On Fri, Aug 28, 2026 at 10:02:42AM -0500, Nathan Bossart wrote: > Here is a patch.
Sorry for the noise. I noticed some silly mistakes in v1, so here's a v2 with those fixed. -- nathan
>From 704573f8367e8065f9e7d02d3af02f21a4870ace Mon Sep 17 00:00:00 2001 From: Nathan Bossart <[email protected]> Date: Fri, 28 Aug 2026 09:54:06 -0500 Subject: [PATCH v2 1/1] Fix pg_stat_autovacuum_scores for TOAST tables. In v19, pg_stat_autovacuum_scores computes a TOAST table's scores from its own storage parameters alone. Autovacuum instead falls back to the main table's parameters when the TOAST table has none of its own, so 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 cannot know a TOAST table's parameters until we have seen its main relation, so the view now makes a preliminary pass over pg_class to collect the main relations' parameters. 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 <[email protected]> Discussion: https://postgr.es/m/CAD21AoB1CJRVfCDh8qYuD3eueiygXxk7F3nybgjN0RZXSD-QUw%40mail.gmail.com Backpatch-through: 19 only --- src/backend/postmaster/autovacuum.c | 75 ++++++++++++++++++++++++++++- 1 file changed, 73 insertions(+), 2 deletions(-) diff --git a/src/backend/postmaster/autovacuum.c b/src/backend/postmaster/autovacuum.c index 0c975d0eda6..badd545ba0e 100644 --- a/src/backend/postmaster/autovacuum.c +++ b/src/backend/postmaster/autovacuum.c @@ -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 +3662,64 @@ 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, which a TOAST table with none of its own + * inherits. We cannot gather these as we go, since a TOAST table may + * precede its main relation in the scan. + */ + 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 +3735,30 @@ 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 +3776,7 @@ pg_stat_get_autovacuum_scores(PG_FUNCTION_ARGS) } table_endscan(scan); table_close(rel, AccessShareLock); + hash_destroy(table_toast_map); return (Datum) 0; } -- 2.55.0
