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Text-format spellings can also include operation, strategy, join type, scan direction or aggregation-stage attributes.", "Text names recorded by this source: Bitmap Index 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": ["The node allocates a tuple-location bitmap using a work_mem-derived budget. A bitmap can retain page-level lossy entries instead of every tuple location; heap rechecks then remain necessary."]}, {"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": "Examples from this manual build", "blocks": [{"code": "EXPLAIN SELECT * FROM tenk1 WHERE unique1 < 100;\n\n                                  QUERY PLAN\n------------------------------------------------------------------------------\n Bitmap Heap Scan on tenk1  (cost=5.07..229.20 rows=101 width=244)\n   Recheck Cond: (unique1 < 100)\n   ->  Bitmap Index Scan on tenk1_unique1  (cost=0.00..5.04 rows=101 width=0)\n         Index Cond: (unique1 < 100)", "source": {"url": "/docs/10/using-explain.html#USING-EXPLAIN-BASICS", "path": "using-explain.html", "label": "PostgreSQL 10.23 \u00b7 using-explain", "sha256": "a4b4304aedb0a2da0145cc7c35b03b319a5c7ee3df35a8ef84ab6d3a610f98f3"}, "paragraphs": ["Example copied from the PostgreSQL 10.23 manual; it was not executed for this collection.", "Now, let's make the condition more restrictive:"]}, {"code": "EXPLAIN SELECT * FROM tenk1 WHERE unique1 < 100 AND stringu1 = 'xxx';\n\n                                  QUERY PLAN\n------------------------------------------------------------------------------\n Bitmap Heap Scan on tenk1  (cost=5.04..229.43 rows=1 width=244)\n   Recheck Cond: (unique1 < 100)\n   Filter: (stringu1 = 'xxx'::name)\n   ->  Bitmap Index Scan on tenk1_unique1  (cost=0.00..5.04 rows=101 width=0)\n         Index Cond: (unique1 < 100)", "source": {"url": "/docs/10/using-explain.html#USING-EXPLAIN-BASICS", "path": "using-explain.html", "label": "PostgreSQL 10.23 \u00b7 using-explain", "sha256": "a4b4304aedb0a2da0145cc7c35b03b319a5c7ee3df35a8ef84ab6d3a610f98f3"}, "paragraphs": ["Example copied from the PostgreSQL 10.23 manual; it was not executed for this collection.", "Now let's add another condition to the WHERE clause:"]}]}, {"title": "Executor implementation notes", "paragraphs": ["nodeBitmapIndexscan.c Routines to support bitmapped index scans of relations", "If we have runtime keys and they've not already been set up, do it now. Array keys are also treated as runtime keys; note that if ExecReScan returns with biss_RuntimeKeysReady still false, then there is an empty array key so we should do nothing.", "Prepare the result bitmap. Normally we just create a new one to pass back; however, our parent node is allowed to store a pre-made one into node->biss_result, in which case we just OR our tuple IDs into the existing bitmap. (This saves needing explicit UNION steps.)", "Recalculates the values of any scan keys whose value depends on information known at runtime, then rescans the indexed relation.", "Reset the runtime-key context so we don't leak memory as each outer tuple is scanned. Note this assumes that we will recalculate *all* runtime keys on each call."]}, {"code": "case T_BitmapIndexScan:\n\t\t\tpname = sname = \"Bitmap Index Scan\";\n\t\t\tbreak;", "title": "EXPLAIN identity in core source"}], "strategies": [], "description": ["Scans an index and produces a bitmap of matching tuple locations."], "evidence_kind": "source and documentation", "explain_names": ["Bitmap Index Scan"], "partial_modes": [], "comparison_data": {"node_tag": "T_BitmapIndexScan", "strategies": [], "text_names": ["Bitmap Index Scan"], "initializer": "ExecInitBitmapIndexScan", "partial_modes": [], "memory_mechanism": "bitmap-lossification", "parallel_callbacks": []}, "comparison_hash": "b81114c9864c11cc43d2183d9c32e01632186cff8cced0f6ff218f56f56485c0", "explain_prefixes": ["Parallel"], "runtime_verified": false, "source_inventory": {"explain": "src/backend/commands/explain.c", "executor": "src/backend/executor/execProcnode.c", "implementation": "src/backend/executor/nodeBitmapIndexscan.c"}, "parallel_callbacks": []}, "11": {"facts": [{"label": "Core node tag", "value": "T_BitmapIndexScan"}, {"label": "Structured EXPLAIN Node Type", "value": "Bitmap Index Scan"}, {"label": "Inputs", "value": "An index"}, {"label": "Output", "value": "Tuple-location bitmap, not a tuple stream"}, {"label": "Executor initializer", "value": "ExecInitBitmapIndexScan"}, {"label": "Memory mechanism", "value": "bitmap-lossification"}], "memory": {"evidence": [{"url": "https://ftp.postgresql.org/pub/source/v11.22/postgresql-11.22.tar.bz2", "path": "src/backend/executor/nodeBitmapIndexscan.c", "label": "src/backend/executor/nodeBitmapIndexscan.c", "sha256": "181aa05754bb5e78dc6e3dca3e202c115ae152e237511ac01e048514a8036ded", "archive_sha256": "2cb7c97d7a0d7278851bbc9c61f467b69c094c72b81740b751108e7892ebe1f0"}, {"url": "https://ftp.postgresql.org/pub/source/v11.22/postgresql-11.22.tar.bz2", "path": "src/backend/nodes/tidbitmap.c", "label": "src/backend/nodes/tidbitmap.c", "sha256": "a47e915ced1ae75d21b8d7b7b67ae09c4bf230069208aa5d9f5b6c2ca6ae85d1", "archive_sha256": "2cb7c97d7a0d7278851bbc9c61f467b69c094c72b81740b751108e7892ebe1f0"}], "mechanism": "bitmap-lossification", "description": "The node allocates a tuple-location bitmap using a work_mem-derived budget. A bitmap can retain page-level lossy entries instead of every tuple location; heap rechecks then remain necessary.", "source_notes": []}, "tables": [{"key": "explain-labels", "rows": [{"label": "Bitmap Index Scan", "identity": "Bitmap Index 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=11", "label": "EXPLAIN"}, {"url": "/docs/11/using-explain.html", "label": "Using