# Copyright (c) 2011 - 2013, SoundCloud Ltd., Rany Keddo, Tobias Bielohlawek, Tobias # Schmidt require 'lhm/command' require 'lhm/migration' require 'lhm/sql_helper' module Lhm # Switches origin with destination table using an atomic rename. # # It should only be used if the MySQL server version is not affected by the # bin log affecting bug #39675. This can be verified using # Lhm::SqlHelper.supports_atomic_switch?. class AtomicSwitcher include Command attr_reader :connection def initialize(migration, connection = nil) @migration = migration @connection = connection @origin = migration.origin @destination = migration.destination end def statements atomic_switch end def atomic_switch [ "rename table `#{ @origin.name }` to `#{ @migration.archive_name }`, " \ "`#{ @destination.name }` to `#{ @origin.name }`" ] end def validate unless @connection.table_exists?(@origin.name) && @connection.table_exists?(@destination.name) error "`#{ @origin.name }` and `#{ @destination.name }` must exist" end end private def execute @connection.sql(statements) end end end