From bf3e55f226c1f1aacac0b2739a6f42973942c6c4 Mon Sep 17 00:00:00 2001 From: Melanie Plageman Date: Mon, 2 Mar 2026 16:31:33 -0500 Subject: [PATCH v39 10/12] Pass down information on table modification to scan node Pass down information to sequential scan, index [only] scan, bitmap table scan, sample scan, and TID range scan nodes on whether or not the query modifies the relation being scanned. A later commit will use this information to update the VM during on-access pruning only if the relation is not modified by the query. Author: Melanie Plageman Reviewed-by: Andres Freund Reviewed-by: Andrey Borodin Reviewed-by: Chao Li Discussion: https://postgr.es/m/4379FDA3-9446-4E2C-9C15-32EFE8D4F31B%40yandex-team.ru --- src/backend/access/heap/heapam_handler.c | 1 + src/backend/executor/nodeBitmapHeapscan.c | 9 ++++++- src/backend/executor/nodeIndexonlyscan.c | 25 +++++++++++++++--- src/backend/executor/nodeIndexscan.c | 32 ++++++++++++++++++++--- src/backend/executor/nodeSamplescan.c | 8 +++++- src/backend/executor/nodeSeqscan.c | 26 +++++++++++++++--- src/backend/executor/nodeTidrangescan.c | 24 ++++++++++++++--- src/include/access/heapam.h | 6 +++++ src/include/access/tableam.h | 3 +++ 9 files changed, 119 insertions(+), 15 deletions(-) diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c index 1e950d8e6e5..aec5199b2e6 100644 --- a/src/backend/access/heap/heapam_handler.c +++ b/src/backend/access/heap/heapam_handler.c @@ -87,6 +87,7 @@ heapam_index_fetch_begin(Relation rel, uint32 flags) hscan->xs_base.rel = rel; hscan->xs_cbuf = InvalidBuffer; hscan->xs_vmbuffer = InvalidBuffer; + hscan->modifies_base_rel = !(flags & SO_HINT_REL_READ_ONLY); return &hscan->xs_base; } diff --git a/src/backend/executor/nodeBitmapHeapscan.c b/src/backend/executor/nodeBitmapHeapscan.c index 324e2bed22c..0f30e6980de 100644 --- a/src/backend/executor/nodeBitmapHeapscan.c +++ b/src/backend/executor/nodeBitmapHeapscan.c @@ -144,11 +144,18 @@ BitmapTableScanSetup(BitmapHeapScanState *node) */ if (!node->ss.ss_currentScanDesc) { + uint32 flags = 0; + + if (!bms_is_member(((Scan *) node->ss.ps.plan)->scanrelid, + node->ss.ps.state->es_modified_relids)) + flags |= SO_HINT_REL_READ_ONLY; + node->ss.ss_currentScanDesc = table_beginscan_bm(node->ss.ss_currentRelation, node->ss.ps.state->es_snapshot, 0, - NULL, 0); + NULL, + flags); } node->ss.ss_currentScanDesc->st.rs_tbmiterator = tbmiterator; diff --git a/src/backend/executor/nodeIndexonlyscan.c b/src/backend/executor/nodeIndexonlyscan.c index 17bf4976cce..3fab715f879 100644 --- a/src/backend/executor/nodeIndexonlyscan.c +++ b/src/backend/executor/nodeIndexonlyscan.c @@ -85,6 +85,12 @@ IndexOnlyNext(IndexOnlyScanState *node) if (scandesc == NULL) { + uint32 flags = 0; + + if (!bms_is_member(((Scan *) node->ss.ps.plan)->scanrelid, + estate->es_modified_relids)) + flags |= SO_HINT_REL_READ_ONLY; + /* * We reach here if the index only scan is not parallel, or if we're * serially executing an index only scan that was planned to be @@ -95,7 +101,8 @@ IndexOnlyNext(IndexOnlyScanState *node) estate->es_snapshot, &node->ioss_Instrument, node->ioss_NumScanKeys, - node->ioss_NumOrderByKeys, 0); + node->ioss_NumOrderByKeys, + flags); node->ioss_ScanDesc = scandesc; @@ -763,6 +770,7 @@ ExecIndexOnlyScanInitializeDSM(IndexOnlyScanState *node, ParallelIndexScanDesc