Lenz Grimmer's blog

Last week I gave a MySQL University Presentation about how to contribute code to MySQL. This time DimDim did not fail to record the session, even though there is a funky overlap of audio from Stefan Hinz (the moderator) and myself at the beginning. I had a bit of a slow start into the presentation, because of a very nasty headache that plagued me that day. But we had a lively discussion at the end and I hope it was useful to the participants.

In case you have missed it, you can now watch the playback or download the session slides:

• Presentation slides: MySQL Code Contributions (PDF)
• Session recording (Adobe Flash Player required)
• Chat transcript

As you may have heard, we're switching to a new release model with the upcoming MySQL 5.4 release.

If you are curious to learn more about what will change in the way in which future versions MySQL will be developed and released, make sure to attend our next MySQL University session about The New MySQL Release Model on Thursday, 11th of June, 14:00 UTC. Tomas Ulin, our director of MySQL server development will go through the planned changes and would also like to get your input and feedback on these changes.

We're using DimDim for broadcasting this session, which allows you to listen to the audio while watching the slides with your web browser. You can comment and discuss via a chat function, too! We're looking forward to your input. To attend, point your browser to this address (Adobe flash player required).

The session will be recorded and posted on the MySQL Forge Wiki, so you can watch the presentation later as well. You can also provide your feedback on the release model by posting on the MySQL Internals mailinglist.

Today I gave my first MySQL University session as a speaker, talking about Backing up MySQL using file system snapshots. The talk went quite well (at least that was my impression) and we had ~10 people attending. The slides (PDF) and a recording of the session are now available from the Wiki page. Unfortunately the recording lacks the audio track, which is a bit of a bummer. We've submitted a support request with the DimDim folks, so hopefully they can provide us with a complete recording.

There was one question during the session that I was not able to answer myself, so I'm asking for your insights here:

Consider we're using InnoDB and MyISAM tables on a file system that can be snapshotted (e.g. Linux LVM or ZFS) and we're performing the following operations:

1. FLUSH TABLES WITH READ LOCK (yes, this won't help for the InnoDB tables)
2. Create the snapshot
3. Store the output of SHOW MASTER/SLAVE status in a file to be part of the backup
4. UNLOCK TABLES
5. Mount the snapshot
6. Start a second MySQL instance that accesses the tables on the snapshot, let InnoDB perform its table recovery
7. Shut down the second instance and perform the backup of the snapshot

The question that came up was if this actually still is a consistent backup, considering that InnoDB rolled back uncommited transactions. Does the state of the tables still match the binary log positions we noted before? I assume yes, as long as the transaction does not involve modifications non-transactional tables.

Another suggestion that came up was to change InnoDB's configuration variable innodb_max_dirty_pages_pct to "0" prior to performing the snapshot, to minimize the amount of dirty pages that have not been written to disk (and thus reducing the time required for recovering later). I wonder if this would make a difference...

What other InnoDB variables might have a noteworthy effect in the context of snapshot backups? I am looking forward to your comments.

My calendar for the upcoming months is already filling up with conferences, trade fairs and other events at which I'll speak about MySQL. Here's a quick overview:

• This coming Thursday at 15:00 CET, I'll be speaking about "Backing up MySQL using file system snapshots" at the MySQL University. The session will be hosted live using DimDim, which is a great online conferencing and presentation system (Flash required). Attendance is free, so come and join me if you want to learn more about this backup technique!
• On Friday, 6th of March at 15:15 I'll give a presentation about "MySQL Backup and Security" in the CeBit Open Source Forum in Hannover, Germany. By the way, Sun will have a large presence themed "Open Source for Open Minds" in Hall 6, Booth E36. There'll be a MySQL info pod as well, which I will help manning from Friday until Sunday, 8th. So make sure to stop by and say hello!
• On March 23-24, there'll be a PHP/MySQL Conference in Warsaw, Poland, organized by IDG. I submitted three talks about various MySQL topics, currently I am still waiting for the confirmation which of these they selected.
• On April 20-23, there is of course the MySQL Conference & Expo in Santa Clara, to which I am very much looking forward to. I'm helping to organize the DotOrg Pavilion in the exhibition hall and will likely give a BoF about a project I'm currently involved in.
• In May 4-5 there is the AMOOCON in Rostock, Germany, which is a conference about Open Source VoIP and communication. I'll talk about "MySQL High Availability Solutions" and "Backup & Security Best Practices" (in German). My colleague Geert will be there as well, giving an in-depth talk about MySQL Cluster.

