{"kind": "plan", "major": "18", "item": {"slug": "cte-scan", "name": "CTE Scan", "name_zh": "CteScan", "category": "\u626b\u63cf", "summary": "\u8bfb\u53d6\u516c\u5171\u8868\u8868\u8fbe\u5f0f\u8ba1\u5212\u7684\u5171\u4eab tuplestore\uff0c\u5fc5\u8981\u65f6\u8bf7\u6c42\u8be5\u8ba1\u5212\u4ea7\u751f\u66f4\u591a\u884c\u3002", "aliases": ["CTE Scan", "CteScan", "T_CteScan"], "content_hash": "618d4ecbcd2939991982113aa6549b7bcf4c88e4908d3e16c6473a089cab23be", "versions": {"10": {"facts": [{"label": "\u6838\u5fc3\u8282\u70b9\u6807\u7b7e", "value": "T_CteScan"}, {"label": "\u7ed3\u6784\u5316 EXPLAIN \u8282\u70b9\u7c7b\u578b", "value": "CTE Scan"}, {"label": "\u8f93\u5165", "value": "CTE \u6267\u884c\u8ba1\u5212\u53ca\u5171\u4eab\u7684 tuplestore"}, {"label": "\u8f93\u51fa", "value": "CTE \u7ed3\u679c\u5143\u7ec4"}, {"label": "\u6267\u884c\u5668\u521d\u59cb\u5316\u51fd\u6570", "value": "ExecInitCteScan"}, {"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/nodeCtescan.c", "label": "src/backend/executor/nodeCtescan.c", "sha256": "76539aff4782b2c3ee3a3bf3cbff825324ba22bd726030a924b4f2ec682b9f0f", "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": "CTE Scan", "identity": "CTE Scan"}], "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/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": "https://ftp.postgresql.org/pub/source/v10.23/postgresql-10.23.tar.bz2", "line": 971, "path": "src/backend/commands/explain.c", "label": "src/backend/commands/explain.c:971", "sha256": "a785298532047cfeda969e78c3597a343dc1c56d61ba85830b0f16a02a14b5a1", "archive_sha256": "94a4b2528372458e5662c18d406629266667c437198160a18cdfd2c4a4d6eee9"}, {"url": "https://ftp.postgresql.org/pub/source/v10.23/postgresql-10.23.tar.bz2", "line": 262, "path": "src/backend/executor/execProcnode.c", "label": "src/backend/executor/execProcnode.c:262", "sha256": "cea76648bb38ae55f18f989768bee1a4ee025691ceea0f86bccb29dcdc166acc", "archive_sha256": "94a4b2528372458e5662c18d406629266667c437198160a18cdfd2c4a4d6eee9"}, {"url": "https://ftp.postgresql.org/pub/source/v10.23/postgresql-10.23.tar.bz2", "path": "src/backend/executor/nodeCtescan.c", "label": "src/backend/executor/nodeCtescan.c", "sha256": "76539aff4782b2c3ee3a3bf3cbff825324ba22bd726030a924b4f2ec682b9f0f", "archive_sha256": "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"}], "node_tag": "T_CteScan", "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\uff1aCTE Scan.", "\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": "\u6267\u884c\u5668\u5b9e\u73b0\u8bf4\u660e", "paragraphs": ["\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", "\u82e5\u80fd\u4ece\u5143\u7ec4\u5b58\u50a8\u518d\u53d6\u5f97\u4e00\u4e2a\u5143\u7ec4\uff0c\u5219\u8fd4\u56de\u5b83\u3002", "\u6ce8\u610f\uff1a\u8c03\u7528 tuplestore_gettupleslot \u65f6\u5fc5\u987b\u4f7f\u7528 copy=true\uff0c\u56e0\u4e3a\u5176\u4ed6\u8282\u70b9\u5171\u4eab\u8be5\u5143\u7ec4\u5b58\u50a8\uff0c\u5e76\u53ef\u80fd\u5728\u4e0b\u6b21\u8c03\u7528\u4e4b\u524d\u5199\u5165\u5b83\u3002", "\u6ce8\u610f\uff1aeof_cte \u72b6\u6001\u53d8\u91cf\u7528\u4e8e\u907f\u514d\u7ee7\u7eed\u8c03\u7528 CTE \u8ba1\u5212\u3002\u9057\u61be\u7684\u662f\u5b83\u4e0d\u53ef\u7701\u7565\uff0c\u56e0\u4e3a\u67d0\u4e9b\u8ba1\u5212\u8282\u70b9\u5df2\u7ecf\u8fd4\u56de NULL \u540e\u82e5\u518d\u6b21\u88ab\u8c03\u7528\uff0c\u5e76\u4e0d\u80fd\u7a33\u5065\u5904\u7406\u3002"]}, {"code": "case T_CteScan:\n\t\t\tpname = sname = \"CTE Scan\";\n\t\t\tbreak;", "title": "\u6838\u5fc3\u6e90\u7801\u4e2d\u7684 EXPLAIN \u6807\u8bc6"}], "strategies": [], "description": ["\u8bfb\u53d6\u516c\u5171\u8868\u8868\u8fbe\u5f0f\u8ba1\u5212\u7684\u5171\u4eab tuplestore\uff0c\u5fc5\u8981\u65f6\u8bf7\u6c42\u8be5\u8ba1\u5212\u4ea7\u751f\u66f4\u591a\u884c\u3002"], "localization": {"status": "complete", "sources": [], "language": "zh", "original_text": {"/versions/10/description/0": "Reads the shared tuplestore of a common-table-expression plan, asking that plan for more rows when needed.", "/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": "A CTE plan and shared tuplestore", "/versions/10/facts/3/label": "Output", "/versions/10/facts/3/value": "CTE result 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": "Executor implementation notes", "/versions/10/sections/4/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: CTE Scan.", "/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": "If we are not at the end of the tuplestore, or are going backwards, try to fetch a tuple from tuplestore.", "/versions/10/sections/3/paragraphs/1": "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/sections/3/paragraphs/2": "If we can fetch another tuple from the tuplestore, return it.", "/versions/10/sections/3/paragraphs/3": "Note: we have to use copy=true in the tuplestore_gettupleslot call, because we are sharing the tuplestore with other nodes that might write into the tuplestore before we get called again.", "/versions/10/sections/3/paragraphs/4": "Note: the eof_cte state variable exists to short-circuit further calls of the CTE plan. It's not optional, unfortunately, because some plan node types are not robust about being called again when they've already returned NULL.", "/versions/10/tables/0/columns/0/label": "Text-format label", "/versions/10/tables/0/columns/1/label": "Structured node identity"}, "fallback_fields": [], "source_language": "en", "original_snapshot_sha256": "9c2f6929b6928af410b5a43a56525f2be1db7a6e2e5cda97e705bff21ba36713"}, "evidence_kind": "source and documentation", "explain_names": ["CTE Scan"], "partial_modes": [], "comparison_data": {"node_tag": "T_CteScan", "strategies": [], "text_names": ["CTE Scan"], "initializer": "ExecInitCteScan", "partial_modes": [], "memory_mechanism": "tuplestore", "parallel_callbacks": []}, "comparison_hash": "b99869b4fa614eb4c00675da9cf14c4d017018c55dbc2f0ea18d335cccb0a3aa", "explain_prefixes": ["Parallel"], "runtime_verified": false, "source_inventory": {"explain": "src/backend/commands/explain.c", "executor": "src/backend/executor/execProcnode.c", 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"\u7ed3\u6784\u5316\u8282\u70b9\u6807\u8bc6"}]}], "related": [{"url": "/wiki/sql/explain/?v=11", "label": "EXPLAIN"}, {"url": "/docs/11/using-explain.html", "label": "\u4f7f\u7528 EXPLAIN"}, {"url": "/docs/11/parallel-plans.html", "label": "\u5e76\u884c\u8ba1\u5212"}, {"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": 1096, "path": "src/backend/commands/explain.c", "label": "src/backend/commands/explain.c:1096", "sha256": "9df8400c1a4377179572ceb916d6020fca4e2760f74bf416d77ed97476523bbd", "archive_sha256": "2cb7c97d7a0d7278851bbc9c61f467b69c094c72b81740b751108e7892ebe1f0"}, {"url": "https://ftp.postgresql.org/pub/source/v11.22/postgresql-11.22.tar.bz2", "line": 262, "path": "src/backend/executor/execProcnode.c", "label": "src/backend/executor/execProcnode.c:262", "sha256": "95ef4d4a5df4c29f14af9763fae2c530449bdacdf3853d9ff297adf1fed6153b", "archive_sha256": "2cb7c97d7a0d7278851bbc9c61f467b69c094c72b81740b751108e7892ebe1f0"}, {"url": "https://ftp.postgresql.org/pub/source/v11.22/postgresql-11.22.tar.bz2", "path": "src/backend/executor/nodeCtescan.c", "label": "src/backend/executor/nodeCtescan.c", "sha256": "73f6fbda36cb2584110cfcf80fbe746dfbf7621bc0924697a8d24d64e859eb38", "archive_sha256": "2cb7c97d7a0d7278851bbc9c61f467b69c094c72b81740b751108e7892ebe1f0"}, {"url": "https://ftp.postgresql.org/pub/source/v11.22/postgresql-11.22.tar.bz2", "path": "src/include/nodes/plannodes.h", "label": "src/include/nodes/plannodes.h", "sha256": "5e0511194183800e8d6eb293fd4b40639c7d3118e2d199c8e7865ba4fa4cf67f", "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": "2cb7c97d7a0d7278851bbc9c61f467b69c094c72b81740b751108e7892ebe1f0"}], "node_tag": "T_CteScan", "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\uff1aCTE Scan.", "\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": "\u6267\u884c\u5668\u5b9e\u73b0\u8bf4\u660e", "paragraphs": ["\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", "\u82e5\u80fd\u4ece\u5143\u7ec4\u5b58\u50a8\u518d\u53d6\u5f97\u4e00\u4e2a\u5143\u7ec4\uff0c\u5219\u8fd4\u56de\u5b83\u3002", "\u6ce8\u610f\uff1a\u8c03\u7528 tuplestore_gettupleslot \u65f6\u5fc5\u987b\u4f7f\u7528 copy=true\uff0c\u56e0\u4e3a\u5176\u4ed6\u8282\u70b9\u5171\u4eab\u8be5\u5143\u7ec4\u5b58\u50a8\uff0c\u5e76\u53ef\u80fd\u5728\u4e0b\u6b21\u8c03\u7528\u4e4b\u524d\u5199\u5165\u5b83\u3002", "\u6ce8\u610f\uff1aeof_cte \u72b6\u6001\u53d8\u91cf\u7528\u4e8e\u907f\u514d\u7ee7\u7eed\u8c03\u7528 CTE \u8ba1\u5212\u3002\u9057\u61be\u7684\u662f\u5b83\u4e0d\u53ef\u7701\u7565\uff0c\u56e0\u4e3a\u67d0\u4e9b\u8ba1\u5212\u8282\u70b9\u5df2\u7ecf\u8fd4\u56de NULL \u540e\u82e5\u518d\u6b21\u88ab\u8c03\u7528\uff0c\u5e76\u4e0d\u80fd\u7a33\u5065\u5904\u7406\u3002"]}, {"code": "case T_CteScan:\n\t\t\tpname = sname = \"CTE Scan\";\n\t\t\tbreak;", "title": "\u6838\u5fc3\u6e90\u7801\u4e2d\u7684 EXPLAIN \u6807\u8bc6"}], "strategies": [], "description": ["\u8bfb\u53d6\u516c\u5171\u8868\u8868\u8fbe\u5f0f\u8ba1\u5212\u7684\u5171\u4eab tuplestore\uff0c\u5fc5\u8981\u65f6\u8bf7\u6c42\u8be5\u8ba1\u5212\u4ea7\u751f\u66f4\u591a\u884c\u3002"], "localization": {"status": "complete", "sources": [], "language": "zh", "original_text": {"/versions/11/description/0": "Reads