Fix in_memory utility command hook with missing_ok flag.

Author: Alexander Korotkov

contrib/in_memory/in_memory.c

@@ -26,6 +26,7 @@
 #include "postmaster/autovacuum.h"
 #include "replication/message.h"
 #include "storage/ipc.h"
+#include "storage/lmgr.h"
 #include "storage/lwlock.h"
 #include "storage/proc.h"
 #include "storage/shmem.h"
@@ -345,8 +346,7 @@ in_memory_utility_command(PlannedStmt *pstmt,
 	}
 	else if (IsA(pstmt->utilityStmt, AlterTableStmt))
 	{
-		AlterTableStmt  *stmt = (AlterTableStmt*)pstmt->utilityStmt;
-		RangeVar		*rv;
+		AlterTableStmt *stmt = (AlterTableStmt * )pstmt->utilityStmt;
 		Relation		rel;
 		Oid				myrelid;
 		LOCKMODE		mode;
@@ -365,20 +365,22 @@ in_memory_utility_command(PlannedStmt *pstmt,
 		}
 		if (mode != AccessExclusiveLock)
 			goto done_alter_table;
-		rv = stmt->relation;
-		rel = heap_openrv(rv, AccessExclusiveLock);
-		myrelid = RelationGetRelid(rel);
+		myrelid = AlterTableLookupRelation(stmt, AccessExclusiveLock);
+
+		if (!OidIsValid(myrelid))
+			goto done_alter_table;
 
 		if (!check_fdw_is_in_memory_relid(myrelid))
 		{
-			heap_close(rel, AccessExclusiveLock);
+			UnlockRelationOid(myrelid, AccessExclusiveLock);
 			goto done_alter_table;
 		}
 
+		rel = heap_open(myrelid, NoLock);
 		validate_fdw_alter_table_commands(myrelid, stmt->cmds, rel);
 		call_next = true;
 		heap_close(rel, AccessExclusiveLock);
-		
+
 done_alter_table:
 		(void)0;
 	}