "channel": "stable", "revision": "555610c24d53e4316da5b7d3fc25c279d96856d5e0e23ee308c328c5fa881d9f", "source_url": "https://ftp.postgresql.org/pub/source/v18.6/postgresql-18.6.tar.bz2", "source_snapshot_utc": ""}, "sources": [{"url": "https://ftp.postgresql.org/pub/source/v18.6/postgresql-18.6.tar.bz2", "line": 1516, "path": "src/backend/commands/explain.c", "label": "src/backend/commands/explain.c:1516", "sha256": "34c86d6070224a0e981efef51f79101d6d505e5874f1684ace183034bab14bb4", "archive_sha256": "555610c24d53e4316da5b7d3fc25c279d96856d5e0e23ee308c328c5fa881d9f"}, {"url": "https://ftp.postgresql.org/pub/source/v18.6/postgresql-18.6.tar.bz2", "line": 315, "path": "src/backend/executor/execProcnode.c", "label": "src/backend/executor/execProcnode.c:315", "sha256": 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"sha256": "27a85416bafed557006c705ab5d0c5dce3d3c1702812bb54d136f2ac4c41055a", "archive_sha256": "555610c24d53e4316da5b7d3fc25c279d96856d5e0e23ee308c328c5fa881d9f"}, {"url": "https://pg.center/docs/18/using-explain.html#USING-EXPLAIN-BASICS", "path": "using-explain.html", "label": "PostgreSQL 18.6 \u00b7 using-explain", "sha256": "60040c30180093418a0affe56dd27dff9df2504b705b38039589e458bf5c31ed", "language": "en", "original_url": "/docs/18/using-explain.html#USING-EXPLAIN-BASICS"}], "node_tag": "T_Material", "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\uff1aMaterialize.", "\u5e76\u884c\u611f\u77e5\u4e0e\u5e76\u884c\u5b89\u5168\u662f\u4e0d\u540c\u7684\u8ba1\u5212\u5c5e\u6027\u3002\u5728\u5e76\u884c\u5de5\u4f5c\u8fdb\u7a0b\u5185\u8fd0\u884c\u7684\u8282\u70b9\u4e0d\u4e00\u5b9a\u662f\u5e76\u884c\u611f\u77e5\u8282\u70b9\u3002"]}, {"title": "\u5185\u5b58\u4e0e\u4e34\u65f6\u5b58\u50a8", "paragraphs": ["\u6b64\u8282\u70b9\u4f7f\u7528 work_mem \u521b\u5efa tuplestore\u3002tuplestore \u53ef\u4ee5\u5c06\u5b58\u50a8\u7684\u5143\u7ec4\u79fb\u5230\u4e34\u65f6\u6587\u4ef6\uff0c\u4f46\u8fd9\u4e0d\u610f\u5473\u7740 work_mem \u9650\u5236\u4e86\u8282\u70b9\u7684\u5168\u90e8\u5185\u5b58\u5206\u914d\u3002"]}, {"title": "\u5e76\u884c\u6267\u884c\u4e0e\u8fd0\u884c\u4fe1\u606f\u91c7\u96c6", "paragraphs": ["\u4ee5\u4e0b\u6e90\u7801\u56de\u8c03\u53ef\u4ee5\u534f\u8c03\u6267\u884c\u6216\u6536\u96c6\u5de5\u4f5c\u8fdb\u7a0b\u7684\u6d4b\u91cf\u6570\u636e\u3002\u56de\u8c03\u5b58\u5728\u4e0d\u4ee3\u8868\u8be5\u8282\u70b9\u666e\u904d\u652f\u6301\u5171\u4eab\u5e76\u884c\u626b\u63cf\u6216\u5171\u4eab\u72b6\u6001\u3002", "\u6b64\u6784\u5efa\u7684\u56de\u8c03\uff1anone extracted from this node implementation."]}, {"title": "\u540c\u7248\u672c\u624b\u518c\u8bf4\u660e", "paragraphs": ["\u89c4\u5212\u5668\u5728\u8fde\u63a5\u5185\u4fa7\u5173\u7cfb\u4e4b\u4e0a\u52a0\u5165 Materialize \u8282\u70b9\uff0c\u5c06\u5176\u7269\u5316\u3002\u56e0\u6b64\uff0c\u5c3d\u7ba1\u5d4c\u5957\u5faa\u73af\u8fde\u63a5\u9700\u8981\u4e3a\u5916\u4fa7\u7684\u6bcf\u4e00\u884c\u8bfb\u53d6\u4e00\u6b21\u5185\u4fa7\u6570\u636e\u3001\u5171\u5341\u6b21\uff0ct2 \u7684\u7d22\u5f15\u626b\u63cf\u4e5f\u53ea\u6267\u884c\u4e00\u6b21\u3002Materialize \u5728\u8bfb\u53d6\u65f6\u5c06\u6570\u636e\u4fdd\u5b58\u5728\u5185\u5b58\u4e2d\uff0c\u540e\u7eed\u5404\u8f6e\u76f4\u63a5\u4ece\u5185\u5b58\u8fd4\u56de\u6570\u636e\u3002"]}, {"title": "\u672c\u7248\u624b\u518c\u4e2d\u7684\u793a\u4f8b", "blocks": [{"code": "EXPLAIN SELECT *\nFROM tenk1 t1, tenk2 t2\nWHERE t1.unique1 < 10 AND t2.unique2 < 10 AND t1.hundred < t2.hundred;\n\n                                         QUERY PLAN\n---------------------------------------------------------------------------------------------\n Nested Loop  (cost=4.65..49.36 rows=33 width=488)\n   Join Filter: (t1.hundred < t2.hundred)\n   ->  Bitmap Heap Scan on tenk1 t1  (cost=4.36..39.38 rows=10 width=244)\n         Recheck Cond: (unique1 < 10)\n         ->  Bitmap Index Scan on tenk1_unique1  (cost=0.00..4.36 rows=10 width=0)\n               Index Cond: (unique1 < 10)\n   ->  Materialize  (cost=0.29..8.51 rows=10 width=244)\n         ->  Index Scan using tenk2_unique2 on tenk2 t2  (cost=0.29..8.46 rows=10 width=244)\n               Index Cond: (unique2 < 10)", "source": {"url": "/docs/18/using-explain.html#USING-EXPLAIN-BASICS", "path": "using-explain.html", "label": "PostgreSQL 18.6 \u00b7 using-explain", "sha256": "60040c30180093418a0affe56dd27dff9df2504b705b38039589e458bf5c31ed"}, "paragraphs": ["\u793a\u4f8b\u6458\u81ea PostgreSQL 18.6 \u624b\u518c\uff1b\u672c\u767e\u79d1\u672a\u5b9e\u9645\u6267\u884c\u6b64\u793a\u4f8b\u3002", "\u672c\u4f8b\u4e2d\uff0c\u8fde\u63a5\u7684\u8f93\u51fa\u884c\u6570\u7b49\u4e8e\u4e24\u6b21\u626b\u63cf\u884c\u6570\u7684\u4e58\u79ef\uff0c\u4f46\u5e76\u975e\u603b\u662f\u5982\u6b64\uff1a\u53ef\u80fd\u5b58\u5728\u540c\u65f6\u5f15\u7528\u4e24\u4e2a\u8868\u7684\u989d\u5916 WHERE \u5b50\u53e5\uff0c\u53ea\u80fd\u5728\u8fde\u63a5\u65f6\u5e94\u7528\uff0c\u65e0\u6cd5\u5e94\u7528\u5230\u4efb\u4f55\u5355\u4fa7\u8f93\u5165\u626b\u63cf\u3002\u793a\u4f8b\u5982\u4e0b\uff1a"]}]}, {"title": "\u6267\u884c\u5668\u5b9e\u73b0\u8bf4\u660e", "paragraphs": ["\u53ea\u8981\u5f53\u524d\u4f4d\u4e8e tuplestore \u5df2\u6536\u96c6\u6570\u636e\u7684\u672b\u5c3e\uff0c\u6bcf\u6b21\u8c03\u7528\u5c31\u4ece\u5b50\u8ba1\u5212\u83b7\u53d6\u4e00\u884c\u65b0\u6570\u636e\uff0c\u5728\u8fd4\u56de\u4e4b\u524d\u5c06\u5176\u5b58\u5165 tuplestore\u3002\u53ea\u6709\u8bf7\u6c42\u53cd\u5411\u626b\u63cf\u3001\u91cd\u626b\u6216\u6807\u8bb0\uff0f\u6062\u590d\u65f6\uff0c\u624d\u4ece tuplestore \u8bfb\u53d6\u3002", "\u9996\u6b21\u6267\u884c\u4e14\u9700\u8981\u5143\u7ec4\u5b58\u50a8\u65f6\uff0c\u521d\u59cb\u5316\u5b83\u3002", "\u5206\u914d\u7b2c\u4e8c\u4e2a\u8bfb\u53d6\u6307\u9488\u4f5c\u4e3a\u6807\u8bb0\u3002\u5df2\u77e5\u5176\u7d22\u5f15\u5fc5\u4e3a 1\uff0c\u56e0\u6b64\u65e0\u9700\u53e6\u884c\u4fdd\u5b58\u3002", "\u5982\u679c\u5c1a\u672a\u5230\u8fbe tuplestore \u672b\u5c3e\uff0c\u6216\u6b63\u5728\u53cd\u5411\u626b\u63cf\uff0c\u5219\u5c1d\u8bd5\u4ece tuplestore \u83b7\u53d6\u5143\u7ec4\u3002", "\u5728\u5143\u7ec4\u5b58\u50a8\u672b\u5c3e\u53cd\u8f6c\u626b\u63cf\u65b9\u5411\u65f6\uff0c\u7b2c\u4e00\u6b21 