the shared tuplestore of a common-table-expression plan, asking that plan for more rows when needed.", "/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": "A CTE plan and shared tuplestore", "/versions/11/facts/3/label": "Output", "/versions/11/facts/3/value": "CTE result tuples", "/versions/11/facts/4/label": "Executor initializer", "/versions/11/facts/5/label": "Memory mechanism", "/versions/11/tables/0/title": "EXPLAIN labels in this source build", "/versions/11/related/1/label": "Using EXPLAIN", "/versions/11/related/2/label": "Parallel plans", "/versions/11/sections/0/title": "EXPLAIN names and attributes", "/versions/11/sections/1/title": "Memory and temporary storage", "/versions/11/sections/2/title": "Parallel execution and instrumentation", "/versions/11/sections/3/title": "Executor implementation notes", "/versions/11/sections/4/title": "EXPLAIN identity in core source", "/versions/11/memory/description": "This 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: CTE Scan.", "/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": "If we are not at the end of the tuplestore, or are going backwards, try to fetch a tuple from tuplestore.", "/versions/11/sections/3/paragraphs/1": "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/sections/3/paragraphs/2": "If we can fetch another tuple from the tuplestore, return it.", "/versions/11/sections/3/paragraphs/3": "Note: we have to use copy=true in the tuplestore_gettupleslot call, because we are sharing the tuplestore with other nodes that might write into the tuplestore before we get called again.", "/versions/11/sections/3/paragraphs/4": "Note: the eof_cte state variable exists to short-circuit further calls of the CTE plan. It's not optional, unfortunately, because some plan node types are not robust about being called again when they've already returned NULL.", "/versions/11/tables/0/columns/0/label": "Text-format label", "/versions/11/tables/0/columns/1/label": "Structured node identity"}, "fallback_fields": [], "source_language": "en", "original_snapshot_sha256": "530dc69c6bad7794c312ebcf8e9b3486e1c0092476615ef21e5fb362c935ce57"}, "evidence_kind": "source and documentation", "explain_names": ["CTE Scan"], "partial_modes": [], "comparison_data": {"node_tag": "T_CteScan", "strategies": [], "text_names": ["CTE Scan"], "initializer": "ExecInitCteScan", "partial_modes": [], "memory_mechanism": "tuplestore", "parallel_callbacks": []}, "comparison_hash": "b99869b4fa614eb4c00675da9cf14c4d017018c55dbc2f0ea18d335cccb0a3aa", "explain_prefixes": ["Parallel"], "runtime_verified": false, "source_inventory": {"explain": "src/backend/commands/explain.c", "executor": "src/backend/executor/execProcnode.c", "implementation": "src/backend/executor/nodeCtescan.c"}, "parallel_callbacks": []}, "12": {"facts": [{"label": "\u6838\u5fc3\u8282\u70b9\u6807\u7b7e", "value": "T_CteScan"}, {"label": "\u7ed3\u6784\u5316 EXPLAIN \u8282\u70b9\u7c7b\u578b", "value": "CTE Scan"}, {"label": "\u8f93\u5165", "value": "CTE \u6267\u884c\u8ba1\u5212\u53ca\u5171\u4eab\u7684 tuplestore"}, {"label": "\u8f93\u51fa", "value": "CTE \u7ed3\u679c\u5143\u7ec4"}, {"label": "\u6267\u884c\u5668\u521d\u59cb\u5316\u51fd\u6570", "value": "ExecInitCteScan"}, {"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/nodeCtescan.c", "label": "src/backend/executor/nodeCtescan.c", "sha256": "b1c4e77ae9019fe1231099661b21bbb56a6dcade05f21a266786494fc86af1ab", "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": "8df3c0474782589d3c6f374b5133b1bd14d168086edbc13c6e72e67dd4527a3b"}], "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": "CTE Scan", "identity": "CTE Scan"}], "title": "\u672c\u6784\u5efa\u4e2d\u7684 EXPLAIN \u6807\u7b7e", "columns": [{"key": "label", "label": "\u6587\u672c\u683c\u5f0f\u6807\u7b7e"}, {"key": "identity", "label": "\u7ed3\u6784\u5316\u8282\u70b9\u6807\u8bc6"}]}], "related": [{"url": "/wiki/sql/explain/?v=12", "label": "EXPLAIN"}, {"url": "/docs/12/using-explain.html", "label": "\u4f7f\u7528 EXPLAIN"}, {"url": "/docs/12/parallel-plans.html", "label": "\u5e76\u884c\u8ba1\u5212"}, {"url": "/wiki/guc/work_mem/?v=12", "label": "work_mem"}], "release": {"ref": "PostgreSQL 12.22 source archive", "label": "12.22", "major": "12", "channel": "historical", "revision": "8df3c0474782589d3c6f374b5133b1bd14d168086edbc13c6e72e67dd4527a3b", "source_url": "https://ftp.postgresql.org/pub/source/v12.22/postgresql-12.22.tar.bz2", "source_snapshot_utc": ""}, "sources": [{"url": "https://ftp.postgresql.org/pub/source/v12.22/postgresql-12.22.tar.bz2", "line": 1167, "path": "src/backend/commands/explain.c", "label": "src/backend/commands/explain.c:1167", "sha256": "d02ea84fdaa201de5d9360645a9f24bfbd2c31f7d45a639e09560ac0e6b6471d", "archive_sha256": "8df3c0474782589d3c6f374b5133b1bd14d168086edbc13c6e72e67dd4527a3b"}, {"url": "https://ftp.postgresql.org/pub/source/v12.22/postgresql-12.22.tar.bz2", "line": 262, "path": "src/backend/executor/execProcnode.c", "label": "src/backend/executor/execProcnode.c:262", "sha256": "311b17379fe54e3f342fe5ad41c43afbdfa1b844978db2bb2eb22b82520d3256", "archive_sha256": "8df3c0474782589d3c6f374b5133b1bd14d168086edbc13c6e72e67dd4527a3b"}, {"url": "https://ftp.postgresql.org/pub/source/v12.22/postgresql-12.22.tar.bz2", "path": "src/backend/executor/nodeCtescan.c", "label": "src/backend/executor/nodeCtescan.c", "sha256": "b1c4e77ae9019fe1231099661b21bbb56a6dcade05f21a266786494fc86af1ab", "archive_sha256": "8df3c0474782589d3c6f374b5133b1bd14d168086edbc13c6e72e67dd4527a3b"}, {"url": "https://ftp.postgresql.org/pub/source/v12.22/postgresql-12.22.tar.bz2", "path": "src/include/nodes/plannodes.h", "label": "src/include/nodes/plannodes.h", "sha256": "b0c4a0aeb48660ce06e5e700d5529ca9066fd16682bd15783d6e71b5420b07b0", "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": "8df3c0474782589d3c6f374b5133b1bd14d168086edbc13c6e72e67dd4527a3b"}], "node_tag": "T_CteScan", "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\uff1aCTE Scan.", "\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": "\u6267\u884c\u5668\u5b9e\u73b0\u8bf4\u660e", "paragraphs": ["\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", "\u82e5\u80fd\u4ece\u5143\u7ec4\u5b58\u50a8\u518d\u53d6\u5f97\u4e00\u4e2a\u5143\u7ec4\uff0c\u5219\u8fd4\u56de\u5b83\u3002", "\u6ce8\u610f\uff1a\u8c03\u7528 tuplestore_gettupleslot \u65f6\u5fc5\u987b\u4f7f\u7528 copy=true\uff0c\u56e0\u4e3a\u5176\u4ed6\u8282\u70b9\u5171\u4eab\u8be5\u5143\u7ec4\u5b58\u50a8\uff0c\u5e76\u53ef\u80fd\u5728\u4e0b\u6b21\u8c03\u7528\u4e4b\u524d\u5199\u5165\u5b83\u3002", "\u6ce8\u610f\uff1aeof_cte \u72b6\u6001\u53d8\u91cf\u7528\u4e8e\u907f\u514d\u7ee7\u7eed\u8c03\u7528 CTE \u8ba1\u5212\u3002\u9057\u61be\u7684\u662f\u5b83\u4e0d\u53ef\u7701\u7565\uff0c\u56e0\u4e3a\u67d0\u4e9b\u8ba1\u5212\u8282\u70b9\u5df2\u7ecf\u8fd4\u56de NULL \u540e\u82e5\u518d\u6b21\u88ab\u8c03\u7528\uff0c\u5e76\u4e0d\u80fd\u7a33\u5065\u5904\u7406\u3002"]}, {"code": "case T_CteScan:\n\t\t\tpname = sname = \"CTE Scan\";\n\t\t\tbreak;", "title": "\u6838\u5fc3\u6e90\u7801\u4e2d\u7684 EXPLAIN \u6807\u8bc6"}], "strategies": [], "description": ["\u8bfb\u53d6\u516c\u5171\u8868\u8868\u8fbe\u5f0f\u8ba1\u5212\u7684\u5171\u4eab tuplestore\uff0c\u5fc5\u8981\u65f6\u8bf7\u6c42\u8be5\u8ba1\u5212\u4ea7\u751f\u66f4\u591a\u884c\u3002"], "localization": {"status": "complete", "sources": [], "language": "zh", "original_text": {"/versions/12/description/0": "Reads the shared tuplestore of a common-table-expression plan, asking that plan for more rows when needed.", "/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": "A CTE plan and shared tuplestore", "/versions/12/facts/3/label": "Output", "/versions/12/facts/3/value": "CTE result tuples", "/versions/12/facts/4/label": "Executor initializer", "/versions/12/facts/5/label": "Memory mechanism", "/versions/12/tables/0/title": "EXPLAIN labels in this source build", "/versions/12/related/1/label": "Using EXPLAIN", "/versions/12/related/2/label": "Parallel plans", "/versions/12/sections/0/title": "EXPLAIN names and attributes", "/versions/12/sections/1/title": "Memory and temporary storage", "/versions/12/sections/2/title": "Parallel execution and instrumentation", "/versions/12/sections/3/title": "Executor implementation notes", "/versions/12/sections/4/title": "EXPLAIN identity in core source", "/versions/12/memory/description": "This 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: CTE Scan.", "/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": "If we are not at the end of the tuplestore, or are going backwards, try to fetch a tuple from tuplestore.", "/versions/12/sections/3/paragraphs/1": "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/sections/3/paragraphs/2": "If we can fetch another tuple from the tuplestore, return it.", "/versions/12/sections/3/paragraphs/3": "Note: we have to use copy=true in the tuplestore_gettupleslot call, because we are sharing the tuplestore with other nodes that might write into the tuplestore before we get called again.", "/versions/12/sections/3/paragraphs/4": "Note: the eof_cte state variable exists to short-circuit further calls of the CTE plan. It's not optional, unfortunately, because