mysql热备如何保证数据的完整性

如果要确保事务的完整性（ACID），在使用 mysqldump 进行备份时可以添加 --single-transaction 选项，

  --single-transaction
                      Creates a consistent snapshot by dumping all tables in a
                      single transaction. Works ONLY for tables stored in
                      storage engines which support multiversioning (currently
                      only InnoDB does); the dump is NOT guaranteed to be
                      consistent for other storage engines. While a
                      --single-transaction dump is in process, to ensure a
                      valid dump file (correct table contents and binary log
                      position), no other connection should use the following
                      statements: ALTER TABLE, DROP TABLE, RENAME TABLE,
                      TRUNCATE TABLE, as consistent snapshot is not isolated
                      from them. Option automatically turns off --lock-tables.


http://dev.mysql.com/doc/refman/5.6/en/mysqldump.html#option_mysqldump_single-transaction

使用--single-transaction选项进行备份时，且事务分离级别设定为“REPEATABLE READ”时，
MySQL支持InnoDB表同时写入，但由此会消耗一部分系统资源，因此备份时间会比不使用该选项的时间长。
如果要使用该选项，建议备份时间安排在相对空闲的时间段。

另外需要注意的是只有InnoDB和NDB存储引擎支持事务