From e3e1c5de4eacb02b252f50d6aa8aba2b8b986960 Mon Sep 17 00:00:00 2001
From: Ian Barwick <ian@2ndquadrant.com>
Date: Mon, 4 Apr 2016 12:56:00 +0900
Subject: [PATCH] Use "immediately_reserve" parameter in
 pg_create_physical_replication_slot (9.6)

---
 dbutils.c | 18 ++++++++++++++----
 dbutils.h |  3 ++-
 repmgr.c  |  6 ++++--
 3 files changed, 20 insertions(+), 7 deletions(-)

diff --git a/dbutils.c b/dbutils.c
index 5a378f90..243231cb 100644
--- a/dbutils.c
+++ b/dbutils.c
@@ -889,7 +889,7 @@ get_repmgr_schema_quoted(PGconn *conn)
 
 
 bool
-create_replication_slot(PGconn *conn, char *slot_name)
+create_replication_slot(PGconn *conn, char *slot_name, int server_version_num)
 {
 	char				sqlquery[QUERY_STR_LEN];
 	int					query_res;
@@ -926,9 +926,19 @@ create_replication_slot(PGconn *conn, char *slot_name)
 		return false;
 	}
 
-	sqlquery_snprintf(sqlquery,
-					  "SELECT * FROM pg_create_physical_replication_slot('%s')",
-					  slot_name);
+	/* In 9.6 and later, reserve the LSN straight away */
+	if (server_version_num >= 90600)
+	{
+		sqlquery_snprintf(sqlquery,
+						  "SELECT * FROM pg_create_physical_replication_slot('%s', TRUE)",
+						  slot_name);
+	}
+	else
+	{
+		sqlquery_snprintf(sqlquery,
+						  "SELECT * FROM pg_create_physical_replication_slot('%s')",
+						  slot_name);
+	}
 
 	log_debug(_("create_replication_slot(): Creating slot '%s' on primary\n"), slot_name);
 	log_verbose(LOG_DEBUG, "create_replication_slot():\n%s\n", sqlquery);
diff --git a/dbutils.h b/dbutils.h
index 9d08c8bd..8d980d8e 100644
--- a/dbutils.h
+++ b/dbutils.h
@@ -115,7 +115,7 @@ int			wait_connection_availability(PGconn *conn, long long timeout);
 bool		cancel_query(PGconn *conn, int timeout);
 char       *get_repmgr_schema(void);
 char       *get_repmgr_schema_quoted(PGconn *conn);
-bool		create_replication_slot(PGconn *conn, char *slot_name);
+bool		create_replication_slot(PGconn *conn, char *slot_name, int server_version_num);
 int			get_slot_record(PGconn *conn, char *slot_name, t_replication_slot *record);
 bool		drop_replication_slot(PGconn *conn, char *slot_name);
 bool		start_backup(PGconn *conn, char *first_wal_segment, bool fast_checkpoint);
@@ -133,3 +133,4 @@ int		    get_node_replication_state(PGconn *conn, char *node_name, char *output)
 t_server_type parse_node_type(const char *type);
 int			get_data_checksum_version(const char *data_directory);
 #endif
+
diff --git a/repmgr.c b/repmgr.c
index 22c8477f..74a70334 100644
--- a/repmgr.c
+++ b/repmgr.c
@@ -1585,7 +1585,7 @@ do_standby_clone(void)
 	 */
 	if (options.use_replication_slots)
 	{
-		if (create_replication_slot(upstream_conn, repmgr_slot_name) == false)
+		if (create_replication_slot(upstream_conn, repmgr_slot_name, server_version_num) == false)
 		{
 			PQfinish(upstream_conn);
 			exit(ERR_DB_QUERY);
@@ -2368,7 +2368,9 @@ do_standby_follow(void)
 
 	if (options.use_replication_slots)
 	{
-		if (create_replication_slot(master_conn, repmgr_slot_name) == false)
+ 		int	server_version_num = get_server_version(master_conn, NULL);
+
+		if (create_replication_slot(master_conn, repmgr_slot_name, server_version_num) == false)
 		{
 			PQExpBufferData event_details;
 			initPQExpBuffer(&event_details);