From eac4e11efc7c19091b8076f6193b90aa3989b19e Mon Sep 17 00:00:00 2001 From: Melanie Plageman Date: Fri, 5 Apr 2024 19:30:43 -0400 Subject: [PATCH v16 11/18] Add BitmapHeapScanDesc and scan functions Future commits will push all prefetching related code into the heap AM to eliminate a layering violation. Move all of the members used to manage prefetching for bitmap heap scan from the BitmapHeapScanState into a new scan descriptor BitmapHeapScanDesc. With this new scan descriptor, add all of the relevant functions for beginning, rescanning, and ending a bitmap heap scan. There is a lot of bitmap-specific logic to do there now, so it makes sense for bitmap heap scan to have its own. Author: Melanie Plageman Discussion: https://postgr.es/m/CAAKRu_ZwCwWFeL_H3ia26bP2e7HiKLWt0ZmGXPVwPO6uXq0vaA%40mail.gmail.com --- src/backend/access/heap/heapam.c | 98 +++++++++++++++++++---- src/backend/access/heap/heapam_handler.c | 42 +++++----- src/backend/executor/nodeBitmapHeapscan.c | 47 +++++------ src/include/access/heapam.h | 36 ++++++--- src/include/access/tableam.h | 45 +++++++++-- src/tools/pgindent/typedefs.list | 1 + 6 files changed, 193 insertions(+), 76 deletions(-) diff --git a/src/backend/access/heap/heapam.c b/src/backend/access/heap/heapam.c index 10f2faaa60..82faf447e9 100644 --- a/src/backend/access/heap/heapam.c +++ b/src/backend/access/heap/heapam.c @@ -13,8 +13,11 @@ * * INTERFACE ROUTINES * heap_beginscan - begin relation scan + * heap_beginscan_bm - begin bitmap heap scan * heap_rescan - restart a relation scan + * heap_rescan_bm - restart a bitmap heap scan * heap_endscan - end relation scan + * heap_endscan_bm - end a bitmap heap scan * heap_getnext - retrieve next tuple in scan * heap_fetch - retrieve tuple with given tid * heap_insert - insert tuple into a relation @@ -938,6 +941,43 @@ continue_page: * ---------------------------------------------------------------- */ +TableScanDesc +heap_beginscan_bm(Relation relation, Snapshot snapshot, uint32 flags) +{ + BitmapHeapScanDesc scan; + + /* + * increment relation ref count while scanning relation + * + * This is just to make really sure the relcache entry won't go away while + * the scan has a pointer to it. Caller should be holding the rel open + * anyway, so this is redundant in all normal scenarios... + */ + RelationIncrementReferenceCount(relation); + scan = (BitmapHeapScanDesc) palloc(sizeof(BitmapHeapScanDescData)); + + scan->heap_common.rs_base.rs_rd = relation; + scan->heap_common.rs_base.rs_snapshot = snapshot; + scan->heap_common.rs_base.rs_nkeys = 0; + scan->heap_common.rs_base.rs_flags = flags; + scan->heap_common.rs_base.rs_parallel = NULL; + scan->heap_common.rs_strategy = NULL; + + Assert(snapshot && IsMVCCSnapshot(snapshot)); + + /* we only need to set this up once */ + scan->heap_common.rs_ctup.t_tableOid = RelationGetRelid(relation); + + scan->heap_common.rs_parallelworkerdata = NULL; + scan->heap_common.rs_base.rs_key = NULL; + + initscan(&scan->heap_common, NULL, false); + + scan->vmbuffer = InvalidBuffer; + + return (TableScanDesc) scan; +} + TableScanDesc heap_beginscan(Relation relation, Snapshot snapshot, @@ -967,8 +1007,6 @@ heap_beginscan(Relation relation, Snapshot snapshot, scan->rs_base.rs_flags = flags; scan->rs_base.rs_parallel = parallel_scan; scan->rs_strategy = NULL; /* set in initscan */ - scan->rs_vmbuffer = InvalidBuffer; - scan->rs_empty_tuples_pending = 0; /* * Disable page-at-a-time mode if it's not a MVCC-safe