schemasync是一个开源的命令行工具，用于读取源db和目标db的schema，自动生成同步更新和回滚的sql，方便自动化的schema同步。
网址：http://www.schemasync.org
源码：https://github.com/mmatuson/SchemaSync
命令格式
schemasync [options]
# source/target 格式: mysql://user:pass@host:port/database
# 输出(sql脚本):
使用方法
先下载SchemaSync：
wget http://www.schemasync.org/downloads/SchemaSync-0.9.2.tar.gz
然后解压：
tar xvzf SchemaSync-0.9.2.tar.gz
执行安装（需要python的setuptools）
python setup.py install
还需要安装 python-mySQLdb
apt-get install python-mysqldb
好了，现在可以用schemasync命令比较任意两个mysql DB实例，并自动生成两者之间同步和回滚的SQL语句：
schemasync mysql://root:pass@host1:3306/db_A mysql://root:pass@host2:3306/db_B
Migration scripts created for mysql://localhost/db_B
Patch Script: ~/db_B.20140716.patch.sql
Revert Script: ~/db_B.20140716.revert.sql
可以看到它自动产生了两个sql文件，*patch.sql是更新的sql脚本，*revert.sql则是回滚用的sql脚本。下面列出两个脚本的示例。
输出文件内容
more db_B.20140716.patch.sql
--
-- Schema Sync 0.9.1 Patch Script
-- Created: Wed, Jul 16, 2014
-- Server Version: 5.5.37-0ubuntu0.12.04.1-log
-- Apply To: host2/db_B
--
USE `db_B`;
ALTER DATABASE `db_B` CHARACTER SET=latin1 COLLATE=latin1_swedish_ci;
CREATE TABLE `contact` ( `Id` int(11) DEFAULT NULL, `PhoneNumber` varchar(255) DEFAULT NULL) ENGINE=InnoDB DEFAULT CHARSET=latin1;
CREATE TABLE `person` ( `Id` int(11) DEFAULT NULL, `LastName` varchar(255) DEFAULT NULL) ENGINE=InnoDB DEFAULT CHARSET=latin1;
DROP TABLE `cond_instances`;
DROP TABLE `events_waits_current`;
DROP TABLE `events_waits_history`;
DROP TABLE `events_waits_history_long`;
DROP TABLE `events_waits_summary_by_instance`;
DROP TABLE `events_waits_summary_by_thread_by_event_name`;
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DROP TABLE `events_waits_summary_global_by_event_name`;
DROP TABLE `file_instances`;
DROP TABLE `file_summary_by_event_name`;
DROP TABLE `file_summary_by_instance`;
DROP TABLE `mutex_instances`;
DROP TABLE `performance_timers`;
DROP TABLE `rwlock_instances`;
DROP TABLE `setup_consumers`;
DROP TABLE `setup_instruments`;
DROP TABLE `setup_timers`;
DROP TABLE `threads`;
more db_B.20140716.revert.sql
--
-- Schema Sync 0.9.1 Revert Script
-- Created: Wed, Jul 16, 2014
-- Server Version: 5.5.37-0ubuntu0.12.04.1-log
-- Apply To: host2/db_B
--
USE `db_B`;
ALTER DATABASE `db_B` CHARACTER SET=utf8 COLLATE=utf8_general_ci;
DROP TABLE `contact`;
DROP TABLE `person`;
CREATE TABLE `cond_instances` ( `NAME` varchar(128) NOT NULL, `OBJECT_INSTANCE_BEGIN` bigint(20) NOT NULL) ENGINE=db_B DEFAULT CHARSET=utf8;
