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

Based on traditional replication, there may be a problem of delay in copying from the library. After the master goes down, if the master cannot be recovered at this time, the slave can only be used instead of the master. The slave is in a backward state, which will lead to data loss. Part of the problem can be solved by semi-synchronous replication.

The rpl_semi_sync_master_wait_point parameter controls at which stage the master waits for ACK acknowledgements from slaves in MySQL's semi-synchronous replication. In MySQL 5.7, this parameter has two main values: after_commit and after_sync.

1) rpl_semi_sync_master_wait_point=after_commit: master writes its binlog to bin-log file and syncs, commits transactions to storage engine, and waits for ACK. When at least one slave receives binlog, it writes relay-log and returns ACK acknowledgement. After receiving the ACK from the library, the master returns the result to the client.

2) rpl_semi_sync_master_wait_point=after_sync(new in MySQL 5.7): master writes its binlog to binlog file and sync, then enters wait ACK, when at least one slave receives binlog, writes relay-log and returns ACK acknowledgement message. After receiving the acknowledgement from the repository, the master commits the transaction to the storage engine and returns it to the client.

Welcome to subscribe "Shulou Technology Information " to get latest news, interesting things and hot topics in the IT industry, and controls the hottest and latest Internet news, technology news and IT industry trends.