snapshot. @@ -1026,6 +1064,29 @@ heap_beginscan(Relation relation, Snapshot snapshot, return (TableScanDesc) scan; } +/* + * Cleanup BitmapHeapScan table state + */ +void +heap_endscan_bm(TableScanDesc sscan) +{ + BitmapHeapScanDesc scan = (BitmapHeapScanDesc) sscan; + + if (BufferIsValid(scan->heap_common.rs_cbuf)) + ReleaseBuffer(scan->heap_common.rs_cbuf); + + if (BufferIsValid(scan->vmbuffer)) + ReleaseBuffer(scan->vmbuffer); + + /* + * decrement relation reference count and free scan descriptor storage + */ + RelationDecrementReferenceCount(scan->heap_common.rs_base.rs_rd); + + pfree(scan); +} + + void heap_rescan(TableScanDesc sscan, ScanKey key, bool set_params, bool allow_strat, bool allow_sync, bool allow_pagemode) @@ -1057,12 +1118,6 @@ heap_rescan(TableScanDesc sscan, ScanKey key, bool set_params, if (BufferIsValid(scan->rs_cbuf)) ReleaseBuffer(scan->rs_cbuf); - if (BufferIsValid(scan->rs_vmbuffer)) - { - ReleaseBuffer(scan->rs_vmbuffer); - scan->rs_vmbuffer = InvalidBuffer; - } - /* * reinitialize scan descriptor */ @@ -1082,12 +1137,6 @@ heap_endscan(TableScanDesc sscan) if (BufferIsValid(scan->rs_cbuf)) ReleaseBuffer(scan->rs_cbuf); - if (BufferIsValid(scan->rs_vmbuffer)) - { - ReleaseBuffer(scan->rs_vmbuffer); - scan->rs_vmbuffer = InvalidBuffer; - } - /* * decrement relation reference count and free scan descriptor storage */ @@ -1334,6 +1383,27 @@ heap_getnextslot_tidrange(TableScanDesc sscan, ScanDirection direction, return true; } +void +heap_rescan_bm(TableScanDesc sscan) +{ + BitmapHeapScanDesc scan = (BitmapHeapScanDesc) sscan; + + if (BufferIsValid(scan->heap_common.rs_cbuf)) + ReleaseBuffer(scan->heap_common.rs_cbuf); + + if (BufferIsValid(scan->vmbuffer)) + ReleaseBuffer(scan->vmbuffer); + scan->vmbuffer = InvalidBuffer; + + scan->empty_tuples_pending = 0; + + /* + * reinitialize heap scan descriptor + */ + initscan(&scan->heap_common, NULL, true); +} + + /* * heap_fetch - retrieve tuple with given tid * diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c index 5e57d19d91..43721cbd42 100644 --- a/src/backend/access/heap/heapam_handler.c +++ b/src/backend/access/heap/heapam_handler.c @@ -2187,11 +2187,12 @@ heapam_estimate_rel_size(Relation rel, int32 *attr_widths, */ static bool -heapam_scan_bitmap_next_block(TableScanDesc scan, +heapam_scan_bitmap_next_block(TableScanDesc sscan, BlockNumber *blockno, bool *recheck, long *lossy_pages, long *exact_pages) { - HeapScanDesc hscan = (HeapScanDesc) scan; + BitmapHeapScanDesc scan = (BitmapHeapScanDesc) sscan; + HeapScanDesc hscan = &scan->heap_common; BlockNumber block; Buffer buffer; Snapshot snapshot; @@ -2208,12 +2209,12 @@ heapam_scan_bitmap_next_block(TableScanDesc scan, { CHECK_FOR_INTERRUPTS(); - tbmres = bhs_iterate(&scan->rs_bhs_iterator); + tbmres = bhs_iterate(&sscan->rs_bhs_iterator); if (tbmres == NULL) { /* no more entries in the bitmap */ - Assert(hscan->rs_empty_tuples_pending == 0); + Assert(scan->empty_tuples_pending == 0); return false; } @@ -2236,15 +2237,15 @@ heapam_scan_bitmap_next_block(TableScanDesc scan, * heap, the bitmap entries don't need rechecking, and all tuples on the * page are visible to our transaction. */ - if (!(scan->rs_flags & SO_NEED_TUPLE) && + if (!