Tag Archive for benchmarks at Xaprb

Today is the first day at the conference (aside from the tutorials, which were yesterday). Here’s what I went to:

New Subquery Optimizations in 6.0

By Sergey Petrunia. This was a similar session to one I went to last year. MySQL has a few cases where subqueries are badly optimized, and this session went into the details of how this is being addressed in MySQL 6.0. There are several new optimization techniques for all types of subqueries, such as inside-out subqueries, materialization, and converting to joins. The optimizations apply to scalar subqueries and subqueries in the FROM clause. Performance results are very good, depending on which data you choose to illustrate. The overall point is that the worst-case subquery nastiness should be resolved. I’m speaking of WHERE NOT IN(SELECT…) and friends. It remains to be seen how this shakes out as 6.0 matures, and what edge cases will pop up.

The Lost Art Of the Self Join

This was just great. Among many other things, Beat Vontobel showed how a Su Doku can be solved entirely with declarative queries: a very large self-join query against a table of digits and a table of the board’s initial state. I had been promoting this session because last year’s was so very good. I can’t wait to see what he comes up with for next year. Can he find another creative idea? Time will tell.

He wasn’t able to solve a 9×9 puzzle with MySQL because of the limitation on the number of joins, but PostgreSQL had no trouble doing it.

EXPLAIN Demystified

This was my session, of course. (Slides will be on the O’Reilly conference site, if they aren’t already). It went great, I thought. The room was full and people were standing in the back of the room and in the door. The questions came fast and furious; all really good questions. I think we ended up exploring a lot of the MySQL query execution method, strengths, and weaknesses by the time we were through. And I gave away all the remaining Maatkit t-shirts. Hopefully the people who took them will wear them tomorrow and the conference will be sea of deep, rich red shirts.

Someone did an audio recording of the session, but I don’t recall who it was.

Investigating InnoDB Scalability Limits

This session was given by Peter Zaitsev (disclosure: I now work for Percona, the company he co-founded). Peter and Vadim Tkachenko spent a lot of time over the last weeks and months running a dizzying array of benchmarks on MySQL 5.0.22, 5.0.51, and 5.1.24 (if I recall the versions correctly). They were able to show InnoDB’s scaling patterns for a number of different micro-benchmarks on a variety of configurations. If you didn’t attend, please look up the slides if you care about InnoDB performance. A lot of work went into the benchmarks — a lot of work. The slides should be on the conference website or on our blog, http://www.mysqlperformanceblog.com/.

Replication Tricks and Tips

Lars Thalmann and Mats Kindahl gave this session. At a high level, I’d say it was a run-down of all the different ways you can use MySQL replication. Replication is really a flexible tool, and they covered a large array of the most important ways you can use it to achieve different purposes. Many of the techniques they mentioned are implemented by various tools in Maatkit. A couple of the others are implemented in MySQL Master Master Manager and MySQL Semi Multi-Master tools. Don’t re-code these! You can save weeks of work and get quality code by using the pre-built tools. (I built Maatkit, so I know exactly how tricky it is to get some of these things right.)

BoF Sessions

I dropped in on a few BoF sessions, including the Sphinx one and the PBXT/Blob Streaming one. (Keep an eye on the PrimeBase folks — they are up to great things.) Ronald Bradford protected me from those who wanted to get me drunk. Hint: it’s really easy… I have to say, though, Monty’s black vodka was amazing.

Speaking of Blob Streaming, Paul McCullagh and I were talking earlier in the day about the project’s name, MyBS. This has been smirked about a few times. I think it’s a great name, because after all my initials are BS (I usually insert one of my four middle names in to alleviate this problem, but I digress). The conversation went like this:

Me: I like it. My initials are BS.

Paul: BS actually means British Standard, so it can’t be bad.

Me: Better than American Standard. That’s a toilet.

We also debated the merits of watching the original move The Blob. It’s a classic. It must be good.

Technorati Tags:Beat Vontobel, benchmarks, innodb, Lars Thalmann, Mats Kindahl, mysqluc2008, Paul McCullagh, pbxt, Percona, Peter Zaitsev, replication, Sergey Petrunia, Sphinx, Su Doku, The Blob, Vadim Tkachenko

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It’s been a while since I’ve written about progress on the book. I actually stopped working on it as much at the beginning of the month, because on October 31st I managed to finish a first draft of the last big chapter (Scaling and High Availability)! Now I’m back to full-time work at my employer, and I’m working on the book in the evenings and weekends only.

This doesn’t mean the book is close to being done, though. The editor is sending out some chapters for technical review, and there’s still a lot more writing and revising to be done.

Last weekend I revised the Security chapter from the first edition, which I think will be the only chapter that we’ll just revise and update, rather than completely rewriting (well, maybe the Architecture chapter could be considered a revision instead of a rewrite, but it’s a stretch; we changed it a lot). I removed a lot of the material that repeated the MySQL manual, and added a lot of information and best practices on grants, new privileges and objects in MySQL 5, common tasks, common mistakes, and so on. The chapter ended up being nearly as long, even though I stripped out all the code listings and so on from the first edition (in fact, I reduced the first edition’s material to a few paragraphs).

Beyond that, though, there are little details to finish out in many of the chapters. Examples that need to be finished, figures that need to be re-drawn, material that doesn’t quite fit and needs to be re-arranged or even moved to another chapter; it’s a lot of work. Peter Zaitsev has been reviewing some of the core chapters on query and schema optimization etc, and I’m revising them in response to his comments. That’s what I spent today doing.

I think the biggest chunks of work that remain are going to be making chapters 3, 4, 5, 6 and 7 (benchmarking, profiling, schema, indexing, query optimization, advanced features, and server tuning) flow together well. The challenge here is how to organize the vast amount of material so it reads well, without too many forward references, and still be useful as a reference work. The detail we’ve gone into is incredible. It makes it very hard to find the single best place to mention each little bit of wisdom, because all of this material is completely inter-related. It’s tough to flatten the graph of knowledge into a one-dimensional narrative.

It’s not just these chapters that have a lot of inter-related material, of course. It’s hard to talk about tuning the server settings (chapter 7) without bringing the OS and hardware (chapter 8) into it, and whenever you do this you also need to think about measuring and monitoring status information (chapter 14). Of course, you need to do that for benchmarking and profiling, too (chapter 3). I’m sure you see the dilemma!

The good news is, if we succeed in doing this well, you will find the book enormously useful. Stay tuned!

Technorati Tags:benchmarks, high availability, High Performance MySQL, indexing, mysql, optimization, Peter Zaitsev, privileges, profiling, query optimization, scaling, schema optimization, security, server status, sql, tuning

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