Deny split and merge for subpartitions

Author: ildus

expected/pathman_subpartitions.out

@@ -300,8 +300,46 @@ SELECT tableoid::regclass, * FROM subpartitions.abc;	/* Should create subpartiti
  subpartitions.abc_2_3 | 125 | 125
 (10 rows)
 
+/* split_range_partition */
+SELECT split_range_partition('subpartitions.abc_2', 150);
+ERROR:  could not split partition if it has children
+SELECT split_range_partition('subpartitions.abc_2_2', 75);
+ split_range_partition 
+-----------------------
+ {50,100}
+(1 row)
+
+SELECT subpartitions.partitions_tree('subpartitions.abc');
+     partitions_tree      
+--------------------------
+ subpartitions.abc
+  subpartitions.abc_1
+    subpartitions.abc_1_1
+    subpartitions.abc_1_2
+  subpartitions.abc_2
+    subpartitions.abc_2_1
+    subpartitions.abc_2_2
+    subpartitions.abc_2_4
+    subpartitions.abc_2_3
+(9 rows)
+
+/* merge_range_partitions */
+SELECT append_range_partition('subpartitions.abc', 'subpartitions.abc_3');
+ append_range_partition 
+------------------------
+ subpartitions.abc_3
+(1 row)
+
+select merge_range_partitions('subpartitions.abc_2', 'subpartitions.abc_3');
+ERROR:  cannot merge partitions
+select merge_range_partitions('subpartitions.abc_2_1', 'subpartitions.abc_2_2');
+ merge_range_partitions 
+------------------------
+ 
+(1 row)
+
 DROP TABLE subpartitions.abc CASCADE;
-NOTICE:  drop cascades to 10 other objects
+NOTICE:  drop cascades to 11 other objects
 DROP SCHEMA subpartitions CASCADE;
 NOTICE:  drop cascades to function subpartitions.partitions_tree(regclass,text)
 DROP EXTENSION pg_pathman;

range.sql

@@ -313,20 +313,29 @@ CREATE OR REPLACE FUNCTION @extschema@.split_range_partition(
 	OUT p_range		ANYARRAY)
 RETURNS ANYARRAY AS $$
 DECLARE
-	parent_relid	REGCLASS;
-	part_type		INTEGER;
-	part_expr		TEXT;
-	part_expr_type	REGTYPE;
-	check_name		TEXT;
-	check_cond		TEXT;
-	new_partition	TEXT;
+	parent_relid		REGCLASS;
+	inhparent			REGCLASS;
+	part_type			INTEGER;
+	part_expr			TEXT;
+	part_expr_type		REGTYPE;
+	check_name			TEXT;
+	check_cond			TEXT;
+	new_partition		TEXT;
 
 BEGIN
 	parent_relid = @extschema@.get_parent_of_partition(partition_relid);
 
 	PERFORM @extschema@.validate_relname(parent_relid);
 	PERFORM @extschema@.validate_relname(partition_relid);
 
+	EXECUTE format('SELECT inhparent::REGCLASS FROM pg_inherits WHERE inhparent = $1 LIMIT 1')
+	USING partition_relid
+	INTO inhparent;
+
+	if inhparent IS NOT NULL THEN
+		RAISE EXCEPTION 'could not split partition if it has children';
+	END IF;
+
 	/* Acquire lock on parent */
 	PERFORM @extschema@.prevent_part_modification(parent_relid);
 

sql/pathman_subpartitions.sql

@@ -97,7 +97,15 @@ SELECT tableoid::regclass, * FROM subpartitions.abc;	/* Should be in subpartitio
 UPDATE subpartitions.abc SET b = 125 WHERE a = 125 and b = 75;
 SELECT tableoid::regclass, * FROM subpartitions.abc;	/* Should create subpartitions.abc_2_3 */
 
+/* split_range_partition */
+SELECT split_range_partition('subpartitions.abc_2', 150);
+SELECT split_range_partition('subpartitions.abc_2_2', 75);
+SELECT subpartitions.partitions_tree('subpartitions.abc');
 
+/* merge_range_partitions */
+SELECT append_range_partition('subpartitions.abc', 'subpartitions.abc_3');
+select merge_range_partitions('subpartitions.abc_2', 'subpartitions.abc_3');
+select merge_range_partitions('subpartitions.abc_2_1', 'subpartitions.abc_2_2');
 
 DROP TABLE subpartitions.abc CASCADE;
 DROP SCHEMA subpartitions CASCADE;

src/init.c

@@ -406,7 +406,7 @@ fini_local_cache(void)
  * find_inheritance_children
  *
  * Returns an array containing the OIDs of all relations which
- * inherit *directly* from the relation with OID 'parentrelId'.
+ * inherit *directly* from the relation with OID 'parent_relid'.
  *
  * The specified lock type is acquired on each child relation (but not on the
  * given rel; caller should already have locked it).  If lockmode is NoLock
@@ -416,7 +416,7 @@ fini_local_cache(void)
  * borrowed from pg_inherits.c
  */
 find_children_status
-find_inheritance_children_array(Oid parentrelId,
+find_inheritance_children_array(Oid parent_relid,
 								LOCKMODE lockmode,
 								bool nowait,
 								uint32 *children_size,	/* ret value #1 */
@@ -444,7 +444,7 @@ find_inheritance_children_array(Oid parentrelId,
 	 * Can skip the scan if pg_class shows the
 	 * relation has never had a subclass.
 	 */
-	if (!has_subclass(parentrelId))
+	if (!has_subclass(parent_relid))
 		return FCS_NO_CHILDREN;
 
 	/*
@@ -459,7 +459,7 @@ find_inheritance_children_array(Oid parentrelId,
 	ScanKeyInit(&key[0],
 				Anum_pg_inherits_inhparent,
 				BTEqualStrategyNumber, F_OIDEQ,
-				ObjectIdGetDatum(parentrelId));
+				ObjectIdGetDatum(parent_relid));
 
 	scan = systable_beginscan(relation, InheritsParentIndexId, true,
 							  NULL, 1, key);

src/pl_range_funcs.c

@@ -16,9 +16,10 @@
 #include "xact_handling.h"
 
 #include "access/xact.h"
+#include "catalog/heap.h"
 #include "catalog/namespace.h"
+#include "catalog/pg_inherits_fn.h"
 #include "catalog/pg_type.h"
-#include "catalog/heap.h"
 #include "commands/tablecmds.h"
 #include "executor/spi.h"
 #include "nodes/nodeFuncs.h"
@@ -636,7 +637,17 @@ merge_range_partitions(PG_FUNCTION_ARGS)
 	/* Extract partition Oids from array */
 	partitions = palloc(sizeof(Oid) * nparts);
 	for (i = 0; i < nparts; i++)
-		partitions[i] = DatumGetObjectId(datums[i]);
+	{
+		Oid		partition_relid;
+		partition_relid = DatumGetObjectId(datums[i]);
+
+		/* check that is not has subpartitions */
+		if (has_subclass(partition_relid))
+			ereport(ERROR, (errmsg("cannot merge partitions"),
+							errdetail("at least one of specified partitions has children")));
+
+		partitions[i] = partition_relid;
+	}
 
 	if (nparts < 2)
 		ereport(ERROR, (errmsg("cannot merge partitions"),