some plan node types are not robust about being called again when they've already returned NULL.", "/versions/12/tables/0/columns/0/label": "Text-format label", "/versions/12/tables/0/columns/1/label": "Structured node identity"}, "fallback_fields": [], "source_language": "en", "original_snapshot_sha256": "66ad3da228dcd6afa8b3bc647ae504216f1347248887dc07b7008f803f363bb1"}, "evidence_kind": "source and documentation", "explain_names": ["CTE Scan"], "partial_modes": [], "comparison_data": {"node_tag": "T_CteScan", "strategies": [], "text_names": ["CTE Scan"], "initializer": "ExecInitCteScan", "partial_modes": [], "memory_mechanism": "tuplestore", "parallel_callbacks": []}, "comparison_hash": "b99869b4fa614eb4c00675da9cf14c4d017018c55dbc2f0ea18d335cccb0a3aa", "explain_prefixes": ["Parallel"], "runtime_verified": false, "source_inventory": {"explain": "src/backend/commands/explain.c", "executor": "src/backend/executor/execProcnode.c", "implementation": "src/backend/executor/nodeCtescan.c"}, "parallel_callbacks": []}, "13": {"facts": [{"label": "\u6838\u5fc3\u8282\u70b9\u6807\u7b7e", "value": "T_CteScan"}, {"label": "\u7ed3\u6784\u5316 EXPLAIN \u8282\u70b9\u7c7b\u578b", "value": "CTE Scan"}, {"label": "\u8f93\u5165", "value": "CTE \u6267\u884c\u8ba1\u5212\u53ca\u5171\u4eab\u7684 tuplestore"}, {"label": "\u8f93\u51fa", "value": "CTE \u7ed3\u679c\u5143\u7ec4"}, {"label": "\u6267\u884c\u5668\u521d\u59cb\u5316\u51fd\u6570", "value": "ExecInitCteScan"}, {"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/nodeCtescan.c", "label": "src/backend/executor/nodeCtescan.c", "sha256": "85c31c9845b3947381b9bbb91678b12390efaeea48ebda730f7b1e5e0783411a", "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": "6ec3c82726af92b7dec873fa1cdf881eca92a4219787dfad05acb6b10e041fd6"}], "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": "CTE Scan", "identity": "CTE Scan"}], "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=13", "label": "EXPLAIN"}, {"url": "/docs/13/using-explain.html", "label": "\u4f7f\u7528 EXPLAIN"}, {"url": "/docs/13/parallel-plans.html", "label": "\u5e76\u884c\u8ba1\u5212"}, {"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": 1225, "path": "src/backend/commands/explain.c", "label": "src/backend/commands/explain.c:1225", "sha256": "541713e0e7f1c9cc352c2b6028964d440c19d2678a4463000094c24a88c1e730", "archive_sha256": "6ec3c82726af92b7dec873fa1cdf881eca92a4219787dfad05acb6b10e041fd6"}, {"url": "https://ftp.postgresql.org/pub/source/v13.23/postgresql-13.23.tar.bz2", "line": 262, "path": "src/backend/executor/execProcnode.c", "label": "src/backend/executor/execProcnode.c:262", "sha256": "d085ee99acfa00587e6ade3a1d9f8108a0566beedbbee3f54a50c9fc0cc2e875", "archive_sha256": "6ec3c82726af92b7dec873fa1cdf881eca92a4219787dfad05acb6b10e041fd6"}, {"url": "https://ftp.postgresql.org/pub/source/v13.23/postgresql-13.23.tar.bz2", "path": "src/backend/executor/nodeCtescan.c", "label": "src/backend/executor/nodeCtescan.c", "sha256": "85c31c9845b3947381b9bbb91678b12390efaeea48ebda730f7b1e5e0783411a", "archive_sha256": "6ec3c82726af92b7dec873fa1cdf881eca92a4219787dfad05acb6b10e041fd6"}, {"url": "https://ftp.postgresql.org/pub/source/v13.23/postgresql-13.23.tar.bz2", "path": "src/include/nodes/plannodes.h", "label": "src/include/nodes/plannodes.h", "sha256": "dcb296833777b02008c4b6bae8e8f7c6423b7ffba21f36702597c9d596d039ab", "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": "6ec3c82726af92b7dec873fa1cdf881eca92a4219787dfad05acb6b10e041fd6"}], "node_tag": "T_CteScan", "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\uff1aCTE Scan.", "\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": "\u6267\u884c\u5668\u5b9e\u73b0\u8bf4\u660e", "paragraphs": ["\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", "\u82e5\u80fd\u4ece\u5143\u7ec4\u5b58\u50a8\u518d\u53d6\u5f97\u4e00\u4e2a\u5143\u7ec4\uff0c\u5219\u8fd4\u56de\u5b83\u3002", "\u6ce8\u610f\uff1a\u8c03\u7528 tuplestore_gettupleslot \u65f6\u5fc5\u987b\u4f7f\u7528 copy=true\uff0c\u56e0\u4e3a\u5176\u4ed6\u8282\u70b9\u5171\u4eab\u8be5\u5143\u7ec4\u5b58\u50a8\uff0c\u5e76\u53ef\u80fd\u5728\u4e0b\u6b21\u8c03\u7528\u4e4b\u524d\u5199\u5165\u5b83\u3002", "\u6ce8\u610f\uff1aeof_cte \u72b6\u6001\u53d8\u91cf\u7528\u4e8e\u907f\u514d\u7ee7\u7eed\u8c03\u7528 CTE \u8ba1\u5212\u3002\u9057\u61be\u7684\u662f\u5b83\u4e0d\u53ef\u7701\u7565\uff0c\u56e0\u4e3a\u67d0\u4e9b\u8ba1\u5212\u8282\u70b9\u5df2\u7ecf\u8fd4\u56de NULL \u540e\u82e5\u518d\u6b21\u88ab\u8c03\u7528\uff0c\u5e76\u4e0d\u80fd\u7a33\u5065\u5904\u7406\u3002"]}, {"code": "case T_CteScan:\n\t\t\tpname = sname = \"CTE Scan\";\n\t\t\tbreak;", "title": "\u6838\u5fc3\u6e90\u7801\u4e2d\u7684 EXPLAIN \u6807\u8bc6"}], "strategies": [], "description": ["\u8bfb\u53d6\u516c\u5171\u8868\u8868\u8fbe\u5f0f\u8ba1\u5212\u7684\u5171\u4eab tuplestore\uff0c\u5fc5\u8981\u65f6\u8bf7\u6c42\u8be5\u8ba1\u5212\u4ea7\u751f\u66f4\u591a\u884c\u3002"], "localization": {"status": "complete", "sources": [], "language": "zh", "original_text": {"/versions/13/description/0": "Reads the shared tuplestore of a common-table-expression plan, asking that plan for more rows when needed.", "/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": "A CTE plan and shared tuplestore", "/versions/13/facts/3/label": "Output", "/versions/13/facts/3/value": "CTE result tuples", "/versions/13/facts/4/label": "Executor initializer", "/versions/13/facts/5/label": "Memory mechanism", "/versions/13/tables/0/title": "EXPLAIN labels in this source build", "/versions/13/related/1/label": "Using EXPLAIN", "/versions/13/related/2/label": "Parallel plans", "/versions/13/sections/0/title": "EXPLAIN names and attributes", "/versions/13/sections/1/title": "Memory and temporary storage", "/versions/13/sections/2/title": "Parallel execution and instrumentation", "/versions/13/sections/3/title": "Executor implementation notes", "/versions/13/sections/4/title": "EXPLAIN identity in core source", "/versions/13/memory/description": "This 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: CTE Scan.", "/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": "If we are not at the end of the tuplestore, or are going backwards, try to fetch a tuple from tuplestore.", "/versions/13/sections/3/paragraphs/1": "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/sections/3/paragraphs/2": "If we can fetch another tuple from the tuplestore, return it.", "/versions/13/sections/3/paragraphs/3": "Note: we have to use copy=true in the tuplestore_gettupleslot call, because we are sharing the tuplestore with other nodes that might write into the tuplestore before we get called again.", "/versions/13/sections/3/paragraphs/4": "Note: the eof_cte state variable exists to short-circuit further calls of the CTE plan. It's not optional, unfortunately, because some plan node types are not robust about being called again when they've already returned NULL.", "/versions/13/tables/0/columns/0/label": "Text-format label", "/versions/13/tables/0/columns/1/label": "Structured node identity"}, "fallback_fields": [], "source_language": "en", "original_snapshot_sha256": "a0f2816a423583f83de75b94029816d1d0895b97086af05090604ce9a40c0c39"}, "evidence_kind": "source and documentation", "explain_names": ["CTE Scan"], "partial_modes": [], "comparison_data": {"node_tag": "T_CteScan", "strategies": [], "text_names": ["CTE Scan"], "initializer": "ExecInitCteScan", "partial_modes": [], "memory_mechanism": "tuplestore", "parallel_callbacks": []}, "comparison_hash": "b99869b4fa614eb4c00675da9cf14c4d017018c55dbc2f0ea18d335cccb0a3aa", "explain_prefixes": ["Parallel"], "runtime_verified": false, "source_inventory": {"explain": "src/backend/commands/explain.c", "executor": "src/backend/executor/execProcnode.c", "implementation": "src/backend/executor/nodeCtescan.c"}, "parallel_callbacks": []}, "14": {"facts": [{"label": "\u6838\u5fc3\u8282\u70b9\u6807\u7b7e", "value": "T_CteScan"}, {"label": "\u7ed3\u6784\u5316 EXPLAIN \u8282\u70b9\u7c7b\u578b", "value": "CTE Scan"}, {"label": "\u8f93\u5165", "value": "CTE \u6267\u884c\u8ba1\u5212\u53ca\u5171\u4eab\u7684 tuplestore"}, {"label": "\u8f93\u51fa", "value": "CTE \u7ed3\u679c\u5143\u7ec4"}, {"label": "\u6267\u884c\u5668\u521d\u59cb\u5316\u51fd\u6570", "value": "ExecInitCteScan"}, {"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/nodeCtescan.c", "label": "src/backend/executor/nodeCtescan.c", "sha256": "da1f7fed71edfdb58ca0f1be133173ec3253d22135916cf3ff61d1fdc60cfb77", "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": "a7fa7ed3d558172355f51406097a7bd4f6b473be80f311ef7cda96bf383d8897"}], "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": "CTE Scan", "identity": "CTE Scan"}], "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=14", "label": "EXPLAIN"}, {"url": "/docs/14/using-explain.html", "label": "\u4f7f\u7528 EXPLAIN"}, {"url": "/docs/14/parallel-plans.html", "label": "\u5e76\u884c\u8ba1\u5212"}, {"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": 1264, "path": "src/backend/commands/explain.c", "label": "src/backend/commands/explain.c:1264", "sha256": "e091be4e2a083b8dea39ccd09beedede22c1716ef974da66c214a44f48be8c41", "archive_sha256": "a7fa7ed3d558172355f51406097a7bd4f6b473be80f311ef7cda96bf383d8897"}, {"url": "https://ftp.postgresql.org/pub/source/v14.24/postgresql-14.24.tar.bz2", "line": 