From c861e77d627be8cc8cf2eda540e1f268ce47ed7b Mon Sep 17 00:00:00 2001 From: Melanie Plageman Date: Wed, 4 Dec 2024 16:40:16 -0500 Subject: [PATCH] Track skippable blocks scanned Add counters and logging to vacuum to track what skippable pages were scanned due to SKIP_PAGES_THRESHOLD and which of those were frozen. --- src/backend/access/heap/vacuumlazy.c | 23 +++++++++++++++++++++++ 1 file changed, 23 insertions(+) diff --git a/src/backend/access/heap/vacuumlazy.c b/src/backend/access/heap/vacuumlazy.c index 6a3588cf817..8af64e1a720 100644 --- a/src/backend/access/heap/vacuumlazy.c +++ b/src/backend/access/heap/vacuumlazy.c @@ -214,6 +214,9 @@ typedef struct LVRelState BlockNumber next_unskippable_block; /* next unskippable block */ bool next_unskippable_allvis; /* its visibility status */ Buffer next_unskippable_vmbuffer; /* buffer containing its VM bit */ + + BlockNumber skippable_blocks_scanned; + BlockNumber frozen_skippable_blocks_scanned; } LVRelState; /* Struct for saving and restoring vacuum error information. */ @@ -427,6 +430,8 @@ heap_vacuum_rel(Relation rel, VacuumParams *params, vacrel->live_tuples = 0; vacrel->recently_dead_tuples = 0; vacrel->missed_dead_tuples = 0; + vacrel->skippable_blocks_scanned = 0; + vacrel->frozen_skippable_blocks_scanned = 0; /* * Get cutoffs that determine which deleted tuples are considered DEAD, @@ -664,6 +669,9 @@ heap_vacuum_rel(Relation rel, VacuumParams *params, vacrel->scanned_pages, orig_rel_pages == 0 ? 100.0 : 100.0 * vacrel->scanned_pages / orig_rel_pages); + appendStringInfo(&buf, _("skippable blocks scanned: %u. frozen skippable blocks scanned: %u.\n"), + vacrel->skippable_blocks_scanned, + vacrel->frozen_skippable_blocks_scanned); appendStringInfo(&buf, _("tuples: %lld removed, %lld remain, %lld are dead but not yet removable\n"), (long long) vacrel->tuples_deleted, @@ -1150,13 +1158,28 @@ heap_vac_scan_next_block(LVRelState *vacrel, BlockNumber *blkno, /* Now we must be in one of the two remaining states: */ if (next_block < vacrel->next_unskippable_block) { + uint8 vmbits = 0; + Buffer vmbuffer = InvalidBuffer; + /* * 2. We are processing a range of blocks that we could have skipped * but chose not to. We know that they are all-visible in the VM, * otherwise they would've been unskippable. */ + vacrel->skippable_blocks_scanned++; + *blkno = vacrel->current_block = next_block; *all_visible_according_to_vm = true; + + vmbits = visibilitymap_get_status(vacrel->rel, + vacrel->current_block, + &vmbuffer); + if (vmbits & VISIBILITYMAP_ALL_FROZEN) + vacrel->frozen_skippable_blocks_scanned++; + + if (vmbuffer != InvalidBuffer) + ReleaseBuffer(vmbuffer); + return true; } else -- 2.34.1