Fix replica identity check for a partitioned table.

The current publisher code checks if UPDATE or DELETE can be executed with
the replica identity of the table even if it's a partitioned table. We can
skip checking the replica identity for partitioned tables because the
operations are actually performed on the leaf partitions (not the
partitioned table).

Reported-by: Brad Nicholson
Author: Hou Zhijie
Reviewed-by: Peter Smith, Amit Kapila
Backpatch-through: 13
Discussion: https://postgr.es/m/CAMMnM%3D8i5DohH%3DYKzV0_wYuYSYvuOJoL9F5nzXTc%2ByzsG1f6rg%40mail.gmail.com

src/backend/executor/execReplication.c

@@ -569,6 +569,13 @@ CheckCmdReplicaIdentity(Relation rel, CmdType cmd)
 {
 	PublicationDesc pubdesc;
 
+	/*
+	 * Skip checking the replica identity for partitioned tables, because the
+	 * operations are actually performed on the leaf partitions.
+	 */
+	if (rel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE)
+		return;
+
 	/* We only need to do checks for UPDATE and DELETE. */
 	if (cmd != CMD_UPDATE && cmd != CMD_DELETE)
 		return;

src/test/regress/expected/publication.out

@@ -214,6 +214,8 @@ ALTER PUBLICATION testpub_forparted ADD TABLE testpub_parted;
 Tables:
     "public.testpub_parted"
 
+-- works despite missing REPLICA IDENTITY, because no actual update happened
+UPDATE testpub_parted SET a = 1 WHERE false;
 -- should now fail, because parent's publication replicates updates
 UPDATE testpub_parted1 SET a = 1;
 ERROR:  cannot update table "testpub_parted1" because it does not have a replica identity and publishes updates

src/test/regress/sql/publication.sql

@@ -119,6 +119,8 @@ UPDATE testpub_parted1 SET a = 1;
 -- only parent is listed as being in publication, not the partition
 ALTER PUBLICATION testpub_forparted ADD TABLE testpub_parted;
 \dRp+ testpub_forparted
+-- works despite missing REPLICA IDENTITY, because no actual update happened
+UPDATE testpub_parted SET a = 1 WHERE false;
 -- should now fail, because parent's publication replicates updates
 UPDATE testpub_parted1 SET a = 1;
 ALTER TABLE testpub_parted DETACH PARTITION testpub_parted1;