269, "path": "src/backend/executor/execProcnode.c", "label": "src/backend/executor/execProcnode.c:269", "sha256": "72da1c5ad457f1d92a39ab73531701794df858419e3b89d6e6cb7079634e68fa", "archive_sha256": "a7fa7ed3d558172355f51406097a7bd4f6b473be80f311ef7cda96bf383d8897"}, {"url": "https://ftp.postgresql.org/pub/source/v14.24/postgresql-14.24.tar.bz2", "path": "src/backend/executor/nodeCtescan.c", "label": "src/backend/executor/nodeCtescan.c", "sha256": "da1f7fed71edfdb58ca0f1be133173ec3253d22135916cf3ff61d1fdc60cfb77", "archive_sha256": "a7fa7ed3d558172355f51406097a7bd4f6b473be80f311ef7cda96bf383d8897"}, {"url": "https://ftp.postgresql.org/pub/source/v14.24/postgresql-14.24.tar.bz2", "path": "src/include/nodes/plannodes.h", "label": "src/include/nodes/plannodes.h", "sha256": "302f51a16b570dba7ec4e7bc045f7df5800d21630280354d1a24025f3baec75d", "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": "a7fa7ed3d558172355f51406097a7bd4f6b473be80f311ef7cda96bf383d8897"}], "node_tag": "T_CteScan", "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\uff1aCTE Scan.", "\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": "\u6267\u884c\u5668\u5b9e\u73b0\u8bf4\u660e", "paragraphs": ["\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", "\u82e5\u80fd\u4ece\u5143\u7ec4\u5b58\u50a8\u518d\u53d6\u5f97\u4e00\u4e2a\u5143\u7ec4\uff0c\u5219\u8fd4\u56de\u5b83\u3002", "\u6ce8\u610f\uff1a\u8c03\u7528 tuplestore_gettupleslot \u65f6\u5fc5\u987b\u4f7f\u7528 copy=true\uff0c\u56e0\u4e3a\u5176\u4ed6\u8282\u70b9\u5171\u4eab\u8be5\u5143\u7ec4\u5b58\u50a8\uff0c\u5e76\u53ef\u80fd\u5728\u4e0b\u6b21\u8c03\u7528\u4e4b\u524d\u5199\u5165\u5b83\u3002", "\u6ce8\u610f\uff1aeof_cte \u72b6\u6001\u53d8\u91cf\u7528\u4e8e\u907f\u514d\u7ee7\u7eed\u8c03\u7528 CTE \u8ba1\u5212\u3002\u9057\u61be\u7684\u662f\u5b83\u4e0d\u53ef\u7701\u7565\uff0c\u56e0\u4e3a\u67d0\u4e9b\u8ba1\u5212\u8282\u70b9\u5df2\u7ecf\u8fd4\u56de NULL \u540e\u82e5\u518d\u6b21\u88ab\u8c03\u7528\uff0c\u5e76\u4e0d\u80fd\u7a33\u5065\u5904\u7406\u3002"]}, {"code": "case T_CteScan:\n\t\t\tpname = sname = \"CTE Scan\";\n\t\t\tbreak;", "title": "\u6838\u5fc3\u6e90\u7801\u4e2d\u7684 EXPLAIN \u6807\u8bc6"}], "strategies": [], "description": ["\u8bfb\u53d6\u516c\u5171\u8868\u8868\u8fbe\u5f0f\u8ba1\u5212\u7684\u5171\u4eab tuplestore\uff0c\u5fc5\u8981\u65f6\u8bf7\u6c42\u8be5\u8ba1\u5212\u4ea7\u751f\u66f4\u591a\u884c\u3002"], "localization": {"status": "complete", "sources": [], "language": "zh", "original_text": {"/versions/14/description/0": "Reads the shared tuplestore of a common-table-expression plan, asking that plan for more rows when needed.", "/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": "A CTE plan and shared tuplestore", "/versions/14/facts/3/label": "Output", "/versions/14/facts/3/value": "CTE result 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": "Executor implementation notes", "/versions/14/sections/4/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: CTE Scan.", "/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": "If we are not at the end of the tuplestore, or are going backwards, try to fetch a tuple from tuplestore.", "/versions/14/sections/3/paragraphs/1": "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/sections/3/paragraphs/2": "If we can fetch another tuple from the tuplestore, return it.", "/versions/14/sections/3/paragraphs/3": "Note: we have to use copy=true in the tuplestore_gettupleslot call, because we are sharing the tuplestore with other nodes that might write into the tuplestore before we get called again.", "/versions/14/sections/3/paragraphs/4": "Note: the eof_cte state variable exists to short-circuit further calls of the CTE plan. It's not optional, unfortunately, because some plan node types are not robust about being called again when they've already returned NULL.", "/versions/14/tables/0/columns/0/label": "Text-format label", "/versions/14/tables/0/columns/1/label": "Structured node identity"}, "fallback_fields": [], "source_language": "en", "original_snapshot_sha256": "2a176cf9851289c40b8f0f6e85c0403a5860609816ca972f692d69b2377fcb66"}, "evidence_kind": "source and documentation", "explain_names": ["CTE Scan"], "partial_modes": [], "comparison_data": {"node_tag": "T_CteScan", "strategies": [], "text_names": ["CTE Scan"], "initializer": "ExecInitCteScan", "partial_modes": [], "memory_mechanism": "tuplestore", "parallel_callbacks": []}, "comparison_hash": "b99869b4fa614eb4c00675da9cf14c4d017018c55dbc2f0ea18d335cccb0a3aa", "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/nodeCtescan.c"}, "parallel_callbacks": []}, "15": {"facts": [{"label": "\u6838\u5fc3\u8282\u70b9\u6807\u7b7e", "value": "T_CteScan"}, {"label": "\u7ed3\u6784\u5316 EXPLAIN \u8282\u70b9\u7c7b\u578b", "value": "CTE Scan"}, {"label": "\u8f93\u5165", "value": "CTE \u6267\u884c\u8ba1\u5212\u53ca\u5171\u4eab\u7684 tuplestore"}, {"label": "\u8f93\u51fa", "value": "CTE \u7ed3\u679c\u5143\u7ec4"}, {"label": "\u6267\u884c\u5668\u521d\u59cb\u5316\u51fd\u6570", "value": "ExecInitCteScan"}, {"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/nodeCtescan.c", "label": "src/backend/executor/nodeCtescan.c", "sha256": "585e8d9566e2fa33c4339750f285bbff38815a4f03ddf8c5558c57447cc8aca4", "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": "e1a64a87a46b825b88c082e4518161a47aab53c45694964f8ba1df28f7859f89"}], "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": "CTE Scan", "identity": "CTE Scan"}], "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=15", "label": "EXPLAIN"}, {"url": "/docs/15/using-explain.html", "label": "\u4f7f\u7528 EXPLAIN"}, {"url": "/docs/15/parallel-plans.html", "label": "\u5e76\u884c\u8ba1\u5212"}, {"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": 1267, "path": "src/backend/commands/explain.c", "label": "src/backend/commands/explain.c:1267", "sha256": "bb3b442d0f1b098aa8707335250102f027a596cd94117308bd16d1d36b258f5c", "archive_sha256": "e1a64a87a46b825b88c082e4518161a47aab53c45694964f8ba1df28f7859f89"}, {"url": 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"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": "e1a64a87a46b825b88c082e4518161a47aab53c45694964f8ba1df28f7859f89"}], "node_tag": "T_CteScan", "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\uff1aCTE Scan.", "\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": "\u6267\u884c\u5668\u5b9e\u73b0\u8bf4\u660e", "paragraphs": ["\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", "\u82e5\u80fd\u4ece\u5143\u7ec4\u5b58\u50a8\u518d\u53d6\u5f97\u4e00\u4e2a\u5143\u7ec4\uff0c\u5219\u8fd4\u56de\u5b83\u3002", "\u6ce8\u610f\uff1a\u8c03\u7528 tuplestore_gettupleslot \u65f6\u5fc5\u987b\u4f7f\u7528 copy=true\uff0c\u56e0\u4e3a\u5176\u4ed6\u8282\u70b9\u5171\u4eab\u8be5\u5143\u7ec4\u5b58\u50a8\uff0c\u5e76\u53ef\u80fd\u5728\u4e0b\u6b21\u8c03\u7528\u4e4b\u524d\u5199\u5165\u5b83\u3002", "\u6ce8\u610f\uff1aeof_cte \u72b6\u6001\u53d8\u91cf\u7528\u4e8e\u907f\u514d\u7ee7\u7eed\u8c03\u7528 CTE \u8ba1\u5212\u3002\u9057\u61be\u7684\u662f\u5b83\u4e0d\u53ef\u7701\u7565\uff0c\u56e0\u4e3a\u67d0\u4e9b\u8ba1\u5212\u8282\u70b9\u5df2\u7ecf\u8fd4\u56de NULL \u540e\u82e5\u518d\u6b21\u88ab\u8c03\u7528\uff0c\u5e76\u4e0d\u80fd\u7a33\u5065\u5904\u7406\u3002"]}, {"code": "case T_CteScan:\n\t\t\tpname = sname = \"CTE Scan\";\n\t\t\tbreak;", "title": "\u6838\u5fc3\u6e90\u7801\u4e2d\u7684 EXPLAIN \u6807\u8bc6"}], "strategies": [], "description": ["\u8bfb\u53d6\u516c\u5171\u8868\u8868\u8fbe\u5f0f\u8ba1\u5212\u7684\u5171\u4eab tuplestore\uff0c\u5fc5\u8981\u65f6\u8bf7\u6c42\u8be5\u8ba1\u5212\u4ea7\u751f\u66f4\u591a\u884c\u3002"], "localization": {"status": "complete", "sources": [], "language": "zh", "original_text": {"/versions/15/description/0": "Reads the shared tuplestore of a common-table-expression plan, asking that plan for more rows when needed.", "/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": "A CTE plan and shared tuplestore", "/versions/15/facts/3/label": "Output", "/versions/15/facts/3/value": "CTE result tuples", "/versions/15/facts/4/label": "Executor initializer", "/versions/15/facts/5/label": "Memory mechanism", "/versions/15/tables/0/title": "EXPLAIN labels in this source build", "/versions/15/related/1/label": "Using EXPLAIN", "/versions/15/related/2/label": "Parallel plans", "/versions/15/sections/0/title": "EXPLAIN names and attributes", "/versions/15/sections/1/title": "Memory and temporary storage", "/versions/15/sections/2/title": "Parallel execution and instrumentation", "/versions/15/sections/3/title": "Executor implementation notes", "/versions/15/sections/4/title": "EXPLAIN identity in core source", "/versions/15/memory/description": "This 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: CTE Scan.", "/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": "If we are not at the end of the tuplestore, or are going backwards, try to fetch a tuple from tuplestore.", "/versions/15/sections/3/paragraphs/1": "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/sections/3/paragraphs/2": "If we can fetch another tuple from the tuplestore, return it.", "/versions/15/sections/3/paragraphs/3": "Note: we have to use copy=true in the tuplestore_gettupleslot call, because we are sharing the tuplestore with other nodes that might write into the tuplestore before we get called again.", "/versions/15/sections/3/paragraphs/4": "Note: the eof_cte state variable exists to short-circuit further calls of the CTE plan. It's not optional, unfortunately, because some plan node types are not robust about being called again when they've already returned NULL.", "/versions/15/tables/0/columns/0/label": "Text-format label", "/versions/15/tables/0/columns/1/label": "Structured node identity"}, "fallback_fields": [], "source_language": "en", "original_snapshot_sha256": "66d342d9d7a5b4b6b051eef6b21f4269192be4c7e4aac2aa8ec8afa23cdf5e6a"}, "evidence_kind": "source and documentation", "explain_names": ["CTE Scan"], "partial_modes": [], "comparison_data": {"node_tag": "T_CteScan", "strategies": [], "text_names": ["CTE Scan"], "initializer": "ExecInitCteScan", "partial_modes": [], "memory_mechanism": "tuplestore", "parallel_callbacks": []}, "comparison_hash": "b99869b4fa614eb4c00675da9cf14c4d017018c55dbc2f0ea18d335cccb0a3aa", "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/nodeCtescan.c"}, "parallel_callbacks": []}, "16": {"facts": [{"label": "\u6838\u5fc3\u8282\u70b9\u6807\u7b7e", "value": "T_CteScan"}, {"label": "\u7ed3\u6784\u5316 EXPLAIN \u8282\u70b9\u7c7b\u578b", "value": "CTE Scan"}, {"label": "\u8f93\u5165", "value": "CTE \u6267\u884c\u8ba1\u5212\u53ca\u5171\u4eab\u7684 tuplestore"}, {"label": "\u8f93\u51fa", "value": "CTE \u7ed3\u679c\u5143\u7ec4"}, {"label": "\u6267\u884c\u5668\u521d\u59cb\u5316\u51fd\u6570", "value": "ExecInitCteScan"}, {"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/nodeCtescan.c", "label": "src/backend/executor/nodeCtescan.c", "sha256": "7dbbb7d771920642c931327e7a14362ed0cea40b688d3011d522ac2ce0a6bb94", "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": "c1575341fa7bd40f5274ea465b34390f4dc64cdd0770af327005caaeb9f6b7ed"}], "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": "CTE Scan", "identity": "CTE Scan"}], "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=16", "label": "EXPLAIN"}, {"url": "/docs/16/using-explain.html", "label": "\u4f7f\u7528 EXPLAIN"}, {"url": "/docs/16/parallel-plans.html", "label": "\u5e76\u884c\u8ba1\u5212"}, {"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": 1300, "path": "src/backend/commands/explain.c", "label": "src/backend/commands/explain.c:1300", "sha256": "8e017f0116dbea471339b40c37a667cc9f95039e7e0329c783e5e8ce194de7e1", "archive_sha256": "c1575341fa7bd40f5274ea465b34390f4dc64cdd0770af327005caaeb9f6b7ed"}, {"url": "https://ftp.postgresql.org/pub/source/v16.15/postgresql-16.15.tar.bz2", "line": 269, "path": "src/backend/executor/execProcnode.c", "label": "src/backend/executor/execProcnode.c:269", "sha256": "e48c08e555f8cb4e4bb43df516c4b8906ce9bc374b2a745d98a1fc8c22cc5099", "archive_sha256": "c1575341fa7bd40f5274ea465b34390f4dc64cdd0770af327005caaeb9f6b7ed"}, {"url": "https://ftp.postgresql.org/pub/source/v16.15/postgresql-16.15.tar.bz2", "path": "src/backend/executor/nodeCtescan.c", "label": "src/backend/executor/nodeCtescan.c", "sha256": "7dbbb7d771920642c931327e7a14362ed0cea40b688d3011d522ac2ce0a6bb94", "archive_sha256": "c1575341fa7bd40f5274ea465b34390f4dc64cdd0770af327005caaeb9f6b7ed"}, {"url": "https://ftp.postgresql.org/pub/source/v16.15/postgresql-16.15.tar.bz2", "path": "src/include/nodes/plannodes.h", "label": "src/include/nodes/plannodes.h", "sha256": "97db47353db76326b874589a5ad0a04501cc74cd72e237e7bd956e7472c41f1f", "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": "c1575341fa7bd40f5274ea465b34390f4dc64cdd0770af327005caaeb9f6b7ed"}], "node_tag": "T_CteScan", "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\uff1aCTE Scan.", "\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": "\u6267\u884c\u5668\u5b9e\u73b0\u8bf4\u660e", "paragraphs": ["\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", "\u82e5\u80fd\u4ece\u5143\u7ec4\u5b58\u50a8\u518d\u53d6\u5f97\u4e00\u4e2a\u5143\u7ec4\uff0c\u5219\u8fd4\u56de\u5b83\u3002", "\u6ce8\u610f\uff1a\u8c03\u7528 tuplestore_gettupleslot \u65f6\u5fc5\u987b\u4f7f\u7528 copy=true\uff0c\u56e0\u4e3a\u5176\u4ed6\u8282\u70b9\u5171\u4eab\u8be5\u5143\u7ec4\u5b58\u50a8\uff0c\u5e76\u53ef\u80fd\u5728\u4e0b\u6b21\u8c03\u7528\u4e4b\u524d\u5199\u5165\u5b83\u3002", "\u6ce8\u610f\uff1aeof_cte \u72b6\u6001\u53d8\u91cf\u7528\u4e8e\u907f\u514d\u7ee7\u7eed\u8c03\u7528 CTE \u8ba1\u5212\u3002\u9057\u61be\u7684\u662f\u5b83\u4e0d\u53ef\u7701\u7565\uff0c\u56e0\u4e3a\u67d0\u4e9b\u8ba1\u5212\u8282\u70b9\u5df2\u7ecf\u8fd4\u56de NULL \u540e\u82e5\u518d\u6b21\u88ab\u8c03\u7528\uff0c\u5e76\u4e0d\u80fd\u7a33\u5065\u5904\u7406\u3002"]}, {"code": "case T_CteScan:\n\t\t\tpname = sname = \"CTE Scan\";\n\t\t\tbreak;", "title": "\u6838\u5fc3\u6e90\u7801\u4e2d\u7684 EXPLAIN \u6807\u8bc6"}], "strategies": [], "description": ["\u8bfb\u53d6\u516c\u5171\u8868\u8868\u8fbe\u5f0f\u8ba1\u5212\u7684\u5171\u4eab tuplestore\uff0c\u5fc5\u8981\u65f6\u8bf7\u6c42\u8be5\u8ba1\u5212\u4ea7\u751f\u66f4\u591a\u884c\u3002"], "localization": {"status": "complete", "sources": [], "language": "zh", "original_text": {"/versions/16/description/0": "Reads the shared tuplestore of a common-table-expression plan, asking that plan for more rows when needed.", "/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": "A CTE plan and shared tuplestore", "/versions/16/facts/3/label": "Output", "/versions/16/facts/3/value": "CTE result 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": "Executor implementation notes", "/versions/16/sections/4/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: CTE Scan.", "/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": "If we are not at the end of the tuplestore, or are going backwards, try to fetch a tuple from tuplestore.", "/versions/16/sections/3/paragraphs/1": "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/sections/3/paragraphs/2": "If we can fetch another tuple from the tuplestore, return it.", "/versions/16/sections/3/paragraphs/3": "Note: we have to use copy=true in the tuplestore_gettupleslot call, because we are sharing the tuplestore with other nodes that might write into the tuplestore before we get called again.", "/versions/16/sections/3/paragraphs/4": "Note: the eof_cte state variable exists to short-circuit further calls of the CTE plan. It's not optional, unfortunately, because some plan node types are not robust about being called again when they've already returned NULL.", "/versions/16/tables/0/columns/0/label": "Text-format label", "/versions/16/tables/0/columns/1/label": "Structured node identity"}, "fallback_fields": [], "source_language": "en", "original_snapshot_sha256": "8af63a780b7fdebcea8a79e0a912d5118f91ea334d0bbfce45607499dad34500"}, "evidence_kind": "source and documentation", "explain_names": ["CTE Scan"], "partial_modes": [], "comparison_data": {"node_tag": "T_CteScan", "strategies": [], "text_names": ["CTE Scan"], "initializer": "ExecInitCteScan", "partial_modes": [], "memory_mechanism": "tuplestore", "parallel_callbacks": []}, "comparison_hash": "b99869b4fa614eb4c00675da9cf14c4d017018c55dbc2f0ea18d335cccb0a3aa", "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/nodeCtescan.c"}, "parallel_callbacks": []}, "17": {"facts": [{"label": "\u6838\u5fc3\u8282\u70b9\u6807\u7b7e", "value": "T_CteScan"}, {"label": "\u7ed3\u6784\u5316 EXPLAIN \u8282\u70b9\u7c7b\u578b", "value": "CTE Scan"}, {"label": "\u8f93\u5165", "value": "CTE \u6267\u884c\u8ba1\u5212\u53ca\u5171\u4eab\u7684 tuplestore"}, {"label": "\u8f93\u51fa", "value": "CTE \u7ed3\u679c\u5143\u7ec4"}, {"label": "\u6267\u884c\u5668\u521d\u59cb\u5316\u51fd\u6570", "value": "ExecInitCteScan"}, {"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/nodeCtescan.c", "label": "src/backend/executor/nodeCtescan.c", "sha256": "19d5e7416c4d57b92f9e0c5c706079b00106a922f26be3f6c40346f5cc5a09b3", "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": "dd27f2b3c59e73ed14aa3324901242bf69a032a6347805f274e6260322d42979"}], "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": "CTE Scan", "identity": "CTE Scan"}], "title": "\u672c\u6784\u5efa\u4e2d\u7684 EXPLAIN \u6807\u7b7e", "columns": [{"key": "label", "label": "\u6587\u672c\u683c\u5f0f\u6807\u7b7e"}, {"key": "identity", "label": "\u7ed3\u6784\u5316\u8282\u70b9\u6807\u8bc6"}]}], "related": [{"url": "/wiki/sql/explain/?v=17", "label": "EXPLAIN"}, {"url": "/docs/17/using-explain.html", "label": "\u4f7f\u7528 EXPLAIN"}, {"url": "/docs/17/parallel-plans.html", "label": "\u5e76\u884c\u8ba1\u5212"}, {"url": "/wiki/guc/work_mem/?v=17", "label": "work_mem"}], "release": {"ref": "PostgreSQL 17.11 source archive", "label": "17.11", "major": "17", "channel": "stable", "revision": "dd27f2b3c59e73ed14aa3324901242bf69a032a6347805f274e6260322d42979", "source_url": "https://ftp.postgresql.org/pub/source/v17.11/postgresql-17.11.tar.bz2", "source_snapshot_utc": ""}, "sources": [{"url": "https://ftp.postgresql.org/pub/source/v17.11/postgresql-17.11.tar.bz2", "line": 