EXPLAIN"}, {"url": "/docs/11/parallel-plans.html", "label": "Parallel plans"}, {"url": "/wiki/guc/enable_bitmapscan/?v=11", "label": "enable_bitmapscan"}, {"url": "/wiki/guc/work_mem/?v=11", "label": "work_mem"}, {"url": "/wiki/indexam/?v=11", "label": "Index AM"}], "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": 1075, "path": "src/backend/commands/explain.c", "label": "src/backend/commands/explain.c:1075", "sha256": "9df8400c1a4377179572ceb916d6020fca4e2760f74bf416d77ed97476523bbd", "archive_sha256": "2cb7c97d7a0d7278851bbc9c61f467b69c094c72b81740b751108e7892ebe1f0"}, {"url": "https://ftp.postgresql.org/pub/source/v11.22/postgresql-11.22.tar.bz2", "line": 227, "path": "src/backend/executor/execProcnode.c", "label": "src/backend/executor/execProcnode.c:227", "sha256": "95ef4d4a5df4c29f14af9763fae2c530449bdacdf3853d9ff297adf1fed6153b", "archive_sha256": "2cb7c97d7a0d7278851bbc9c61f467b69c094c72b81740b751108e7892ebe1f0"}, {"url": "https://ftp.postgresql.org/pub/source/v11.22/postgresql-11.22.tar.bz2", "path": "src/backend/executor/nodeBitmapIndexscan.c", "label": "src/backend/executor/nodeBitmapIndexscan.c", "sha256": "181aa05754bb5e78dc6e3dca3e202c115ae152e237511ac01e048514a8036ded", "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/nodes/tidbitmap.c", "label": "src/backend/nodes/tidbitmap.c", "sha256": "a47e915ced1ae75d21b8d7b7b67ae09c4bf230069208aa5d9f5b6c2ca6ae85d1", "archive_sha256": "2cb7c97d7a0d7278851bbc9c61f467b69c094c72b81740b751108e7892ebe1f0"}, {"url": "/docs/11/using-explain.html#USING-EXPLAIN-BASICS", "path": "using-explain.html", "label": "PostgreSQL 11.22 \u00b7 using-explain", "sha256": "8411bc78085d4737e32d7cca103d859da6c6539e33ec5e2fba46e74c6f199d8a"}], "node_tag": "T_BitmapIndexScan", "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: Bitmap Index 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": ["The node allocates a tuple-location bitmap using a work_mem-derived budget. A bitmap can retain page-level lossy entries instead of every tuple location; heap rechecks then remain necessary."]}, {"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": "Examples from this manual build", "blocks": [{"code": "EXPLAIN SELECT * FROM tenk1 WHERE unique1 < 100;\n\n                                  QUERY PLAN\n------------------------------------------------------------------------------\n Bitmap Heap Scan on tenk1  (cost=5.07..229.20 rows=101 width=244)\n   Recheck Cond: (unique1 < 100)\n   ->  Bitmap Index Scan on tenk1_unique1  (cost=0.00..5.04 rows=101 width=0)\n         Index Cond: (unique1 < 100)", "source": {"url": "/docs/11/using-explain.html#USING-EXPLAIN-BASICS", "path": "using-explain.html", "label": "PostgreSQL 11.22 \u00b7 using-explain", "sha256": "8411bc78085d4737e32d7cca103d859da6c6539e33ec5e2fba46e74c6f199d8a"}, "paragraphs": ["Example copied from the PostgreSQL 11.22 manual; it was not executed for this collection.", "Now, let's make the condition more restrictive:"]}, {"code": "EXPLAIN SELECT * FROM tenk1 WHERE unique1 < 100 AND stringu1 = 'xxx';\n\n                                  QUERY PLAN\n------------------------------------------------------------------------------\n Bitmap Heap Scan on tenk1  (cost=5.04..229.43 rows=1 width=244)\n   Recheck Cond: (unique1 < 100)\n   Filter: (stringu1 = 'xxx'::name)\n   ->  Bitmap Index Scan on tenk1_unique1  (cost=0.00..5.04 rows=101 width=0)\n         Index Cond: (unique1 < 100)", "source": {"url": "/docs/11/using-explain.html#USING-EXPLAIN-BASICS", "path": "using-explain.html", "label": "PostgreSQL 11.22 \u00b7 using-explain", "sha256": "8411bc78085d4737e32d7cca103d859da6c6539e33ec5e2fba46e74c6f199d8a"}, "paragraphs": ["Example copied from the PostgreSQL 11.22 manual; it was not executed for this collection.", "Now let's add another condition to the WHERE clause:"]}]}, {"title": "Executor implementation notes", "paragraphs": ["nodeBitmapIndexscan.c Routines to support bitmapped index scans of relations", "If we have runtime keys and they've not already been set up, do it now. Array keys are also treated as runtime keys; note that if ExecReScan returns with biss_RuntimeKeysReady still false, then there is an empty array key so we should do nothing.", "Prepare the result bitmap. Normally we just create a new one to pass back; however, our parent node is allowed to store a pre-made one into node->biss_result, in which case we just OR our tuple IDs into the existing bitmap. (This saves needing explicit UNION steps.)", "Recalculates the values of any scan keys whose value depends on information known at runtime, then rescans the indexed relation.", "Reset the runtime-key context so we don't leak memory as each outer tuple is scanned. Note this assumes that we will recalculate *all* runtime keys on each call."]}, {"code": "case T_BitmapIndexScan:\n\t\t\tpname = sname = \"Bitmap Index Scan\";\n\t\t\tbreak;", "title": "EXPLAIN identity in core source"}], "strategies": [], "description": ["Scans an index and produces a bitmap of matching tuple locations."], "evidence_kind": "source and documentation", "explain_names": ["Bitmap Index Scan"], "partial_modes": [], "comparison_data": {"node_tag": "T_BitmapIndexScan", "strategies": [], "text_names": ["Bitmap Index Scan"], "initializer": "ExecInitBitmapIndexScan", "partial_modes": [], "memory_mechanism": "bitmap-lossification", "parallel_callbacks": []}, "comparison_hash": "b81114c9864c11cc43d2183d9c32e01632186cff8cced0f6ff218f56f56485c0", "explain_prefixes": ["Parallel"], "runtime_verified": false, "source_inventory": {"explain": "src/backend/commands/explain.c", "executor": "src/backend/executor/execProcnode.c", "implementation": "src/backend/executor/nodeBitmapIndexscan.c"}, "parallel_callbacks": []}, "12": {"facts": [{"label": "Core