Use elog, not Assert, to report failure to provide an outer snapshot.

tglsfdc · tglsfdc · commit f260436459a6 · 2021-07-31T11:50:14.000-04:00
As of commit 84f5c29, executing SQL commands (via SPI or otherwise) requires having either an active Portal, or a caller-established active snapshot. We were simply Assert'ing that that's the case. But we've now had a couple different reports of people testing extensions that didn't meet this requirement, and were confused by the resulting crash. Let's convert the Assert to a test-and-elog, in hopes of making the issue clearer for extension authors. Per gripes from Liu Huailing and RekGRpth. Back-patch to v11, like the prior commit. Discussion: https://postgr.es/m/OSZPR01MB6215671E3C5956A034A080DFBEEC9@OSZPR01MB6215.jpnprd01.prod.outlook.com Discussion: https://postgr.es/m/17035-14607d308ac8643c@postgresql.org
diff --git a/src/backend/tcop/pquery.c b/src/backend/tcop/pquery.c
@@ -1779,7 +1779,8 @@ EnsurePortalSnapshotExists(void)
 
 	/* Otherwise, we'd better have an active Portal */
 	portal = ActivePortal;
-	Assert(portal != NULL);
+	if (unlikely(portal == NULL))
+		elog(ERROR, "cannot execute SQL without an outer snapshot or portal");
 	Assert(portal->portalSnapshot == NULL);
 
 	/* Create a new snapshot and make it active */