1489, "path": "src/backend/commands/explain.c", "label": "src/backend/commands/explain.c:1489", "sha256": "741251b1a3b6d269a52a673d42eb63b02e13a5872db7b359b137086ab21b63c8", "archive_sha256": "dd27f2b3c59e73ed14aa3324901242bf69a032a6347805f274e6260322d42979"}, {"url": "https://ftp.postgresql.org/pub/source/v17.11/postgresql-17.11.tar.bz2", "line": 269, "path": "src/backend/executor/execProcnode.c", "label": "src/backend/executor/execProcnode.c:269", "sha256": "a77576e158b94cb01fa8c5174ba133004eabdd727660323f8afc66c8d2e757b8", "archive_sha256": "dd27f2b3c59e73ed14aa3324901242bf69a032a6347805f274e6260322d42979"}, {"url": "https://ftp.postgresql.org/pub/source/v17.11/postgresql-17.11.tar.bz2", "path": "src/backend/executor/nodeCtescan.c", "label": "src/backend/executor/nodeCtescan.c", "sha256": "19d5e7416c4d57b92f9e0c5c706079b00106a922f26be3f6c40346f5cc5a09b3", "archive_sha256": "dd27f2b3c59e73ed14aa3324901242bf69a032a6347805f274e6260322d42979"}, {"url": "https://ftp.postgresql.org/pub/source/v17.11/postgresql-17.11.tar.bz2", "path": "src/include/nodes/plannodes.h", "label": "src/include/nodes/plannodes.h", "sha256": "d390dd69e2d3f5085beb42b33e46ff0676a2959b916a12b82118a7e545f8e562", "archive_sha256": "dd27f2b3c59e73ed14aa3324901242bf69a032a6347805f274e6260322d42979"}, {"url": "https://ftp.postgresql.org/pub/source/v17.11/postgresql-17.11.tar.bz2", "path": "src/backend/utils/sort/tuplestore.c", "label": "src/backend/utils/sort/tuplestore.c", "sha256": "0d4316ed2d09288c2e3be15be1ce01b88622354bcd571ac7ebc45aa9319b90e7", "archive_sha256": "dd27f2b3c59e73ed14aa3324901242bf69a032a6347805f274e6260322d42979"}], "node_tag": "T_CteScan", "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\uff1aCTE Scan.", "\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": "\u6267\u884c\u5668\u5b9e\u73b0\u8bf4\u660e", "paragraphs": ["\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", "\u82e5\u80fd\u4ece\u5143\u7ec4\u5b58\u50a8\u518d\u53d6\u5f97\u4e00\u4e2a\u5143\u7ec4\uff0c\u5219\u8fd4\u56de\u5b83\u3002", "\u6ce8\u610f\uff1a\u8c03\u7528 tuplestore_gettupleslot \u65f6\u5fc5\u987b\u4f7f\u7528 copy=true\uff0c\u56e0\u4e3a\u5176\u4ed6\u8282\u70b9\u5171\u4eab\u8be5\u5143\u7ec4\u5b58\u50a8\uff0c\u5e76\u53ef\u80fd\u5728\u4e0b\u6b21\u8c03\u7528\u4e4b\u524d\u5199\u5165\u5b83\u3002", "\u6ce8\u610f\uff1aeof_cte \u72b6\u6001\u53d8\u91cf\u7528\u4e8e\u907f\u514d\u7ee7\u7eed\u8c03\u7528 CTE \u8ba1\u5212\u3002\u9057\u61be\u7684\u662f\u5b83\u4e0d\u53ef\u7701\u7565\uff0c\u56e0\u4e3a\u67d0\u4e9b\u8ba1\u5212\u8282\u70b9\u5df2\u7ecf\u8fd4\u56de NULL \u540e\u82e5\u518d\u6b21\u88ab\u8c03\u7528\uff0c\u5e76\u4e0d\u80fd\u7a33\u5065\u5904\u7406\u3002"]}, {"code": "case T_CteScan:\n\t\t\tpname = sname = \"CTE Scan\";\n\t\t\tbreak;", "title": "\u6838\u5fc3\u6e90\u7801\u4e2d\u7684 EXPLAIN \u6807\u8bc6"}], "strategies": [], "description": ["\u8bfb\u53d6\u516c\u5171\u8868\u8868\u8fbe\u5f0f\u8ba1\u5212\u7684\u5171\u4eab tuplestore\uff0c\u5fc5\u8981\u65f6\u8bf7\u6c42\u8be5\u8ba1\u5212\u4ea7\u751f\u66f4\u591a\u884c\u3002"], "localization": {"status": "complete", "sources": [], "language": "zh", "original_text": {"/versions/17/description/0": "Reads the shared tuplestore of a common-table-expression plan, asking that plan for more rows when needed.", "/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": "A CTE plan and shared tuplestore", "/versions/17/facts/3/label": "Output", "/versions/17/facts/3/value": "CTE result tuples", "/versions/17/facts/4/label": "Executor initializer", "/versions/17/facts/5/label": "Memory mechanism", "/versions/17/tables/0/title": "EXPLAIN labels in this source build", "/versions/17/related/1/label": "Using EXPLAIN", "/versions/17/related/2/label": "Parallel plans", "/versions/17/sections/0/title": "EXPLAIN names and attributes", "/versions/17/sections/1/title": "Memory and temporary storage", "/versions/17/sections/2/title": "Parallel execution and instrumentation", "/versions/17/sections/3/title": "Executor implementation notes", "/versions/17/sections/4/title": "EXPLAIN identity in core source", "/versions/17/memory/description": "This 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: CTE Scan.", "/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": "If we are not at the end of the tuplestore, or are going backwards, try to fetch a tuple from tuplestore.", "/versions/17/sections/3/paragraphs/1": "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/sections/3/paragraphs/2": "If we can fetch another tuple from the tuplestore, return it.", "/versions/17/sections/3/paragraphs/3": "Note: we have to use copy=true in the tuplestore_gettupleslot call, because we are sharing the tuplestore with other nodes that might write into the tuplestore before we get called again.", "/versions/17/sections/3/paragraphs/4": "Note: the eof_cte state variable exists to short-circuit further calls of the CTE plan. It's not optional, unfortunately, because some plan node types are not robust about being called again when they've already returned NULL.", "/versions/17/tables/0/columns/0/label": "Text-format label", "/versions/17/tables/0/columns/1/label": "Structured node identity"}, "fallback_fields": [], "source_language": "en", "original_snapshot_sha256": "d6c5e007e4944c557640fea05a1d4884e49e1d5d13711f08dcd653cb7aa1acf2"}, "evidence_kind": "source and documentation", "explain_names": ["CTE Scan"], "partial_modes": [], "comparison_data": {"node_tag": "T_CteScan", "strategies": [], "text_names": ["CTE Scan"], "initializer": "ExecInitCteScan", "partial_modes": [], "memory_mechanism": "tuplestore", "parallel_callbacks": []}, "comparison_hash": "b99869b4fa614eb4c00675da9cf14c4d017018c55dbc2f0ea18d335cccb0a3aa", "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/nodeCtescan.c"}, "parallel_callbacks": []}, "18": {"facts": [{"label": "\u6838\u5fc3\u8282\u70b9\u6807\u7b7e", "value": "T_CteScan"}, {"label": "\u7ed3\u6784\u5316 EXPLAIN \u8282\u70b9\u7c7b\u578b", "value": "CTE Scan"}, {"label": "\u8f93\u5165", "value": "CTE \u6267\u884c\u8ba1\u5212\u53ca\u5171\u4eab\u7684 tuplestore"}, {"label": "\u8f93\u51fa", "value": "CTE \u7ed3\u679c\u5143\u7ec4"}, {"label": "\u6267\u884c\u5668\u521d\u59cb\u5316\u51fd\u6570", "value": "ExecInitCteScan"}, {"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/nodeCtescan.c", "label": "src/backend/executor/nodeCtescan.c", "sha256": "63062406215ef682db58a20cb932ef30b83a6dca24557b625cf199d429fc8140", "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": "CTE Scan", "identity": "CTE Scan"}], "title": "\u672c\u6784\u5efa\u4e2d\u7684 EXPLAIN \u6807\u7b7e", "columns": [{"key": "label", "label": "\u6587\u672c\u683c\u5f0f\u6807\u7b7e"}, {"key": "identity", "label": "\u7ed3\u6784\u5316\u8282\u70b9\u6807\u8bc6"}]}], "related": [{"url": "/wiki/sql/explain/?v=18", "label": "EXPLAIN"}, {"url": "/docs/18/using-explain.html", "label": "\u4f7f\u7528 EXPLAIN"}, {"url": "/docs/18/parallel-plans.html", "label": "\u5e76\u884c\u8ba1\u5212"}, {"url": "/wiki/guc/work_mem/?v=18", "label": "work_mem"}], "release": {"ref": "PostgreSQL 18.6 source archive", "label": "18.6", "major": "18", "channel": "stable", "revision": "555610c24d53e4316da5b7d3fc25c279d96856d5e0e23ee308c328c5fa881d9f", "source_url": "https://ftp.postgresql.org/pub/source/v18.6/postgresql-18.6.tar.bz2", "source_snapshot_utc": ""}, "sources": [{"url": "https://ftp.postgresql.org/pub/source/v18.6/postgresql-18.6.tar.bz2", "line": 1474, "path": "src/backend/commands/explain.c", "label": "src/backend/commands/explain.c:1474", "sha256": "34c86d6070224a0e981efef51f79101d6d505e5874f1684ace183034bab14bb4", "archive_sha256": "555610c24d53e4316da5b7d3fc25c279d96856d5e0e23ee308c328c5fa881d9f"}, {"url": "https://ftp.postgresql.org/pub/source/v18.6/postgresql-18.6.tar.bz2", "line": 269, "path": "src/backend/executor/execProcnode.c", "label": "src/backend/executor/execProcnode.c:269", "sha256": "f8a06a3f539077249b20664b2812433db6d7bd12b2c0ca633525db43d06f112a", "archive_sha256": "555610c24d53e4316da5b7d3fc25c279d96856d5e0e23ee308c328c5fa881d9f"}, {"url": "https://ftp.postgresql.org/pub/source/v18.6/postgresql-18.6.tar.bz2", "path": "src/backend/executor/nodeCtescan.c", "label": "src/backend/executor/nodeCtescan.c", "sha256": "63062406215ef682db58a20cb932ef30b83a6dca24557b625cf199d429fc8140", "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"}], "node_tag": "T_CteScan", "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\uff1aCTE Scan.", "\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": "\u6267\u884c\u5668\u5b9e\u73b0\u8bf4\u660e", "paragraphs": ["\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", "\u82e5\u80fd\u4ece\u5143\u7ec4\u5b58\u50a8\u518d\u53d6\u5f97\u4e00\u4e2a\u5143\u7ec4\uff0c\u5219\u8fd4\u56de\u5b83\u3002", "\u6ce8\u610f\uff1a\u8c03\u7528 tuplestore_gettupleslot \u65f6\u5fc5\u987b\u4f7f\u7528 copy=true\uff0c\u56e0\u4e3a\u5176\u4ed6\u8282\u70b9\u5171\u4eab\u8be5\u5143\u7ec4\u5b58\u50a8\uff0c\u5e76\u53ef\u80fd\u5728\u4e0b\u6b21\u8c03\u7528\u4e4b\u524d\u5199\u5165\u5b83\u3002", "\u6ce8\u610f\uff1aeof_cte \u72b6\u6001\u53d8\u91cf\u7528\u4e8e\u907f\u514d\u7ee7\u7eed\u8c03\u7528 CTE \u8ba1\u5212\u3002\u9057\u61be\u7684\u662f\u5b83\u4e0d\u53ef\u7701\u7565\uff0c\u56e0\u4e3a\u67d0\u4e9b\u8ba1\u5212\u8282\u70b9\u5df2\u7ecf\u8fd4\u56de NULL \u540e\u82e5\u518d\u6b21\u88ab\u8c03\u7528\uff0c\u5e76\u4e0d\u80fd\u7a33\u5065\u5904\u7406\u3002"]}, {"code": "case