(hscan->rs_base.rs_flags & SO_NEED_TUPLE) && !tbmres->recheck && - VM_ALL_VISIBLE(scan->rs_rd, tbmres->blockno, &hscan->rs_vmbuffer)) + VM_ALL_VISIBLE(hscan->rs_base.rs_rd, tbmres->blockno, &scan->vmbuffer)) { /* can't be lossy in the skip_fetch case */ Assert(tbmres->ntuples >= 0); - Assert(hscan->rs_empty_tuples_pending >= 0); + Assert(scan->empty_tuples_pending >= 0); - hscan->rs_empty_tuples_pending += tbmres->ntuples; + scan->empty_tuples_pending += tbmres->ntuples; return true; } @@ -2255,18 +2256,18 @@ heapam_scan_bitmap_next_block(TableScanDesc scan, * Acquire pin on the target heap page, trading in any pin we held before. */ hscan->rs_cbuf = ReleaseAndReadBuffer(hscan->rs_cbuf, - scan->rs_rd, + hscan->rs_base.rs_rd, block); hscan->rs_cblock = block; buffer = hscan->rs_cbuf; - snapshot = scan->rs_snapshot; + snapshot = hscan->rs_base.rs_snapshot; ntup = 0; /* * Prune and repair fragmentation for the whole page, if possible. */ - heap_page_prune_opt(scan->rs_rd, buffer); + heap_page_prune_opt(hscan->rs_base.rs_rd, buffer); /* * We must hold share lock on the buffer content while examining tuple @@ -2294,7 +2295,7 @@ heapam_scan_bitmap_next_block(TableScanDesc scan, HeapTupleData heapTuple; ItemPointerSet(&tid, block, offnum); - if (heap_hot_search_buffer(&tid, scan->rs_rd, buffer, snapshot, + if (heap_hot_search_buffer(&tid, hscan->rs_base.rs_rd, buffer, snapshot, &heapTuple, NULL, true)) hscan->rs_vistuples[ntup++] = ItemPointerGetOffsetNumber(&tid); } @@ -2320,16 +2321,16 @@ heapam_scan_bitmap_next_block(TableScanDesc scan, continue; loctup.t_data = (HeapTupleHeader) PageGetItem(page, lp); loctup.t_len = ItemIdGetLength(lp); - loctup.t_tableOid = scan->rs_rd->rd_id; + loctup.t_tableOid = hscan->rs_base.rs_rd->rd_id; ItemPointerSet(&loctup.t_self, block, offnum); valid = HeapTupleSatisfiesVisibility(&loctup, snapshot, buffer); if (valid) { hscan->rs_vistuples[ntup++] = offnum; - PredicateLockTID(scan->rs_rd, &loctup.t_self, snapshot, + PredicateLockTID(hscan->rs_base.rs_rd, &loctup.t_self, snapshot, HeapTupleHeaderGetXmin(loctup.t_data)); } - HeapCheckForSerializableConflictOut(valid, scan->rs_rd, &loctup, + HeapCheckForSerializableConflictOut(valid, hscan->rs_base.rs_rd, &loctup, buffer, snapshot); } } @@ -2358,18 +2359,19 @@ static bool heapam_scan_bitmap_next_tuple(TableScanDesc scan, TupleTableSlot *slot) { - HeapScanDesc hscan = (HeapScanDesc) scan; + BitmapHeapScanDesc bscan = (BitmapHeapScanDesc) scan; + HeapScanDesc hscan = &bscan->heap_common; OffsetNumber targoffset; Page page; ItemId lp; - if (hscan->rs_empty_tuples_pending > 0) + if (bscan->empty_tuples_pending > 0) { /* * If we don't have to fetch the tuple, just return nulls. */ ExecStoreAllNullTuple(slot); - hscan->rs_empty_tuples_pending--; + bscan->empty_tuples_pending--; return true; } @@ -2704,6 +2706,10 @@ static const TableAmRoutine heapam_methods = { .scan_set_tidrange = heap_set_tidrange, .scan_getnextslot_tidrange = heap_getnextslot_tidrange, + .scan_rescan_bm = heap_rescan_bm, + .scan_begin_bm = heap_beginscan_bm, + .scan_end_bm = heap_endscan_bm, + .parallelscan_estimate = table_block_parallelscan_estimate, .parallelscan_initialize = table_block_parallelscan_initialize, .parallelscan_reinitialize = table_block_parallelscan_reinitialize, diff --git a/src/backend/executor/nodeBitmapHeapscan.c b/src/backend/executor/nodeBitmapHeapscan.c index 70b560b8ee..0b28c46d08 100644 --- a/src/backend/executor/nodeBitmapHeapscan.c +++ b/src/backend/executor/nodeBitmapHeapscan.c @@ -151,6 +151,8 @@ BitmapHeapNext(BitmapHeapScanState *node) */ if (!node->initialized) { + uint32 extra_flags = 0; + /* * The leader will immediately come out of the function, but others * will be