Inherit parent's AM for partition MERGE/SPLIT operations

This commit makes new partitions created by ALTER TABLE ... SPLIT PARTITION
and ALTER TABLE ... MERGE PARTITIONS commands inherit the paret table access
method.

Reported-by: Alexander Lakhin
Discussion: https://postgr.es/m/84ada05b-be5c-473e-6d1c-ebe5dd21b190%40gmail.com
Reviewed-by: Pavel Borisov

doc/src/sgml/ref/alter_table.sgml

@@ -1158,6 +1158,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
       SQL command <literal>CREATE TABLE <replaceable class="parameter">partition_nameN</replaceable> (LIKE <replaceable class="parameter">name</replaceable> INCLUDING ALL EXCLUDING INDEXES EXCLUDING IDENTITY)</literal>.
       The indexes and identity are created later, after moving the data
       into the new partitions.
+      New partitions will have the same table access method as the parent.
       If the parent table is persistent then new partitions are created
       persistent.  If the parent table is temporary then new partitions
       are also created temporary.
@@ -1227,6 +1228,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
       SQL command <literal>CREATE TABLE <replaceable class="parameter">partition_name</replaceable> (LIKE <replaceable class="parameter">name</replaceable> INCLUDING ALL EXCLUDING INDEXES EXCLUDING IDENTITY)</literal>.
       The indexes and identity are created later, after moving the data
       into the new partition.
+      The new partition will have the same table access method as the parent.
       If the parent table is persistent then the new partition is created
       persistent.  If the parent table is temporary then the new partition
       is also created temporary.

src/backend/commands/tablecmds.c

@@ -21213,6 +21213,11 @@ moveSplitTableRows(Relation rel, Relation splitRel, List *partlist, List *newPar
  *
  * Emulates command: CREATE [TEMP] TABLE <newPartName> (LIKE <modelRel's name>
  * INCLUDING ALL EXCLUDING INDEXES EXCLUDING IDENTITY)
+ *
+ * Also, this function sets the new partition access method same as parent
+ * table access methods (similarly to CREATE TABLE ... PARTITION OF).  It
+ * checks that parent and child tables have compatible persistence.
+ *
  * Function returns the created relation (locked in AccessExclusiveLock mode).
  */
 static Relation
@@ -21243,6 +21248,7 @@ createPartitionTable(RangeVar *newPartName, Relation modelRel,
 	createStmt->oncommit = ONCOMMIT_NOOP;
 	createStmt->tablespacename = NULL;
 	createStmt->if_not_exists = false;
+	createStmt->accessMethod = get_am_name(modelRel->rd_rel->relam);
 
 	tlc = makeNode(TableLikeClause);
 	tlc->relation = makeRangeVar(get_namespace_name(RelationGetNamespace(modelRel)),

src/test/regress/expected/partition_merge.out

@@ -862,6 +862,24 @@ SET search_path = partitions_merge_schema, pg_temp, public;
 -- Can't merge temporary partitions into a persistent partition
 ALTER TABLE t MERGE PARTITIONS (tp_0_1, tp_1_2) INTO tp_0_2;
 ROLLBACK;
+-- Check the new partition inherits parent's table access method
+SET search_path = partitions_merge_schema, public;
+CREATE ACCESS METHOD partitions_merge_heap TYPE TABLE HANDLER heap_tableam_handler;
+CREATE TABLE t (i int) PARTITION BY RANGE (i) USING partitions_merge_heap;
+CREATE TABLE tp_0_1 PARTITION OF t FOR VALUES FROM (0) TO (1);
+CREATE TABLE tp_1_2 PARTITION OF t FOR VALUES FROM (1) TO (2);
+ALTER TABLE t MERGE PARTITIONS (tp_0_1, tp_1_2) INTO tp_0_2;
+SELECT c.relname, a.amname
+FROM pg_class c JOIN pg_am a ON c.relam = a.oid
+WHERE c.oid IN ('t'::regclass, 'tp_0_2'::regclass);
+ relname |        amname         
+---------+-----------------------
+ tp_0_2  | partitions_merge_heap
+ t       | partitions_merge_heap
+(2 rows)
+
+DROP TABLE t;
+DROP ACCESS METHOD partitions_merge_heap;
 RESET search_path;
 --
 DROP SCHEMA partitions_merge_schema;

