added create_foreign_key() func to the documentation; added tests for attach_range_partition() and replace_hash_partition()

Author: zilder

README.md

@@ -290,6 +290,14 @@ set_set_spawn_using_bgw(relation REGCLASS, value BOOLEAN)
 ```
 When INSERTing new data beyond the partitioning range, use SpawnPartitionsWorker to create new partitions in a separate transaction.
 
+```plpgsql
+create_foreign_key(fk_table    REGCLASS,
+                   fk_attr     TEXT,
+                   pk_table    REGCLASS)
+```
+Create a foreign key constraint on `fk_table` for `fk_attr` column which references partitioning key on partitioned `pk_table`. `pk_table` must have UNIQUE indexes on parent and all partitions for key column. This constraint implements RESTRICT behaviour ON DELETE and ON UPDATE actions. You can remove FK constraint regular way by performing `ALTER TABLE ... DROP CONSTRAINT ...`
+
+
 ## Views and tables
 
 #### `pathman_config` --- main config storage

README.rus.md

@@ -77,9 +77,11 @@ SELECT append_range_partition('abc');
 
 INSERT INTO abc VALUES (350);
 INSERT INTO xxx (abc_id) VALUES (350);
-/* Partition cannot be dropped unless there are references from FK table */
+/* Partition cannot be dropped or detached unless there are references from FK table */
 DROP TABLE abc_4;
 ERROR:  update or delete on table "abc_4" violates foreign key constraint "xxx_abc_id_fkey" on table "xxx"
+SELECT detach_range_partition('abc_4');
+ERROR:  update or delete on table "abc_4" violates foreign key constraint "xxx_abc_id_fkey" on table "xxx"
 /* Successful partition drop */
 DELETE FROM xxx WHERE abc_id = 350;
 DROP TABLE abc_4;
@@ -102,5 +104,31 @@ SELECT add_range_partition('abc', 301, 401, 'abc_x');
  abc_x
 (1 row)
 
+/* Check replace_hash_partition() func */
+ALTER TABLE xxx DROP CONSTRAINT xxx_abc_id_fkey;
+DELETE FROM xxx;
+SELECT drop_partitions('abc', true);
+ drop_partitions 
+-----------------
+               4
+(1 row)
+
+SELECT create_hash_partitions('abc', 'id', 3);
+ create_hash_partitions 
+------------------------
+                      3
+(1 row)
+
+SELECT create_foreign_key('xxx', 'abc_id', 'abc');
+ create_foreign_key 
+--------------------
+ 
+(1 row)
+
+INSERT INTO abc SELECT generate_series(1, 10);
+INSERT INTO xxx (abc_id) SELECT generate_series(1, 10);
+CREATE TABLE abc_x (LIKE abc INCLUDING ALL);
+SELECT replace_hash_partition('abc_1', 'abc_x');
+ERROR:  update or delete on table "abc_1" violates foreign key constraint "xxx_abc_id_fkey" on table "xxx"
 DROP EXTENSION pg_pathman CASCADE;
-NOTICE:  drop cascades to constraint xxx_abc_id_fkey on table xxx
+NOTICE:  drop cascades to 4 other objects

expected/pathman_ri.out

@@ -130,6 +130,7 @@ BEGIN
 	INTO old_constr_def;
 
 	/* Detach old partition */
+	PERFORM @extschema@.prepare_partition_drop(parent_relid, old_partition);
 	EXECUTE format('ALTER TABLE %s NO INHERIT %s', old_partition, parent_relid);
 	EXECUTE format('ALTER TABLE %s DROP CONSTRAINT %s',
 				   old_partition,

hash.sql

@@ -613,8 +613,6 @@ BEGIN
 								RETURNING *)
 	SELECT count(*) from config_num_deleted INTO conf_num_del;
 
-	DELETE FROM @extschema@.pathman_config_params WHERE partrel = parent_relid;
-
 	IF conf_num_del = 0 THEN
 		RAISE EXCEPTION 'relation "%" has no partitions', parent_relid::TEXT;
 	END IF;
@@ -638,6 +636,8 @@ BEGIN
 		WHERE oid = v_rec.tbl
 		INTO v_relkind;
 
+		PERFORM @extschema@.prepare_partition_drop(parent_relid, v_rec.tbl);
+
 		/*
 		 * Determine the kind of child relation. It can be either regular
 		 * table (r) or foreign table (f). Depending on relkind we use
@@ -652,6 +652,8 @@ BEGIN
 		v_part_count := v_part_count + 1;
 	END LOOP;
 
+	DELETE FROM @extschema@.pathman_config_params WHERE partrel = parent_relid;
+
 	/* Notify backend about changes */
 	PERFORM @extschema@.on_remove_partitions(parent_relid);
 

init.sql

@@ -55,8 +55,9 @@ SELECT append_range_partition('abc');
 INSERT INTO abc VALUES (350);
 INSERT INTO xxx (abc_id) VALUES (350);
 
-/* Partition cannot be dropped unless there are references from FK table */
+/* Partition cannot be dropped or detached unless there are references from FK table */
 DROP TABLE abc_4;
+SELECT detach_range_partition('abc_4');
 
 /* Successful partition drop */
 DELETE FROM xxx WHERE abc_id = 350;
@@ -67,4 +68,15 @@ SELECT merge_range_partitions('abc_2', 'abc_3');
 SELECT split_range_partition('abc_2', 200);
 SELECT add_range_partition('abc', 301, 401, 'abc_x');
 
+/* Check replace_hash_partition() func */
+ALTER TABLE xxx DROP CONSTRAINT xxx_abc_id_fkey;
+DELETE FROM xxx;
+SELECT drop_partitions('abc', true);
+SELECT create_hash_partitions('abc', 'id', 3);
+SELECT create_foreign_key('xxx', 'abc_id', 'abc');
+INSERT INTO abc SELECT generate_series(1, 10);
+INSERT INTO xxx (abc_id) SELECT generate_series(1, 10);
+CREATE TABLE abc_x (LIKE abc INCLUDING ALL);
+SELECT replace_hash_partition('abc_1', 'abc_x');
+
 DROP EXTENSION pg_pathman CASCADE;

sql/pathman_ri.sql

@@ -19,8 +19,8 @@
 #include "catalog/indexing.h"
 #include "catalog/pg_am.h"
 #include "catalog/pg_constraint.h"
-#if PG_VERSION_NUM >= 90600
 /* Constraint function were moved to pg_constraint_fn.h in version 9.6 */
+#if PG_VERSION_NUM >= 90600
 #include "catalog/pg_constraint_fn.h"
 #endif
 #include "catalog/pg_type.h"