blocked until leader populates the TBM and wakes them up. @@ -193,33 +195,26 @@ BitmapHeapNext(BitmapHeapScanState *node) } } + /* + * We can potentially skip fetching heap pages if we do not need any + * columns of the table, either for checking non-indexable quals or + * for returning data. This test is a bit simplistic, as it checks + * the stronger condition that there's no qual or return tlist at all. + * But in most cases it's probably not worth working harder than that. + */ + if (node->ss.ps.plan->qual != NIL || node->ss.ps.plan->targetlist != NIL) + extra_flags |= SO_NEED_TUPLE; + /* * If this is the first scan of the underlying table, create the table * scan descriptor and begin the scan. */ - if (!scan) - { - uint32 extra_flags = 0; + scan = table_beginscan_bm(node->ss.ss_currentScanDesc, + node->ss.ss_currentRelation, + node->ss.ps.state->es_snapshot, + extra_flags); - /* - * We can potentially skip fetching heap pages if we do not need - * any columns of the table, either for checking non-indexable - * quals or for returning data. This test is a bit simplistic, as - * it checks the stronger condition that there's no qual or return - * tlist at all. But in most cases it's probably not worth working - * harder than that. - */ - if (node->ss.ps.plan->qual != NIL || node->ss.ps.plan->targetlist != NIL) - extra_flags |= SO_NEED_TUPLE; - - scan = table_beginscan_bm(node->ss.ss_currentRelation, - node->ss.ps.state->es_snapshot, - 0, - NULL, - extra_flags); - - node->ss.ss_currentScanDesc = scan; - } + node->ss.ss_currentScanDesc = scan; bhs_begin_iterate(&scan->rs_bhs_iterator, tbm, dsa, pstate ? @@ -593,10 +588,6 @@ ExecReScanBitmapHeapScan(BitmapHeapScanState *node) { PlanState *outerPlan = outerPlanState(node); - /* rescan to release any page pin */ - if (node->ss.ss_currentScanDesc) - table_rescan(node->ss.ss_currentScanDesc, NULL); - /* release bitmaps and buffers if any */ if (node->pf_iterator.exhausted) bhs_end_iterate(&node->pf_iterator); @@ -642,10 +633,10 @@ ExecEndBitmapHeapScan(BitmapHeapScanState *node) /* - * close heap scan + * close bitmapheap scan */ if (scanDesc) - table_endscan(scanDesc); + table_endscan_bm(scanDesc); /* * release bitmaps and buffers if any diff --git a/src/include/access/heapam.h b/src/include/access/heapam.h index 750ea30852..545760aab5 100644 --- a/src/include/access/heapam.h +++ b/src/include/access/heapam.h @@ -76,22 +76,35 @@ typedef struct HeapScanDescData */ ParallelBlockTableScanWorkerData *rs_parallelworkerdata; + /* these fields only used in page-at-a-time mode and for bitmap scans */ + int rs_cindex; /* current tuple's index in vistuples */ + int rs_ntuples; /* number of visible tuples on page */ + OffsetNumber rs_vistuples[MaxHeapTuplesPerPage]; /* their offsets */ +} HeapScanDescData; +typedef struct HeapScanDescData *HeapScanDesc; + + +typedef struct BitmapHeapScanDescData +{ + /* All the non-BitmapHeapScan specific members */ + HeapScanDescData heap_common; + + /* + * Members common to Parallel and Serial BitmapHeapScan + */ + /* * These fields are only used for bitmap scans for the "skip fetch" * optimization. Bitmap scans needing no fields from the heap may skip * fetching an all visible block, instead using the number of tuples per * block reported by the bitmap to determine how many NULL-filled tuples - * to return. + * to return. They are common to parallel and serial BitmapHeapScans */ - Buffer rs_vmbuffer; - int rs_empty_tuples_pending; + Buffer