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Inspect the same-build implementation and its expressions or provider.", "source_notes": []}, "tables": [{"key": "explain-labels", "rows": [{"label": "Subquery Scan", "identity": "Subquery Scan"}], "title": "EXPLAIN labels in this source build", "columns": [{"key": "label", "label": "Text-format label"}, {"key": "identity", "label": "Structured node identity"}]}], "related": [{"url": "/wiki/sql/explain/?v=18", "label": "EXPLAIN"}, {"url": "/docs/18/using-explain.html", "label": "Using EXPLAIN"}, {"url": "/docs/18/parallel-plans.html", "label": "Parallel plans"}], "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": 1462, "path": "src/backend/commands/explain.c", "label": "src/backend/commands/explain.c:1462", "sha256": "34c86d6070224a0e981efef51f79101d6d505e5874f1684ace183034bab14bb4", "archive_sha256": "555610c24d53e4316da5b7d3fc25c279d96856d5e0e23ee308c328c5fa881d9f"}, {"url": "https://ftp.postgresql.org/pub/source/v18.6/postgresql-18.6.tar.bz2", "line": 249, "path": "src/backend/executor/execProcnode.c", "label": "src/backend/executor/execProcnode.c:249", "sha256": "f8a06a3f539077249b20664b2812433db6d7bd12b2c0ca633525db43d06f112a", "archive_sha256": "555610c24d53e4316da5b7d3fc25c279d96856d5e0e23ee308c328c5fa881d9f"}, {"url": "https://ftp.postgresql.org/pub/source/v18.6/postgresql-18.6.tar.bz2", "path": "src/backend/executor/nodeSubqueryscan.c", "label": "src/backend/executor/nodeSubqueryscan.c", "sha256": "9e5a1653e5b1678c457026f940a36bb2927cbfb1fa1f6a6a296e1bd1453ef29b", "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"}], "node_tag": "T_SubqueryScan", "sections": [{"title": "EXPLAIN names and attributes", "paragraphs": ["Structured formats use the Node Type above. Text-format spellings can also include operation, strategy, join type, scan direction or aggregation-stage attributes.", "Text names recorded by this source: Subquery Scan.", "Parallel-aware and parallel-safe are different plan properties. A node running inside a parallel worker is not necessarily a parallel-aware node."]}, {"title": "Memory and temporary storage", "paragraphs": ["This extraction does not assign a universal memory limit or spill policy to this node. Inspect the same-build implementation and its expressions or provider."]}, {"title": "Parallel execution and instrumentation", "paragraphs": ["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.", "Callbacks in this build: none extracted from this node implementation."]}, {"title": "Executor implementation notes", "paragraphs": ["nodeSubqueryscan.c Support routines for scanning subqueries (subselects in rangetable).", "This is just enough different from sublinks (nodeSubplan.c) to mean that we need two sets of code. Ought to look at trying to unify the cases.", "We just return the subplan's result slot, rather than expending extra cycles for ExecCopySlot(). (Our own ScanTupleSlot is used only for EvalPlanQual rechecks.)", "SubqueryRecheck -- access method routine to recheck a tuple in EvalPlanQual", "Scans the subquery sequentially and returns the next qualifying tuple. We call the ExecScan() routine and pass it the appropriate access method functions."]}, {"code": "case T_SubqueryScan:\n\t\t\tpname = sname = \"Subquery Scan\";\n\t\t\tbreak;", "title": "EXPLAIN identity in core source"}], "strategies": [], "description": ["Scans the output of a subquery plan."], "evidence_kind": "source and documentation", "explain_names": ["Subquery Scan"], "partial_modes": [], "comparison_data": {"node_tag": "T_SubqueryScan", "strategies": [], "text_names": ["Subquery Scan"], "initializer": "ExecInitSubqueryScan", "partial_modes": [], "memory_mechanism": "unclassified", "parallel_callbacks": []}, "comparison_hash": "2c67fdef6b55d5dfeedc05274c332f8e523a7b8dd3ffef1c7cb79b9d6d33566f", "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/nodeSubqueryscan.c"}, "parallel_callbacks": []}, "comparison": {"left": "17", "right": "18", "status": "unchanged", "diff": ""}}