Invalidate partitions of table being attached/detached

Failing to do that, any direct inserts/updates of those partitions
would fail to enforce the correct constraint, that is, one that
considers the new partition constraint of their parent table.

Backpatch to 10.

Reported by: Hou Zhijie <houzj.fnst@fujitsu.com>
Author: Amit Langote <amitlangote09@gmail.com>
Author: Álvaro Herrera <alvherre@alvh.no-ip.org>
Reviewed-by: Nitin Jadhav <nitinjadhavpostgres@gmail.com>
Reviewed-by: Pavel Borisov <pashkin.elfe@gmail.com>

Discussion: https://postgr.es/m/OS3PR01MB5718DA1C4609A25186D1FBF194089%40OS3PR01MB5718.jpnprd01.prod.outlook.com

src/backend/commands/tablecmds.c

@@ -15330,6 +15330,22 @@ ATExecAttachPartition(List **wqueue, Relation rel, PartitionCmd *cmd)
 
 	ObjectAddressSet(address, RelationRelationId, RelationGetRelid(attachrel));
 
+	/*
+	 * If the partition we just attached is partitioned itself, invalidate
+	 * relcache for all descendent partitions too to ensure that their
+	 * rd_partcheck expression trees are rebuilt; partitions already locked
+	 * at the beginning of this function.
+	 */
+	if (attachrel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE)
+	{
+		ListCell *l;
+
+		foreach(l, attachrel_children)
+		{
+			CacheInvalidateRelcacheByRelid(lfirst_oid(l));
+		}
+	}
+
 	/* keep our lock until commit */
 	heap_close(attachrel, NoLock);
 
@@ -15879,6 +15895,25 @@ ATExecDetachPartition(Relation rel, RangeVar *name)
 	 */
 	CacheInvalidateRelcache(rel);
 
+	/*
+	 * If the partition we just detached is partitioned itself, invalidate
+	 * relcache for all descendent partitions too to ensure that their
+	 * rd_partcheck expression trees are rebuilt; must lock partitions
+	 * before doing so, using the same lockmode as what partRel has been
+	 * locked with by the caller.
+	 */
+	if (partRel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE)
+	{
+		List   *children;
+
+		children = find_all_inheritors(RelationGetRelid(partRel),
+									   AccessExclusiveLock, NULL);
+		foreach(cell, children)
+		{
+			CacheInvalidateRelcacheByRelid(lfirst_oid(cell));
+		}
+	}
+
 	ObjectAddressSet(address, RelationRelationId, RelationGetRelid(partRel));
 
 	/* keep our lock until commit */

src/test/regress/expected/alter_table.out

@@ -4305,3 +4305,23 @@ select indexrelid::regclass, indisclustered from pg_index
 (2 rows)
 
 drop table alttype_cluster;
+--
+-- Check that attaching or detaching a partitioned partition correctly leads
+-- to its partitions' constraint being updated to reflect the parent's
+-- newly added/removed constraint
+create table target_parted (a int, b int) partition by list (a);
+create table attach_parted (a int, b int) partition by list (b);
+create table attach_parted_part1 partition of attach_parted for values in (1);
+-- insert a row directly into the leaf partition so that its partition
+-- constraint is built and stored in the relcache
+insert into attach_parted_part1 values (1, 1);
+-- the following better invalidate the partition constraint of the leaf
+-- partition too...
+alter table target_parted attach partition attach_parted for values in (1);
+-- ...such that the following insert fails
+insert into attach_parted_part1 values (2, 1);
+ERROR:  new row for relation "attach_parted_part1" violates partition constraint
+DETAIL:  Failing row contains (2, 1).
+-- ...and doesn't when the partition is detached along with its own partition
+alter table target_parted detach partition attach_parted;
+insert into attach_parted_part1 values (2, 1);

src/test/regress/sql/alter_table.sql

@@ -2860,3 +2860,22 @@ select indexrelid::regclass, indisclustered from pg_index
   where indrelid = 'alttype_cluster'::regclass
   order by indexrelid::regclass::text;
 drop table alttype_cluster;
+
+--
+-- Check that attaching or detaching a partitioned partition correctly leads
+-- to its partitions' constraint being updated to reflect the parent's
+-- newly added/removed constraint
+create table target_parted (a int, b int) partition by list (a);
+create table attach_parted (a int, b int) partition by list (b);
+create table attach_parted_part1 partition of attach_parted for values in (1);
+-- insert a row directly into the leaf partition so that its partition
+-- constraint is built and stored in the relcache
+insert into attach_parted_part1 values (1, 1);
+-- the following better invalidate the partition constraint of the leaf
+-- partition too...
+alter table target_parted attach partition attach_parted for values in (1);
+-- ...such that the following insert fails
+insert into attach_parted_part1 values (2, 1);
+-- ...and doesn't when the partition is detached along with its own partition
+alter table target_parted detach partition attach_parted;
+insert into attach_parted_part1 values (2, 1);