Shulou(Shulou.com)06/01 Report--

1. Network delay

Since mysql master-slave replication is an asynchronous replication based on binlog, and binlog files are transmitted through the network, it is only natural that network delay is the vast majority of reasons for master-slave non-synchronization, especially the probability of data synchronization across computer rooms is very high, so do read-write separation and pay attention to the pre-design from the business layer.

two。 The load of the master and slave machines is not consistent.

Because mysql master-slave replication starts 1 io thread above the master database, and starts 1 SQL thread and 1 io thread from above, any one of the machines has a high load and is too busy, resulting in a shortage of resources in any of these threads, and there will be master inconsistency.

Inconsistent 3.max_allowed_packet settings

The max_allowed_packet set above the master database is larger than that of the slave database. When a large sql statement can be executed on the master database, the setting from the master database is too small to be executed, resulting in the master never being consistent.

The key value of 4.key starting from the increment key is not consistent with the master caused by the inconsistency of the self-increment step size setting.

In the case of abnormal 5.mysql downtime, if sync_binlog=1 or innodb_flush_log_at_trx_commit=1 is not set, it is very likely that the binlog or relaylog file will be corrupted, resulting in inconsistency of the master.

The master-slave out of sync caused by 6.mysql 's own bug.

7. The version is inconsistent, especially when the high version is the master and the low version is the slave, the function supported on the master database is not supported from the database.

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