Consider only relations part of partition trees in partition functions

This changes the partition functions so as tables and indexes which are
not part of partition trees are handled the same way as what is done for
undefined objects and unsupported relkinds: pg_partition_tree() returns
no rows and pg_partition_root() returns a NULL result.  Hence,
partitioned tables, partitioned indexes and relations whose flag
pg_class.relispartition is set are considered as valid objects to
process.

Previously, tables and indexes not included in a partition tree were
processed the same way as a partition or a partitioned table, which
caused the functions to return inconsistent results for inherited
tables, especially when inheriting from multiple tables.

Reported-by: Álvaro Herrera
Author: Amit Langote, Michael Paquier
Reviewed-by: Tom Lane
Discussion: https://postgr.es/m/20190228193203.GA26151@alvherre.pgsql

1 files changed, 3 insertions, 10 deletions

diff --git a/src/backend/utils/adt/partitionfuncs.c b/src/backend/utils/adt/partitionfuncs.c
index 36d9f69cbcc..a2fe4f34b6d 100644
--- a/src/backend/utils/adt/partitionfuncs.c
+++ b/src/backend/utils/adt/partitionfuncs.c
@@ -35,17 +35,17 @@ static bool
 check_rel_can_be_partition(Oid relid)
 {
 	char		relkind;
+	bool		relispartition;
 
 	/* Check if relation exists */
 	if (!SearchSysCacheExists1(RELOID, ObjectIdGetDatum(relid)))
 		return false;
 
 	relkind = get_rel_relkind(relid);
+	relispartition = get_rel_relispartition(relid);
 
 	/* Only allow relation types that can appear in partition trees. */
-	if (relkind != RELKIND_RELATION &&
-		relkind != RELKIND_FOREIGN_TABLE &&
-		relkind != RELKIND_INDEX &&
+	if (!relispartition &&
 		relkind != RELKIND_PARTITIONED_TABLE &&
 		relkind != RELKIND_PARTITIONED_INDEX)
 		return false;
@@ -189,13 +189,6 @@ pg_partition_root(PG_FUNCTION_ARGS)
 	if (!check_rel_can_be_partition(relid))
 		PG_RETURN_NULL();
 
-	/*
-	 * If the relation is not a partition (it may be the partition parent),
-	 * return itself as a result.
-	 */
-	if (!get_rel_relispartition(relid))
-		PG_RETURN_OID(relid);
-
 	/* Fetch the top-most parent */
 	ancestors = get_partition_ancestors(relid);
 	rootrelid = llast_oid(ancestors);