MySQL 8.4 Support in Percona Toolkit 3.7.0

Percona Toolkit 3.7.0 has been released on Dec 23, 2024. The main feature of this release is MySQL 8.4 support.

In this blog, I will explain what has been changed. A full list of improvements and bug fixes can be found in the release notes.

TLDR;

• Replication statements in 8.4 are fully supported by the Percona Toolkit
• pt-slave-delay has been deprecated.
• pt-slave-find has been renamed to pt-replica-find. The old name has been deprecated but exists in the repository as an alias of the pt-replica-find.
• pt-slave-restart has been renamed to pt-replica-restart. Old name has been deprecated but exists in the repository as an alias of the pt-replica-restart.
• Basic SSL support has been added to the tools where it was not working before (see https://perconadev.atlassian.net/browse/PT-191 ), and Percona Toolkit now supports caching_sha2_password and sha256_passwordauthentication plugins. Full implementation of https://perconadev.atlassian.net/browse/PT-191 is planned for the next version.

Replication Statements

MySQL 8.4 removed earlier deprecated offensive language, such as SLAVE or MASTER. This made tools written for earlier versions not compatible with the new version. Percona Toolkit was also affected, and I had to rewrite it.

However, Percona Toolkit should be able to run not only with MySQL 8.4 but also with older versions. So, the change was not a simple grep and replace of offensive words. It is not even possible for version MySQL 8.0 because new syntax was first introduced in 8.0.23 for the CHANGE REPLICATION SOURCE and START/STOP REPLICA commands. Earlier versions weren’t aware of this change.

Another challenge was the fact that I could replace all occurrences of the word SLAVE with REPLICA. Still, I could not do the same for the MASTER and SOURCE pairs because replication source-related commands are mapped differently:

So, I added selectors that use the correct command depending on the MySQL server version.

I intentionally implemented new syntax for version 8.4 only, so I do not have to check every single minor version of 8.0. I also did not implement new syntax for MariaDB. This may happen in the future.

However, all messages displayed to the user use the new syntax. If you rely on old syntax somewhere in your scripts, adjust them.

Internally, most of the functions were renamed to use the new syntax, but the important module lib/MasterSlave.pm kept its name.

Deprecated and Outdated Tools

As a result of this change, pt-slave-delay has been deprecated. The tool stays in the repository and works as before when connected to MySQL 8.0 or an earlier version. However, it refuses to work with MySQL 8.4. The tool will be removed in one of the future versions.

Tools pt-slave-find and pt-slave-restart were renamed to pt-replica-find and pt-replica-restart. Aliases with old names still exist, so you have time to change your scripts. However, expect that these aliases will be removed in one of the future versions as well.

Tool pt-variable-advisor has been updated to reflect current default values.

Basic SSL Support

Percona Toolkit did not have consistent SSL support: some of the tools were able to connect using SSL, and others did not. This was reported at https://perconadev.atlassian.net/browse/PT-191. In this version, I added option “s” for DSN that instructs DBD::mysql to open a secure connection with the database. As a result, Percona Toolkit now supports caching_sha2_password and sha256_password authentication plugins. But other SSL options are still missed. Full SSL support will be added in the next version.

Conclusion

Percona Toolkit fully supports MySQL 8.4. If you use pt-slave-find and pt-slave-restart, consider calling them by their new names pt-replica-find and pt-replica-restart. Tool pt-slave-delay has been deprecated and will be removed in future versions. Use built-in feature delayed replication instead. ∎