The MySQL Users Conference is going to be an excellent conference with a lot of change going on in the MySQL world. Some of the key areas to be looking at include:MySQL strategic directions.Increasing vertical scalability of MySQL with upcoming MySQL software releases, new and enhanced storage engines and patches.Enhanced diagnostics with DTrace.New BI software products and tools.Performance

I found this yesterday while tracking down a locking issue for a client. They had a connection time out on a lock, but before it times out, SHOW PROCESSLIST had the status 'statistics' so it wasn't actually executing the query yet. So, what was it doing and why did it time out there?

The answer actually was remarkably simple, but I did have to take a peek in the MySQL server source code (horay for Open Source!) The server sets the thd_proc_info to 'statistics' when calling the join optimiser, that's the part of the optimiser that works out the best join order.

A lesser known feature of the join optimiser is that if it works out that only one row can match (lookup on primary or unique key field), it'll try to retrieve the row. If there's no match, there's an "impossible WHERE clause" and essentially the entire query is optimised away and 0 rows returned.

If there is a match, all references to columns in …

I found this yesterday while tracking down a locking issue for a client. They had a connection time out on a lock, but before it times out, SHOW PROCESSLIST had the status ’statistics’ so it wasn’t actually executing the query yet. So, what was it doing and why did it time out there?

The answer actually was remarkably simple, but I did have to take a peek in the MySQL server source code (horay for Open Source!) The server sets the thd_proc_info to ’statistics’ when calling the join optimiser, that’s the part of the optimiser that works out the best join order.

A lesser known feature of the join optimiser is that if it works out that only one row can match (lookup on primary or unique key field), it’ll try to retrieve the row. If there’s no match, there’s an “impossible WHERE clause” and essentially the entire query is optimised away and 0 rows returned.

If there is a match, all references to columns in …

Tokutek officially announced the TokuDB for MySQL v2.0 Storage Engine, v2.0 on April 16th, 2009.  TokuDB uses Fractal Tree (TM) technology to boost MySQL performance for users challenged with interactive querying in high volume, always-on applications.  As a pure SW storage engine, TokuDB provides drop-in compatibility for existing MySQL code and applications.  Curt Monash posted an introduction to Fractal Tree technology over on Monash Research’s DBMS2 blog.  TokuDB is …

I’m wrapping up some Gearman work and packing for the users conference, it should be fun and exciting! I thought I’d send out a reminder that Brian and I will be talking about Gearman at both the MySQL UC and Percona Performance conference, including the possibility of a new release of Gearman. Here’s a hint:

lap> ./gearmand/gearmand -vv -t 4
Starting up
Initializing libevent for main thread
Method for libevent: epoll
Trying to listen on 0.0.0.0:4730
Listening on 0.0.0.0:4730
Creating wakeup pipe
Creating 4 threads
Initializing libevent for IO thread
Creating IO thread wakeup pipe
Thread 1 created
[   1] Entering thread event loop
Initializing …

Hi,

We will be present at MySQL Conference & Expo, 2009. If you are around Silicon Valley, don’t forget to meet the team behind your favorite MySQL tools at Booth #317. We are happy to offer a flat 20% discount on all purchases made during this month. Use the coupon code: uc2009 during the purchase.

Also, we are pleased to announce the release of MONyog 3.06.

Changes (as compared to 3.05) include:

Bug fixes:
* Installation on Windows could fail with a js32.dll-related error. Waiting a few seconds and ‘retry’ would solve this but now the error does not come.
* Fixed a ‘false alert’ related to settings for temporary tables (the error occurred because of comparing an integer with a non-integer).
* With slow query logs generated from servers greater than 5.1 Query Analyzer “Max” column would show a value without …

Recently, it was reported (see MySQL bug #43660) that “SHOW INDEXES/ANALYZE does NOT update cardinality for indexes of InnoDB table”. The problem appeared to happen only on 64-bit systems, but not 32-bit systems. The bug turns out to be a case of mistaken identity. The real criminal here wasn’t the SHOW INDEXES or the ANALYZE command, but something else entirely. It wasn’t specific to 64-bit platforms, either. Read on for the interesting story about this mystery and its solution …

InnoDB estimates statistics for the query optimizer by picking random pages from an index. Upon detailed analysis, we found that the algorithm that picks random pages for estimation always picked the same page, thus producing the same result every time. This made it appear that the index cardinality was not updated by ANALYZE TABLE. Going deeper, the reason the algorithm always selected the same …

I am now in San Francisco, tomorrow I'll be leaving town for Santa Clara and the MySQL User conference. If you are at the conference, say hello and if there is anything you want to talk to me about, do so, I'll spend my time out and about at the conference.
I am involved in 2 talks:

• On Tuesday at 11:55 I am doing an introduction to libmysqld. If have not used libmysqld, and are interested in what it is and how it can be used, pop by this talk. I will also demo a small libmysqld application, so you know what can be done. It's actually pretty cool.
• On Thursday at 11:55, me and Robert Krzykawski from bWin are to present some real-world experiences with HA for MySQL. I will do an introductory talk here, with some HA for MySQL basics, and then Robert will tell you about the real world. bWin games is a big user of MySQL and has quite a load on their systems, so …

The BoF schedule for MySQL Conference and Expo (2009) is now published. Lenz Grimmer, Sergei Golubchik, Tomas Ulin and myself will be available during a BoF which focuses on MySQL Community Code Contributions. Lenz will be moderating. For background material, you may start here.

The BoF schedule for MySQL Conference and Expo (2009) is now published. Lenz Grimmer, Sergei Golubchik, Tomas Ulin and myself will be available during a BoF which focuses on MySQL Community Code Contributions. Lenz will be moderating. For background material, you may start here.