FAQ系列 | 从MySQL 5.6到5.7复制错误解决

0、导读

在MySQL 5.7下采用多源复制方式,从5.6复制数据过来,会有问题吗?

1、问题描述

Q群里有位朋友想尝鲜5.7的多源复制,于是用MySQL 5.7版本作为slave,把MySQL 5.6作为master,想要将数据进行汇总,发现此路不通。

他在my.cnf中设置了2个选项,开启并发复制:

slave_parallel_type    = LOGICAL_CLOCK

slave_parallel_workers = 4

启动复制线程后,结果在错误日志中不断有类似下面的信息:

Transaction is tagged with inconsistent logical timestamps: sequence_number (823267087) <= last_committed (1301275374434324336)

执行 SHOW SLAVE STATUS\G 查看状态:

*************************** 1. row ***************************

Slave_IO_State: Waiting for master to send event

Last_Errno: 1756

Last_Error: … The slave coordinator and worker threads are stopped, possibly leaving data in inconsistent state. A restart should restore consistency automatically, although using non-transactional storage for data or info tables or DDL queries could lead to problems. In such cases you have to examine your data (see documentation for details).

Last_SQL_Errno: 1756

Last_SQL_Error: … The slave coordinator and worker threads are stopped, possibly leaving data in inconsistent state. A restart should restore consistency automatically, although using non-transactional storage for data or info tables or DDL queries could lead to problems. In such cases you have to examine your data (see documentation for details).

Last_IO_Error_Timestamp:

Last_SQL_Error_Timestamp: 160523 18:49:05

*************************** 2. row ***************************

Slave_IO_State: Waiting for master to send event

Last_Errno: 1756

Last_Error: … The slave coordinator and worker threads are stopped, possibly leaving data in inconsistent state. A restart should restore consistency automatically, although using non-transactional storage for data or info tables or DDL queries could lead to problems. In such cases you have to examine your data (see documentation for details).

Skip_Counter: 0

Last_SQL_Errno: 1756

Last_SQL_Error: … The slave coordinator and worker threads are stopped, possibly leaving data in inconsistent state. A restart should restore consistency automatically, although using non-transactional storage for data or info tables or DDL queries could lead to problems. In such cases you have to examine your data (see documentation for details).

2、原因分析

上面这些错误提示可以看到,主要原因是:slave端采用了基于 LOGICAL_CLOCK 类型的并行复制,但master端的binlog格式并不支持这种方式,所以slave端无法正确读取binlog并行apply。

3、解决方案

虽然仍旧可以采用MySQL 5.7作为slave,但就无法开启基于 LOGICAL_CLOCK 类型的并行复制了。需要改回传统模式就可以了:

slave_parallel_type    = DATABASE

此外,在MySQL复制方案中,强烈建议不要让主从大版本不一样,很容易出现各种各样的问题。

 

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