node tag", "value": "T_BitmapIndexScan"}, {"label": "Structured EXPLAIN Node Type", "value": "Bitmap Index Scan"}, {"label": "Inputs", "value": "An index"}, {"label": "Output", "value": "Tuple-location bitmap, not a tuple stream"}, {"label": "Executor initializer", "value": "ExecInitBitmapIndexScan"}, {"label": "Memory mechanism", "value": "bitmap-lossification"}], "memory": {"evidence": [{"url": "https://ftp.postgresql.org/pub/source/v12.22/postgresql-12.22.tar.bz2", "path": "src/backend/executor/nodeBitmapIndexscan.c", "label": "src/backend/executor/nodeBitmapIndexscan.c", "sha256": "7fe85640bde0b6f74d609c1d443f5622ea6d7dc2d77e2a92cd6fdf51a572ae64", "archive_sha256": "8df3c0474782589d3c6f374b5133b1bd14d168086edbc13c6e72e67dd4527a3b"}, {"url": "https://ftp.postgresql.org/pub/source/v12.22/postgresql-12.22.tar.bz2", "path": "src/backend/nodes/tidbitmap.c", "label": "src/backend/nodes/tidbitmap.c", "sha256": "8a18d2e770adab40a9172ebc6895501ec22f650b479c4e9ce44ca010c57ad24d", "archive_sha256": "8df3c0474782589d3c6f374b5133b1bd14d168086edbc13c6e72e67dd4527a3b"}], "mechanism": "bitmap-lossification", "description": "The node allocates a tuple-location bitmap using a work_mem-derived budget. 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Text-format spellings can also include operation, strategy, join type, scan direction or aggregation-stage attributes.", "Text names recorded by this source: Bitmap Index 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": ["The node allocates a tuple-location bitmap using a work_mem-derived budget. A bitmap can retain page-level lossy entries instead of every tuple location; heap rechecks then remain necessary."]}, {"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": "Examples from this manual build", "blocks": [{"code": "EXPLAIN SELECT * FROM tenk1 WHERE unique1 < 100;\n\n                                  QUERY PLAN\n------------------------------------------------------------------------------\n Bitmap Heap Scan on tenk1  (cost=5.07..229.20 rows=101 width=244)\n   Recheck Cond: (unique1 < 100)\n   ->  Bitmap Index Scan on tenk1_unique1  (cost=0.00..5.04 rows=101 width=0)\n         Index Cond: (unique1 < 100)", "source": {"url": "/docs/12/using-explain.html#USING-EXPLAIN-BASICS", "path": "using-explain.html", "label": "PostgreSQL 12.22 \u00b7 using-explain", "sha256": "06297525f2180b07e752837a3351be9c871b56559f535bcd0a67dec9baac10c0"}, "paragraphs": ["Example copied from the PostgreSQL 12.22 manual; it was not executed for this collection.", "Now, let's make the condition more restrictive:"]}, {"code": "EXPLAIN SELECT * FROM tenk1 WHERE unique1 < 100 AND stringu1 = 'xxx';\n\n                                  QUERY PLAN\n------------------------------------------------------------------------------\n Bitmap Heap Scan on tenk1  (cost=5.04..229.43 rows=1 width=244)\n   Recheck Cond: (unique1 < 100)\n   Filter: (stringu1 = 'xxx'::name)\n   ->  Bitmap Index Scan on tenk1_unique1  (cost=0.00..5.04 rows=101 width=0)\n         Index Cond: (unique1 < 100)", "source": {"url": "/docs/12/using-explain.html#USING-EXPLAIN-BASICS", "path": "using-explain.html", "label": "PostgreSQL 12.22 \u00b7 using-explain", "sha256": "06297525f2180b07e752837a3351be9c871b56559f535bcd0a67dec9baac10c0"}, "paragraphs": ["Example copied from the PostgreSQL 12.22 manual; it was not executed for this collection.", "Now let's add another condition to the WHERE clause:"]}]}, {"title": "Executor implementation notes", "paragraphs": ["nodeBitmapIndexscan.c Routines to support bitmapped index scans of relations", "If we have runtime keys and they've not already been set up, do it now. Array keys are also treated as runtime keys; note that if ExecReScan returns with biss_RuntimeKeysReady still false, then there is an empty array key so we should do nothing.", "Prepare the result bitmap. Normally we just create a new one to pass back; however, our parent node is allowed to store a pre-made one into node->biss_result, in which case we just OR our tuple IDs into the existing bitmap. (This saves needing explicit UNION steps.)", "Recalculates the values of any scan keys whose value depends on information known at runtime, then rescans the indexed relation.", "Reset the runtime-key context so we don't leak memory as each outer tuple is scanned. Note this assumes that we will recalculate *all* runtime keys on each call."]}, {"code": "case T_BitmapIndexScan:\n\t\t\tpname = sname = \"Bitmap Index Scan\";\n\t\t\tbreak;", "title": "EXPLAIN identity in core source"}], "strategies": [], "description": ["Scans an index and produces a bitmap of matching tuple locations."], "evidence_kind": "source and documentation", "explain_names": ["Bitmap Index Scan"], "partial_modes": [], "comparison_data": {"node_tag": "T_BitmapIndexScan", "strategies": [], "text_names": ["Bitmap Index Scan"], "initializer": "ExecInitBitmapIndexScan", "partial_modes": [], "memory_mechanism": "bitmap-lossification", "parallel_callbacks": []}, "comparison_hash": "b81114c9864c11cc43d2183d9c32e01632186cff8cced0f6ff218f56f56485c0", "explain_prefixes": ["Parallel"], "runtime_verified": false, "source_inventory": {"explain": "src/backend/commands/explain.c", "executor": "src/backend/executor/execProcnode.c", "implementation": "src/backend/executor/nodeBitmapIndexscan.c"}, "parallel_callbacks": []}, "13": {"facts": [{"label": "Core node tag", "value": "T_BitmapIndexScan"}, {"label": "Structured EXPLAIN Node Type", "value": "Bitmap Index Scan"}, {"label": "Inputs", "value": "An index"}, {"label": "Output", "value": "Tuple-location bitmap, not a tuple stream"}, {"label": "Executor initializer", "value": "ExecInitBitmapIndexScan"}, {"label": "Memory