Many people have asked me what do I think was the best thing about Percona Live UK. I always answered: that it happened in the first place! This was the first time we had such a large and high-quality MySQL conference in Europe, and many well known bloggers and speakers that can't always travel to Santa Clara were present.

More importantly, many MySQL users who don't travel to Santa Clara could now see them speak and meet with them. I met at least 4 hard core MySQL DBA's from Helsinki that I've never met before. We had to travel to London to meet each other! (But if you are in Helsinki, we have our first MySQL user group tomorrow, this should fix things!)

When I walked into the conference venue, I introduced myself to a person that stood there talking to Baron Schwartz. He introduced himself as Schlomi Noach. Then we …

There are moments in history that become like signpost that everyone remembers the rest of their lives. Like where were you when you heard the news that JFK had been shot, or those 9/11 planes hit the WTC twin towers. If you work with MySQL and high-availability, then this week will be remembered as such. And if you're a European MySQL geek, you will remember that we were at the Percona Live UK conference when Galera clustering 1.0 was announced. Btw, the conference itself was also historical, at least for European MySQL users. I will have to write a separate blog post about the conference, because it was a great one, and I have to post slides of my 2 talks too. But this blog post is dedicated to the stable release of Galera.

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Stockholm – October 25th 2011

Severalnines, provider of automation and management software for easily usable, highly available and auto-scalable cloud database platforms, today announces the release of ClusterControl™ for MySQL Galera in cooperation with Codership, the replication experts organisation that leverages the latest developments in computer science to produce fast and scalable synchronous replication solutions that "just work" for databases and similar applications.

Introducing ClusterControl™ for MySQL Galera

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Blackhole tables are often used on a so-called “relay slave” where some operation needs to happen but no data needs to exist. This used to have a bug that prevented AUTO_INCREMENT columns from propagating the right values through replication, but that was fixed. It turns out there’s another bug, though, that has the same effect. This one is caused when there is an INSERT into a Blackhole table, where the source data is SELECT-ed from another Blackhole table.

I think it’s wise to keep it simple. MySQL has tons of cool little features that theoretically suit edge-case uses and make ninja tricks possible, but I really trust the core plain-Jane functionality so much more than these edge-case features. That’s precisely because they often have some edge-case bugs, especially with replication.

Suomeksi: MySQL käyttäjätapaaminen Helsingissä 1. marraskuuta. Klikkaa allaolevaa linkkiä ilmoittautuaksesi, siellä saat myös lisätietoa suomeksi.

Finally it's here! So many of you have always asked about it. Markus and other Elisa guys. Osma and Ilkka at Habbo Hotel. And others... MySQL was born in Helsinki, InnoDB was born in Helsinki, a lesser known database / also MySQL engine called Solid was born in Helsinki, and 2 great replication companies, Continuent with multiple generations of clustering for MySQL, and Codership with Galera, are Helsinki companies. And amidst this embarrassment of riches, what did we not have?

A MySQL User Group.

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Team Codership will give a Galera presentation in the next event of the distinguished PerconaLive conference series in London (Oct 25).

We will send a three person mini-delegation in the conference, and here we follow the guidelines we have been preaching to the Galera community for long: always have at least three members in the cluster for high availability. With the presence of conference buffets, evening reception, London attractions, pubs & night life, Chelsea stadium etc..., our team may have to do a few internal failovers. But, three member staffing guarantees that at least one of us is available at all times for any discussion you may want to get us involved with, preferably HA, replication or clustering related, as these topics make our world tick.

Our …

I'm looking at the schedule for Percona Live UK coming up in 2 weeks from now and realize there's quite a smorgasbord of High Availability talks. What's more interesting, I see that we will be presenting some opposite opinions for the audience to digest:

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Update 2012-01-09: I have now been able to understand the poor(ish) results in this benchmark. They are very likely due to a bad hardware setup and neither Galera nor InnoDB is to blame. See http://openlife.cc/blogs/2012/january/re-doing-galera-disk-bound-benchmark

People commenting on my results for benchmarking Galera on a disk bound workload seemed to be confused by the performance degrading when writing to more than one master, and not convinced at my speculations on the reasons. Since sysbench 0.5 has the benchmarks in the form of LUA scripts, it was temptingly easy to tweak those a little to see if my speculations were correct. So yesterday I did run tests again with a slightly modified sysbench workload. …

2 concepts I've been an active advocate of during the past few years are both supported by Galera: Multi-threaded (aka parallel) slave, and allowing out-of-order commits on such a parallel slave. In trying to optimize Galera settings for the disk bound workload I just reported on, I also came to test these alternatives.

Single threaded vs Multi threaded slave

All of my previously reported tests have been run with wsrep_slave_threads=32. For the memory-bound workload there was no difference using one thread or more, but I left it at 32 "just in case". For the disk bound workload there is a clear benefit in having a multi-threaded slave:

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Update 2012-01-09: I have now been able to understand the poor(ish) results in this benchmark. They are very likely due to a bad hardware setup and neither Galera nor InnoDB is to blame. See http://openlife.cc/blogs/2012/january/re-doing-galera-disk-bound-benchmark

After getting very good results with Galera with using a memory bound workload, I was eager to then also test a disk bound workload. Also this time I learned a lot about how Galera behaves and will try to share those findings here.

Setup

The setup for these tests is exactly the same as in last weeks benchmarks, except …