report_autovac_workitem_request_failure.patch

diff --git a/src/backend/postmaster/autovacuum.c b/src/backend/postmaster/autovacuum.c
index 75c2362..f322bd6 100644
--- a/src/backend/postmaster/autovacuum.c
+++ b/src/backend/postmaster/autovacuum.c
@@ -3199,6 +3199,7 @@ AutoVacuumRequestWork(AutoVacuumWorkItemType type, Oid relationId,
 					  BlockNumber blkno)
 {
 	int			i;
+	bool		requested = false;
 
 	LWLockAcquire(AutovacuumLock, LW_EXCLUSIVE);
 
@@ -3218,11 +3219,17 @@ AutoVacuumRequestWork(AutoVacuumWorkItemType type, Oid relationId,
 		workitem->avw_database = MyDatabaseId;
 		workitem->avw_relation = relationId;
 		workitem->avw_blockNumber = blkno;
+		requested = true;
 
 		/* done */
 		break;
 	}
 
+	if (!requested)
+		ereport(LOG, (errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED),
+					  errmsg("could not request an autovacuum work item %d for OID %u",
+							 type, relationId)));
+
 	LWLockRelease(AutovacuumLock);
 }