mechanism", "value": "bitmap-lossification"}], "memory": {"evidence": [{"url": "https://ftp.postgresql.org/pub/source/v13.23/postgresql-13.23.tar.bz2", "path": "src/backend/executor/nodeBitmapIndexscan.c", "label": "src/backend/executor/nodeBitmapIndexscan.c", "sha256": "bed645648d6c8ab8ba338b23d5b6bf1bd22bed1a3f7d72db0397d526339c4073", "archive_sha256": "6ec3c82726af92b7dec873fa1cdf881eca92a4219787dfad05acb6b10e041fd6"}, {"url": "https://ftp.postgresql.org/pub/source/v13.23/postgresql-13.23.tar.bz2", "path": "src/backend/nodes/tidbitmap.c", "label": "src/backend/nodes/tidbitmap.c", "sha256": "a0823f106dd0af7415c44a788a8b258dc13afc6dab320d0dec0a2d17f418fdb8", "archive_sha256": "6ec3c82726af92b7dec873fa1cdf881eca92a4219787dfad05acb6b10e041fd6"}], "mechanism": "bitmap-lossification", "description": "The node allocates a tuple-location bitmap using a work_mem-derived budget. A bitmap can retain page-level lossy entries instead of every tuple location; heap rechecks then remain necessary.", "source_notes": []}, "tables": [{"key": "explain-labels", "rows": [{"label": "Bitmap Index Scan", "identity": "Bitmap Index 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=13", "label": "EXPLAIN"}, {"url": "/docs/13/using-explain.html", "label": "Using EXPLAIN"}, {"url": "/docs/13/parallel-plans.html", "label": "Parallel plans"}, {"url": "/wiki/guc/enable_bitmapscan/?v=13", "label": "enable_bitmapscan"}, {"url": "/wiki/guc/work_mem/?v=13", "label": "work_mem"}, {"url": "/wiki/indexam/?v=13", "label": "Index AM"}], "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": 1204, "path": "src/backend/commands/explain.c", "label": "src/backend/commands/explain.c:1204", "sha256": "541713e0e7f1c9cc352c2b6028964d440c19d2678a4463000094c24a88c1e730", "archive_sha256": "6ec3c82726af92b7dec873fa1cdf881eca92a4219787dfad05acb6b10e041fd6"}, {"url": "https://ftp.postgresql.org/pub/source/v13.23/postgresql-13.23.tar.bz2", "line": 227, "path": "src/backend/executor/execProcnode.c", "label": "src/backend/executor/execProcnode.c:227", "sha256": "d085ee99acfa00587e6ade3a1d9f8108a0566beedbbee3f54a50c9fc0cc2e875", "archive_sha256": "6ec3c82726af92b7dec873fa1cdf881eca92a4219787dfad05acb6b10e041fd6"}, {"url": "https://ftp.postgresql.org/pub/source/v13.23/postgresql-13.23.tar.bz2", "path": "src/backend/executor/nodeBitmapIndexscan.c", "label": "src/backend/executor/nodeBitmapIndexscan.c", "sha256": "bed645648d6c8ab8ba338b23d5b6bf1bd22bed1a3f7d72db0397d526339c4073", "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/nodes/tidbitmap.c", "label": "src/backend/nodes/tidbitmap.c", "sha256": "a0823f106dd0af7415c44a788a8b258dc13afc6dab320d0dec0a2d17f418fdb8", "archive_sha256": "6ec3c82726af92b7dec873fa1cdf881eca92a4219787dfad05acb6b10e041fd6"}, {"url": "/docs/13/using-explain.html#USING-EXPLAIN-BASICS", "path": "using-explain.html", "label": "PostgreSQL 13.23 \u00b7 using-explain", "sha256": "650fd8629382d5dc8f9f8412c50ec5f32442a9ad2f98ca88e5348a7c2bd0ac7a"}], "node_tag": "T_BitmapIndexScan", "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: Bitmap Index 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": ["The node allocates a tuple-location bitmap using a work_mem-derived budget. A bitmap can retain page-level lossy entries instead of every tuple location; heap rechecks then remain necessary."]}, {"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": "Examples from this manual build", "blocks": [{"code": "EXPLAIN SELECT * FROM tenk1 WHERE unique1 < 100;\n\n                                  QUERY PLAN\n------------------------------------------------------------------------------\n Bitmap Heap Scan on tenk1  (cost=5.07..229.20 rows=101 width=244)\n   Recheck Cond: (unique1 < 100)\n   ->  Bitmap Index Scan on tenk1_unique1  (cost=0.00..5.04 rows=101 width=0)\n         Index Cond: (unique1 < 100)", "source": {"url": "/docs/13/using-explain.html#USING-EXPLAIN-BASICS", "path": "using-explain.html", "label": "PostgreSQL 13.23 \u00b7 using-explain", "sha256": "650fd8629382d5dc8f9f8412c50ec5f32442a9ad2f98ca88e5348a7c2bd0ac7a"}, "paragraphs": ["Example copied from the PostgreSQL 13.23 manual; it was not executed for this collection.", "Now, let's make the condition more restrictive:"]}, {"code": "EXPLAIN SELECT * FROM tenk1 WHERE unique1 < 100 AND stringu1 = 'xxx';\n\n                                  QUERY PLAN\n------------------------------------------------------------------------------\n Bitmap Heap Scan on tenk1  (cost=5.04..229.43 rows=1 width=244)\n   Recheck Cond: (unique1 < 100)\n   Filter: (stringu1 = 'xxx'::name)\n   ->  Bitmap Index Scan on tenk1_unique1  (cost=0.00..5.04 rows=101 width=0)\n         Index Cond: (unique1 < 100)", "source": {"url": "/docs/13/using-explain.html#USING-EXPLAIN-BASICS", "path": "using-explain.html", "label": "PostgreSQL 13.23 \u00b7 using-explain", "sha256": "650fd8629382d5dc8f9f8412c50ec5f32442a9ad2f98ca88e5348a7c2bd0ac7a"}, "paragraphs": ["Example copied from the PostgreSQL 13.23 manual; it was not executed for this collection.", "Now let's add another condition to the WHERE clause:"]}]}, {"title": "Executor implementation notes", "paragraphs": ["nodeBitmapIndexscan.c Routines to support bitmapped index scans of relations", "If we have runtime keys and they've not already been set up, do it now. Array keys are also treated as runtime keys; note that if ExecReScan returns with biss_RuntimeKeysReady still false, then there is an empty array key so we should do nothing.", "Prepare the result bitmap. Normally we just create a new one to pass back; however, our parent node is allowed to store a pre-made one into node->biss_result, in which case we just OR our tuple IDs into the existing bitmap. (This saves needing explicit UNION steps.)", "Recalculates the values of any scan keys whose value depends on information known at runtime, then rescans the indexed relation.", "Reset the runtime-key context so we don't leak memory as each outer tuple is scanned. Note this assumes that we will recalculate *all* runtime keys on each call."]