src/test/regress/expected/partition_split.out

@@ -85,8 +85,8 @@ ALTER TABLE sales_range SPLIT PARTITION sales_feb_mar_apr2022 INTO
    PARTITION sales_mar2022 FOR VALUES FROM ('2022-03-01') TO ('2022-04-01'),
    PARTITION sales_apr2022 FOR VALUES FROM ('2022-04-01') TO ('2022-06-01'));
 ERROR:  upper bound of partition "sales_apr2022" is greater than upper bound of split partition
-LINE 4:    PARTITION sales_apr2022 FOR VALUES FROM ('2022-04-01') TO...
+LINE 4: ... sales_apr2022 FOR VALUES FROM ('2022-04-01') TO ('2022-06-0...
-                                                    ^
+                                                             ^
 -- ERROR:  lower bound of partition "sales_mar2022" conflicts with upper bound of previous partition "sales_feb2022"
 ALTER TABLE sales_range SPLIT PARTITION sales_feb_mar_apr2022 INTO
   (PARTITION sales_feb2022 FOR VALUES FROM ('2022-02-01') TO ('2022-03-01'),
@@ -1494,6 +1494,25 @@ SELECT c.oid::pg_catalog.regclass, pg_catalog.pg_get_expr(c.relpartbound, c.oid)
 (2 rows)
 
 DROP TABLE t;
+-- Check new partitions inherits parent's table access method
+CREATE ACCESS METHOD partition_split_heap TYPE TABLE HANDLER heap_tableam_handler;
+CREATE TABLE t (i int) PARTITION BY RANGE (i) USING partition_split_heap;
+CREATE TABLE tp_0_2 PARTITION OF t FOR VALUES FROM (0) TO (2);
+ALTER TABLE t SPLIT PARTITION tp_0_2 INTO
+  (PARTITION tp_0_1 FOR VALUES FROM (0) TO (1),
+   PARTITION tp_1_2 FOR VALUES FROM (1) TO (2));
+SELECT c.relname, a.amname
+FROM pg_class c JOIN pg_am a ON c.relam = a.oid
+WHERE c.oid IN ('t'::regclass, 'tp_0_1'::regclass, 'tp_1_2'::regclass);
+ relname |        amname        
+---------+----------------------
+ t       | partition_split_heap
+ tp_0_1  | partition_split_heap
+ tp_1_2  | partition_split_heap
+(3 rows)
+
+DROP TABLE t;
+DROP ACCESS METHOD partition_split_heap;
 --
 DROP SCHEMA partition_split_schema;
 DROP SCHEMA partition_split_schema2;

src/test/regress/sql/partition_merge.sql

@@ -535,6 +535,19 @@ SET search_path = partitions_merge_schema, pg_temp, public;
 ALTER TABLE t MERGE PARTITIONS (tp_0_1, tp_1_2) INTO tp_0_2;
 ROLLBACK;
 
+-- Check the new partition inherits parent's table access method
+SET search_path = partitions_merge_schema, public;
+CREATE ACCESS METHOD partitions_merge_heap TYPE TABLE HANDLER heap_tableam_handler;
+CREATE TABLE t (i int) PARTITION BY RANGE (i) USING partitions_merge_heap;
+CREATE TABLE tp_0_1 PARTITION OF t FOR VALUES FROM (0) TO (1);
+CREATE TABLE tp_1_2 PARTITION OF t FOR VALUES FROM (1) TO (2);
+ALTER TABLE t MERGE PARTITIONS (tp_0_1, tp_1_2) INTO tp_0_2;
+SELECT c.relname, a.amname
+FROM pg_class c JOIN pg_am a ON c.relam = a.oid
+WHERE c.oid IN ('t'::regclass, 'tp_0_2'::regclass);
+DROP TABLE t;
+DROP ACCESS METHOD partitions_merge_heap;
+
 RESET search_path;
 
 --

src/test/regress/sql/partition_split.sql

@@ -880,6 +880,20 @@ SELECT c.oid::pg_catalog.regclass, pg_catalog.pg_get_expr(c.relpartbound, c.oid)
 
 DROP TABLE t;
 
+-- Check new partitions inherits parent's table access method
+CREATE ACCESS METHOD partition_split_heap TYPE TABLE HANDLER heap_tableam_handler;
+CREATE TABLE t (i int) PARTITION BY RANGE (i) USING partition_split_heap;
+CREATE TABLE tp_0_2 PARTITION OF t FOR VALUES FROM (0) TO (2);
+ALTER TABLE t SPLIT PARTITION tp_0_2 INTO
+  (PARTITION tp_0_1 FOR VALUES FROM (0) TO (1),
+   PARTITION tp_1_2 FOR VALUES FROM (1) TO (2));
+SELECT c.relname, a.amname
+FROM pg_class c JOIN pg_am a ON c.relam = a.oid
+WHERE c.oid IN ('t'::regclass, 'tp_0_1'::regclass, 'tp_1_2'::regclass);
+DROP TABLE t;
+DROP ACCESS METHOD partition_split_heap;
+
+
 --
 DROP SCHEMA partition_split_schema;
 DROP SCHEMA partition_split_schema2;