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Fix pg_stat_autovacuum_scores for TOAST tables.

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In v19, pg_stat_autovacuum_scores computes a TOAST table's scores
from its own storage parameters alone.  On the other hand,
autovacuum falls back to the main table's parameters when the TOAST
table has none.  This means that the view may report scores that
don't match what autovacuum would calculate.  This contradicts the
documented promise that the view generates its results the same way
autovacuum workers do.  To fix, teach the view to do the same
fallback.  As in do_autovacuum(), we must make a preliminary pass
over pg_class to collect the main tables' parameters, since the
pg_class scan may see TOAST tables before their main tables.

Commit fad70a09ff for v20 improved autovacuum's handling of TOAST
storage parameters and adjusted the view to match, but it was
deemed too intrusive to back-patch.  This fix is for v19 only.

Oversight in commit 87f61f0c82.

Reported-by: Masahiko Sawada <sawada.mshk@gmail.com>
Reviewed-by: Masahiko Sawada <sawada.mshk@gmail.com>
Discussion: https://postgr.es/m/CAD21AoB1CJRVfCDh8qYuD3eueiygXxk7F3nybgjN0RZXSD-QUw%40mail.gmail.com
Backpatch-through: 19 only
This commit is contained in:
Nathan Bossart
2026-08-28 15:11:06 -05:00
parent 0ab90a5c94
commit 7ddb9c41a1
1 changed files with 71 additions and 2 deletions
Download Patch File Download Diff File Expand all files Collapse all files

73
src/backend/postmaster/autovacuum.c
View File

@@ -3652,6 +3652,8 @@ pg_stat_get_autovacuum_scores(PG_FUNCTION_ARGS)
TableScanDesc scan;
HeapTuple tup;
ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
HTAB *table_toast_map;
HASHCTL ctl;
InitMaterializedSRF(fcinfo, 0);
@@ -3660,13 +3662,62 @@ pg_stat_get_autovacuum_scores(PG_FUNCTION_ARGS)
recentXid = ReadNextTransactionId();
recentMulti = ReadNextMultiXactId();
/* scan pg_class */
/* create hash table for toast <-> main relid mapping */
ctl.keysize = sizeof(Oid);
ctl.entrysize = sizeof(av_relation);
ctl.hcxt = CurrentMemoryContext;
table_toast_map = hash_create("TOAST to main relid map",
100,
&ctl,
HASH_ELEM | HASH_BLOBS | HASH_CONTEXT);
rel = table_open(RelationRelationId, AccessShareLock);
/*
* Do an initial pass over pg_class to collect the main relations'
* autovacuum parameters.
*/
scan = table_beginscan_catalog(rel, 0, NULL);
while ((tup = heap_getnext(scan, ForwardScanDirection)) != NULL)
{
Form_pg_class form = (Form_pg_class) GETSTRUCT(tup);
AutoVacOpts *avopts;
av_relation *hentry;
bool found;
/* skip ineligible entries */
if (form->relkind != RELKIND_RELATION &&
form->relkind != RELKIND_MATVIEW)
continue;
if (form->relpersistence == RELPERSISTENCE_TEMP)
continue;
if (!OidIsValid(form->reltoastrelid))
continue;
avopts = extract_autovac_opts(tup, RelationGetDescr(rel));
if (avopts == NULL)
continue;
hentry = hash_search(table_toast_map, &form->reltoastrelid,
HASH_ENTER, &found);
Assert(!found); /* rels cannot share a TOAST table */
/* hash_search already filled in the key */
hentry->ar_relid = form->oid;
hentry->ar_hasrelopts = true;
memcpy(&hentry->ar_reloptions, avopts, sizeof(AutoVacOpts));
pfree(avopts);
}
table_endscan(scan);
/* now scan pg_class again to compute the scores */
scan = table_beginscan_catalog(rel, 0, NULL);
while ((tup = heap_getnext(scan, ForwardScanDirection)) != NULL)
{
Form_pg_class form = (Form_pg_class) GETSTRUCT(tup);
AutoVacOpts *avopts;
bool free_avopts = false;
bool dovacuum;
bool doanalyze;
bool wraparound;
@@ -3682,13 +3733,30 @@ pg_stat_get_autovacuum_scores(PG_FUNCTION_ARGS)
if (form->relpersistence == RELPERSISTENCE_TEMP)
continue;
/*
* fetch reloptions -- if this toast table does not have them, try the
* main rel
*/
avopts = extract_autovac_opts(tup, RelationGetDescr(rel));
if (avopts)
free_avopts = true;
else if (form->relkind == RELKIND_TOASTVALUE)
{
av_relation *hentry;
bool found;
hentry = hash_search(table_toast_map, &form->oid,
HASH_FIND, &found);
if (found && hentry->ar_hasrelopts)
avopts = &hentry->ar_reloptions;
}
relation_needs_vacanalyze(form->oid, avopts, form,
effective_multixact_freeze_max_age,
LOG_NEVER,
&dovacuum, &doanalyze, &wraparound,
&scores);
if (avopts)
if (free_avopts)
pfree(avopts);
vals[0] = ObjectIdGetDatum(form->oid);
@@ -3706,6 +3774,7 @@ pg_stat_get_autovacuum_scores(PG_FUNCTION_ARGS)
}
table_endscan(scan);
table_close(rel, AccessShareLock);
hash_destroy(table_toast_map);
return (Datum) 0;
}