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.
Which command is used to verify the data consistency within replication streams in MySQL?
You may script pt-table-checksum / pt-table-sync steps and cron checksum script to periodically check the data consistency within replication stream.
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.
What is Binlog replication?
This section describes replication between MySQL servers based on the binary log file position method, where the MySQL instance operating as the source (where the database changes originate) writes updates and changes as “events” to the binary log. Each replica receives a copy of the entire contents of the binary log.
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):
What are the advanced replication technologies that MySQL 8 possesses?
Relevant replication areas that have been improved in MySQL 8: Observability: more replication applier queuing details; improved tracing for Group Replication; replication filters statistics; additional cluster statistics on group replication; enhanced visibility into row-based replication.
How do you sync tables between databases?
This example has four steps:
- Set up the databases. Create the example databases on your SQL Server.
- Set up the comparison. Specify the data sources you want to compare.
- Select objects to synchronize. Review the results and select the objects you want to synchronize.
- Synchronize the databases.
How does PT table checksum in Percona work?
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. The tool’s “EXIT STATUS” is non-zero if any differences are found, or if any warnings or errors occur.
Is there a size limit on PT table checksum?
You can configure the sensitivity of this safeguard with the –chunk-size-limit option. If a table will be checksummed in a single chunk because it has a small number of rows, then pt-table-checksum additionally verifies that the table isn’t oversized on replicas.
How does PT-table-checksum-filter work in MySQL?
You can then use pt-checksum-filter to compare the results in both databases easily. pt-table-checksum examines table structure only on the first host specified, so if anything differs on the others, it won’t notice. It ignores views. The checksums work on MySQL version 3.23.58 through 6.0-alpha.
Which is the best checksum function to use?
The results are generally consistent to within a tenth of a second on repeated runs. CRC32 is the default checksum function to use, and should be enough for most cases. If you need stronger guarantees that your data is identical, you should use one of the other functions.