CREATE TABLE `events_waits_current` ( `THREAD_ID` int(11) NOT NULL, `EVENT_ID` bigint(20) unsigned NOT NULL, `EVENT_NAME` varchar(128) NOT NULL, `SOURCE` varchar(64) DEFAULT NULL, `TIMER_START` bigint(20) unsigned DEFAULT NULL, `TIMER_END` bigint(20) unsigned DEFAULT NULL, `TIMER_WAIT` bigint(20) unsigned DEFAULT NULL, `SPINS` int(10) unsigned DEFAULT NULL, `OBJECT_SCHEMA` varchar(64) DEFAULT NULL, `OBJECT_NAME` varchar(512) DEFAULT NULL, `OBJECT_TYPE` varchar(64) DEFAULT NULL, `OBJECT_INSTANCE_BEGIN` bigint(20) NOT NULL, `NESTING_EVENT_ID` bigint(20) unsigned DEFAULT NULL, `OPERATION` varchar(16) NOT NULL, `NUMBER_OF_BYTES` bigint(20) unsigned DEFAULT NULL, `FLAGS` int(10) unsigned DEFAULT NULL) ENGINE=db_B DEFAULT CHARSET=utf8;
CREATE TABLE `events_waits_history` ( `THREAD_ID` int(11) NOT NULL, `EVENT_ID` bigint(20) unsigned NOT NULL, `EVENT_NAME` varchar(128) NOT NULL, `SOURCE` varchar(64) DEFAULT NULL, `TIMER_START` bigint(20) unsigned DEFAULT NULL, `TIMER_END` bigint(20) unsigned DEFAULT NULL, `TIMER_WAIT` bigint(20) unsigned DEFAULT NULL, `SPINS` int(10) unsigned DEFAULT NULL, `OBJECT_SCHEMA` varchar(64) DEFAULT NULL, `OBJECT_NAME` varchar(512) DEFAULT NULL, `OBJECT_TYPE` varchar(64) DEFAULT NULL, `OBJECT_INSTANCE_BEGIN` bigint(20) NOT NULL, `NESTING_EVENT_ID` bigint(20) unsigned DEFAULT NULL, `OPERATION` varchar(16) NOT NULL, `NUMBER_OF_BYTES` bigint(20) unsigned DEFAULT NULL, `FLAGS` int(10) unsigned DEFAULT NULL) ENGINE=db_B DEFAULT CHARSET=utf8;
CREATE TABLE `events_waits_history_long` ( `THREAD_ID` int(11) NOT NULL, `EVENT_ID` bigint(20) unsigned NOT NULL, `EVENT_NAME` varchar(128) NOT NULL, `SOURCE` varchar(64) DEFAULT NULL, `TIMER_START` bigint(20) unsigned DEFAULT NULL, `TIMER_END` bigint(20) unsigned DEFAULT NULL, `TIMER_WAIT` bigint(20) unsigned DEFAULT NULL, `SPINS` int(10) unsigned DEFAULT NULL, `OBJECT_SCHEMA` varchar(64) DEFAULT NULL, `OBJECT_NAME` varchar(512) DEFAULT NULL, `OBJECT_TYPE` varchar(64) DEFAULT NULL, `OBJECT_INSTANCE_BEGIN` bigint(20) NOT NULL, `NESTING_EVENT_ID` bigint(20) unsigned DEFAULT NULL, `OPERATION` varchar(16) NOT NULL, `NUMBER_OF_BYTES` bigint(20) unsigned DEFAULT NULL, `FLAGS` int(10) unsigned DEFAULT NULL) ENGINE=db_B DEFAULT CHARSET=utf8;
CREATE TABLE `events_waits_summary_by_instance` ( `EVENT_NAME` varchar(128) NOT NULL, `OBJECT_INSTANCE_BEGIN` bigint(20) NOT NULL, `COUNT_STAR` bigint(20) unsigned NOT NULL, `SUM_TIMER_WAIT` bigint(20) unsigned NOT NULL, `MIN_TIMER_WAIT` bigint(20) unsigned NOT NULL, `AVG_TIMER_WAIT` bigint(20) unsigned NOT NULL, `MAX_TIMER_WAIT` bigint(20) unsigned NOT NULL) ENGINE=PERFORMANCE_SCHEMA DEFAULT CHARSET=utf8;
CREATE TABLE `events_waits_summary_by_thread_by_event_name` (`THREAD_ID` int(11) NOT NULL, `EVENT_NAME` varchar(128) NOT NULL, `COUNT_STAR` bigint(20) unsigned NOT NULL, `SUM_TIMER_WAIT` bigint(20) unsigned NOT NULL, `MIN_TIMER_WAIT` bigint(20) unsigned NOT NULL, `AVG_TIMER_WAIT` bigint(20) unsigned NOT NULL, `MAX_TIMER_WAIT` bigint(20) unsigned NOT NULL) ENGINE=PERFORMANCE_SCHEMA DEFAULT CHARSET=utf8;
