Check for existing master record before deleting it

Otherwise repmgr implies it's deleting a record which isn't actually
there.

dbutils.c

@@ -1382,3 +1382,23 @@ update_node_record_set_upstream(PGconn *conn, char *cluster_name, int this_node_
 
 	return true;
 }
+
+
+PGresult *
+get_node_record(PGconn *conn, char *cluster, int node_id)
+{
+	char		sqlquery[QUERY_STR_LEN];
+
+	sprintf(sqlquery,
+			"SELECT id, upstream_node_id, conninfo, type, slot_name, active "
+			"  FROM %s.repl_nodes "
+			" WHERE cluster = '%s' "
+			"   AND id = %i",
+			get_repmgr_schema_quoted(conn),
+			cluster,
+			node_id);
+
+	log_debug("get_node_record(): %s\n", sqlquery);
+
+	return PQexec(conn, sqlquery);
+}

dbutils.h

@@ -67,5 +67,6 @@ bool		create_node_record(PGconn *conn, char *action, int node, char *type, int u
 bool		delete_node_record(PGconn *conn, int node, char *action);
 bool        create_event_record(PGconn *conn, t_configuration_options *options, int node_id, char *event, bool successful, char *details);
 bool        update_node_record_set_upstream(PGconn *conn, char *cluster_name, int this_node_id, int new_upstream_node_id);
+PGresult *	get_node_record(PGconn *conn, char *cluster, int node_id);
 
 #endif

repmgr.c

@@ -753,28 +753,38 @@ do_master_register(void)
 		exit(ERR_BAD_CONFIG);
 	}
 
+	PQfinish(master_conn);
+
 	/* XXX we should check if a node with a different ID is registered as
 	   master, otherwise it would be possible to insert a duplicate record
 	   with --force, which would result in an unwelcome "multi-master" situation
 	*/
-	PQfinish(master_conn);
 
 	/* Delete any existing record for this node if --force set */
 	if (runtime_options.force)
 	{
+		PGresult *res;
 		bool node_record_deleted;
 
-		log_notice(_("deleting existing master record with id %i\n"), options.node);
+		begin_transaction(conn);
 
-		node_record_deleted = delete_node_record(conn,
+		res = get_node_record(conn, options.cluster_name, options.node);
-												 options.node,
+		if (PQntuples(res))
-												 "master register");
-
-		if (node_record_deleted == false)
 		{
-			PQfinish(conn);
+			log_notice(_("deleting existing master record with id %i\n"), options.node);
-			exit(ERR_BAD_CONFIG);
+
+			node_record_deleted = delete_node_record(conn,
+													 options.node,
+													 "master register");
+			if (node_record_deleted == false)
+			{
+				rollback_transaction(conn);
+				PQfinish(conn);
+				exit(ERR_BAD_CONFIG);
+			}
 		}
+
+		commit_transaction(conn);
 	}
 
 

repmgrd.c

@@ -2226,23 +2226,12 @@ check_and_create_pid_file(const char *pid_file)
 t_node_info
 get_node_info(PGconn *conn, char *cluster, int node_id)
 {
-	char		sqlquery[QUERY_STR_LEN];
 	PGresult   *res;
 
 	t_node_info node_info = { NODE_NOT_FOUND, NO_UPSTREAM_NODE, "", InvalidXLogRecPtr, UNKNOWN, false, false};
 
-	sprintf(sqlquery,
+	res = get_node_record(conn, cluster, node_id);
-			"SELECT id, upstream_node_id, conninfo, type, slot_name, active "
-			"  FROM %s.repl_nodes "
-			" WHERE cluster = '%s' "
-			"   AND id = %i",
-			get_repmgr_schema_quoted(conn),
-			local_options.cluster_name,
-			node_id);
 
-	log_debug("get_node_info(): %s\n", sqlquery);
-
-	res = PQexec(my_local_conn, sqlquery);
 	if (PQresultStatus(res) != PGRES_TUPLES_OK)
 	{
 		PQExpBufferData errmsg;