gettupleslot \u4f1a\u53d6\u5f97\u6700\u540e\u6dfb\u52a0\u7684\u5143\u7ec4\uff1b\u4f46\u82e5\u53ef\u80fd\uff0c\u6211\u4eec\u5e0c\u671b\u8fd4\u56de\u5b83\u4e4b\u524d\u7684\u90a3\u4e2a\uff0c\u56e0\u6b64\u989d\u5916\u8bfb\u53d6\u4e00\u6b21\u3002"]}, {"code": "case T_Material:\n\t\t\tpname = sname = \"Materialize\";\n\t\t\tbreak;", "title": "\u6838\u5fc3\u6e90\u7801\u4e2d\u7684 EXPLAIN \u6807\u8bc6"}], "strategies": [], "description": ["\u5b58\u50a8\u5b50\u8ba1\u5212\u8f93\u51fa\uff0c\u4ee5\u4fbf\u518d\u6b21\u8bfb\u53d6\u8fd9\u4e9b\u884c\u3002"], "localization": {"status": "complete", "sources": [], "language": "zh", "original_text": {"/versions/18/description/0": "Stores its child output so the rows can be read again.", "/versions/18/facts/0/label": "Core node tag", "/versions/18/facts/1/label": "Structured EXPLAIN Node Type", "/versions/18/facts/2/label": "Inputs", "/versions/18/facts/2/value": "One child plan", "/versions/18/facts/3/label": "Output", "/versions/18/facts/3/value": "Materialized tuples", "/versions/18/facts/4/label": "Executor initializer", "/versions/18/facts/5/label": "Memory mechanism", "/versions/18/tables/0/title": "EXPLAIN labels in this source build", "/versions/18/related/1/label": "Using EXPLAIN", "/versions/18/related/2/label": "Parallel plans", "/versions/18/sections/0/title": "EXPLAIN names and attributes", "/versions/18/sections/1/title": "Memory and temporary storage", "/versions/18/sections/2/title": "Parallel execution and instrumentation", "/versions/18/sections/3/title": "Same-version manual discussion", "/versions/18/sections/4/title": "Examples from this manual build", "/versions/18/sections/5/title": "Executor implementation notes", "/versions/18/sections/6/title": "EXPLAIN identity in core source", "/versions/18/memory/description": "This node creates a tuplestore with work_mem. The tuplestore can move stored tuples to temporary files; this does not make work_mem a cap on every allocation made by the node.", "/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: Materialize.", "/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 node creates a tuplestore with work_mem. The tuplestore can move stored tuples to temporary files; this does not make work_mem a cap on every allocation made by the node.", "/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": "Notice that here the planner has chosen to \u201c materialize \u201d the inner relation of the join, by putting a Materialize plan node atop it. This means that the t2 index scan will be done just once, even though the nested-loop join node needs to read that data ten times, once for each row from the outer relation. The Materialize node saves the data in memory as it's read, and then returns the data from memory on each subsequent pass.", "/versions/18/sections/5/paragraphs/0": "As long as we are at the end of the data collected in the tuplestore, we collect one new row from the subplan on each call, and stash it aside in the tuplestore before returning it. The tuplestore is only read if we are asked to scan backwards, rescan, or mark/restore.", "/versions/18/sections/5/paragraphs/1": "If first time through, and we need a tuplestore, initialize it.", "/versions/18/sections/5/paragraphs/2": "Allocate a second read pointer to serve as the mark. We know it must have index 1, so needn't store that.", "/versions/18/sections/5/paragraphs/3": "If we are not at the end of the tuplestore, or are going backwards, try to fetch a tuple from tuplestore.", "/versions/18/sections/5/paragraphs/4": "When reversing direction at tuplestore EOF, the first gettupleslot call will fetch the last-added tuple; but we want to return the one before that, if possible. So do an extra fetch.", "/versions/18/tables/0/columns/0/label": "Text-format label", "/versions/18/tables/0/columns/1/label": "Structured node identity", "/versions/18/sections/4/blocks/0/paragraphs/0": "Example copied from the PostgreSQL 18.6 manual; it was not executed for this collection.", "/versions/18/sections/4/blocks/0/paragraphs/1": "In this example the join's output row count is the same as the product of the two scans' row counts, but that's not true in all cases because there can be additional WHERE clauses that mention both tables and so can only be applied at the join point, not to either input scan. Here's an example:"}, "fallback_fields": [], "source_language": "en", "original_snapshot_sha256": "36a80e3c236de93a6ea0c0ef5c79a17982d69a3472ab22d748e6eb3e2f12f6e2"}, "evidence_kind": "source and documentation", "explain_names": ["Materialize"], "partial_modes": [], "comparison_data": {"node_tag": "T_Material", "strategies": [], "text_names": ["Materialize"], "initializer": "ExecInitMaterial", "partial_modes": [], "memory_mechanism": "tuplestore", "parallel_callbacks": []}, "comparison_hash": "c1d37bf334409fe6ded8ce560fe45fd495ff89ceda2808b6f5ef18daca520393", "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/nodeMaterial.c"}, "parallel_callbacks": []}, "19": {"facts": [{"label": "\u6838\u5fc3\u8282\u70b9\u6807\u7b7e", "value": "T_Material"}, {"label": "\u7ed3\u6784\u5316 EXPLAIN \u8282\u70b9\u7c7b\u578b", "value": "Materialize"}, {"label": "\u8f93\u5165", "value": "\u4e00\u4e2a\u5b50\u8ba1\u5212"}, {"label": "\u8f93\u51fa", "value": "\u5df2\u7269\u5316\u7684\u5143\u7ec4"}, {"label": "\u6267\u884c\u5668\u521d\u59cb\u5316\u51fd\u6570", "value": "ExecInitMaterial"}, {"label": "\u5185\u5b58\u673a\u5236", "value": "tuplestore"}], "memory": {"evidence": [{"url": "https://ftp.postgresql.org/pub/source/v19beta4/postgresql-19beta4.tar.bz2", "path": "src/backend/executor/nodeMaterial.c", "label": "src/backend/executor/nodeMaterial.c", "sha256": "e858bde29453059dc45da0304c970f1f6196f3efe11d50fb131f8ad387e21d82", "archive_sha256": "83157ee9c599d03b2f7a3d73ef3a56ec24e0e79cc2b3501a64d1364f56398c86"}, {"url": "https://ftp.postgresql.org/pub/source/v19beta4/postgresql-19beta4.tar.bz2", "path": "src/backend/utils/sort/tuplestore.c", "label": "src/backend/utils/sort/tuplestore.c", "sha256": "cda3af245b88d079a32616b4cc5316913d349ba3acaab5fc1fd8aec479cc51ee", "archive_sha256": 