Fix assert failure triggered by "CREATE INDEX CONCURRENTLY"

When resource group is enabled, StartTransaction() may acquire a catalog
snapshot within GetResGroupIdForRole, resulting in a valid xmin. However,
the transaction status does not meet the requirements for "CREATE INDEX
CONCURRENTLY".

Author: fairyfar

src/backend/commands/resgroupcmds.c

@@ -34,6 +34,7 @@
 #include "commands/resgroupcmds.h"
 #include "miscadmin.h"
 #include "nodes/pg_list.h"
+#include "storage/proc.h"
 #include "utils/builtins.h"
 #include "utils/datetime.h"
 #include "utils/fmgroids.h"
@@ -716,10 +717,17 @@ GetResGroupIdForRole(Oid roleid)
 	HeapTuple	tuple;
 	Oid			groupId;
 	bool		isNull;
+	bool		releaseSnapshot;
 	Relation	rel;
 	ScanKeyData	key;
 	SysScanDesc	 sscan;
 
+	/*
+	 * StartTransaction() might hold a catalog snapshot with a valid xmin.
+	 * As this fails the "CREATE INDEX CONCURRENTLY" status checks, explicitly
+	 * release the snapshot.
+	 */
+	releaseSnapshot = MyProc->xmin == InvalidTransactionId;
 	rel = table_open(AuthIdRelationId, AccessShareLock);
 
 	ScanKeyInit(&key,
@@ -757,6 +765,9 @@ GetResGroupIdForRole(Oid roleid)
 	 */
 	table_close(rel, AccessShareLock);
 
+	if (releaseSnapshot)
+		InvalidateCatalogSnapshot();
+
 	if (!OidIsValid(groupId))
 		groupId = InvalidOid;
 

src/test/isolation2/expected/resgroup/resgroup_transaction.out

@@ -237,3 +237,16 @@ DROP
 -- cleanup
 DROP VIEW rg_test_monitor;
 DROP
+
+-- ----------------------------------------------------------------------
+-- Test: "CREATE INDEX CONCURRENTLY" when compiled with enable-cassert
+-- ----------------------------------------------------------------------
+
+CREATE TABLE t(a text, b text);
+CREATE
+CREATE INDEX CONCURRENTLY t_idx ON t(a, b);
+CREATE
+DROP INDEX CONCURRENTLY t_idx;
+DROP
+DROP TABLE t;
+DROP

src/test/isolation2/sql/resgroup/resgroup_transaction.sql

@@ -134,3 +134,12 @@ DROP FUNCTION rg_drop_func();
 
 -- cleanup
 DROP VIEW rg_test_monitor;
+
+-- ----------------------------------------------------------------------
+-- Test: "CREATE INDEX CONCURRENTLY" when compiled with enable-cassert
+-- ----------------------------------------------------------------------
+
+CREATE TABLE t(a text, b text);
+CREATE INDEX CONCURRENTLY t_idx ON t(a, b);
+DROP INDEX CONCURRENTLY t_idx;
+DROP TABLE t;