vmbuffer; + int empty_tuples_pending; +} BitmapHeapScanDescData; - /* these fields only used in page-at-a-time mode and for bitmap scans */ - int rs_cindex; /* current tuple's index in vistuples */ - int rs_ntuples; /* number of visible tuples on page */ - OffsetNumber rs_vistuples[MaxHeapTuplesPerPage]; /* their offsets */ -} HeapScanDescData; -typedef struct HeapScanDescData *HeapScanDesc; +typedef struct BitmapHeapScanDescData *BitmapHeapScanDesc; /* * Descriptor for fetches from heap via an index. @@ -289,6 +302,11 @@ extern void heap_set_tidrange(TableScanDesc sscan, ItemPointer mintid, extern bool heap_getnextslot_tidrange(TableScanDesc sscan, ScanDirection direction, TupleTableSlot *slot); +extern TableScanDesc heap_beginscan_bm(Relation relation, Snapshot snapshot, uint32 flags); + +extern void heap_endscan_bm(TableScanDesc scan); +extern void heap_rescan_bm(TableScanDesc sscan); + extern bool heap_fetch(Relation relation, Snapshot snapshot, HeapTuple tuple, Buffer *userbuf, bool keep_buf); extern bool heap_hot_search_buffer(ItemPointer tid, Relation relation, diff --git a/src/include/access/tableam.h b/src/include/access/tableam.h index 618ab2b449..3b0fa0610b 100644 --- a/src/include/access/tableam.h +++ b/src/include/access/tableam.h @@ -391,6 +391,21 @@ typedef struct TableAmRoutine ScanDirection direction, TupleTableSlot *slot); + /* + * TODO: add comment + */ + TableScanDesc (*scan_begin_bm) (Relation rel, + Snapshot snapshot, + uint32 flags); + + void (*scan_rescan_bm) (TableScanDesc scan); + + /* + * Release resources and deallocate scan. If TableScanDesc.temp_snap, + * TableScanDesc.rs_snapshot needs to be unregistered. + */ + void (*scan_end_bm) (TableScanDesc scan); + /* ------------------------------------------------------------------------ * Parallel table scan related functions. * ------------------------------------------------------------------------ @@ -929,18 +944,34 @@ table_beginscan_strat(Relation rel, Snapshot snapshot, } /* - * table_beginscan_bm is an alternative entry point for setting up a - * TableScanDesc for a bitmap heap scan. Although that scan technology is - * really quite unlike a standard seqscan, there is just enough commonality to - * make it worth using the same data structure. + * table_beginscan_bm is the entry point for setting up a TableScanDesc for a + * bitmap heap scan. */ static inline TableScanDesc -table_beginscan_bm(Relation rel, Snapshot snapshot, - int nkeys, struct ScanKeyData *key, uint32 extra_flags) +table_beginscan_bm(TableScanDesc scan, Relation rel, Snapshot snapshot, + uint32 extra_flags) { uint32 flags = SO_TYPE_BITMAPSCAN | SO_ALLOW_PAGEMODE | extra_flags; - return rel->rd_tableam->scan_begin(rel, snapshot, nkeys, key, NULL, flags); + /* + * If this is the first scan of the underlying table, create the table + * scan descriptor and begin the scan. + */ + if (!scan) + scan = rel->rd_tableam->scan_begin_bm(rel, snapshot, flags); + + scan->rs_rd->rd_tableam->scan_rescan_bm(scan); + + return scan; +} + +/* + * End Bitmap Table Scan + */ +static inline void +table_endscan_bm(TableScanDesc scan) +{ + scan->rs_rd->rd_tableam->scan_end_bm(scan); } /* diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 848ce9b30c..8369c15a82 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -263,6 +263,7 @@ BitmapHeapIterator BitmapHeapPath BitmapHeapScan BitmapHeapScanState +BitmapHeapScanDesc BitmapIndexScan BitmapIndexScanState BitmapOr -- 2.40.1