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What is pt table checksum?
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. If any data is different, you can resolve the problem with pt-table-sync.
What is checksum in mysql?
CHECKSUM TABLE reports a checksum for the contents of a table. You can use this statement to verify that the contents are the same before and after a backup, rollback, or other operation that is intended to put the data back to a known state. This statement requires the SELECT privilege for the table.
How does PT table checksum work?
Usage. 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. If any data is different, you can resolve the problem with pt-table-sync.
Is there a way to not do PT table checksum?
Also, the –replicate-check-only option will not do any checksumming. ( from the docs ): If specified, pt-table-checksum doesn’t checksum any tables. It checks replicas for differences found by previous checksumming, and then exits.
Why do I get PT table checksum error in Percona?
This could be the problem if, for example, the slave’s MySQL runs with a different TCP port, the hostname is not resolved correctly or both the master and slave are on the same host, or this is Galera-based replication. In this case, there is –recursion-method option to try with different discovery methods: ‘hosts’ or ‘cluster’.
How does MySQL-PT-table-checksum help required database?
As for load, pt-table-checksum comes with some options to throttle itself. Namely –max-load and –max-lag. The tool keeps track of how quickly the server is able to execute the queries, and adjusts the chunks as it learns more about the server’s performance.
Which is faster PT table checksum or MD5?
Take into consideration that by default, pt-table-checksum use CRC32 checksums. CRC32 is not a cryptographic algorithm and for that reason it is prone to have collisions. On the other hand, CRC32 algorithm is faster and less CPU-intensive than MD5 and SHA1.