Add decoding of sequences to built-in replication

This commit adds support for decoding of sequences to the built-in
replication (the infrastructure was added by commit 0da92dc530).

The syntax and behavior mostly mimics handling of tables, i.e. a
publication may be defined as FOR ALL SEQUENCES (replicating all
sequences in a database), FOR ALL SEQUENCES IN SCHEMA (replicating
all sequences in a particular schema) or individual sequences.

To publish sequence modifications, the publication has to include
'sequence' action. The protocol is extended with a new message,
describing sequence increments.

A new system view pg_publication_sequences lists all the sequences
added to a publication, both directly and indirectly. Various psql
commands (\d and \dRp) are improved to also display publications
including a given sequence, or sequences included in a publication.

Author: Tomas Vondra, Cary Huang
Reviewed-by: Peter Eisentraut, Amit Kapila, Hannu Krosing, Andres
             Freund, Petr Jelinek
Discussion: https://postgr.es/m/d045f3c2-6cfb-06d3-5540-e63c320df8bc@enterprisedb.com
Discussion: https://postgr.es/m/1710ed7e13b.cd7177461430746.3372264562543607781@highgo.ca

1 files changed, 56 insertions, 0 deletions

diff --git a/src/backend/replication/logical/worker.c b/src/backend/replication/logical/worker.c
index 82dcffc2db8..f3868b3e1f8 100644
--- a/src/backend/replication/logical/worker.c
+++ b/src/backend/replication/logical/worker.c
@@ -143,6 +143,7 @@
 #include "catalog/pg_subscription.h"
 #include "catalog/pg_subscription_rel.h"
 #include "catalog/pg_tablespace.h"
+#include "commands/sequence.h"
 #include "commands/tablecmds.h"
 #include "commands/tablespace.h"
 #include "commands/trigger.h"
@@ -1144,6 +1145,57 @@ apply_handle_origin(StringInfo s)
 }
 
 /*
+ * Handle SEQUENCE message.
+ */
+static void
+apply_handle_sequence(StringInfo s)
+{
+	LogicalRepSequence	seq;
+	Oid					relid;
+
+	if (handle_streamed_transaction(LOGICAL_REP_MSG_SEQUENCE, s))
+		return;
+
+	logicalrep_read_sequence(s, &seq);
+
+	/*
+	 * Non-transactional sequence updates should not be part of a remote
+	 * transaction. There should not be any running transaction.
+	 */
+	Assert((!seq.transactional) || in_remote_transaction);
+	Assert(!(!seq.transactional && in_remote_transaction));
+	Assert(!(!seq.transactional && IsTransactionState()));
+
+	/*
+	 * Make sure we're in a transaction (needed by SetSequence). For
+	 * non-transactional updates we're guaranteed to start a new one,
+	 * and we'll commit it at the end.
+	 */
+	if (!IsTransactionState())
+	{
+		StartTransactionCommand();
+		maybe_reread_subscription();
+	}
+
+	relid = RangeVarGetRelid(makeRangeVar(seq.nspname,
+										  seq.seqname, -1),
+							 RowExclusiveLock, false);
+
+	/* lock the sequence in AccessExclusiveLock, as expected by SetSequence */
+	LockRelationOid(relid, AccessExclusiveLock);
+
+	/* apply the sequence change */
+	SetSequence(relid, seq.transactional, seq.last_value, seq.log_cnt, seq.is_called);
+
+	/*
+	 * Commit the per-stream transaction (we only do this when not in
+	 * remote transaction, i.e. for non-transactional sequence updates.
+	 */
+	if (!in_remote_transaction)
+		CommitTransactionCommand();
+}
+
+/*
  * Handle STREAM START message.
  */
 static void
@@ -2511,6 +2563,10 @@ apply_dispatch(StringInfo s)
 			 */
 			break;
 
+		case LOGICAL_REP_MSG_SEQUENCE:
+			apply_handle_sequence(s);
+			return;
+
 		case LOGICAL_REP_MSG_STREAM_START:
 			apply_handle_stream_start(s);
 			break;