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Add relallfrozen to pg_class

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Add relallfrozen, an estimate of the number of pages marked all-frozen
in the visibility map.

pg_class already has relallvisible, an estimate of the number of pages
in the relation marked all-visible in the visibility map. This is used
primarily for planning.

relallfrozen, together with relallvisible, is useful for estimating the
outstanding number of all-visible but not all-frozen pages in the
relation for the purposes of scheduling manual VACUUMs and tuning vacuum
freeze parameters.

A future commit will use relallfrozen to trigger more frequent vacuums
on insert-focused workloads with significant volume of frozen data.

Bump catalog version

Author: Melanie Plageman <melanieplageman@gmail.com>
Reviewed-by: Nathan Bossart <nathandbossart@gmail.com>
Reviewed-by: Robert Treat <rob@xzilla.net>
Reviewed-by: Corey Huinker <corey.huinker@gmail.com>
Reviewed-by: Greg Sabino Mullane <htamfids@gmail.com>
Discussion: https://postgr.es/m/flat/CAAKRu_aj-P7YyBz_cPNwztz6ohP%2BvWis%3Diz3YcomkB3NpYA--w%40mail.gmail.com
This commit is contained in:
Melanie Plageman
2025-03-03 11:18:05 -05:00
parent 8492feb98f
commit 99f8f3fbbc
14 changed files with 190 additions and 70 deletions
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18
src/backend/access/heap/vacuumlazy.c
View File

@@ -623,7 +623,8 @@ heap_vacuum_rel(Relation rel, VacuumParams *params,
minmulti_updated;
BlockNumber orig_rel_pages,
new_rel_pages,
new_rel_allvisible;
new_rel_allvisible,
new_rel_allfrozen;
PGRUsage ru0;
TimestampTz starttime = 0;
PgStat_Counter startreadtime = 0,
@@ -898,10 +899,18 @@ heap_vacuum_rel(Relation rel, VacuumParams *params,
* pg_class.relpages to
*/
new_rel_pages = vacrel->rel_pages; /* After possible rel truncation */
visibilitymap_count(rel, &new_rel_allvisible, NULL);
visibilitymap_count(rel, &new_rel_allvisible, &new_rel_allfrozen);
if (new_rel_allvisible > new_rel_pages)
new_rel_allvisible = new_rel_pages;
/*
* An all-frozen block _must_ be all-visible. As such, clamp the count of
* all-frozen blocks to the count of all-visible blocks. This matches the
* clamping of relallvisible above.
*/
if (new_rel_allfrozen > new_rel_allvisible)
new_rel_allfrozen = new_rel_allvisible;
/*
* Now actually update rel's pg_class entry.
*
@@ -910,7 +919,8 @@ heap_vacuum_rel(Relation rel, VacuumParams *params,
* scan every page that isn't skipped using the visibility map.
*/
vac_update_relstats(rel, new_rel_pages, vacrel->new_live_tuples,
new_rel_allvisible, vacrel->nindexes > 0,
new_rel_allvisible, new_rel_allfrozen,
vacrel->nindexes > 0,
vacrel->NewRelfrozenXid, vacrel->NewRelminMxid,
&frozenxid_updated, &minmulti_updated, false);
@@ -3720,7 +3730,7 @@ update_relstats_all_indexes(LVRelState *vacrel)
vac_update_relstats(indrel,
istat->num_pages,
istat->num_index_tuples,
0,
0, 0,
false,
InvalidTransactionId,
InvalidMultiXactId,