MySQL 8 second release candidate is out (MySQL 8.0.4). Besides fixes to replication issues we have also delivered a couple of enhancements in this release. Let me quickly summarize them.

• Additional instrumentation for Group Replication (WL#9856). We have instrumented mutexes and condition synchronization objects on the group communication library. These are exposed as usual through performance schema.
• Support for name resolution in Group Replication whitelist (WL#10803). The user can now specify whitelist entries using names in addition to IP addresses. This is particularly helpful in deployments that rely on machine names and assign random addresses taken from a pool of IPs.

In addition to enhancements and bug fixing, we have also removed one deprecated feature.

• Removed the option group_replication_allow_local_disjoint_gtids_join (WL#11139). This option allowed the user to instruct the system to skip the check that both joiner and existing group members servers have compatible transaction execution histories. Thus, with this option enabled, a server would be able to join the group, even if it had a mismatching set of executed transactions when compared to the other servers. From interactions with our users, turns out that this option causes more harm than good. As such, after having it deprecated, we are now removing this feature.

Go and try out MySQL 8.0.4. We would love to hear your thoughts, comments and experiences with this release candidate. It is not generally available yet, thus not production ready. Therefore, use it at your own risk. You can reach us through bug reports, feature requests, the replication mailing list or by just leaving a comment on this (or other) blog posts.

Thanks!