MySQL needs single master to check data integrity

MySQL slaves can drift out of sync. Many of our clients are surprised to find some data differences in their replication topology, once we do some checking and sniffing around. Such checks require a single reliable or authoritative master to compare against.

Click through to the end for multi-master solutions that work with MySQL.

Reason 5 – No way to do integrity checking

MySQL’s statement based replication has a number of problems. It is notoriously bad at handling stored procedures. There are also lots of problems around non-deterministic functions. When you’re lucky it fails with an error. But many environments have replication problems and data inconsistencies that they don’t even know about.

This problem of data drift is well known in MySQL replication. Luckly there is a solution. Formerly part of Maatkit, now redubbed percona toolkit, the table checksum tool attacks this problem head on. pt-table-checksum is a great tool, but won’t help you much when you don’t have a single master.

Which database holds the correct view of all your data?

NEXT: Reason 6 – Active-active breaks transaction isolation

PREV: Reason 4 – Cannot clone & build a slave without a single master

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