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"/wiki/guc/enable_material/?v=19", "label": "enable_material"}, {"url": "/wiki/guc/work_mem/?v=19", "label": "work_mem"}], "release": {"ref": "PostgreSQL 19beta4 source archive", "label": "19beta4", "major": "19", "channel": "preview", "revision": "83157ee9c599d03b2f7a3d73ef3a56ec24e0e79cc2b3501a64d1364f56398c86", "source_url": "https://ftp.postgresql.org/pub/source/v19beta4/postgresql-19beta4.tar.bz2", "source_snapshot_utc": ""}, "sources": [{"url": "https://ftp.postgresql.org/pub/source/v19beta4/postgresql-19beta4.tar.bz2", "line": 1528, "path": "src/backend/commands/explain.c", "label": "src/backend/commands/explain.c:1528", "sha256": "8b115b1c194a4b54ae630209a741e293b1df49a9052f10b2de9ca092a48998e3", "archive_sha256": "83157ee9c599d03b2f7a3d73ef3a56ec24e0e79cc2b3501a64d1364f56398c86"}, {"url": "https://ftp.postgresql.org/pub/source/v19beta4/postgresql-19beta4.tar.bz2", "line": 315, "path": "src/backend/executor/execProcnode.c", "label": "src/backend/executor/execProcnode.c:315", 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"\u5e76\u884c\u611f\u77e5\u4e0e\u5e76\u884c\u5b89\u5168\u662f\u4e0d\u540c\u7684\u8ba1\u5212\u5c5e\u6027\u3002\u5728\u5e76\u884c\u5de5\u4f5c\u8fdb\u7a0b\u5185\u8fd0\u884c\u7684\u8282\u70b9\u4e0d\u4e00\u5b9a\u662f\u5e76\u884c\u611f\u77e5\u8282\u70b9\u3002"]}, {"title": "\u5185\u5b58\u4e0e\u4e34\u65f6\u5b58\u50a8", "paragraphs": ["\u6b64\u8282\u70b9\u4f7f\u7528 work_mem \u521b\u5efa tuplestore\u3002tuplestore \u53ef\u4ee5\u5c06\u5b58\u50a8\u7684\u5143\u7ec4\u79fb\u5230\u4e34\u65f6\u6587\u4ef6\uff0c\u4f46\u8fd9\u4e0d\u610f\u5473\u7740 work_mem \u9650\u5236\u4e86\u8282\u70b9\u7684\u5168\u90e8\u5185\u5b58\u5206\u914d\u3002"]}, {"title": "\u5e76\u884c\u6267\u884c\u4e0e\u8fd0\u884c\u4fe1\u606f\u91c7\u96c6", "paragraphs": ["\u4ee5\u4e0b\u6e90\u7801\u56de\u8c03\u53ef\u4ee5\u534f\u8c03\u6267\u884c\u6216\u6536\u96c6\u5de5\u4f5c\u8fdb\u7a0b\u7684\u6d4b\u91cf\u6570\u636e\u3002\u56de\u8c03\u5b58\u5728\u4e0d\u4ee3\u8868\u8be5\u8282\u70b9\u666e\u904d\u652f\u6301\u5171\u4eab\u5e76\u884c\u626b\u63cf\u6216\u5171\u4eab\u72b6\u6001\u3002", "\u6b64\u6784\u5efa\u7684\u56de\u8c03\uff1anone extracted from this node implementation."]}, {"title": "\u540c\u7248\u672c\u624b\u518c\u8bf4\u660e", "paragraphs": ["\u89c4\u5212\u5668\u5728\u8fde\u63a5\u5185\u4fa7\u5173\u7cfb\u4e4b\u4e0a\u52a0\u5165 Materialize \u8282\u70b9\uff0c\u5c06\u5176\u7269\u5316\u3002\u56e0\u6b64\uff0c\u5c3d\u7ba1\u5d4c\u5957\u5faa\u73af\u8fde\u63a5\u9700\u8981\u4e3a\u5916\u4fa7\u7684\u6bcf\u4e00\u884c\u8bfb\u53d6\u4e00\u6b21\u5185\u4fa7\u6570\u636e\u3001\u5171\u5341\u6b21\uff0ct2 \u7684\u7d22\u5f15\u626b\u63cf\u4e5f\u53ea\u6267\u884c\u4e00\u6b21\u3002Materialize \u5728\u8bfb\u53d6\u65f6\u5c06\u6570\u636e\u4fdd\u5b58\u5728\u5185\u5b58\u4e2d\uff0c\u540e\u7eed\u5404\u8f6e\u76f4\u63a5\u4ece\u5185\u5b58\u8fd4\u56de\u6570\u636e\u3002"]}, {"title": "\u672c\u7248\u624b\u518c\u4e2d\u7684\u793a\u4f8b", "blocks": [{"code": "EXPLAIN SELECT *\nFROM tenk1 t1, tenk2 t2\nWHERE t1.unique1 < 10 AND t2.unique2 < 10 AND t1.hundred < t2.hundred;\n\n                                         QUERY PLAN\n---------------------------------------------------------------------------------------------\n Nested Loop  (cost=4.65..49.36 rows=33 width=488)\n   Join Filter: (t1.hundred < t2.hundred)\n   ->  Bitmap Heap Scan on tenk1 t1  (cost=4.36..39.38 rows=10 width=244)\n         Recheck Cond: (unique1 < 10)\n         ->  Bitmap Index Scan on tenk1_unique1  (cost=0.00..4.36 rows=10 width=0)\n               Index Cond: (unique1 < 10)\n   ->  Materialize  (cost=0.29..8.51 rows=10 width=244)\n         ->  Index Scan using tenk2_unique2 on tenk2 t2  (cost=0.29..8.46 rows=10 width=244)\n               Index Cond: (unique2 < 10)", "source": {"url": "/docs/19/using-explain.html#USING-EXPLAIN-BASICS", "path": "using-explain.html", "label": "PostgreSQL 19beta4 \u00b7 using-explain", "sha256": "52f111fbd213e2200146319d01a9dcc2ea90001617d2a28edc52f7954c2dd70b"}, "paragraphs": ["\u793a\u4f8b\u6458\u81ea PostgreSQL 19beta4 \u624b\u518c\uff1b\u672c\u767e\u79d1\u672a\u5b9e\u9645\u6267\u884c\u6b64\u793a\u4f8b\u3002", "\u672c\u4f8b\u4e2d\uff0c\u8fde\u63a5\u7684\u8f93\u51fa\u884c\u6570\u7b49\u4e8e\u4e24\u6b21\u626b\u63cf\u884c\u6570\u7684\u4e58\u79ef\uff0c\u4f46\u5e76\u975e\u603b\u662f\u5982\u6b64\uff1a\u53ef\u80fd\u5b58\u5728\u540c\u65f6\u5f15\u7528\u4e24\u4e2a\u8868\u7684\u989d\u5916 WHERE \u5b50\u53e5\uff0c\u53ea\u80fd\u5728\u8fde\u63a5\u65f6\u5e94\u7528\uff0c\u65e0\u6cd5\u5e94\u7528\u5230\u4efb\u4f55\u5355\u4fa7\u8f93\u5165\u626b\u63cf\u3002\u793a\u4f8b\u5982\u4e0b\uff1a"]}]}, {"title": "\u6267\u884c\u5668\u5b9e\u73b0\u8bf4\u660e", "paragraphs": ["\u53ea\u8981\u5f53\u524d\u4f4d\u4e8e tuplestore \u5df2\u6536\u96c6\u6570\u636e\u7684\u672b\u5c3e\uff0c\u6bcf\u6b21\u8c03\u7528\u5c31\u4ece\u5b50\u8ba1\u5212\u83b7\u53d6\u4e00\u884c\u65b0\u6570\u636e\uff0c\u5728\u8fd4\u56de\u4e4b\u524d\u5c06\u5176\u5b58\u5165 tuplestore\u3002\u53ea\u6709\u8bf7\u6c42\u53cd\u5411\u626b\u63cf\u3001\u91cd\u626b\u6216\u6807\u8bb0\uff0f\u6062\u590d\u65f6\uff0c\u624d\u4ece tuplestore \u8bfb\u53d6\u3002", "\u9996\u6b21\u6267\u884c\u4e14\u9700\u8981\u5143\u7ec4\u5b58\u50a8\u65f6\uff0c\u521d\u59cb\u5316\u5b83\u3002", "\u5206\u914d\u7b2c\u4e8c\u4e2a\u8bfb\u53d6\u6307\u9488\u4f5c\u4e3a\u6807\u8bb0\u3002\u5df2\u77e5\u5176\u7d22\u5f15\u5fc5\u4e3a 1\uff0c\u56e0\u6b64\u65e0\u9700\u53e6\u884c\u4fdd\u5b58\u3002", "\u5982\u679c\u5c1a\u672a\u5230\u8fbe tuplestore \u672b\u5c3e\uff0c\u6216\u6b63\u5728\u53cd\u5411\u626b\u63cf\uff0c\u5219\u5c1d\u8bd5\u4ece tuplestore \u83b7\u53d6\u5143\u7ec4\u3002", "\u5728\u5143\u7ec4\u5b58\u50a8\u672b\u5c3e\u53cd\u8f6c\u626b\u63cf\u65b9\u5411\u65f6\uff0c\u7b2c\u4e00\u6b21 gettupleslot \u4f1a\u53d6\u5f97\u6700\u540e\u6dfb\u52a0\u7684\u5143\u7ec4\uff1b\u4f46\u82e5\u53ef\u80fd\uff0c\u6211\u4eec\u5e0c\u671b\u8fd4\u56de\u5b83\u4e4b\u524d\u7684\u90a3\u4e2a\uff0c\u56e0\u6b64\u989d\u5916\u8bfb\u53d6\u4e00\u6b21\u3002"]}, {"code": "case