}, {"code": "case T_BitmapIndexScan:\n\t\t\tpname = sname = \"Bitmap Index Scan\";\n\t\t\tbreak;", "title": "EXPLAIN identity in core source"}], "strategies": [], "description": ["Scans an index and produces a bitmap of matching tuple locations."], "evidence_kind": "source and documentation", "explain_names": ["Bitmap Index Scan"], "partial_modes": [], "comparison_data": {"node_tag": "T_BitmapIndexScan", "strategies": [], "text_names": ["Bitmap Index Scan"], "initializer": "ExecInitBitmapIndexScan", "partial_modes": [], "memory_mechanism": "bitmap-lossification", "parallel_callbacks": []}, "comparison_hash": "b81114c9864c11cc43d2183d9c32e01632186cff8cced0f6ff218f56f56485c0", "explain_prefixes": ["Parallel"], "runtime_verified": false, "source_inventory": {"explain": "src/backend/commands/explain.c", "executor": "src/backend/executor/execProcnode.c", "implementation": "src/backend/executor/nodeBitmapIndexscan.c"}, "parallel_callbacks": []}, "14": {"facts": [{"label": "Core node tag", "value": "T_BitmapIndexScan"}, {"label": "Structured EXPLAIN Node Type", "value": "Bitmap Index Scan"}, {"label": "Inputs", "value": "An index"}, {"label": "Output", "value": "Tuple-location bitmap, not a tuple stream"}, {"label": "Executor initializer", "value": "ExecInitBitmapIndexScan"}, {"label": "Memory mechanism", "value": "bitmap-lossification"}], "memory": {"evidence": [{"url": "https://ftp.postgresql.org/pub/source/v14.24/postgresql-14.24.tar.bz2", "path": "src/backend/executor/nodeBitmapIndexscan.c", "label": "src/backend/executor/nodeBitmapIndexscan.c", "sha256": "ed88a656eb113183830b115dc514d98401e2163a56ae54c911c381f8d0ad012c", "archive_sha256": "a7fa7ed3d558172355f51406097a7bd4f6b473be80f311ef7cda96bf383d8897"}, {"url": "https://ftp.postgresql.org/pub/source/v14.24/postgresql-14.24.tar.bz2", "path": "src/backend/nodes/tidbitmap.c", "label": "src/backend/nodes/tidbitmap.c", "sha256": "6b86639c01e2be18b9e08a99d5aa46e09747cade936cc703d9d30bfe8d61fa1c", "archive_sha256": "a7fa7ed3d558172355f51406097a7bd4f6b473be80f311ef7cda96bf383d8897"}], "mechanism": "bitmap-lossification", "description": "The node allocates a tuple-location bitmap using a work_mem-derived budget. 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Text-format spellings can also include operation, strategy, join type, scan direction or aggregation-stage attributes.", "Text names recorded by this source: Bitmap Index 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": ["The node allocates a tuple-location bitmap using a work_mem-derived budget. A bitmap can retain page-level lossy entries instead of every tuple location; heap rechecks then remain necessary."]}, {"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": "Examples from this manual build", "blocks": [{"code": "EXPLAIN SELECT * FROM tenk1 WHERE unique1 < 100;\n\n                                  QUERY PLAN\n------------------------------------------------------------------------------\n Bitmap Heap Scan on tenk1  (cost=5.07..229.20 rows=101 width=244)\n   Recheck Cond: (unique1 < 100)\n   ->  Bitmap Index Scan on tenk1_unique1  (cost=0.00..5.04 rows=101 width=0)\n         Index Cond: (unique1 < 100)", "source": {"url": "/docs/14/using-explain.html#USING-EXPLAIN-BASICS", "path": "using-explain.html", "label": "PostgreSQL 14.24 \u00b7 using-explain", "sha256": "7f5ab59cb21a035ada45ea3426c5d1cca3f781273483677f73fdd76753555206"}, "paragraphs": ["Example copied from the PostgreSQL 14.24 manual; it was not executed for this collection.", "Now, let's make the condition more restrictive:"]}, {"code": "EXPLAIN SELECT * FROM tenk1 WHERE unique1 < 100 AND stringu1 = 'xxx';\n\n                                  QUERY PLAN\n------------------------------------------------------------------------------\n Bitmap Heap Scan on tenk1  (cost=5.04..229.43 rows=1 width=244)\n   Recheck Cond: (unique1 < 100)\n   Filter: (stringu1 = 'xxx'::name)\n   ->  Bitmap Index Scan on tenk1_unique1  (cost=0.00..5.04 rows=101 width=0)\n         Index Cond: (unique1 < 100)", "source": {"url": "/docs/14/using-explain.html#USING-EXPLAIN-BASICS", "path": "using-explain.html", "label": "PostgreSQL 14.24 \u00b7 using-explain", "sha256": "7f5ab59cb21a035ada45ea3426c5d1cca3f781273483677f73fdd76753555206"}, "paragraphs": ["Example copied from the PostgreSQL 14.24 manual; it was not executed for this collection.", "Now let's add another condition to the WHERE clause:"]}]}, {"title": "Executor implementation notes", "paragraphs": ["nodeBitmapIndexscan.c Routines to support bitmapped index scans of relations", "If we have runtime keys and they've not already been set up, do it now. Array keys are also treated as runtime keys; note that if ExecReScan returns with biss_RuntimeKeysReady still false, then there is an empty array key so we should do nothing.", "Prepare the result bitmap. Normally we just create a new one to pass back; however, our parent node is allowed to store a pre-made one into node->biss_result, in which case we just OR our tuple IDs into the existing bitmap. (This saves needing explicit UNION steps.)", "Recalculates the values of any scan keys whose value depends on information known at runtime, then rescans the indexed relation.", "Reset the runtime-key context so we don't leak memory as each outer tuple is scanned. 