CREATE TABLE `events_waits_summary_global_by_event_name` ( `EVENT_NAME` varchar(128) NOT NULL, `COUNT_STAR` bigint(20) unsigned NOT NULL, `SUM_TIMER_WAIT` bigint(20) unsigned NOT NULL, `MIN_TIMER_WAIT` bigint(20) unsigned NOT NULL, `AVG_TIMER_WAIT` bigint(20) unsigned NOT NULL, `MAX_TIMER_WAIT` bigint(20) unsigned NOT NULL) ENGINE=db_B DEFAULT CHARSET=utf8;
CREATE TABLE `file_instances` ( `FILE_NAME` varchar(512) NOT NULL, `EVENT_NAME` varchar(128) NOT NULL, `OPEN_COUNT` int(10) unsigned NOT NULL) ENGINE=db_B DEFAULT CHARSET=utf8;
CREATE TABLE `file_summary_by_event_name` ( `EVENT_NAME` varchar(128) NOTNULL, `COUNT_READ` bigint(20) unsigned NOT NULL, `COUNT_WRITE` bigint(20) unsigned NOT NULL, `SUM_NUMBER_OF_BYTES_READ` bigint(20) unsigned NOT NULL, `SUM_NUMBER_OF_BYTES_WRITE` bigint(20) unsigned NOT NULL) ENGINE=PERFORMANCE_SCHEMA DEFAULT CHARSET=utf8;
CREATE TABLE `file_summary_by_instance` ( `FILE_NAME` varchar(512) NOT NULL, `EVENT_NAME` varchar(128) NOT NULL, `COUNT_READ` bigint(20) unsigned NOT NULL, `COUNT_WRITE` bigint(20) unsigned NOT NULL, `SUM_NUMBER_OF_BYTES_READ` bigint(20) unsigned NOT NULL, `SUM_NUMBER_OF_BYTES_WRITE` bigint(20) unsigned NOT NULL) ENGINE=db_B DEFAULT CHARSET=utf8;
CREATE TABLE `mutex_instances` ( `NAME` varchar(128) NOT NULL, `OBJECT_INSTANCE_BEGIN` bigint(20) NOT NULL, `LOCKED_BY_THREAD_ID` int(11) DEFAULT NULL) ENGINE=db_B DEFAULT CHARSET=utf8;
CREATE TABLE `performance_timers` ( `TIMER_NAME` enum('CYCLE','NANOSECOND','MICROSECOND','MILLISECOND','TICK') NOT NULL, `TIMER_FREQUENCY` bigint(20) DEFAULT NULL, `TIMER_RESOLUTION` bigint(20) DEFAULT NULL, `TIMER_OVERHEAD` bigint(20) DEFAULT NULL) ENGINE=db_B DEFAULT CHARSET=utf8;
CREATE TABLE `rwlock_instances` ( `NAME` varchar(128) NOT NULL, `OBJECT_INSTANCE_BEGIN` bigint(20) NOT NULL, `WRITE_LOCKED_BY_THREAD_ID` int(11) DEFAULT NULL, `READ_LOCKED_BY_COUNT` int(10) unsigned NOT NULL) ENGINE=PERFORMANCE_SCHEMA DEFAULT CHARSET=utf8;CREATE TABLE `setup_consumers` ( `NAME` varchar(64) NOT NULL, `ENABLED` enum('YES','NO') NOT NULL) ENGINE=db_B DEFAULT CHARSET=utf8;
CREATE TABLE `setup_instruments` ( `NAME` varchar(128) NOT NULL, `ENABLED` enum('YES','NO') NOT NULL, `TIMED` enum('YES','NO') NOT NULL) ENGINE=PERFORMANCE_SCHEMA DEFAULT CHARSET=utf8;
CREATE TABLE `setup_timers` ( `NAME` varchar(64) NOT NULL, `TIMER_NAME` enum('CYCLE','NANOSECOND','MICROSECOND','MILLISECOND','TICK') NOT NULL) ENGINE=db_B DEFAULT CHARSET=utf8;
CREATE TABLE `threads` ( `THREAD_ID` int(11) NOT NULL, `PROCESSLIST_ID` in t(11) DEFAULT NULL, `NAME` varchar(128) NOT NULL) ENGINE=PERFORMANCE_SCHEMA DEFAULT CHARSET=utf8;