T_Material:\n\t\t\tpname = sname = \"Materialize\";\n\t\t\tbreak;", "title": "\u6838\u5fc3\u6e90\u7801\u4e2d\u7684 EXPLAIN \u6807\u8bc6"}], "strategies": [], "description": ["\u5b58\u50a8\u5b50\u8ba1\u5212\u8f93\u51fa\uff0c\u4ee5\u4fbf\u518d\u6b21\u8bfb\u53d6\u8fd9\u4e9b\u884c\u3002"], "localization": {"status": "complete", "sources": [], "language": "zh", "original_text": {"/versions/19/description/0": "Stores its child output so the rows can be read again.", "/versions/19/facts/0/label": "Core node tag", "/versions/19/facts/1/label": "Structured EXPLAIN Node Type", "/versions/19/facts/2/label": "Inputs", "/versions/19/facts/2/value": "One child plan", "/versions/19/facts/3/label": "Output", "/versions/19/facts/3/value": "Materialized tuples", "/versions/19/facts/4/label": "Executor initializer", "/versions/19/facts/5/label": "Memory mechanism", "/versions/19/tables/0/title": "EXPLAIN labels in this source build", "/versions/19/related/1/label": "Using EXPLAIN", "/versions/19/related/2/label": "Parallel plans", "/versions/19/sections/0/title": "EXPLAIN names and attributes", "/versions/19/sections/1/title": "Memory and temporary storage", "/versions/19/sections/2/title": "Parallel execution and instrumentation", "/versions/19/sections/3/title": "Same-version manual discussion", "/versions/19/sections/4/title": "Examples from this manual build", "/versions/19/sections/5/title": "Executor implementation notes", "/versions/19/sections/6/title": "EXPLAIN identity in core source", "/versions/19/memory/description": "This node creates a tuplestore with work_mem. The tuplestore can move stored tuples to temporary files; this does not make work_mem a cap on every allocation made by the node.", "/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: Materialize.", "/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 node creates a tuplestore with work_mem. The tuplestore can move stored tuples to temporary files; this does not make work_mem a cap on every allocation made by the node.", "/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": "Notice that here the planner has chosen to \u201c materialize \u201d the inner relation of the join, by putting a Materialize plan node atop it. This means that the t2 index scan will be done just once, even though the nested-loop join node needs to read that data ten times, once for each row from the outer relation. The Materialize node saves the data in memory as it's read, and then returns the data from memory on each subsequent pass.", "/versions/19/sections/5/paragraphs/0": "As long as we are at the end of the data collected in the tuplestore, we collect one new row from the subplan on each call, and stash it aside in the tuplestore before returning it. The tuplestore is only read if we are asked to scan backwards, rescan, or mark/restore.", "/versions/19/sections/5/paragraphs/1": "If first time through, and we need a tuplestore, initialize it.", "/versions/19/sections/5/paragraphs/2": "Allocate a second read pointer to serve as the mark. We know it must have index 1, so needn't store that.", "/versions/19/sections/5/paragraphs/3": "If we are not at the end of the tuplestore, or are going backwards, try to fetch a tuple from tuplestore.", "/versions/19/sections/5/paragraphs/4": "When reversing direction at tuplestore EOF, the first gettupleslot call will fetch the last-added tuple; but we want to return the one before that, if possible. So do an extra fetch.", "/versions/19/tables/0/columns/0/label": "Text-format label", "/versions/19/tables/0/columns/1/label": "Structured node identity", "/versions/19/sections/4/blocks/0/paragraphs/0": "Example copied from the PostgreSQL 19beta4 manual; it was not executed for this collection.", "/versions/19/sections/4/blocks/0/paragraphs/1": "In this example the join's output row count is the same as the product of the two scans' row counts, but that's not true in all cases because there can be additional WHERE clauses that mention both tables and so can only be applied at the join point, not to either input scan. Here's an example:"}, "fallback_fields": [], "source_language": "en", "original_snapshot_sha256": "099f0c44dd37d48d295c55d925996b9e0e9f7fe5d494f4b06bbc20eefebad021"}, "evidence_kind": "source and documentation", "explain_names": ["Materialize"], "partial_modes": [], "comparison_data": {"node_tag": "T_Material", "strategies": [], "text_names": ["Materialize"], "initializer": "ExecInitMaterial", "partial_modes": [], "memory_mechanism": "tuplestore", "parallel_callbacks": []}, "comparison_hash": "c1d37bf334409fe6ded8ce560fe45fd495ff89ceda2808b6f5ef18daca520393", "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/nodeMaterial.c"}, "parallel_callbacks": []}, "20": {"facts": [{"label": "\u6838\u5fc3\u8282\u70b9\u6807\u7b7e", "value": "T_Material"}, {"label": "\u7ed3\u6784\u5316 EXPLAIN \u8282\u70b9\u7c7b\u578b", "value": "Materialize"}, {"label": "\u8f93\u5165", "value": "\u4e00\u4e2a\u5b50\u8ba1\u5212"}, {"label": "\u8f93\u51fa", "value": "\u5df2\u7269\u5316\u7684\u5143\u7ec4"}, {"label": "\u6267\u884c\u5668\u521d\u59cb\u5316\u51fd\u6570", "value": "ExecInitMaterial"}, {"label": "\u5185\u5b58\u673a\u5236", "value": "tuplestore"}], "memory": {"evidence": [{"url": "https://ftp.postgresql.org/pub/snapshot/dev/postgresql-snapshot.tar.bz2", "path": "src/backend/executor/nodeMaterial.c", "label": "src/backend/executor/nodeMaterial.c", "sha256": "e858bde29453059dc45da0304c970f1f6196f3efe11d50fb131f8ad387e21d82", "archive_sha256": "4d3346909b201ac1648232cf290462a7070c119326f56196f1f0253ed80fae41"}, {"url": "https://ftp.postgresql.org/pub/snapshot/dev/postgresql-snapshot.tar.bz2", "path": "src/backend/utils/sort/tuplestore.c", "label": "src/backend/utils/sort/tuplestore.c", "sha256": "46a50e4790274348dfdc6e24f63ae12809d38e639d19378c01d6daff55e61644", "archive_sha256": 