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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": "Examples from this manual build", "blocks": [{"code": "EXPLAIN SELECT * FROM tenk1 WHERE unique1 < 100;\n\n                                  QUERY PLAN\n------------------------------------------------------------------------------\n Bitmap Heap Scan on tenk1  (cost=5.07..229.20 rows=101 width=244)\n   Recheck Cond: (unique1 < 100)\n   ->  Bitmap Index Scan on tenk1_unique1  (cost=0.00..5.04 rows=101 width=0)\n         Index Cond: (unique1 < 100)", "source": {"url": "/docs/15/using-explain.html#USING-EXPLAIN-BASICS", "path": "using-explain.html", "label": "PostgreSQL 15.19 \u00b7 using-explain", "sha256": "d1f509457c647da453d2575c772d91022a0f115dd84f9a3b20f5ff25a243648f"}, "paragraphs": ["Example copied from the PostgreSQL 15.19 manual; it was not executed for this collection.", "Now, let's make the condition more restrictive:"]}, {"code": "EXPLAIN SELECT * FROM tenk1 WHERE unique1 < 100 AND stringu1 = 'xxx';\n\n                                  QUERY PLAN\n------------------------------------------------------------------------------\n Bitmap Heap Scan on tenk1  (cost=5.04..229.43 rows=1 width=244)\n   Recheck Cond: (unique1 < 100)\n   Filter: (stringu1 = 'xxx'::name)\n   ->  Bitmap Index Scan on tenk1_unique1  (cost=0.00..5.04 rows=101 width=0)\n         Index Cond: (unique1 < 100)", "source": {"url": "/docs/15/using-explain.html#USING-EXPLAIN-BASICS", "path": "using-explain.html", "label": "PostgreSQL 15.19 \u00b7 using-explain", "sha256": "d1f509457c647da453d2575c772d91022a0f115dd84f9a3b20f5ff25a243648f"}, "paragraphs": ["Example copied from the PostgreSQL 15.19 manual; it was not executed for this collection.", "Now let's add another condition to the WHERE clause:"]}]}, {"title": "Executor implementation notes", "paragraphs": ["nodeBitmapIndexscan.c Routines to support bitmapped index scans of relations", "If we have runtime keys and they've not already been set up, do it now. Array keys are also treated as runtime keys; note that if ExecReScan returns with biss_RuntimeKeysReady still false, then there is an empty array key so we should do nothing.", "Prepare the result bitmap. Normally we just create a new one to pass back; however, our parent node is allowed to store a pre-made one into node->biss_result, in which case we just OR our tuple IDs into the existing bitmap. (This saves needing explicit UNION steps.)", "Recalculates the values of any scan keys whose value depends on information known at runtime, then rescans the indexed relation.", "Reset the runtime-key context so we don't leak memory as each outer tuple is scanned. 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Array keys are also treated as runtime keys; note that if ExecReScan returns with biss_RuntimeKeysReady still false, then there is an empty array key so we should do nothing.", "Prepare the result bitmap. Normally we just create a new one to pass back; however, our parent node is allowed to store a pre-made one into node->biss_result, in which case we just OR our tuple IDs into the existing bitmap. (This saves needing explicit UNION steps.)", "Recalculates the values of any scan keys whose value depends on information known at runtime, then rescans the indexed relation.", "Reset the runtime-key context so we don't leak memory as each outer tuple is scanned. 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Array keys are also treated as runtime keys; note that if ExecReScan returns with biss_RuntimeKeysReady still false, then there is an empty array key so we should do nothing.", "Prepare the result bitmap. Normally we just create a new one to pass back; however, our parent node is allowed to store a pre-made one into node->biss_result, in which case we just OR our tuple IDs into the existing bitmap. (This saves needing explicit UNION steps.)", "Recalculates the values of any scan keys whose value depends on information known at runtime, then rescans the indexed relation.", "Reset the runtime-key context so we don't leak memory as each outer tuple is scanned. 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Text-format spellings can also include operation, strategy, join type, scan direction or aggregation-stage attributes.", "Text names recorded by this source: Bitmap Index 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": ["The node allocates a tuple-location bitmap using a work_mem-derived budget. A bitmap can retain page-level lossy entries instead of every tuple location; heap rechecks then remain necessary."]}, {"title": "Parallel execution and instrumentation", "paragraphs": ["The source callbacks below can coordinate execution or collect worker instrumentation. 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However, the number of index searches often won't have such a simple correspondence to the query predicate:"]}, {"title": "Examples from this manual build", "blocks": [{"code": "EXPLAIN SELECT * FROM tenk1 WHERE unique1 < 100;\n\n                                  QUERY PLAN\n------------------------------------------------------------------------------\n Bitmap Heap Scan on tenk1  (cost=5.06..224.98 rows=100 width=244)\n   Recheck Cond: (unique1 < 100)\n   ->  Bitmap Index Scan on tenk1_unique1  (cost=0.00..5.04 rows=100 width=0)\n         Index Cond: (unique1 < 100)", "source": {"url": "/docs/18/using-explain.html#USING-EXPLAIN-BASICS", "path": "using-explain.html", "label": "PostgreSQL 18.6 \u00b7 using-explain", "sha256": "60040c30180093418a0affe56dd27dff9df2504b705b38039589e458bf5c31ed"}, "paragraphs": ["Example copied from the PostgreSQL 18.6 manual; it was not executed for this collection.", "Now, let's make the condition more restrictive:"]}, {"code": "EXPLAIN SELECT * FROM tenk1 WHERE unique1 < 100 AND stringu1 = 'xxx';\n\n                                  