How do I fix MySQL replication lag?
To minimize slave SQL_THREAD lag, focus on query optimization. My recommendation is to enable the configuration option log_slow_slave_statements so that the queries executed by slave that take more than long_query_time will be logged to the slow log.
Why does MySQL replication lag?
The most certain cases in MySQL relies on bad queries being replicated such as lack of primary keys or bad indexes, a poor network hardware or malfunctioning network card, a distant location between different regions or zones, or some processes such as physical backups running can cause your MySQL database to delay …
How do you resolve replication lag?
To mitigate replication lag for large operations we use batching. We never apply a change to 100,000 rows all at once. Any big update is broken into small segments, subtasks, of some 50 or 100 rows each. As an example, say our app needs to purge some rows that satisfy a condition from a very large table.
How do I know if MySQL replicate is in sync?
Check MySQL Replication Status on Query Servers
- Start the MySQL command-line utility on the slave server: # cd /opt/mysql/mysql/bin.
- Check the replication status using the show slave status command (the status of the slave server is conveyed by the Slave_IO_Running and Slave_SQL_Running column values):
Does replication improve consistency?
Replication can improve reliability by introducing redundancy. If one data store fails, replicated data stores can continue to serve requests. A major downside to replicating data is that it introduces the problem of keeping replicas up-to-date with each other (keeping the data consistent).
What is database replication lag?
Replication lag occurs when the slaves (or secondaries) cannot keep up with the updates occuring on the master (or primary). Unapplied changes accumulate in the slaves’ relay logs and the version of the database on the slaves becomes increasingly different from that of the master.
Does replication affect latency?
Benefits of data replication Improved network performance: Having the same data in multiple locations can lower data access latency, since required data can be retrieved closer to where the transaction is executing.
How do you guarantee monotonic read consistency?
o Monotonic-read consistency guarantees that if a process has seen a value of x at time t, it will never see an older version of x at a later time. Example: Automatically reading your personal calendar updates from different servers.