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"src/backend/utils/sort/tuplestore.c", "label": "src/backend/utils/sort/tuplestore.c", "sha256": "46a50e4790274348dfdc6e24f63ae12809d38e639d19378c01d6daff55e61644", "archive_sha256": "4d3346909b201ac1648232cf290462a7070c119326f56196f1f0253ed80fae41"}, {"url": "https://pg.center/docs/devel/using-explain.html#USING-EXPLAIN-BASICS", "path": "using-explain.html", "label": "PostgreSQL 20devel \u00b7 using-explain", "sha256": "99cfea3035876ea63f88b75ba8c964b51a32a70606544e09f769c0b60a234b31", "language": "en", "original_url": "/docs/devel/using-explain.html#USING-EXPLAIN-BASICS"}], "node_tag": "T_Material", "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\uff1aMaterialize.", "\u5e76\u884c\u611f\u77e5\u4e0e\u5e76\u884c\u5b89\u5168\u662f\u4e0d\u540c\u7684\u8ba1\u5212\u5c5e\u6027\u3002\u5728\u5e76\u884c\u5de5\u4f5c\u8fdb\u7a0b\u5185\u8fd0\u884c\u7684\u8282\u70b9\u4e0d\u4e00\u5b9a\u662f\u5e76\u884c\u611f\u77e5\u8282\u70b9\u3002"]}, {"title": "\u5185\u5b58\u4e0e\u4e34\u65f6\u5b58\u50a8", "paragraphs": ["\u6b64\u8282\u70b9\u4f7f\u7528 work_mem \u521b\u5efa tuplestore\u3002tuplestore \u53ef\u4ee5\u5c06\u5b58\u50a8\u7684\u5143\u7ec4\u79fb\u5230\u4e34\u65f6\u6587\u4ef6\uff0c\u4f46\u8fd9\u4e0d\u610f\u5473\u7740 work_mem \u9650\u5236\u4e86\u8282\u70b9\u7684\u5168\u90e8\u5185\u5b58\u5206\u914d\u3002"]}, {"title": "\u5e76\u884c\u6267\u884c\u4e0e\u8fd0\u884c\u4fe1\u606f\u91c7\u96c6", "paragraphs": ["\u4ee5\u4e0b\u6e90\u7801\u56de\u8c03\u53ef\u4ee5\u534f\u8c03\u6267\u884c\u6216\u6536\u96c6\u5de5\u4f5c\u8fdb\u7a0b\u7684\u6d4b\u91cf\u6570\u636e\u3002\u56de\u8c03\u5b58\u5728\u4e0d\u4ee3\u8868\u8be5\u8282\u70b9\u666e\u904d\u652f\u6301\u5171\u4eab\u5e76\u884c\u626b\u63cf\u6216\u5171\u4eab\u72b6\u6001\u3002", "\u6b64\u6784\u5efa\u7684\u56de\u8c03\uff1anone extracted from this node implementation."]}, {"title": "\u540c\u7248\u672c\u624b\u518c\u8bf4\u660e", "paragraphs": ["\u89c4\u5212\u5668\u5728\u8fde\u63a5\u5185\u4fa7\u5173\u7cfb\u4e4b\u4e0a\u52a0\u5165 Materialize \u8282\u70b9\uff0c\u5c06\u5176\u7269\u5316\u3002\u56e0\u6b64\uff0c\u5c3d\u7ba1\u5d4c\u5957\u5faa\u73af\u8fde\u63a5\u9700\u8981\u4e3a\u5916\u4fa7\u7684\u6bcf\u4e00\u884c\u8bfb\u53d6\u4e00\u6b21\u5185\u4fa7\u6570\u636e\u3001\u5171\u5341\u6b21\uff0ct2 \u7684\u7d22\u5f15\u626b\u63cf\u4e5f\u53ea\u6267\u884c\u4e00\u6b21\u3002Materialize \u5728\u8bfb\u53d6\u65f6\u5c06\u6570\u636e\u4fdd\u5b58\u5728\u5185\u5b58\u4e2d\uff0c\u540e\u7eed\u5404\u8f6e\u76f4\u63a5\u4ece\u5185\u5b58\u8fd4\u56de\u6570\u636e\u3002"]}, {"title": "\u672c\u7248\u624b\u518c\u4e2d\u7684\u793a\u4f8b", "blocks": [{"code": "EXPLAIN SELECT *\nFROM tenk1 t1, tenk2 t2\nWHERE t1.unique1 < 10 AND t2.unique2 < 10 AND t1.hundred < t2.hundred;\n\n                                         QUERY PLAN\n---------------------------------------------------------------------------------------------\n Nested Loop  (cost=4.65..49.36 rows=33 width=488)\n   Join Filter: (t1.hundred < t2.hundred)\n   ->  Bitmap Heap Scan on tenk1 t1  (cost=4.36..39.38 rows=10 width=244)\n         Recheck Cond: (unique1 < 10)\n         ->  Bitmap Index Scan on tenk1_unique1  (cost=0.00..4.36 rows=10 width=0)\n               Index Cond: (unique1 < 10)\n   ->  Materialize  (cost=0.29..8.51 rows=10 width=244)\n         ->  Index Scan using tenk2_unique2 on tenk2 t2  (cost=0.29..8.46 rows=10 width=244)\n               Index Cond: (unique2 < 10)", "source": {"url": "/docs/devel/using-explain.html#USING-EXPLAIN-BASICS", "path": "using-explain.html", "label": "PostgreSQL 20devel \u00b7 using-explain", "sha256": "99cfea3035876ea63f88b75ba8c964b51a32a70606544e09f769c0b60a234b31"}, "paragraphs": ["\u793a\u4f8b\u6458\u81ea PostgreSQL 20devel \u624b\u518c\uff1b\u672c\u767e\u79d1\u672a\u5b9e\u9645\u6267\u884c\u6b64\u793a\u4f8b\u3002", "\u672c\u4f8b\u4e2d\uff0c\u8fde\u63a5\u7684\u8f93\u51fa\u884c\u6570\u7b49\u4e8e\u4e24\u6b21\u626b\u63cf\u884c\u6570\u7684\u4e58\u79ef\uff0c\u4f46\u5e76\u975e\u603b\u662f\u5982\u6b64\uff1a\u53ef\u80fd\u5b58\u5728\u540c\u65f6\u5f15\u7528\u4e24\u4e2a\u8868\u7684\u989d\u5916 WHERE \u5b50\u53e5\uff0c\u53ea\u80fd\u5728\u8fde\u63a5\u65f6\u5e94\u7528\uff0c\u65e0\u6cd5\u5e94\u7528\u5230\u4efb\u4f55\u5355\u4fa7\u8f93\u5165\u626b\u63cf\u3002\u793a\u4f8b\u5982\u4e0b\uff1a"]}]}, {"title": "\u6267\u884c\u5668\u5b9e\u73b0\u8bf4\u660e", "paragraphs": ["\u53ea\u8981\u5f53\u524d\u4f4d\u4e8e tuplestore \u5df2\u6536\u96c6\u6570\u636e\u7684\u672b\u5c3e\uff0c\u6bcf\u6b21\u8c03\u7528\u5c31\u4ece\u5b50\u8ba1\u5212\u83b7\u53d6\u4e00\u884c\u65b0\u6570\u636e\uff0c\u5728\u8fd4\u56de\u4e4b\u524d\u5c06\u5176\u5b58\u5165 tuplestore\u3002\u53ea\u6709\u8bf7\u6c42\u53cd\u5411\u626b\u63cf\u3001\u91cd\u626b\u6216\u6807\u8bb0\uff0f\u6062\u590d\u65f6\uff0c\u624d\u4ece tuplestore \u8bfb\u53d6\u3002", "\u9996\u6b21\u6267\u884c\u4e14\u9700\u8981\u5143\u7ec4\u5b58\u50a8\u65f6\uff0c\u521d\u59cb\u5316\u5b83\u3002", "\u5206\u914d\u7b2c\u4e8c\u4e2a\u8bfb\u53d6\u6307\u9488\u4f5c\u4e3a\u6807\u8bb0\u3002\u5df2\u77e5\u5176\u7d22\u5f15\u5fc5\u4e3a 1\uff0c\u56e0\u6b64\u65e0\u9700\u53e6\u884c\u4fdd\u5b58\u3002", "\u5982\u679c\u5c1a\u672a\u5230\u8fbe tuplestore \u672b\u5c3e\uff0c\u6216\u6b63\u5728\u53cd\u5411\u626b\u63cf\uff0c\u5219\u5c1d\u8bd5\u4ece tuplestore \u83b7\u53d6\u5143\u7ec4\u3002", "\u5728\u5143\u7ec4\u5b58\u50a8\u672b\u5c3e\u53cd\u8f6c\u626b\u63cf\u65b9\u5411\u65f6\uff0c\u7b2c\u4e00\u6b21 gettupleslot \u4f1a\u53d6\u5f97\u6700\u540e\u6dfb\u52a0\u7684\u5143\u7ec4\uff1b\u4f46\u82e5\u53ef\u80fd\uff0c\u6211\u4eec\u5e0c\u671b\u8fd4\u56de\u5b83\u4e4b\u524d\u7684\u90a3\u4e2a\uff0c\u56e0\u6b64\u989d\u5916\u8bfb\u53d6\u4e00\u6b21\u3002"]}, {"code": "case T_Material:\n\t\t\tpname = sname = \"Materialize\";\n\t\t\tbreak;", "title": "\u6838\u5fc3\u6e90\u7801\u4e2d\u7684 EXPLAIN \u6807\u8bc6"}], "strategies": [], "description": ["\u5b58\u50a8\u5b50\u8ba1\u5212\u8f93\u51fa\uff0c\u4ee5\u4fbf\u518d\u6b21\u8bfb\u53d6\u8fd9\u4e9b\u884c\u3002"], "localization": {"status": "complete", "sources": [], "language": "zh", "original_text": {"/summary": "Stores its child output so the rows can be read again.", "/category": "Materialization", "/versions/20/description/0": "Stores