piscan; bool instrument = node->ss.ps.instrument != NULL; bool parallel_aware = node->ss.ps.plan->parallel_aware; + uint32 flags = 0; if (!instrument && !parallel_aware) { @@ -784,13 +792,18 @@ ExecIndexOnlyScanInitializeDSM(IndexOnlyScanState *node, return; } + if (!bms_is_member(((Scan *) node->ss.ps.plan)->scanrelid, + estate->es_modified_relids)) + flags |= SO_HINT_REL_READ_ONLY; + node->ioss_ScanDesc = index_beginscan_parallel(node->ss.ss_currentRelation, node->ioss_RelationDesc, &node->ioss_Instrument, node->ioss_NumScanKeys, node->ioss_NumOrderByKeys, - piscan, 0); + piscan, flags); + node->ioss_ScanDesc->xs_want_itup = true; node->ioss_VMBuffer = InvalidBuffer; @@ -831,6 +844,7 @@ ExecIndexOnlyScanInitializeWorker(IndexOnlyScanState *node, ParallelIndexScanDesc piscan; bool instrument = node->ss.ps.instrument != NULL; bool parallel_aware = node->ss.ps.plan->parallel_aware; + uint32 flags = 0; if (!instrument && !parallel_aware) { @@ -850,13 +864,18 @@ ExecIndexOnlyScanInitializeWorker(IndexOnlyScanState *node, return; } + if (!bms_is_member(((Scan *) node->ss.ps.plan)->scanrelid, + node->ss.ps.state->es_modified_relids)) + flags |= SO_HINT_REL_READ_ONLY; + node->ioss_ScanDesc = index_beginscan_parallel(node->ss.ss_currentRelation, node->ioss_RelationDesc, &node->ioss_Instrument, node->ioss_NumScanKeys, node->ioss_NumOrderByKeys, - piscan, 0); + piscan, flags); + node->ioss_ScanDesc->xs_want_itup = true; /* diff --git a/src/backend/executor/nodeIndexscan.c b/src/backend/executor/nodeIndexscan.c index 88bdf0a52d1..6a235ef25ce 100644 --- a/src/backend/executor/nodeIndexscan.c +++ b/src/backend/executor/nodeIndexscan.c @@ -104,6 +104,12 @@ IndexNext(IndexScanState *node) if (scandesc == NULL) { + uint32 flags = 0; + + if (!bms_is_member(((Scan *) node->ss.ps.plan)->scanrelid, + estate->es_modified_relids)) + flags |= SO_HINT_REL_READ_ONLY; + /* * We reach here if the index scan is not parallel, or if we're * serially executing an index scan that was planned to be parallel. @@ -113,7 +119,8 @@ IndexNext(IndexScanState *node) estate->es_snapshot, &node->iss_Instrument, node->iss_NumScanKeys, - node->iss_NumOrderByKeys, 0); + node->iss_NumOrderByKeys, + flags); node->iss_ScanDesc = scandesc; @@ -200,6 +207,12 @@ IndexNextWithReorder(IndexScanState *node) if (scandesc == NULL) { + uint32 flags = 0; + + if (!bms_is_member(((Scan *) node->ss.ps.plan)->scanrelid, + estate->es_modified_relids)) + flags |= SO_HINT_REL_READ_ONLY; + /* * We reach here if the index scan is not parallel, or if we're * serially executing an index scan that was planned to be parallel. @@ -209,7 +222,8 @@ IndexNextWithReorder(IndexScanState *node) estate->es_snapshot, &node->iss_Instrument, node->iss_NumScanKeys, - node->iss_NumOrderByKeys, 0); + node->iss_NumOrderByKeys, + flags); node->iss_ScanDesc = scandesc; @@ -1699,6 +1713,7 @@ ExecIndexScanInitializeDSM(IndexScanState *node, ParallelIndexScanDesc piscan; bool instrument = node->ss.ps.instrument != NULL; bool parallel_aware = node->ss.ps.plan->parallel_aware; + uint32 flags = 0; if (!instrument && !parallel_aware) { @@ -1720,13 +1735,17 @@ ExecIndexScanInitializeDSM(IndexScanState *node, return; } + if (!bms_is_member(((Scan *) node->ss.ps.plan)->scanrelid, + estate->es_modified_relids)) + flags |= SO_HINT_REL_READ_ONLY; + node->iss_ScanDesc = index_beginscan_parallel(node->ss.ss_currentRelation, node->iss_RelationDesc, &node->iss_Instrument, node->iss_NumScanKeys, node->iss_NumOrderByKeys, - piscan, 0); + piscan, flags); /* * If no run-time keys to calculate or they are ready, go ahead and pass @@ -1765,6 +1784,7 @@ ExecIndexScanInitializeWorker(IndexScanState *node, ParallelIndexScanDesc piscan; bool instrument = node->ss.ps.instrument != NULL; bool parallel_aware = node->ss.ps.plan->parallel_aware; + uint32 flags = 0; if (!instrument && !parallel_aware) { @@ -1784,13 +1804,17 @@ ExecIndexScanInitializeWorker(IndexScanState *node, return; } + if (!bms_is_member(((Scan *) node->ss.ps.plan)->scanrelid, + node->ss.ps.state->es_modified_relids)) + flags |= SO_HINT_REL_READ_ONLY; + node->iss_ScanDesc = index_beginscan_parallel(node->ss.ss_currentRelation, node->iss_RelationDesc, &node->iss_Instrument, node->iss_NumScanKeys, node->iss_NumOrderByKeys, - piscan, 0); + piscan, flags); /* * If no run-time keys to calculate or they are ready, go ahead and pass diff --git a/src/backend/executor/nodeSamplescan.c b/src/backend/executor/nodeSamplescan.c index cc6b23abee0..8d36fcda48a 100644 --- a/src/backend/executor/nodeSamplescan.c +++ b/src/backend/executor/nodeSamplescan.c @@ -292,13 +292,19 @@ tablesample_init(SampleScanState *scanstate) /* Now we can create or reset the HeapScanDesc */ if (scanstate->ss.ss_currentScanDesc == NULL) { + uint32 flags = 0; + + if (!bms_is_member(((Scan *) scanstate->ss.ps.plan)->scanrelid, + scanstate->ss.ps.state->es_modified_relids)) + flags |= SO_HINT_REL_READ_ONLY; + scanstate->ss.ss_currentScanDesc = table_beginscan_sampling(scanstate->ss.ss_currentRelation, scanstate->ss.ps.state->es_snapshot, 0, NULL, scanstate->use_bulkread, allow_sync, - scanstate->use_pagemode, 0); + scanstate->use_pagemode, flags); } else { diff --git a/src/backend/executor/nodeSeqscan.c b/src/backend/executor/nodeSeqscan.c index c2d9b7293de..9356973802b 100644 --- a/src/backend/executor/nodeSeqscan.c +++ b/src/backend/executor/nodeSeqscan.c @@ -65,13 +65,20 @@ SeqNext(SeqScanState *node) if (scandesc == NULL) { + uint32 flags = 0; + + if (!bms_is_member(((Scan *) node->ss.ps.plan)->scanrelid, + estate->es_modified_relids)) + flags |= SO_HINT_REL_READ_ONLY; + /* * We reach here if the scan is not parallel, or if we're serially * executing a scan that was planned to be parallel. */ scandesc = table_beginscan(node->ss.ss_currentRelation, estate->es_snapshot, - 0, NULL, 0); + 0, NULL, flags); + node->ss.ss_currentScanDesc = scandesc; } @@ -368,14 +375,20 @@ ExecSeqScanInitializeDSM(SeqScanState *node, { EState *estate = node->ss.ps.state; ParallelTableScanDesc pscan; + uint32 flags = 0; pscan = shm_toc_allocate(pcxt->toc, node->pscan_len); table_parallelscan_initialize(node->ss.ss_currentRelation, pscan, estate->es_snapshot); shm_toc_insert(pcxt->toc, node->ss.ps.plan->plan_node_id, pscan); + if (!bms_is_member(((Scan *) node->ss.ps.plan)->scanrelid, + estate->es_modified_relids)) + flags |= SO_HINT_REL_READ_ONLY; + node->ss.ss_currentScanDesc = - table_beginscan_parallel(node->ss.ss_currentRelation, pscan, 0); + table_beginscan_parallel(node->ss.ss_currentRelation, pscan, + flags); } /* ---------------------------------------------------------------- @@ -405,8 +418,15 @@ ExecSeqScanInitializeWorker(SeqScanState *node, ParallelWorkerContext *pwcxt) { ParallelTableScanDesc pscan; + uint32 flags = 0; + + if (!bms_is_member(((Scan *) node->ss.ps.plan)->scanrelid, + node->ss.ps.state->es_modified_relids)) + flags |= SO_HINT_REL_READ_ONLY; pscan = shm_toc_lookup(pwcxt->toc, node->ss.ps.plan->plan_node_id, false); node->ss.ss_currentScanDesc = - table_beginscan_parallel(node->ss.ss_currentRelation, pscan, 0); + table_beginscan_parallel(node->ss.ss_currentRelation, + pscan, + flags); } diff --git a/src/backend/executor/nodeTidrangescan.c b/src/backend/executor/nodeTidrangescan.c index 994f70989bc..04a75e72fe1 100644 --- a/src/backend/executor/nodeTidrangescan.c +++ b/src/backend/executor/nodeTidrangescan.c @@ -242,10 +242,16 @@ TidRangeNext(TidRangeScanState *node) if (scandesc == NULL) { + uint32 flags = 0; + + if (!bms_is_member(((Scan *) node->ss.ps.plan)->scanrelid, + estate->es_modified_relids)) + flags |= SO_HINT_REL_READ_ONLY; + scandesc = table_beginscan_tidrange(node->ss.ss_currentRelation, estate->es_snapshot, &node->trss_mintid, - &node->trss_maxtid, 0); + &node->trss_maxtid, flags); node->ss.ss_currentScanDesc = scandesc; } else @@ -452,15 +458,21 @@ ExecTidRangeScanInitializeDSM(TidRangeScanState *node, ParallelContext *pcxt) { EState *estate = node->ss.ps.state; ParallelTableScanDesc pscan; + uint32 flags = 0; pscan = shm_toc_allocate(pcxt->toc, node->trss_pscanlen); table_parallelscan_initialize(node->ss.ss_currentRelation, pscan, estate->es_snapshot); shm_toc_insert(pcxt->toc, node->ss.ps.plan->plan_node_id, pscan); + + if (!bms_is_member(((Scan *) node->ss.ps.plan)->scanrelid, + estate->es_modified_relids)) + flags |= SO_HINT_REL_READ_ONLY; + node->ss.ss_currentScanDesc = table_beginscan_parallel_tidrange(node->ss.ss_currentRelation, - pscan, 0); + pscan, flags); } /* ---------------------------------------------------------------- @@ -490,9 +502,15 @@ ExecTidRangeScanInitializeWorker(TidRangeScanState *node, ParallelWorkerContext *pwcxt) { ParallelTableScanDesc pscan; + uint32 flags = 0; pscan = shm_toc_lookup(pwcxt->toc, node->ss.ps.plan->plan_node_id, false); + + if (!bms_is_member(((Scan *) node->ss.ps.plan)->scanrelid, + node->ss.ps.state->es_modified_relids)) + flags |= SO_HINT_REL_READ_ONLY; + node->ss.ss_currentScanDesc = table_beginscan_parallel_tidrange(node->ss.ss_currentRelation, - pscan, 0); + pscan, flags); } diff --git a/src/include/access/heapam.h b/src/include/access/heapam.h index c2621dc2fac..978ea90ffa2 100644 --- a/src/include/access/heapam.h +++ b/src/include/access/heapam.h @@ -131,6 +131,12 @@ typedef struct IndexFetchHeapData /* Current heap block's corresponding page in the visibility map */ Buffer xs_vmbuffer; + + /* + * Some optimizations can only be performed if the query does not modify + * the underlying relation. Track that here. + */ + bool modifies_base_rel; } IndexFetchHeapData; /* Result codes for HeapTupleSatisfiesVacuum */ diff --git a/src/include/access/tableam.h b/src/include/access/tableam.h index f1065e30638..57ce94a386f 100644 --- a/src/include/access/tableam.h +++ b/src/include/access/tableam.h @@ -63,6 +63,9 @@ typedef enum ScanOptions /* unregister snapshot at scan end? */ SO_TEMP_SNAPSHOT = 1 << 9, + + /* set if the query doesn't modify the relation */ + SO_HINT_REL_READ_ONLY = 1 << 10, } ScanOptions; /* -- 2.43.0