From 158545b5de5cccd27a3a023875891b9c4459bd89 Mon Sep 17 00:00:00 2001 From: Melanie Plageman Date: Tue, 26 Mar 2024 10:16:11 -0400 Subject: [PATCH v9 15/21] Save dead tuple offsets during heap_page_prune After heap_page_prune() returned, lazy_scan_prune() looped through all of the offsets of LP_DEAD items which it later added to LVRelState->dead_items. Instead take care of this when marking a line pointer or when an existing non-removable LP_DEAD item is encountered in heap_prune_chain(). --- src/backend/access/heap/pruneheap.c | 7 ++++ src/backend/access/heap/vacuumlazy.c | 60 +++++++--------------------- src/include/access/heapam.h | 2 + 3 files changed, 23 insertions(+), 46 deletions(-) diff --git a/src/backend/access/heap/pruneheap.c b/src/backend/access/heap/pruneheap.c index fde5f26bb5a..3529ea69520 100644 --- a/src/backend/access/heap/pruneheap.c +++ b/src/backend/access/heap/pruneheap.c @@ -297,6 +297,7 @@ heap_page_prune_and_freeze(Relation relation, Buffer buffer, presult->live_tuples = 0; presult->recently_dead_tuples = 0; + presult->lpdead_items = 0; /* * Caller will update the VM after pruning, collecting LP_DEAD items, and @@ -971,7 +972,10 @@ heap_prune_chain(Buffer buffer, OffsetNumber rootoffnum, if (unlikely(prstate->mark_unused_now)) heap_prune_record_unused(prstate, offnum); else + { presult->all_visible = false; + presult->deadoffsets[presult->lpdead_items++] = offnum; + } break; } @@ -1175,6 +1179,9 @@ heap_prune_record_dead(PruneState *prstate, OffsetNumber offnum, * all_visible. */ presult->all_visible = false; + + /* Record the dead offset for vacuum */ + presult->deadoffsets[presult->lpdead_items++] = offnum; } /* diff --git a/src/backend/access/heap/vacuumlazy.c b/src/backend/access/heap/vacuumlazy.c index c28e786a1e0..0fb5a7dd24d 100644 --- a/src/backend/access/heap/vacuumlazy.c +++ b/src/backend/access/heap/vacuumlazy.c @@ -1396,23 +1396,11 @@ lazy_scan_prune(LVRelState *vacrel, bool *has_lpdead_items) { Relation rel = vacrel->rel; - OffsetNumber offnum, - maxoff; - ItemId itemid; - int lpdead_items = 0; PruneFreezeResult presult; HeapPageFreeze pagefrz; - OffsetNumber deadoffsets[MaxHeapTuplesPerPage]; Assert(BufferGetBlockNumber(buf) == blkno); - /* - * maxoff might be reduced following line pointer array truncation in - * heap_page_prune_and_freeze(). That's safe for us to ignore, since the - * reclaimed space will continue to look like LP_UNUSED items below. - */ - maxoff = PageGetMaxOffsetNumber(page); - /* Initialize pagefrz */ pagefrz.freeze_required = false; pagefrz.FreezePageRelfrozenXid = vacrel->NewRelfrozenXid; @@ -1425,41 +1413,21 @@ lazy_scan_prune(LVRelState *vacrel, * Prune all HOT-update chains and potentially freeze tuples on this page. * * We count the number of tuples removed from the page by the pruning step - * in presult.ndeleted. It should not be confused with lpdead_items; - * lpdead_items's final value can be thought of as the number of tuples - * that were deleted from indexes. + * in presult.ndeleted. It should not be confused with + * presult.lpdead_items; presult.lpdead_items's final value can be thought + * of as the number of tuples that were deleted from indexes. * * If the relation has no indexes, we can immediately mark would-be dead * items LP_UNUSED, so mark_unused_now should be true if no indexes and * false