its child output so the rows can be read again.", "/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": "One child plan", "/versions/20/facts/3/label": "Output", "/versions/20/facts/3/value": "Materialized 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": "Same-version manual discussion", "/versions/20/sections/4/title": "Examples from this manual build", "/versions/20/sections/5/title": "Executor implementation notes", "/versions/20/sections/6/title": "EXPLAIN identity in core source", "/versions/20/memory/description": "This node creates a tuplestore with work_mem. The tuplestore can move stored tuples to temporary files; this does not make work_mem a cap on every allocation made by the node.", "/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: Materialize.", "/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 node creates a tuplestore with work_mem. The tuplestore can move stored tuples to temporary files; this does not make work_mem a cap on every allocation made by the node.", "/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": "Notice that here the planner has chosen to \u201c materialize \u201d the inner relation of the join, by putting a Materialize plan node atop it. This means that the t2 index scan will be done just once, even though the nested-loop join node needs to read that data ten times, once for each row from the outer relation. The Materialize node saves the data in memory as it's read, and then returns the data from memory on each subsequent pass.", "/versions/20/sections/5/paragraphs/0": "As long as we are at the end of the data collected in the tuplestore, we collect one new row from the subplan on each call, and stash it aside in the tuplestore before returning it. The tuplestore is only read if we are asked to scan backwards, rescan, or mark/restore.", "/versions/20/sections/5/paragraphs/1": "If first time through, and we need a tuplestore, initialize it.", "/versions/20/sections/5/paragraphs/2": "Allocate a second read pointer to serve as the mark. We know it must have index 1, so needn't store that.", "/versions/20/sections/5/paragraphs/3": "If we are not at the end of the tuplestore, or are going backwards, try to fetch a tuple from tuplestore.", "/versions/20/sections/5/paragraphs/4": "When reversing direction at tuplestore EOF, the first gettupleslot call will fetch the last-added tuple; but we want to return the one before that, if possible. So do an extra fetch.", "/versions/20/tables/0/columns/0/label": "Text-format label", "/versions/20/tables/0/columns/1/label": "Structured node identity", "/versions/20/sections/4/blocks/0/paragraphs/0": "Example copied from the PostgreSQL 20devel manual; it was not executed for this collection.", "/versions/20/sections/4/blocks/0/paragraphs/1": "In this example the join's output row count is the same as the product of the two scans' row counts, but that's not true in all cases because there can be additional WHERE clauses that mention both tables and so can only be applied at the join point, not to either input scan. Here's an example:"}, "fallback_fields": [], "source_language": "en", "original_snapshot_sha256": "0a25debe7e491a5f368f8e3da89701d5508bda89b707fe2d9120bef8f05d3192"}, "evidence_kind": "source and documentation", "explain_names": ["Materialize"], "partial_modes": [], "comparison_data": {"node_tag": "T_Material", "strategies": [], "text_names": ["Materialize"], "initializer": "ExecInitMaterial", "partial_modes": [], "memory_mechanism": "tuplestore", "parallel_callbacks": []}, "comparison_hash": "c1d37bf334409fe6ded8ce560fe45fd495ff89ceda2808b6f5ef18daca520393", "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/nodeMaterial.c"}, "parallel_callbacks": []}}}, "snapshot": {"facts": [{"label": "\u6838\u5fc3\u8282\u70b9\u6807\u7b7e", "value": "T_Material"}, {"label": "\u7ed3\u6784\u5316 EXPLAIN \u8282\u70b9\u7c7b\u578b", "value": "Materialize"}, {"label": "\u8f93\u5165", "value": "\u4e00\u4e2a\u5b50\u8ba1\u5212"}, {"label": "\u8f93\u51fa", "value": "\u5df2\u7269\u5316\u7684\u5143\u7ec4"}, {"label": "\u6267\u884c\u5668\u521d\u59cb\u5316\u51fd\u6570", "value": "ExecInitMaterial"}, {"label": "\u5185\u5b58\u673a\u5236", "value": "tuplestore"}], "memory": {"evidence": [{"url": "https://ftp.postgresql.org/pub/source/v18.6/postgresql-18.6.tar.bz2", "path": "src/backend/executor/nodeMaterial.c", "label": "src/backend/executor/nodeMaterial.c", "sha256": "410b7129ca7e86ce3cf59ed7afed813fc6a47d68f5195e14df36559c75c7ef91", "archive_sha256": "555610c24d53e4316da5b7d3fc25c279d96856d5e0e23ee308c328c5fa881d9f"}, {"url": "https://ftp.postgresql.org/pub/source/v18.6/postgresql-18.6.tar.bz2", "path": "src/backend/utils/sort/tuplestore.c", "label": "src/backend/utils/sort/tuplestore.c", "sha256": "27a85416bafed557006c705ab5d0c5dce3d3c1702812bb54d136f2ac4c41055a", "archive_sha256": "555610c24d53e4316da5b7d3fc25c279d96856d5e0e23ee308c328c5fa881d9f"}], "mechanism": "tuplestore", "description": "\u6b64\u8282\u70b9\u4f7f\u7528 work_mem \u521b\u5efa tuplestore\u3002tuplestore \u53ef\u4ee5\u5c06\u5b58\u50a8\u7684\u5143\u7ec4\u79fb\u5230\u4e34\u65f6\u6587\u4ef6\uff0c\u4f46\u8fd9\u4e0d\u610f\u5473\u7740 work_mem \u9650\u5236\u4e86\u8282\u70b9\u7684\u5168\u90e8\u5185\u5b58\u5206\u914d\u3002", "source_notes": []}, "tables": [{"key": "explain-labels", "rows": [{"label": "Materialize", "identity": "Materialize"}], "title": "\u672c\u6784\u5efa\u4e2d\u7684 EXPLAIN \u6807\u7b7e", "columns": [{"key": "label", "label": "\u6587\u672c\u683c\u5f0f\u6807\u7b7e"}, {"key": "identity", "label": "\u7ed3\u6784\u5316\u8282\u70b9\u6807\u8bc6"}]}], "related": [{"url": "/wiki/sql/explain/?v=18", "label": "EXPLAIN"}, {"url": "/docs/18/using-explain.html", "label": "\u4f7f\u7528 EXPLAIN"}, {"url": "/docs/18/parallel-plans.html", "label": "\u5e76\u884c\u8ba1\u5212"}, {"url": "/wiki/guc/enable_material/?v=18", "label": "enable_material"}, {"url": "/wiki/guc/work_mem/?v=18", "label": "work_mem"}], "release": {"ref": "PostgreSQL 18.6 source