diff options
Diffstat (limited to 'src/backend/commands/vacuumlazy.c')
| -rw-r--r-- | src/backend/commands/vacuumlazy.c | 86 |
1 files changed, 63 insertions, 23 deletions
diff --git a/src/backend/commands/vacuumlazy.c b/src/backend/commands/vacuumlazy.c index 9ac84e8293a..f9da24c491f 100644 --- a/src/backend/commands/vacuumlazy.c +++ b/src/backend/commands/vacuumlazy.c @@ -114,9 +114,9 @@ typedef struct LVRelStats BlockNumber pinskipped_pages; /* # of pages we skipped due to a pin */ BlockNumber frozenskipped_pages; /* # of frozen pages we skipped */ BlockNumber tupcount_pages; /* pages whose tuples we counted */ - double scanned_tuples; /* counts only tuples on tupcount_pages */ - double old_rel_tuples; /* previous value of pg_class.reltuples */ + double old_live_tuples; /* previous value of pg_class.reltuples */ double new_rel_tuples; /* new estimated total # of tuples */ + double new_live_tuples; /* new estimated total # of live tuples */ double new_dead_tuples; /* new estimated total # of dead tuples */ BlockNumber pages_removed; double tuples_deleted; @@ -196,7 +196,6 @@ lazy_vacuum_rel(Relation onerel, int options, VacuumParams *params, TransactionId xidFullScanLimit; MultiXactId mxactFullScanLimit; BlockNumber new_rel_pages; - double new_rel_tuples; BlockNumber new_rel_allvisible; double new_live_tuples; TransactionId new_frozen_xid; @@ -245,7 +244,7 @@ lazy_vacuum_rel(Relation onerel, int options, VacuumParams *params, vacrelstats = (LVRelStats *) palloc0(sizeof(LVRelStats)); vacrelstats->old_rel_pages = onerel->rd_rel->relpages; - vacrelstats->old_rel_tuples = onerel->rd_rel->reltuples; + vacrelstats->old_live_tuples = onerel->rd_rel->reltuples; vacrelstats->num_index_scans = 0; vacrelstats->pages_removed = 0; vacrelstats->lock_waiter_detected = false; @@ -311,11 +310,11 @@ lazy_vacuum_rel(Relation onerel, int options, VacuumParams *params, * since then we don't know for certain that all tuples have a newer xmin. */ new_rel_pages = vacrelstats->rel_pages; - new_rel_tuples = vacrelstats->new_rel_tuples; + new_live_tuples = vacrelstats->new_live_tuples; if (vacrelstats->tupcount_pages == 0 && new_rel_pages > 0) { new_rel_pages = vacrelstats->old_rel_pages; - new_rel_tuples = vacrelstats->old_rel_tuples; + new_live_tuples = vacrelstats->old_live_tuples; } visibilitymap_count(onerel, &new_rel_allvisible, NULL); @@ -327,7 +326,7 @@ lazy_vacuum_rel(Relation onerel, int options, VacuumParams *params, vac_update_relstats(onerel, new_rel_pages, - new_rel_tuples, + new_live_tuples, new_rel_allvisible, vacrelstats->hasindex, new_frozen_xid, @@ -335,10 +334,6 @@ lazy_vacuum_rel(Relation onerel, int options, VacuumParams *params, false); /* report results to the stats collector, too */ - new_live_tuples = new_rel_tuples - vacrelstats->new_dead_tuples; - if (new_live_tuples < 0) - new_live_tuples = 0; /* just in case */ - pgstat_report_vacuum(RelationGetRelid(onerel), onerel->rd_rel->relisshared, new_live_tuples, @@ -471,10 +466,11 @@ lazy_scan_heap(Relation onerel, int options, LVRelStats *vacrelstats, TransactionId relminmxid = onerel->rd_rel->relminmxid; BlockNumber empty_pages, vacuumed_pages; - double num_tuples, - tups_vacuumed, - nkeep, - nunused; + double num_tuples, /* total number of nonremovable tuples */ + live_tuples, /* live tuples (reltuples estimate) */ + tups_vacuumed, /* tuples cleaned up by vacuum */ + nkeep, /* dead-but-not-removable tuples */ + nunused; /* unused item pointers */ IndexBulkDeleteResult **indstats; int i; PGRUsage ru0; @@ -505,7 +501,7 @@ lazy_scan_heap(Relation onerel, int options, LVRelStats *vacrelstats, relname))); empty_pages = vacuumed_pages = 0; - num_tuples = tups_vacuumed = nkeep = nunused = 0; + num_tuples = live_tuples = tups_vacuumed = nkeep = nunused = 0; indstats = (IndexBulkDeleteResult **) palloc0(nindexes * sizeof(IndexBulkDeleteResult *)); @@ -988,6 +984,17 @@ lazy_scan_heap(Relation onerel, int options, LVRelStats *vacrelstats, tupgone = false; + /* + * The criteria for counting a tuple as live in this block need to + * match what analyze.c's acquire_sample_rows() does, otherwise + * VACUUM and ANALYZE may produce wildly different reltuples + * values, e.g. when there are many recently-dead tuples. + * + * The logic here is a bit simpler than acquire_sample_rows(), as + * VACUUM can't run inside a transaction block, which makes some + * cases impossible (e.g. in-progress insert from the same + * transaction). + */ switch (HeapTupleSatisfiesVacuum(&tuple, OldestXmin, buf)) { case HEAPTUPLE_DEAD: @@ -1029,6 +1036,12 @@ lazy_scan_heap(Relation onerel, int options, LVRelStats *vacrelstats, relname, blkno, offnum); /* + * Count it as live. Not only is this natural, but it's + * also what acquire_sample_rows() does. + */ + live_tuples += 1; + + /* * Is the tuple definitely visible to all transactions? * * NB: Like with per-tuple hint bits, we can't set the @@ -1073,12 +1086,29 @@ lazy_scan_heap(Relation onerel, int options, LVRelStats *vacrelstats, all_visible = false; break; case HEAPTUPLE_INSERT_IN_PROGRESS: - /* This is an expected case during concurrent vacuum */ + + /* + * This is an expected case during concurrent vacuum. + * + * We do not count these rows as live, because we expect + * the inserting transaction to update the counters at + * commit, and we assume that will happen only after we + * report our results. This assumption is a bit shaky, + * but it is what acquire_sample_rows() does, so be + * consistent. + */ all_visible = false; break; case HEAPTUPLE_DELETE_IN_PROGRESS: /* This is an expected case during concurrent vacuum */ all_visible = false; + + /* + * Count such rows as live. As above, we assume the + * deleting transaction will commit and update the + * counters after we report. + */ + live_tuples += 1; break; default: elog(ERROR, "unexpected HeapTupleSatisfiesVacuum result"); @@ -1281,15 +1311,18 @@ lazy_scan_heap(Relation onerel, int options, LVRelStats *vacrelstats, pfree(frozen); /* save stats for use later */ - vacrelstats->scanned_tuples = num_tuples; vacrelstats->tuples_deleted = tups_vacuumed; vacrelstats->new_dead_tuples = nkeep; /* now we can compute the new value for pg_class.reltuples */ - vacrelstats->new_rel_tuples = vac_estimate_reltuples(onerel, - nblocks, - vacrelstats->tupcount_pages, - num_tuples); + vacrelstats->new_live_tuples = vac_estimate_reltuples(onerel, + nblocks, + vacrelstats->tupcount_pages, + live_tuples); + + /* also compute total number of surviving heap entries */ + vacrelstats->new_rel_tuples = + vacrelstats->new_live_tuples + vacrelstats->new_dead_tuples; /* * Release any remaining pin on visibility map page. @@ -1625,7 +1658,8 @@ lazy_vacuum_index(Relation indrel, ivinfo.analyze_only = false; ivinfo.estimated_count = true; ivinfo.message_level = elevel; - ivinfo.num_heap_tuples = vacrelstats->old_rel_tuples; + /* We can only provide an approximate value of num_heap_tuples here */ + ivinfo.num_heap_tuples = vacrelstats->old_live_tuples; ivinfo.strategy = vac_strategy; /* Do bulk deletion */ @@ -1656,6 +1690,12 @@ lazy_cleanup_index(Relation indrel, ivinfo.analyze_only = false; ivinfo.estimated_count = (vacrelstats->tupcount_pages < vacrelstats->rel_pages); ivinfo.message_level = elevel; + + /* + * Now we can provide a better estimate of total number of surviving + * tuples (we assume indexes are more interested in that than in the + * number of nominally live tuples). + */ ivinfo.num_heap_tuples = vacrelstats->new_rel_tuples; ivinfo.strategy = vac_strategy; |