T_CteScan:\n\t\t\tpname = sname = \"CTE Scan\";\n\t\t\tbreak;", "title": "\u6838\u5fc3\u6e90\u7801\u4e2d\u7684 EXPLAIN \u6807\u8bc6"}], "strategies": [], "description": ["\u8bfb\u53d6\u516c\u5171\u8868\u8868\u8fbe\u5f0f\u8ba1\u5212\u7684\u5171\u4eab tuplestore\uff0c\u5fc5\u8981\u65f6\u8bf7\u6c42\u8be5\u8ba1\u5212\u4ea7\u751f\u66f4\u591a\u884c\u3002"], "localization": {"status": "complete", "sources": [], "language": "zh", "original_text": {"/versions/18/description/0": "Reads the shared tuplestore of a common-table-expression plan, asking that plan for more rows when needed.", "/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": "A CTE plan and shared tuplestore", "/versions/18/facts/3/label": "Output", "/versions/18/facts/3/value": "CTE result 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": "Executor implementation notes", "/versions/18/sections/4/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: CTE Scan.", "/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": "If we are not at the end of the tuplestore, or are going backwards, try to fetch a tuple from tuplestore.", "/versions/18/sections/3/paragraphs/1": "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/sections/3/paragraphs/2": "If we can fetch another tuple from the tuplestore, return it.", "/versions/18/sections/3/paragraphs/3": "Note: we have to use copy=true in the tuplestore_gettupleslot call, because we are sharing the tuplestore with other nodes that might write into the tuplestore before we get called again.", "/versions/18/sections/3/paragraphs/4": "Note: the eof_cte state variable exists to short-circuit further calls of the CTE plan. It's not optional, unfortunately, because some plan node types are not robust about being called again when they've already returned NULL.", "/versions/18/tables/0/columns/0/label": "Text-format label", "/versions/18/tables/0/columns/1/label": "Structured node identity"}, "fallback_fields": [], "source_language": "en", "original_snapshot_sha256": "bac545fc08b3767952273b06e698dfa9acf7a2e8c5776945a6b104e56d235b6d"}, "evidence_kind": "source and documentation", "explain_names": ["CTE Scan"], "partial_modes": [], "comparison_data": {"node_tag": "T_CteScan", "strategies": [], "text_names": ["CTE Scan"], "initializer": "ExecInitCteScan", "partial_modes": [], "memory_mechanism": "tuplestore", "parallel_callbacks": []}, "comparison_hash": "b99869b4fa614eb4c00675da9cf14c4d017018c55dbc2f0ea18d335cccb0a3aa", "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/nodeCtescan.c"}, "parallel_callbacks": []}, "19": {"facts": [{"label": "\u6838\u5fc3\u8282\u70b9\u6807\u7b7e", "value": "T_CteScan"}, {"label": "\u7ed3\u6784\u5316 EXPLAIN \u8282\u70b9\u7c7b\u578b", "value": "CTE Scan"}, {"label": "\u8f93\u5165", "value": "CTE \u6267\u884c\u8ba1\u5212\u53ca\u5171\u4eab\u7684 tuplestore"}, {"label": "\u8f93\u51fa", "value": "CTE \u7ed3\u679c\u5143\u7ec4"}, {"label": "\u6267\u884c\u5668\u521d\u59cb\u5316\u51fd\u6570", "value": "ExecInitCteScan"}, {"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/nodeCtescan.c", "label": "src/backend/executor/nodeCtescan.c", "sha256": "8f2c49a856d16aab38cdb9bc9b3031bc943e2e7ef7d142efa7077e266f5f1650", "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": "83157ee9c599d03b2f7a3d73ef3a56ec24e0e79cc2b3501a64d1364f56398c86"}], "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": "CTE Scan", "identity": "CTE Scan"}], "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=19", "label": "EXPLAIN"}, {"url": "/docs/19/using-explain.html", "label": "\u4f7f\u7528 EXPLAIN"}, {"url": "/docs/19/parallel-plans.html", "label": "\u5e76\u884c\u8ba1\u5212"}, {"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": 1486, "path": "src/backend/commands/explain.c", "label": "src/backend/commands/explain.c:1486", "sha256": "8b115b1c194a4b54ae630209a741e293b1df49a9052f10b2de9ca092a48998e3", "archive_sha256": "83157ee9c599d03b2f7a3d73ef3a56ec24e0e79cc2b3501a64d1364f56398c86"}, {"url": "https://ftp.postgresql.org/pub/source/v19beta4/postgresql-19beta4.tar.bz2", "line": 269, "path": "src/backend/executor/execProcnode.c", "label": "src/backend/executor/execProcnode.c:269", "sha256": "5e39b2037bed672da55104229ecc32da5abde44c26bcad01479edcfa044d09ed", "archive_sha256": "83157ee9c599d03b2f7a3d73ef3a56ec24e0e79cc2b3501a64d1364f56398c86"}, {"url": "https://ftp.postgresql.org/pub/source/v19beta4/postgresql-19beta4.tar.bz2", "path": "src/backend/executor/nodeCtescan.c", "label": "src/backend/executor/nodeCtescan.c", "sha256": "8f2c49a856d16aab38cdb9bc9b3031bc943e2e7ef7d142efa7077e266f5f1650", "archive_sha256": "83157ee9c599d03b2f7a3d73ef3a56ec24e0e79cc2b3501a64d1364f56398c86"}, {"url": "https://ftp.postgresql.org/pub/source/v19beta4/postgresql-19beta4.tar.bz2", "path": "src/include/nodes/plannodes.h", "label": "src/include/nodes/plannodes.h", "sha256": "1c65d5d6b6c81c71531685843647869bcae630779d815a5036b06e070c6c06c7", "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": "83157ee9c599d03b2f7a3d73ef3a56ec24e0e79cc2b3501a64d1364f56398c86"}], "node_tag": "T_CteScan", "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\uff1aCTE Scan.", "\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": "\u6267\u884c\u5668\u5b9e\u73b0\u8bf4\u660e", "paragraphs": ["\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", "\u82e5\u80fd\u4ece\u5143\u7ec4\u5b58\u50a8\u518d\u53d6\u5f97\u4e00\u4e2a\u5143\u7ec4\uff0c\u5219\u8fd4\u56de\u5b83\u3002", "\u6ce8\u610f\uff1a\u8c03\u7528 tuplestore_gettupleslot \u65f6\u5fc5\u987b\u4f7f\u7528 copy=true\uff0c\u56e0\u4e3a\u5176\u4ed6\u8282\u70b9\u5171\u4eab\u8be5\u5143\u7ec4\u5b58\u50a8\uff0c\u5e76\u53ef\u80fd\u5728\u4e0b\u6b21\u8c03\u7528\u4e4b\u524d\u5199\u5165\u5b83\u3002", "\u6ce8\u610f\uff1aeof_cte \u72b6\u6001\u53d8\u91cf\u7528\u4e8e\u907f\u514d\u7ee7\u7eed\u8c03\u7528 CTE \u8ba1\u5212\u3002\u9057\u61be\u7684\u662f\u5b83\u4e0d\u53ef\u7701\u7565\uff0c\u56e0\u4e3a\u67d0\u4e9b\u8ba1\u5212\u8282\u70b9\u5df2\u7ecf\u8fd4\u56de NULL \u540e\u82e5\u518d\u6b21\u88ab\u8c03\u7528\uff0c\u5e76\u4e0d\u80fd\u7a33\u5065\u5904\u7406\u3002"]}, {"code": "case T_CteScan:\n\t\t\tpname = sname = \"CTE Scan\";\n\t\t\tbreak;", "title": "\u6838\u5fc3\u6e90\u7801\u4e2d\u7684 EXPLAIN \u6807\u8bc6"}], "strategies": [], "description": ["\u8bfb\u53d6\u516c\u5171\u8868\u8868\u8fbe\u5f0f\u8ba1\u5212\u7684\u5171\u4eab tuplestore\uff0c\u5fc5\u8981\u65f6\u8bf7\u6c42\u8be5\u8ba1\u5212\u4ea7\u751f\u66f4\u591a\u884c\u3002"], "localization": {"status": "complete", "sources": [], "language": "zh", "original_text": {"/versions/19/description/0": "Reads the shared tuplestore of a common-table-expression plan, asking that plan for more rows when needed.", "/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": "A CTE plan and shared tuplestore", "/versions/19/facts/3/label": "Output", "/versions/19/facts/3/value": "CTE result 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": "Executor implementation notes", "/versions/19/sections/4/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: CTE Scan.", "/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": "If we are not at the end of the tuplestore, or are going backwards, try to fetch a tuple from tuplestore.", "/versions/19/sections/3/paragraphs/1": "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/sections/3/paragraphs/2": "If we can fetch another tuple from the tuplestore, return it.", "/versions/19/sections/3/paragraphs/3": "Note: we have to use copy=true in the tuplestore_gettupleslot call, because we are sharing the tuplestore with other nodes that might write into the tuplestore before we get called again.", "/versions/19/sections/3/paragraphs/4": "Note: the eof_cte state variable exists to short-circuit further calls of the CTE plan. It's not optional, unfortunately, because some plan node types are not robust about being called again when they've already returned NULL.", "/versions/19/tables/0/columns/0/label": "Text-format label", "/versions/19/tables/0/columns/1/label": "Structured node identity"}, "fallback_fields": [], "source_language": "en", "original_snapshot_sha256": "db2140c1d870dc6f9a22d69e01294dec2b3dc907e52e1d2b7ffcd499b3317d18"}, "evidence_kind": "source and documentation", "explain_names": ["CTE Scan"], "partial_modes": [], "comparison_data": {"node_tag": "T_CteScan", "strategies": [], "text_names": ["CTE Scan"], "initializer": "ExecInitCteScan", "partial_modes": [], "memory_mechanism": "tuplestore", "parallel_callbacks": []}, "comparison_hash": "b99869b4fa614eb4c00675da9cf14c4d017018c55dbc2f0ea18d335cccb0a3aa", "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/nodeCtescan.c"}, "parallel_callbacks": []}, "20": {"facts": [{"label": "\u6838\u5fc3\u8282\u70b9\u6807\u7b7e", "value": "T_CteScan"}, {"label": "\u7ed3\u6784\u5316 EXPLAIN \u8282\u70b9\u7c7b\u578b", "value": "CTE Scan"}, {"label": "\u8f93\u5165", "value": "CTE \u6267\u884c\u8ba1\u5212\u53ca\u5171\u4eab\u7684 tuplestore"}, {"label": "\u8f93\u51fa", "value": "CTE \u7ed3\u679c\u5143\u7ec4"}, {"label": "\u6267\u884c\u5668\u521d\u59cb\u5316\u51fd\u6570", "value": "ExecInitCteScan"}, {"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/nodeCtescan.c", "label": "src/backend/executor/nodeCtescan.c", "sha256": "8f2c49a856d16aab38cdb9bc9b3031bc943e2e7ef7d142efa7077e266f5f1650", "archive_sha256": "4d3346909b201ac1648232cf290462a7070c119326f56196f1f0253ed80fae41"}, {"url": 