archive", "label": "18.6", "major": "18", "channel": "stable", "revision": "555610c24d53e4316da5b7d3fc25c279d96856d5e0e23ee308c328c5fa881d9f", "source_url": "https://ftp.postgresql.org/pub/source/v18.6/postgresql-18.6.tar.bz2", "source_snapshot_utc": ""}, "sources": [{"url": "https://ftp.postgresql.org/pub/source/v18.6/postgresql-18.6.tar.bz2", "line": 1516, "path": "src/backend/commands/explain.c", "label": "src/backend/commands/explain.c:1516", "sha256": "34c86d6070224a0e981efef51f79101d6d505e5874f1684ace183034bab14bb4", "archive_sha256": "555610c24d53e4316da5b7d3fc25c279d96856d5e0e23ee308c328c5fa881d9f"}, {"url": "https://ftp.postgresql.org/pub/source/v18.6/postgresql-18.6.tar.bz2", "line": 315, "path": "src/backend/executor/execProcnode.c", "label": "src/backend/executor/execProcnode.c:315", "sha256": "f8a06a3f539077249b20664b2812433db6d7bd12b2c0ca633525db43d06f112a", "archive_sha256": "555610c24d53e4316da5b7d3fc25c279d96856d5e0e23ee308c328c5fa881d9f"}, {"url": "https://ftp.postgresql.org/pub/source/v18.6/postgresql-18.6.tar.bz2", "path": "src/backend/executor/nodeMaterial.c", "label": "src/backend/executor/nodeMaterial.c", "sha256": "410b7129ca7e86ce3cf59ed7afed813fc6a47d68f5195e14df36559c75c7ef91", "archive_sha256": "555610c24d53e4316da5b7d3fc25c279d96856d5e0e23ee308c328c5fa881d9f"}, {"url": "https://ftp.postgresql.org/pub/source/v18.6/postgresql-18.6.tar.bz2", "path": "src/include/nodes/plannodes.h", "label": "src/include/nodes/plannodes.h", "sha256": "52422b327a8049fbbb20d8b96008a0fc0a6fafa60f7eff3c695d5b2e83830120", "archive_sha256": "555610c24d53e4316da5b7d3fc25c279d96856d5e0e23ee308c328c5fa881d9f"}, {"url": "https://ftp.postgresql.org/pub/source/v18.6/postgresql-18.6.tar.bz2", "path": "src/backend/utils/sort/tuplestore.c", "label": "src/backend/utils/sort/tuplestore.c", "sha256": "27a85416bafed557006c705ab5d0c5dce3d3c1702812bb54d136f2ac4c41055a", "archive_sha256": "555610c24d53e4316da5b7d3fc25c279d96856d5e0e23ee308c328c5fa881d9f"}, {"url": "https://pg.center/docs/18/using-explain.html#USING-EXPLAIN-BASICS", "path": "using-explain.html", "label": "PostgreSQL 18.6 \u00b7 using-explain", "sha256": "60040c30180093418a0affe56dd27dff9df2504b705b38039589e458bf5c31ed", "language": "en", "original_url": "/docs/18/using-explain.html#USING-EXPLAIN-BASICS"}], "node_tag": "T_Material", "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\uff1aMaterialize.", "\u5e76\u884c\u611f\u77e5\u4e0e\u5e76\u884c\u5b89\u5168\u662f\u4e0d\u540c\u7684\u8ba1\u5212\u5c5e\u6027\u3002\u5728\u5e76\u884c\u5de5\u4f5c\u8fdb\u7a0b\u5185\u8fd0\u884c\u7684\u8282\u70b9\u4e0d\u4e00\u5b9a\u662f\u5e76\u884c\u611f\u77e5\u8282\u70b9\u3002"]}, {"title": "\u5185\u5b58\u4e0e\u4e34\u65f6\u5b58\u50a8", "paragraphs": ["\u6b64\u8282\u70b9\u4f7f\u7528 work_mem \u521b\u5efa tuplestore\u3002tuplestore \u53ef\u4ee5\u5c06\u5b58\u50a8\u7684\u5143\u7ec4\u79fb\u5230\u4e34\u65f6\u6587\u4ef6\uff0c\u4f46\u8fd9\u4e0d\u610f\u5473\u7740 work_mem \u9650\u5236\u4e86\u8282\u70b9\u7684\u5168\u90e8\u5185\u5b58\u5206\u914d\u3002"]}, {"title": "\u5e76\u884c\u6267\u884c\u4e0e\u8fd0\u884c\u4fe1\u606f\u91c7\u96c6", "paragraphs": ["\u4ee5\u4e0b\u6e90\u7801\u56de\u8c03\u53ef\u4ee5\u534f\u8c03\u6267\u884c\u6216\u6536\u96c6\u5de5\u4f5c\u8fdb\u7a0b\u7684\u6d4b\u91cf\u6570\u636e\u3002\u56de\u8c03\u5b58\u5728\u4e0d\u4ee3\u8868\u8be5\u8282\u70b9\u666e\u904d\u652f\u6301\u5171\u4eab\u5e76\u884c\u626b\u63cf\u6216\u5171\u4eab\u72b6\u6001\u3002", "\u6b64\u6784\u5efa\u7684\u56de\u8c03\uff1anone extracted from this node implementation."]}, {"title": "\u540c\u7248\u672c\u624b\u518c\u8bf4\u660e", "paragraphs": ["\u89c4\u5212\u5668\u5728\u8fde\u63a5\u5185\u4fa7\u5173\u7cfb\u4e4b\u4e0a\u52a0\u5165 Materialize \u8282\u70b9\uff0c\u5c06\u5176\u7269\u5316\u3002\u56e0\u6b64\uff0c\u5c3d\u7ba1\u5d4c\u5957\u5faa\u73af\u8fde\u63a5\u9700\u8981\u4e3a\u5916\u4fa7\u7684\u6bcf\u4e00\u884c\u8bfb\u53d6\u4e00\u6b21\u5185\u4fa7\u6570\u636e\u3001\u5171\u5341\u6b21\uff0ct2 \u7684\u7d22\u5f15\u626b\u63cf\u4e5f\u53ea\u6267\u884c\u4e00\u6b21\u3002Materialize \u5728\u8bfb\u53d6\u65f6\u5c06\u6570\u636e\u4fdd\u5b58\u5728\u5185\u5b58\u4e2d\uff0c\u540e\u7eed\u5404\u8f6e\u76f4\u63a5\u4ece\u5185\u5b58\u8fd4\u56de\u6570\u636e\u3002"]}, {"title": "\u672c\u7248\u624b\u518c\u4e2d\u7684\u793a\u4f8b", "blocks": [{"code": "EXPLAIN SELECT *\nFROM tenk1 t1, tenk2 t2\nWHERE t1.unique1 < 10 AND t2.unique2 < 10 AND t1.hundred < t2.hundred;\n\n                                         QUERY PLAN\n---------------------------------------------------------------------------------------------\n Nested Loop  (cost=4.65..49.36 rows=33 width=488)\n   Join Filter: (t1.hundred < t2.hundred)\n   ->  Bitmap Heap Scan on tenk1 t1  (cost=4.36..39.38 rows=10 width=244)\n         Recheck Cond: (unique1 < 10)\n         ->  Bitmap Index Scan on tenk1_unique1  (cost=0.00..4.36 rows=10 width=0)\n               Index Cond: (unique1 < 10)\n   ->  Materialize  (cost=0.29..8.51 rows=10 width=244)\n         ->  Index Scan using tenk2_unique2 on tenk2 t2  (cost=0.29..8.46 rows=10 width=244)\n               Index Cond: (unique2 < 10)", "source": {"url": "/docs/18/using-explain.html#USING-EXPLAIN-BASICS", "path": "using-explain.html", "label": "PostgreSQL 18.6 \u00b7 using-explain", "sha256": "60040c30180093418a0affe56dd27dff9df2504b705b38039589e458bf5c31ed"}, "paragraphs": ["\u793a\u4f8b\u6458\u81ea PostgreSQL 18.6 \u624b\u518c\uff1b\u672c\u767e\u79d1\u672a\u5b9e\u9645\u6267\u884c\u6b64\u793a\u4f8b\u3002", "\u672c\u4f8b\u4e2d\uff0c\u8fde\u63a5\u7684\u8f93\u51fa\u884c\u6570\u7b49\u4e8e\u4e24\u6b21\u626b\u63cf\u884c\u6570\u7684\u4e58\u79ef\uff0c\u4f46\u5e76\u975e\u603b\u662f\u5982\u6b64\uff1a\u53ef\u80fd\u5b58\u5728\u540c\u65f6\u5f15\u7528\u4e24\u4e2a\u8868\u7684\u989d\u5916 WHERE \u5b50\u53e5\uff0c\u53ea\u80fd\u5728\u8fde\u63a5\u65f6\u5e94\u7528\uff0c\u65e0\u6cd5\u5e94\u7528\u5230\u4efb\u4f55\u5355\u4fa7\u8f93\u5165\u626b\u63cf\u3002\u793a\u4f8b\u5982\u4e0b\uff1a"]}]}, {"title": "\u6267\u884c\u5668\u5b9e\u73b0\u8bf4\u660e", "paragraphs": ["\u53ea\u8981\u5f53\u524d\u4f4d\u4e8e tuplestore \u5df2\u6536\u96c6\u6570\u636e\u7684\u672b\u5c3e\uff0c\u6bcf\u6b21\u8c03\u7528\u5c31\u4ece\u5b50\u8ba1\u5212\u83b7\u53d6\u4e00\u884c\u65b0\u6570\u636e\uff0c\u5728\u8fd4\u56de\u4e4b\u524d\u5c06\u5176\u5b58\u5165 tuplestore\u3002\u53ea\u6709\u8bf7\u6c42\u53cd\u5411\u626b\u63cf\u3001\u91cd\u626b\u6216\u6807\u8bb0\uff0f\u6062\u590d\u65f6\uff0c\u624d\u4ece tuplestore \u8bfb\u53d6\u3002", "\u9996\u6b21\u6267\u884c\u4e14\u9700\u8981\u5143\u7ec4\u5b58\u50a8\u65f6\uff0c\u521d\u59cb\u5316\u5b83\u3002", "\u5206\u914d\u7b2c\u4e8c\u4e2a\u8bfb\u53d6\u6307\u9488\u4f5c\u4e3a\u6807\u8bb0\u3002\u5df2\u77e5\u5176\u7d22\u5f15\u5fc5\u4e3a 1\uff0c\u56e0\u6b64\u65e0\u9700\u53e6\u884c\u4fdd\u5b58\u3002", "\u5982\u679c\u5c1a\u672a\u5230\u8fbe tuplestore \u672b\u5c3e\uff0c\u6216\u6b63\u5728\u53cd\u5411\u626b\u63cf\uff0c\u5219\u5c1d\u8bd5\u4ece tuplestore \u83b7\u53d6\u5143\u7ec4\u3002", "\u5728\u5143\u7ec4\u5b58\u50a8\u672b\u5c3e\u53cd\u8f6c\u626b\u63cf\u65b9\u5411\u65f6\uff0c\u7b2c\u4e00\u6b21 gettupleslot \u4f1a\u53d6\u5f97\u6700\u540e\u6dfb\u52a0\u7684\u5143\u7ec4\uff1b\u4f46\u82e5\u53ef\u80fd\uff0c\u6211\u4eec\u5e0c\u671b\u8fd4\u56de\u5b83\u4e4b\u524d\u7684\u90a3\u4e2a\uff0c\u56e0\u6b64\u989d\u5916\u8bfb\u53d6\u4e00\u6b21\u3002"]}, {"code": "case T_Material:\n\t\t\tpname = sname = \"Materialize\";\n\t\t\tbreak;", "title": "\u6838\u5fc3\u6e90\u7801\u4e2d\u7684 EXPLAIN \u6807\u8bc6"}], "strategies": [], "description": ["\u5b58\u50a8\u5b50\u8ba1\u5212\u8f93\u51fa\uff0c\u4ee5\u4fbf\u518d\u6b21\u8bfb\u53d6\u8fd9\u4e9b\u884c\u3002"], "localization": {"status": "complete", "sources": [], "language": "zh", "original_text": {"/versions/18/description/0": "Stores its child output so the rows can be read again.", "/versions/18/facts/0/label": "Core node tag", "/versions/18/facts/1/label": "Structured EXPLAIN Node Type", "/versions/18/facts/2/label": "Inputs", "/versions/18/facts/2/value": "One child plan", "/versions/18/facts/3/label": "Output", "/versions/18/facts/3/value": "Materialized tuples", "/versions/18/facts/4/label": "Executor initializer", "/versions/18/facts/5/label": "Memory mechanism", "/versions/18/tables/0/title": "EXPLAIN labels in this source build", "/versions/18/related/1/label": "Using EXPLAIN", "/versions/18/related/2/label": "Parallel plans", "/versions/18/sections/0/title": "EXPLAIN names and attributes", "/versions/18/sections/1/title": "Memory and temporary storage", "/versions/18/sections/2/title": "Parallel execution and instrumentation", "/versions/18/sections/3/title": "Same-version manual discussion", "/versions/18/sections/4/title": "Examples from this manual build", "/versions/18/sections/5/title": "Executor implementation notes", "/versions/18/sections/6/title": "EXPLAIN identity in core source", "/versions/18/memory/description": "This node creates a tuplestore with work_mem. The tuplestore can move stored tuples to temporary files; this does not make work_mem a cap on every allocation made by the node.", "/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: Materialize.", "/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 node creates a tuplestore with work_mem. The tuplestore can move stored tuples to temporary files; this does not make work_mem a cap on every allocation made by the node.", "/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": "Notice that here the planner has chosen to \u201c materialize \u201d the inner relation of the join, by putting a Materialize plan node atop it. This means that the t2 index scan will be done just once, even though the nested-loop join node needs to read that data ten times, once for each row from the outer relation. The Materialize node saves the data in memory as it's read, and then returns the data from memory on each subsequent pass.", "/versions/18/sections/5/paragraphs/0": "As long as we are at the end of the data collected in the tuplestore, we collect one new row from the subplan on each call, and stash it aside in the tuplestore before returning it. The tuplestore is only read if we are asked to scan backwards, rescan, or mark/restore.", "/versions/18/sections/5/paragraphs/1": "If first time through, and we need a tuplestore, initialize it.", "/versions/18/sections/5/paragraphs/2": "Allocate a second read pointer to serve as the mark. We know it must have index 1, so needn't store that.", "/versions/18/sections/5/paragraphs/3": "If we are not at the end of the tuplestore, or are going backwards, try to fetch a tuple from tuplestore.", "/versions/18/sections/5/paragraphs/4": "When reversing direction at tuplestore EOF, the first gettupleslot call will fetch the last-added tuple; but we want to return the one before that, if possible. So do an extra fetch.", "/versions/18/tables/0/columns/0/label": "Text-format label", "/versions/18/tables/0/columns/1/label": "Structured node identity", "/versions/18/sections/4/blocks/0/paragraphs/0": "Example copied from the PostgreSQL 18.6 manual; it was not executed for this collection.", "/versions/18/sections/4/blocks/0/paragraphs/1": "In this example the join's output row count is the same as the product of the two scans' row counts, but that's not true in all cases because there can be additional WHERE clauses that mention both tables and so can only be applied at the join point, not to either input scan. Here's an example:"}, "fallback_fields": [], "source_language": "en", "original_snapshot_sha256": "36a80e3c236de93a6ea0c0ef5c79a17982d69a3472ab22d748e6eb3e2f12f6e2"}, "evidence_kind": "source and documentation", "explain_names": ["Materialize"], "partial_modes": [], "comparison_data": {"node_tag": "T_Material", "strategies": [], "text_names": ["Materialize"], "initializer": "ExecInitMaterial", "partial_modes": [], "memory_mechanism": "tuplestore", "parallel_callbacks": []}, "comparison_hash": "c1d37bf334409fe6ded8ce560fe45fd495ff89ceda2808b6f5ef18daca520393", "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/nodeMaterial.c"}, "parallel_callbacks": []}, "comparison": {"left": "17", "right": "18", "status": "unchanged", "diff": ""}}