QUERY PLAN\n------------------------------------------------------------------------------\n Bitmap Heap Scan on tenk1  (cost=5.04..225.20 rows=1 width=244)\n   Recheck Cond: (unique1 < 100)\n   Filter: (stringu1 = 'xxx'::name)\n   ->  Bitmap Index Scan on tenk1_unique1  (cost=0.00..5.04 rows=100 width=0)\n         Index Cond: (unique1 < 100)", "source": {"url": "/docs/18/using-explain.html#USING-EXPLAIN-BASICS", "path": "using-explain.html", "label": "PostgreSQL 18.6 \u00b7 using-explain", "sha256": "60040c30180093418a0affe56dd27dff9df2504b705b38039589e458bf5c31ed"}, "paragraphs": ["Example copied from the PostgreSQL 18.6 manual; it was not executed for this collection.", "Now let's add another condition to the WHERE clause:"]}]}, {"title": "Executor implementation notes", "paragraphs": ["nodeBitmapIndexscan.c Routines to support bitmapped index scans of relations", "If we have runtime keys and they've not already been set up, do it now. Array keys are also treated as runtime keys; note that if ExecReScan returns with biss_RuntimeKeysReady still false, then there is an empty array key so we should do nothing.", "Prepare the result bitmap. Normally we just create a new one to pass back; however, our parent node is allowed to store a pre-made one into node->biss_result, in which case we just OR our tuple IDs into the existing bitmap. (This saves needing explicit UNION steps.)", "Recalculates the values of any scan keys whose value depends on information known at runtime, then rescans the indexed relation.", "Reset the runtime-key context so we don't leak memory as each outer tuple is scanned. 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Array keys are also treated as runtime keys; note that if ExecReScan returns with biss_RuntimeKeysReady still false, then there is an empty array key so we should do nothing.", "Prepare the result bitmap. Normally we just create a new one to pass back; however, our parent node is allowed to store a pre-made one into node->biss_result, in which case we just OR our tuple IDs into the existing bitmap. (This saves needing explicit UNION steps.)", "Recalculates the values of any scan keys whose value depends on information known at runtime, then rescans the indexed relation.", "Reset the runtime-key context so we don't leak memory as each outer tuple is scanned. 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Their presence is not a blanket claim that this node supports a shared parallel scan or shared state.", "Callbacks in this build: ExecBitmapIndexScanEstimate, ExecBitmapIndexScanInitializeDSM, ExecBitmapIndexScanInitializeWorker, ExecBitmapIndexScanRetrieveInstrumentation."]}, {"title": "Same-version manual discussion", "paragraphs": ["Index Scan nodes (as well as Bitmap Index Scan and Index-Only Scan nodes) show an \u201c Index Searches \u201d line that reports the total number of searches across all node executions/ loops :", "Here we see a Bitmap Index Scan node that needed 4 separate index searches. The scan had to search the index from the tenk1_thous_tenthous index root page once per integer value from the predicate's IN construct. However, the number of index searches often won't have such a simple correspondence to the query predicate:"]}, {"title": "Examples from this manual build", "blocks": [{"code": "EXPLAIN SELECT * FROM tenk1 WHERE unique1 < 100;\n\n                                  QUERY PLAN\n------------------------------------------------------------------------------\n Bitmap Heap Scan on tenk1  (cost=5.06..224.98 rows=100 width=244)\n   Recheck Cond: (unique1 < 100)\n   ->  Bitmap Index Scan on tenk1_unique1  (cost=0.00..5.04 rows=100 width=0)\n         Index Cond: (unique1 < 100)", "source": {"url": "/docs/devel/using-explain.html#USING-EXPLAIN-BASICS", "path": "using-explain.html", "label": "PostgreSQL 20devel \u00b7 using-explain", "sha256": "99cfea3035876ea63f88b75ba8c964b51a32a70606544e09f769c0b60a234b31"}, "paragraphs": ["Example copied from the PostgreSQL 20devel manual; it was not executed for this collection.", "Now, let's make the condition more restrictive:"]}, {"code": "EXPLAIN SELECT * FROM tenk1 WHERE unique1 < 100 AND stringu1 = 'xxx';\n\n                                  QUERY PLAN\n------------------------------------------------------------------------------\n Bitmap Heap Scan on tenk1  (cost=5.04..225.20 rows=1 width=244)\n   Recheck Cond: (unique1 < 100)\n   Filter: (stringu1 = 'xxx'::name)\n   ->  Bitmap Index Scan on tenk1_unique1  (cost=0.00..5.04 rows=100 width=0)\n         Index Cond: (unique1 < 100)", "source": {"url": "/docs/devel/using-explain.html#USING-EXPLAIN-BASICS", "path": "using-explain.html", "label": "PostgreSQL 20devel \u00b7 using-explain", "sha256": "99cfea3035876ea63f88b75ba8c964b51a32a70606544e09f769c0b60a234b31"}, "paragraphs": ["Example copied from the PostgreSQL 20devel manual; it was not executed for this collection.", "Now let's add another condition to the WHERE clause:"]}]}, {"title": "Executor implementation notes", "paragraphs": ["nodeBitmapIndexscan.c Routines to support bitmapped index scans of relations", "If we have runtime keys and they've not already been set up, do it now. Array keys are also treated as runtime keys; note that if ExecReScan returns with biss_RuntimeKeysReady still false, then there is an empty array key so we should do nothing.", "Prepare the result bitmap. Normally we just create a new one to pass back; however, our parent node is allowed to store a pre-made one into node->biss_result, in which case we just OR our tuple IDs into the existing bitmap. (This saves needing explicit UNION steps.)", "Recalculates the values of any scan keys whose value depends on information known at runtime, then rescans the indexed relation.", "Reset the runtime-key context so we don't leak memory as each outer tuple is scanned. 