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"7a94ed1652f0d74d50c39971d1cd3e8051dbc0d6058f31b6de71a433ca343521", "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": "4d3346909b201ac1648232cf290462a7070c119326f56196f1f0253ed80fae41"}], "node_tag": "T_CteScan", "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\uff1aCTE Scan.", "\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": "\u6267\u884c\u5668\u5b9e\u73b0\u8bf4\u660e", "paragraphs": ["\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", "\u82e5\u80fd\u4ece\u5143\u7ec4\u5b58\u50a8\u518d\u53d6\u5f97\u4e00\u4e2a\u5143\u7ec4\uff0c\u5219\u8fd4\u56de\u5b83\u3002", "\u6ce8\u610f\uff1a\u8c03\u7528 tuplestore_gettupleslot \u65f6\u5fc5\u987b\u4f7f\u7528 copy=true\uff0c\u56e0\u4e3a\u5176\u4ed6\u8282\u70b9\u5171\u4eab\u8be5\u5143\u7ec4\u5b58\u50a8\uff0c\u5e76\u53ef\u80fd\u5728\u4e0b\u6b21\u8c03\u7528\u4e4b\u524d\u5199\u5165\u5b83\u3002", "\u6ce8\u610f\uff1aeof_cte \u72b6\u6001\u53d8\u91cf\u7528\u4e8e\u907f\u514d\u7ee7\u7eed\u8c03\u7528 CTE \u8ba1\u5212\u3002\u9057\u61be\u7684\u662f\u5b83\u4e0d\u53ef\u7701\u7565\uff0c\u56e0\u4e3a\u67d0\u4e9b\u8ba1\u5212\u8282\u70b9\u5df2\u7ecf\u8fd4\u56de NULL \u540e\u82e5\u518d\u6b21\u88ab\u8c03\u7528\uff0c\u5e76\u4e0d\u80fd\u7a33\u5065\u5904\u7406\u3002"]}, {"code": "case T_CteScan:\n\t\t\tpname = sname = \"CTE Scan\";\n\t\t\tbreak;", "title": "\u6838\u5fc3\u6e90\u7801\u4e2d\u7684 EXPLAIN \u6807\u8bc6"}], "strategies": [], "description": ["\u8bfb\u53d6\u516c\u5171\u8868\u8868\u8fbe\u5f0f\u8ba1\u5212\u7684\u5171\u4eab tuplestore\uff0c\u5fc5\u8981\u65f6\u8bf7\u6c42\u8be5\u8ba1\u5212\u4ea7\u751f\u66f4\u591a\u884c\u3002"], "localization": {"status": "complete", "sources": [], "language": "zh", "original_text": {"/summary": "Reads the shared tuplestore of a common-table-expression plan, asking that plan for more rows when needed.", "/category": "Scan", "/versions/20/description/0": "Reads the shared tuplestore of a common-table-expression plan, asking that plan for more rows when needed.", "/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": "A CTE plan and shared tuplestore", "/versions/20/facts/3/label": "Output", "/versions/20/facts/3/value": "CTE result tuples", "/versions/20/facts/4/label": "Executor initializer", "/versions/20/facts/5/label": "Memory mechanism", "/versions/20/tables/0/title": "EXPLAIN labels in this source build", "/versions/20/related/1/label": "Using EXPLAIN", "/versions/20/related/2/label": "Parallel plans", "/versions/20/sections/0/title": "EXPLAIN names and attributes", "/versions/20/sections/1/title": "Memory and temporary storage", "/versions/20/sections/2/title": "Parallel execution and instrumentation", "/versions/20/sections/3/title": "Executor implementation notes", "/versions/20/sections/4/title": "EXPLAIN identity in core source", "/versions/20/memory/description": "This 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: CTE Scan.", "/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": "If we are not at the end of the tuplestore, or are going backwards, try to fetch a tuple from tuplestore.", "/versions/20/sections/3/paragraphs/1": "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/sections/3/paragraphs/2": "If we can fetch another tuple from the tuplestore, return it.", "/versions/20/sections/3/paragraphs/3": "Note: we have to use copy=true in the tuplestore_gettupleslot call, because we are sharing the tuplestore with other nodes that might write into the tuplestore before we get called again.", "/versions/20/sections/3/paragraphs/4": "Note: the eof_cte state variable exists to short-circuit further calls of the CTE plan. It's not optional, unfortunately, because some plan node types are not robust about being called again when they've already returned NULL.", "/versions/20/tables/0/columns/0/label": "Text-format label", "/versions/20/tables/0/columns/1/label": "Structured node identity"}, "fallback_fields": [], "source_language": "en", "original_snapshot_sha256": "14f5ec590b9f69bfc4ff34a654aff9b45c9d7eee68d3d61b3b7c4c5a88a1ead0"}, "evidence_kind": "source and documentation", "explain_names": ["CTE Scan"], "partial_modes": [], "comparison_data": {"node_tag": "T_CteScan", "strategies": [], "text_names": ["CTE Scan"], "initializer": "ExecInitCteScan", "partial_modes": [], "memory_mechanism": "tuplestore", "parallel_callbacks": []}, "comparison_hash": "b99869b4fa614eb4c00675da9cf14c4d017018c55dbc2f0ea18d335cccb0a3aa", "explain_prefixes": ["Parallel", "Async"], "runtime_verified": false, "source_inventory": {"explain": "src/backend/commands/explain.c", "executor": "src/backend/executor/execProcnode.c", 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"https://ftp.postgresql.org/pub/source/v18.6/postgresql-18.6.tar.bz2", "line": 269, "path": "src/backend/executor/execProcnode.c", "label": "src/backend/executor/execProcnode.c:269", "sha256": "f8a06a3f539077249b20664b2812433db6d7bd12b2c0ca633525db43d06f112a", "archive_sha256": "555610c24d53e4316da5b7d3fc25c279d96856d5e0e23ee308c328c5fa881d9f"}, {"url": "https://ftp.postgresql.org/pub/source/v18.6/postgresql-18.6.tar.bz2", "path": "src/backend/executor/nodeCtescan.c", "label": "src/backend/executor/nodeCtescan.c", "sha256": "63062406215ef682db58a20cb932ef30b83a6dca24557b625cf199d429fc8140", "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"}], "node_tag": "T_CteScan", "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\uff1aCTE Scan.", "\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": "\u6267\u884c\u5668\u5b9e\u73b0\u8bf4\u660e", "paragraphs": ["\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", "\u82e5\u80fd\u4ece\u5143\u7ec4\u5b58\u50a8\u518d\u53d6\u5f97\u4e00\u4e2a\u5143\u7ec4\uff0c\u5219\u8fd4\u56de\u5b83\u3002", "\u6ce8\u610f\uff1a\u8c03\u7528 tuplestore_gettupleslot \u65f6\u5fc5\u987b\u4f7f\u7528 copy=true\uff0c\u56e0\u4e3a\u5176\u4ed6\u8282\u70b9\u5171\u4eab\u8be5\u5143\u7ec4\u5b58\u50a8\uff0c\u5e76\u53ef\u80fd\u5728\u4e0b\u6b21\u8c03\u7528\u4e4b\u524d\u5199\u5165\u5b83\u3002", "\u6ce8\u610f\uff1aeof_cte \u72b6\u6001\u53d8\u91cf\u7528\u4e8e\u907f\u514d\u7ee7\u7eed\u8c03\u7528 CTE \u8ba1\u5212\u3002\u9057\u61be\u7684\u662f\u5b83\u4e0d\u53ef\u7701\u7565\uff0c\u56e0\u4e3a\u67d0\u4e9b\u8ba1\u5212\u8282\u70b9\u5df2\u7ecf\u8fd4\u56de NULL \u540e\u82e5\u518d\u6b21\u88ab\u8c03\u7528\uff0c\u5e76\u4e0d\u80fd\u7a33\u5065\u5904\u7406\u3002"]}, {"code": "case T_CteScan:\n\t\t\tpname = sname = \"CTE Scan\";\n\t\t\tbreak;", "title": "\u6838\u5fc3\u6e90\u7801\u4e2d\u7684 EXPLAIN \u6807\u8bc6"}], "strategies": [], "description": ["\u8bfb\u53d6\u516c\u5171\u8868\u8868\u8fbe\u5f0f\u8ba1\u5212\u7684\u5171\u4eab tuplestore\uff0c\u5fc5\u8981\u65f6\u8bf7\u6c42\u8be5\u8ba1\u5212\u4ea7\u751f\u66f4\u591a\u884c\u3002"], "localization": {"status": "complete", "sources": [], "language": "zh", "original_text": {"/versions/18/description/0": "Reads the shared tuplestore of a common-table-expression plan, asking that plan for more rows when needed.", "/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": "A CTE plan and shared tuplestore", "/versions/18/facts/3/label": "Output", "/versions/18/facts/3/value": "CTE result 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": "Executor implementation notes", "/versions/18/sections/4/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: CTE Scan.", "/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": "If we are not at the end of the tuplestore, or are going backwards, try to fetch a tuple from tuplestore.", "/versions/18/sections/3/paragraphs/1": "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/sections/3/paragraphs/2": "If we can fetch another tuple from the tuplestore, return it.", "/versions/18/sections/3/paragraphs/3": "Note: we have to use copy=true in the tuplestore_gettupleslot call, because we are sharing the tuplestore with other nodes that might write into the tuplestore before we get called again.", "/versions/18/sections/3/paragraphs/4": "Note: the eof_cte state variable exists to short-circuit further calls of the CTE plan. It's not optional, unfortunately, because some plan node types are not robust about being called again when they've already returned NULL.", "/versions/18/tables/0/columns/0/label": "Text-format label", "/versions/18/tables/0/columns/1/label": "Structured node identity"}, "fallback_fields": [], "source_language": "en", "original_snapshot_sha256": "bac545fc08b3767952273b06e698dfa9acf7a2e8c5776945a6b104e56d235b6d"}, "evidence_kind": "source and documentation", "explain_names": ["CTE Scan"], "partial_modes": [], "comparison_data": {"node_tag": "T_CteScan", "strategies": [], "text_names": ["CTE Scan"], "initializer": "ExecInitCteScan", "partial_modes": [], "memory_mechanism": "tuplestore", "parallel_callbacks": []}, "comparison_hash": "b99869b4fa614eb4c00675da9cf14c4d017018c55dbc2f0ea18d335cccb0a3aa", "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/nodeCtescan.c"}, "parallel_callbacks": []}, "comparison": {"left": "17", "right": "18", "status": "unchanged", "diff": ""}}