prohibit add_to_pathman_config() on partitions

Author: funbringer

expected/pathman_basic.out

@@ -1851,6 +1851,18 @@ ORDER BY partition;
 
 DROP TABLE test.provided_part_names CASCADE;
 NOTICE:  drop cascades to 2 other objects
+/* Check that multilivel is prohibited */
+CREATE TABLE test.multi(key int NOT NULL);
+SELECT create_hash_partitions('test.multi', 'key', 3);
+ create_hash_partitions 
+------------------------
+                      3
+(1 row)
+
+SELECT create_hash_partitions('test.multi_1', 'key', 3);
+ERROR:  multilevel partitioning is not supported
+DROP TABLE test.multi CASCADE;
+NOTICE:  drop cascades to 3 other objects
 DROP SCHEMA test CASCADE;
 NOTICE:  drop cascades to 28 other objects
 DROP EXTENSION pg_pathman CASCADE;

sql/pathman_basic.sql

@@ -551,6 +551,12 @@ ORDER BY partition;
 
 DROP TABLE test.provided_part_names CASCADE;
 
+/* Check that multilivel is prohibited */
+CREATE TABLE test.multi(key int NOT NULL);
+SELECT create_hash_partitions('test.multi', 'key', 3);
+SELECT create_hash_partitions('test.multi_1', 'key', 3);
+DROP TABLE test.multi CASCADE;
+
 
 DROP SCHEMA test CASCADE;
 DROP EXTENSION pg_pathman CASCADE;

src/pl_funcs.c

@@ -765,6 +765,7 @@ add_to_pathman_config(PG_FUNCTION_ARGS)
 	Datum				expr_datum;
 
 	PathmanInitState	init_state;
+	PartParentSearch	parent_search;
 
 	if (!PG_ARGISNULL(0))
 	{
@@ -798,6 +799,15 @@ add_to_pathman_config(PG_FUNCTION_ARGS)
 						get_rel_name_or_relid(relid))));
 	}
 
+	/* Check if it's a partition */
+	if (get_parent_of_partition(relid, &parent_search) &&
+		parent_search == PPS_ENTRY_PART_PARENT)
+	{
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("multilevel partitioning is not supported")));
+	}
+
 	/* Select partitioning type */
 	switch (PG_NARGS())
 	{