otherwise. + * + * We will update the VM after collecting LP_DEAD items and freezing + * tuples. Pruning will have determined whether or not the page is + * all-visible. */ heap_page_prune_and_freeze(rel, buf, vacrel->vistest, vacrel->nindexes == 0, &pagefrz, &presult, PRUNE_VACUUM_SCAN, &vacrel->offnum); - /* - * Now scan the page to collect LP_DEAD items and update the variables set - * just above. - */ - for (offnum = FirstOffsetNumber; - offnum <= maxoff; - offnum = OffsetNumberNext(offnum)) - { - /* - * Set the offset number so that we can display it along with any - * error that occurred while processing this tuple. - */ - vacrel->offnum = offnum; - itemid = PageGetItemId(page, offnum); - - - if (ItemIdIsDead(itemid)) - { - deadoffsets[lpdead_items++] = offnum; - continue; - } - - } - vacrel->offnum = InvalidOffsetNumber; Assert(MultiXactIdIsValid(presult.new_relminmxid)); @@ -1492,7 +1460,7 @@ lazy_scan_prune(LVRelState *vacrel, TransactionId debug_cutoff; bool debug_all_frozen; - Assert(lpdead_items == 0); + Assert(presult.lpdead_items == 0); if (!heap_page_is_all_visible(vacrel, buf, &debug_cutoff, &debug_all_frozen)) @@ -1508,7 +1476,7 @@ lazy_scan_prune(LVRelState *vacrel, /* * Now save details of the LP_DEAD items from the page in vacrel */ - if (lpdead_items > 0) + if (presult.lpdead_items > 0) { VacDeadItems *dead_items = vacrel->dead_items; ItemPointerData tmp; @@ -1517,9 +1485,9 @@ lazy_scan_prune(LVRelState *vacrel, ItemPointerSetBlockNumber(&tmp, blkno); - for (int i = 0; i < lpdead_items; i++) + for (int i = 0; i < presult.lpdead_items; i++) { - ItemPointerSetOffsetNumber(&tmp, deadoffsets[i]); + ItemPointerSetOffsetNumber(&tmp, presult.deadoffsets[i]); dead_items->items[dead_items->num_items++] = tmp; } @@ -1531,7 +1499,7 @@ lazy_scan_prune(LVRelState *vacrel, /* Finally, add page-local counts to whole-VACUUM counts */ vacrel->tuples_deleted += presult.ndeleted; vacrel->tuples_frozen += presult.nfrozen; - vacrel->lpdead_items += lpdead_items; + vacrel->lpdead_items += presult.lpdead_items; vacrel->live_tuples += presult.live_tuples; vacrel->recently_dead_tuples += presult.recently_dead_tuples; @@ -1540,7 +1508,7 @@ lazy_scan_prune(LVRelState *vacrel, vacrel->nonempty_pages = blkno + 1; /* Did we find LP_DEAD items? */ - *has_lpdead_items = (lpdead_items > 0); + *has_lpdead_items = (presult.lpdead_items > 0); Assert(!presult.all_visible || !(*has_lpdead_items)); @@ -1608,7 +1576,7 @@ lazy_scan_prune(LVRelState *vacrel, * There should never be LP_DEAD items on a page with PD_ALL_VISIBLE set, * however. */ - else if (lpdead_items > 0 && PageIsAllVisible(page)) + else if (presult.lpdead_items > 0 && PageIsAllVisible(page)) { elog(WARNING, "page containing LP_DEAD items is marked as all-visible in relation \"%s\" page %u", vacrel->relname, blkno); diff --git a/src/include/access/heapam.h b/src/include/access/heapam.h index 79ec4049f12..68b4d5b859c 100644 --- a/src/include/access/heapam.h +++ b/src/include/access/heapam.h @@ -241,6 +241,8 @@ typedef struct PruneFreezeResult /* New value of relminmxid found by heap_page_prune_and_freeze() */ MultiXactId new_relminmxid; + int lpdead_items; /* includes existing LP_DEAD items */ + OffsetNumber deadoffsets[MaxHeapTuplesPerPage]; } PruneFreezeResult; /* 'reason' codes for heap_page_prune_and_freeze() */ -- 2.40.1