Introduce "REFRESH SEQUENCES" for subscriptions.

This patch adds support for a new SQL command:
ALTER SUBSCRIPTION ... REFRESH SEQUENCES
This command updates the sequence entries present in the
pg_subscription_rel catalog table with the INIT state to trigger
resynchronization.

In addition to the new command, the following subscription commands have
been enhanced to automatically refresh sequence mappings:
ALTER SUBSCRIPTION ... REFRESH PUBLICATION
ALTER SUBSCRIPTION ... ADD PUBLICATION
ALTER SUBSCRIPTION ... DROP PUBLICATION
ALTER SUBSCRIPTION ... SET PUBLICATION

These commands will perform the following actions:
Add newly published sequences that are not yet part of the subscription.
Remove sequences that are no longer included in the publication.

This ensures that sequence replication remains aligned with the current
state of the publication on the publisher side.

Note that the actual synchronization of sequence data/values will be
handled in a subsequent patch that introduces a dedicated sequence sync
worker.

Author: Vignesh C <vignesh21@gmail.com>
Reviewed-by: Amit Kapila <amit.kapila16@gmail.com>
Reviewed-by: shveta malik <shveta.malik@gmail.com>
Reviewed-by: Masahiko Sawada <sawada.mshk@gmail.com>
Reviewed-by: Hayato Kuroda <kuroda.hayato@fujitsu.com>
Reviewed-by: Dilip Kumar <dilipbalaut@gmail.com>
Reviewed-by: Peter Smith <smithpb2250@gmail.com>
Reviewed-by: Nisha Moond <nisha.moond412@gmail.com>
Reviewed-by: Shlok Kyal <shlok.kyal.oss@gmail.com>
Reviewed-by: Chao Li <li.evan.chao@gmail.com>
Reviewed-by: Hou Zhijie <houzj.fnst@fujitsu.com>
Discussion: https://postgr.es/m/CAA4eK1LC+KJiAkSrpE_NwvNdidw9F2os7GERUeSxSKv71gXysQ@mail.gmail.com

1 files changed, 23 insertions, 5 deletions

diff --git a/src/backend/executor/execReplication.c b/src/backend/executor/execReplication.c
index b409d4ecbf5..def32774c90 100644
--- a/src/backend/executor/execReplication.c
+++ b/src/backend/executor/execReplication.c
@@ -1112,18 +1112,36 @@ CheckCmdReplicaIdentity(Relation rel, CmdType cmd)
 
 
 /*
- * Check if we support writing into specific relkind.
+ * Check if we support writing into specific relkind of local relation and check
+ * if it aligns with the relkind of the relation on the publisher.
  *
  * The nspname and relname are only needed for error reporting.
  */
 void
-CheckSubscriptionRelkind(char relkind, const char *nspname,
-						 const char *relname)
+CheckSubscriptionRelkind(char localrelkind, char remoterelkind,
+						 const char *nspname, const char *relname)
 {
-	if (relkind != RELKIND_RELATION && relkind != RELKIND_PARTITIONED_TABLE)
+	if (localrelkind != RELKIND_RELATION &&
+		localrelkind != RELKIND_PARTITIONED_TABLE &&
+		localrelkind != RELKIND_SEQUENCE)
 		ereport(ERROR,
 				(errcode(ERRCODE_WRONG_OBJECT_TYPE),
 				 errmsg("cannot use relation \"%s.%s\" as logical replication target",
 						nspname, relname),
-				 errdetail_relkind_not_supported(relkind)));
+				 errdetail_relkind_not_supported(localrelkind)));
+
+	/*
+	 * Allow RELKIND_RELATION and RELKIND_PARTITIONED_TABLE to be treated
+	 * interchangeably, but ensure that sequences (RELKIND_SEQUENCE) match
+	 * exactly on both publisher and subscriber.
+	 */
+	if ((localrelkind == RELKIND_SEQUENCE && remoterelkind != RELKIND_SEQUENCE) ||
+		(localrelkind != RELKIND_SEQUENCE && remoterelkind == RELKIND_SEQUENCE))
+		ereport(ERROR,
+				errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+		/* translator: 3rd and 4th %s are "sequence" or "table" */
+				errmsg("relation \"%s.%s\" type mismatch: source \"%s\", target \"%s\"",
+					   nspname, relname,
+					   remoterelkind == RELKIND_SEQUENCE ? "sequence" : "table",
+					   localrelkind == RELKIND_SEQUENCE ? "sequence" : "table"));
 }