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Text-format spellings can also include operation, strategy, join type, scan direction or aggregation-stage attributes.", "Text names recorded by this source: Bitmap Index 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": ["The node allocates a tuple-location bitmap using a work_mem-derived budget. A bitmap can retain page-level lossy entries instead of every tuple location; heap rechecks then remain necessary."]}, {"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: ExecBitmapIndexScanEstimate, ExecBitmapIndexScanInitializeDSM, ExecBitmapIndexScanInitializeWorker, ExecBitmapIndexScanRetrieveInstrumentation."]}, {"title": "Same-version manual discussion", "paragraphs": ["Index Scan nodes (as well as Bitmap Index Scan and Index-Only Scan nodes) show an \u201c Index Searches \u201d line that reports the total number of searches across all node executions/ loops :", "Here we see a Bitmap Index Scan node that needed 4 separate index searches. The scan had to search the index from the tenk1_thous_tenthous index root page once per integer value from the predicate's IN construct. However, the number of index searches often won't have such a simple correspondence to the query predicate:"]}, {"title": "Examples from this manual build", "blocks": [{"code": "EXPLAIN SELECT * FROM tenk1 WHERE unique1 < 100;\n\n                                  QUERY PLAN\n------------------------------------------------------------------------------\n Bitmap Heap Scan on tenk1  (cost=5.06..224.98 rows=100 width=244)\n   Recheck Cond: (unique1 < 100)\n   ->  Bitmap Index Scan on tenk1_unique1  (cost=0.00..5.04 rows=100 width=0)\n         Index Cond: (unique1 < 100)", "source": {"url": "/docs/18/using-explain.html#USING-EXPLAIN-BASICS", "path": "using-explain.html", "label": "PostgreSQL 18.6 \u00b7 using-explain", "sha256": "60040c30180093418a0affe56dd27dff9df2504b705b38039589e458bf5c31ed"}, "paragraphs": ["Example copied from the PostgreSQL 18.6 manual; it was not executed for this collection.", "Now, let's make the condition more restrictive:"]}, {"code": "EXPLAIN SELECT * FROM tenk1 WHERE unique1 < 100 AND stringu1 = 'xxx';\n\n                                  QUERY PLAN\n------------------------------------------------------------------------------\n Bitmap Heap Scan on tenk1  (cost=5.04..225.20 rows=1 width=244)\n   Recheck Cond: (unique1 < 100)\n   Filter: (stringu1 = 'xxx'::name)\n   ->  Bitmap Index Scan on tenk1_unique1  (cost=0.00..5.04 rows=100 width=0)\n         Index Cond: (unique1 < 100)", "source": {"url": "/docs/18/using-explain.html#USING-EXPLAIN-BASICS", "path": "using-explain.html", "label": "PostgreSQL 18.6 \u00b7 using-explain", "sha256": "60040c30180093418a0affe56dd27dff9df2504b705b38039589e458bf5c31ed"}, "paragraphs": ["Example copied from the PostgreSQL 18.6 manual; it was not executed for this collection.", "Now let's add another condition to the WHERE clause:"]}]}, {"title": "Executor implementation notes", "paragraphs": ["nodeBitmapIndexscan.c Routines to support bitmapped index scans of relations", "If we have runtime keys and they've not already been set up, do it now. Array keys are also treated as runtime keys; note that if ExecReScan returns with biss_RuntimeKeysReady still false, then there is an empty array key so we should do nothing.", "Prepare the result bitmap. Normally we just create a new one to pass back; however, our parent node is allowed to store a pre-made one into node->biss_result, in which case we just OR our tuple IDs into the existing bitmap. (This saves needing explicit UNION steps.)", "Recalculates the values of any scan keys whose value depends on information known at runtime, then rescans the indexed relation.", "Reset the runtime-key context so we don't leak memory as each outer tuple is scanned. Note this assumes that we will recalculate *all* runtime keys on each call."]}, {"code": "case T_BitmapIndexScan:\n\t\t\tpname = sname = \"Bitmap Index Scan\";\n\t\t\tbreak;", "title": "EXPLAIN identity in core source"}], "strategies": [], "description": ["Scans an index and produces a bitmap of matching tuple locations."], "evidence_kind": "source and documentation", "explain_names": ["Bitmap Index Scan"], "partial_modes": [], "comparison_data": {"node_tag": "T_BitmapIndexScan", "strategies": [], "text_names": ["Bitmap Index Scan"], "initializer": "ExecInitBitmapIndexScan", "partial_modes": [], "memory_mechanism": "bitmap-lossification", "parallel_callbacks": ["ExecBitmapIndexScanEstimate", "ExecBitmapIndexScanInitializeDSM", "ExecBitmapIndexScanInitializeWorker", "ExecBitmapIndexScanRetrieveInstrumentation"]}, "comparison_hash": "08e8d1afde24882a70dccba204ec21bdcea148fa12f7f53d14a221b80af1cc37", "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/nodeBitmapIndexscan.c"}, "parallel_callbacks": ["ExecBitmapIndexScanEstimate", "ExecBitmapIndexScanInitializeDSM", "ExecBitmapIndexScanInitializeWorker", "ExecBitmapIndexScanRetrieveInstrumentation"]}, "comparison": {"left": "17", "right": "18", "status": "changed", "diff": "--- PostgreSQL 17\n+++ PostgreSQL 18\n@@ -2,7 +2,12 @@\n   \"initializer\": \"ExecInitBitmapIndexScan\",\n   \"memory_mechanism\": \"bitmap-lossification\",\n   \"node_tag\": \"T_BitmapIndexScan\",\n-  \"parallel_callbacks\": [],\n+  \"parallel_callbacks\": [\n+    \"ExecBitmapIndexScanEstimate\",\n+    \"ExecBitmapIndexScanInitializeDSM\",\n+    \"ExecBitmapIndexScanInitializeWorker\",\n+    \"ExecBitmapIndexScanRetrieveInstrumentation\"\n+  ],\n   \"partial_modes\": [],\n   \"strategies\": [],\n   \"text_names\": ["}}