Fix snapshot handling bug in recent BRIN fix

alvherre · alvherre · commit 8733f0b54c05 · 2025-11-04T20:31:43.000+01:00
Commit a95e3d8 added ActiveSnapshot push+pop when processing work-items (BRIN autosummarization), but forgot to handle the case of a transaction failing during the run, which drops the snapshot untimely. Fix by making the pop conditional on an element being actually there. Author: Álvaro Herrera <alvherre@kurilemu.de> Backpatch-through: 13 Discussion: https://postgr.es/m/202511041648.nofajnuddmwk@alvherre.pgsql
diff --git a/src/backend/postmaster/autovacuum.c b/src/backend/postmaster/autovacuum.c
@@ -2544,7 +2544,8 @@ do_autovacuum(void)
 
 		PushActiveSnapshot(GetTransactionSnapshot());
 		perform_work_item(workitem);
-		PopActiveSnapshot();
+		if (ActiveSnapshotSet())	/* transaction could have aborted */
+			PopActiveSnapshot();
 
 		/*
 		 * Check for config changes before acquiring lock for further jobs.
