MySQL 5.6 GA one year – What is next?

MySQL 5.6 has been GA for just over a year now. See MySQL 5.6.10 Release Notes.  Congratulations on your birthday! That is quite a long time. I was using it earlier in production because it worked and could do things that 5.5 could not do, but earlier versions were to use at your own risk, and indeed if prodded incorrectly would fall on the floor. That is fair enough because they were work in progress, yet if you poked them the right way they did a very good job.  Those dev versions have been long since upgraded which is good so they do not need quite as much care and attention.

So from where I see 5.6 it works very well. One big change that has made a large difference but which I think a lot of people may not really understand or use is the performance_schema database. That provides a huge amount of great and detailed information about what the server is doing, where it is busy and why, and allows you to know these things rather than twiddle and guess which in the past we have been forced to do. So a big thanks for that. It does require quite a lot of study and Mark Leith’s dbahelper goes a long way to making PS useful to the average DBA.  A recent issue came up and I was asked (by Oracle support) to use it to find out the causes: a few SELECTs and hey presto the answers were staring me in the face.  So Oracle is eating its own dog food and it tastes nice…  If you have not had time to look at performance_schema or dbahelper yet take a poke.

The current MySQL 5.6 GA version (5.6.16) is pretty good now. I am aware of a few bugs which I am waiting to get fixed, but all in all the version works pretty well and I am happy with it.  I have filed quite a few feature requests and the reason for these is often to make my day to day life a bit easier, as when MySQL breaks, and as you watch over more servers this happens, things which might not bother other people become more of a problem. This includes better logging, addition of counters to measure more things which help when problems occur or to diagnose how frequently a problem might be happening and now this information is missing.

I am still working on getting systems upgraded to MySQL 5.6 and have some work to go. It is surprising just how long this can take, but that is often due to changes in a growing business which means that new systems appear, changes happen to existing ones and the time needed to get the MySQL 5.6 upgrade tasks done gets a lower priority than ideally I might like. That said MySQL 5.5 works and works well but 5.6 does have new things I want and shortly those remaining systems will have been upgraded and the job will have been done.

Well not quite.  Recently I have been looking at 5.7 DEV. A lot of work is going on there. Some of this is to give us new features that I have wanted for some time:

  • multi-source replication comes to mind, but that is a parallel branch to 5.7 which I think is unfortunate:
    • I still think that pulling this out into a separate process would have made life much easier as I blogged about previously, and indeed is how Sybase replicates, but I guess that is too large a change to be considered.
    • It is not clear if this feature will make it into 5.7 GA but I hope it will (Oracle please add it, MariaDB 10 has this feature, and for some use cases it will be very attractive)
  • more dynamic replication configuration is a much wanted new feature. A number of times I have been unable to reconfigure a slave without restarting the server and this has been most frustrating. It may have meant that I could not do the required change at all and or had to find an alternative work around to solve the problem. So this new feature is clearly helpful.
  • more replication parallelisation, again one of the bottlenecks that many DBAs have come across, promises to make life better
  • improved P_S will carry on and give us more of the information that we need.

So a lot of these new features look quite juicy and more stuff will probably arrive in 5.7.4, so the GA version, when it arrives, is going to be good.

One thing that I have been looking at recently is GTIDs in MySQL. This is quite a topic in itself. Oracle has implemented this in 5.6 a certain way and in MariaDB 10 (currently DEV version) the implementation is approached differently, so that should prove quite interesting as neither mode is compatible.  The end result that DBAs want is to ensure that it is easier to synchronise the state of master and slaves, and to prevent the re-application of transactions that have already been applied to a system.  As it will soon be possible to replicate from multiple sources in MySQL and MariaDB then this topic will become more tricky and help from the “system” is much appreciated.

That said while I have used GTID a little on a few systems and it does seem to work and make life easier, it is not quite as nice and easy to use as one would like. Work seems to be ongoing in that direction to improve things and in helping us make the transition from a non-GTID environment to one which is GTID aware.  All that help is most appreciated.

For a replicated MySQL environment that has to run 24 x 7 x 365 downtime is painful to a DBA, and expensive to a business. Things do break. We expect that, whether that is due to bugs, hardware or even human failure.  We then need to be able to recover these systems as best as we can, as quickly as we can and once we have done that be confident that we understand what broke, what damage was done and what further work may or may not be required to complete the job.  So if replication uses GTID that focus has to be understood and taken into account by the developers, and support for GTID should cover those needs.  That is vitally important.

All in all I am looking forward to the preparation for the next GA version of MySQL even if it is still maybe more than 6 months away. It is a bit like planning your summer holiday in the cold winder. Lots of things to look forward to, plenty of interest in trying them, and the slight frustration you have to wait just a little bit longer before that time comes.  I’m looking forward to the sun already…