Contents
What does PT table checksum do in MySQL?
If specified, pt-table-checksum doesn’t checksum any tables. It checks replicas for differences found by previous checksumming, and then exits. Your first command doesn’t seem to be able to connect to the slave host, which is why it doesn’t report any differences.
How does PT-table checksum-Percona check replication?
pt-table-checksum performs an online replication consistency check by executing checksum queries on the master, which produces different results on replicas that are inconsistent with the master. The optional DSN specifies the master host.
Is there a backwards compatible version of PT-table checksum?
The table referenced in that query is the checksum table, where the checksums are stored. Each row in the table contains the checksum of one chunk of data from some table in the server. Version 2.0 of pt-table-checksum is not backwards compatible with pt-table-sync version 1.0. In some cases this is not a serious problem.
What are the risks of PT-table checksum Percona?
The two main categories of risks are those created by the nature of the tool (e.g. read-only tools vs. read-write tools) and those created by bugs. pt-table-checksum executes queries that cause the MySQL server to checksum its data. This can cause significant server load.
How does PT-table-checksum work in twindb?
You know, pt-table-checksum runs against the master and populates table percona.checksums. twindb-table-compare reads mismatched chunks from percona.checksums, then runs a SELECT against the master and the slave. Then compares the result and shows it to a user as a diff.
What does PT-table-checksum tell you about slaves?
First of all, pt-table-checksum is perfect for checking if the master and its slaves are in-sync. It answers the question “Are the slaves consistent with the master?”. However, if they’re not, pt-table-checksum doesn’t actually tell you what exactly is wrong. Nevertheless, pt-table-sync may give you a partial answer.