Support pre-10 WAL functions

dbutils.c

@@ -2775,8 +2775,15 @@ get_last_wal_receive_location(PGconn *conn)
 	PGresult		   *res;
 	XLogRecPtr		    ptr = InvalidXLogRecPtr;
 
-	// pre-10 !!!
-	res = PQexec(conn, "SELECT pg_catalog.pg_last_wal_receive_lsn()");
+
+	if (server_version_num >= 100000)
+	{
+		res = PQexec(conn, "SELECT pg_catalog.pg_last_wal_receive_lsn()");
+	}
+	else
+	{
+		res = PQexec(conn, "SELECT pg_catalog.pg_last_xlog_receive_location()");
+	}
 
 	if (PQresultStatus(res) == PGRES_TUPLES_OK)
 	{

repmgrd.c

@@ -37,6 +37,7 @@ PGconn	   *local_conn = NULL;
 /* Collate command line errors here for friendlier reporting */
 static ItemList	cli_errors = { NULL, NULL };
 
+int			server_version_num = 0;
 bool        startup_event_logged = false;
 
 MonitoringState monitoring_state = MS_NORMAL;
@@ -286,6 +287,12 @@ main(int argc, char **argv)
 	/* abort if local node not available at startup */
 	local_conn = establish_db_connection(config_file_options.conninfo, true);
 
+	/*
+	 * store the server version number - we'll need this to generate
+	 * version-dependent queries etc.
+	 */
+	server_version_num = get_server_version(local_conn, NULL);
+
 	/*
 	 * sanity checks
 	 *

repmgrd.h

@@ -26,7 +26,8 @@ extern instr_time	degraded_monitoring_start;
 extern t_configuration_options config_file_options;
 extern t_node_info local_node_info;
 extern PGconn	   *local_conn;
-extern bool startup_event_logged;
+extern bool			startup_event_logged;
+extern int			server_version_num;
 
 PGconn *try_reconnect(const char *conninfo, NodeStatus *node_status);