diff --git a/src/backend/catalog/namespace.c b/src/backend/catalog/namespace.c
index 740570c566..f4e0663ad5 100644
--- a/src/backend/catalog/namespace.c
+++ b/src/backend/catalog/namespace.c
@@ -2989,44 +2989,81 @@ CheckSetNamespace(Oid oldNspOid, Oid nspOid)
  *
  * Note: calling this may result in a CommandCounterIncrement operation,
  * if we have to create or clean out the temp namespace.
+ *
+ * This function acquires AccessShareLock on the target
+ * namespace. Without this, the namespace could be dropped before our
+ * transaction commits, leaving behind objects with relnamespace pointing
+ * to a no-longer-existent namespace.
  */
 Oid
 QualifiedNameGetCreationNamespace(List *names, char **objname_p)
 {
 	char	   *schemaname;
 	Oid			namespaceId;
+	Oid         oldnspid = InvalidOid;
+	bool        retry = false;
+	uint64      inval_count;
 
 	/* deconstruct the name list */
 	DeconstructQualifiedName(names, &schemaname, objname_p);
 
-	if (schemaname)
+	for (;;)
 	{
-		/* check for pg_temp alias */
-		if (strcmp(schemaname, "pg_temp") == 0)
+		inval_count = SharedInvalidMessageCounter;
+
+		if (schemaname)
 		{
-			/* Initialize temp namespace */
-			AccessTempTableNamespace(false);
-			return myTempNamespace;
+			/* check for pg_temp alias */
+			if (strcmp(schemaname, "pg_temp") == 0)
+			{
+				/* Initialize temp namespace */
+				AccessTempTableNamespace(false);
+				return myTempNamespace;
+			}
+			/* use exact schema given */
+			namespaceId = get_namespace_oid(schemaname, false);
+			/* we do not check for USAGE rights here! */
 		}
-		/* use exact schema given */
-		namespaceId = get_namespace_oid(schemaname, false);
-		/* we do not check for USAGE rights here! */
-	}
-	else
-	{
-		/* use the default creation namespace */
-		recomputeNamespacePath();
-		if (activeTempCreationPending)
+		else
 		{
-			/* Need to initialize temp namespace */
-			AccessTempTableNamespace(true);
-			return myTempNamespace;
+			/* use the default creation namespace */
+			recomputeNamespacePath();
+			if (activeTempCreationPending)
+			{
+				/* Need to initialize temp namespace */
+				AccessTempTableNamespace(true);
+				return myTempNamespace;
+			}
+			namespaceId = activeCreationNamespace;
+			if (!OidIsValid(namespaceId))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_SCHEMA),
+						 errmsg("no schema has been selected to create in")));
 		}
-		namespaceId = activeCreationNamespace;
-		if (!OidIsValid(namespaceId))
-			ereport(ERROR,
-					(errcode(ERRCODE_UNDEFINED_SCHEMA),
-					 errmsg("no schema has been selected to create in")));
+
+		if (retry)
+		{
+			/* If nothing changed, we're done. */
+			if (namespaceId == oldnspid)
+				break;
+
+			/* If creation namespace has changed, give up old lock. */
+			if (namespaceId != oldnspid)
+				UnlockDatabaseObject(NamespaceRelationId, oldnspid, 0,
+									AccessShareLock);
+		}
+
+		/* Lock namespace. */
+		if (namespaceId != oldnspid)
+			LockDatabaseObject(NamespaceRelationId, namespaceId, 0, AccessShareLock);
+
+		/* If no invalidation message were processed, we're done! */
+		if (inval_count == SharedInvalidMessageCounter)
+			break;
+
+		/* Something may have changed, so recheck our work. */
+		retry = true;
+		oldnspid = namespaceId;
 	}
 
 	return namespaceId;