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commit    7ddb9c41a13534011bb64a856fb5a60e41b82b75
Author:   Nathan Bossart <nathan@postgresql.org>
Date:     Fri Aug 28 20:11:06 2026 +0000

    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.  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


 src/backend/postmaster/autovacuum.c | 73 ++++++++++++++++++++++++++++++++++++-
 1 file changed, 71 insertions(+), 2 deletions(-)

diff --git a/src/backend/postmaster/autovacuum.c b/src/backend/postmaster/autovacuum.c
index 0c975d0eda6..d7ca8e72444 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 +3662,62 @@ 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;
 }


[parent: 0ab90a5c9418]