There is a number of additional events in the pipeline, I'll blog about these once my session proposals have been accepted.

Tomorrow (Thursday, 11th of September) at 9:00 PST/16:00 UTC/17:00 GMT/18:00 CET, there will be an new free MySQL University Session. MySQL University started as an internal training program for MySQL engineers, to share and spread knowledge about their areas of expertise and has been available to the public for quite some time now. It covers a wide range of technical topics around the MySQL Server and usually takes place once per week.

For the first time, the presentation will not be performed by (former) MySQL employees/developers, but by two of our "Sun Classic" colleagues: Jyri Virkki (OpenSolaris Web Stack community lead) and Murthy Chintalapati (Sr Engineering Manager, Web Stack development) will talk about the OpenSolaris Web Stack:

OpenSolaris Web Stack is an OpenSolaris project and community building an integrated stack of popular open source web tier infrastructure technologies such as Apache HTTP server, MySQL, memcached, PHP and Ruby On Rails optimized for Solaris platform. This session introduces OpenSolaris Web Stack, its status and future development including addition of newer technologies such as lighttpd, Varnish etc., as well as the ease of use features for developers and deployers. We will also be discussing an experimental web stack IPS package repository and it could be leveraged to build and make available popular end user applications such as Drupal.

MySQL University sessions are free to attend - all you need is an IRC client (to post your questions and comments) and an audio player capable of playing back an OGG audio stream, so you can listen to what is being said. See the Instructions for Attendees on the MySQL University pages for more information on how to log in and attend. The audio stream will be recorded and published on the MySQL University pages for later consumption, in case you can't make it or want to listen to a previous session.

Since almost a year now, we host a weekly training session for our engineers on Thursday (14:00 UTC winter time), coined the "MySQL University". While it's primary purpose is to share and distribute knowledge about a wide variety of topics relevant to our own developers, many of the sessions are of general interest for developers on other projects as well.

Therefore we hold this sessions in the public and everybody is welcome to attend! You can listen to the presentation via an OGG Audio stream, questions can be posted via IRC on the #mysql-university channel on freenode.net. The audio file and IRC log will be saved, so you can also listen to past university sessions at a later point in time again.

Tomorrow's session will be about using the Valgrind memory checker, held by Stewart Smith, a colleague from Australia who is a member of the MySQL Cluster development team.

The next upcoming sessions include topics more closely related to MySQL Server development:

• February 28: New Optimizer Features in MySQL 6.0 (Sergey Petrunia)
• March 6: How to Add a Collation (Alexander Barkov)
• March 13: Checking Threading and Locking With Helgrind (Stewart Smith)
• March 20: Building MySQL Client Applications (Hartmut Holzgraefe)

See the MySQL University page on the MySQL Forge Wiki for more details and follow the instructions for attendees to get connected.

Tomorrow, Thursday 13th Sept. at 13:00 UTC (15:00 CEST/9:00am EST/6:00am PST) Jan will perform a MySQL University session providing an Overview of the MySQL Proxy. If you like to attend, please add your name to the session page and read the Instructions for Attendees. All you need is a PDF viewer to see the slides, an IRC client to post questions and comments and an application capable of playing an OGG audio stream.

Version 0.6.0 of the proxy has just been tagged and we're waiting for the mirror sites to catch up before we publicly announce it and update the download pages.

Just came off today's MySQL University session about How to Build MySQL on Windows - Reggie did a great job on explaining how to build the MySQL Server from Source on Windows using the Microsoft development toolchain and some additional required tools. I am glad to hear that we're making progress on making it easier for Windows developers to work with the source code and Reggie and the other members of our Windows Task Force (what a nice acronym this one makes!) have plenty of other ideas for improving that experience.

If you missed his session, the audio file and IRC log will be published from the MySQL University pages shortly.

And in case you haven't heard about MySQL University before, check out the pages on the MySQL Forge and take a look at the upcoming schedule! Next week, Jan is going to give an introduction to the MySQL Proxy, which will to be an interesting session for sure. Did I mention that attending MySQL University is free and everybody is welcome to join? All you need is an IRC client to post questions and discuss the topic and an application capable of playing OGG audio streams for listening to the presenter. The MySQL Forge Wiki has detailed instructions on how to get going. See you next week!