FreeCert: Get MySQL-certified for free!

In the spirit of our Free Ride program, Proven Scaling is offering fifty (50) free MySQL certification vouchers at this year’s MySQL Conference and Expo in Santa Clara, California from April 23 through April 26.

You must be present at the conference to pick up the free passes, and they are only good at the at-conference certification testing area during the conference itself on April 24-26. Each voucher is good for one test, but it’s up to you which test you take.

Go to Proven Scaling FreeCert to enter!

Temporary tables for SHOW VARIABLES in MySQL 5.0

In MySQL 5.0, with the introduction of information_schema, the SHOW commands were changed to really be wrappers around SELECTs against information_schema. This means that when you issue e.g., a SHOW VARIABLES command, Created_tmp_tables is incremented once, and Handler_write and Handler_read_rnd_next are incremented about once per row in the result. Keep this in mind in your monitoring systems; these numbers could be wildly inaccurate if some part of your application is doing many SHOW commands.

This came to my attention because Connector/J’s ReplicationDriver runs SHOW VARIABLES LIKE 'tx_isolation' whenever you switch between setReadOnly(true) and setReadOnly(false), so in large, complex Java applications don’t be surprised if you see a high number1 of Created_tmp_tables. How can this be solved? Use SELECT instead of SHOW. If you need to access one variable, instead of doing:

SHOW VARIABLES LIKE 'tx_isolation'

This will copy all variables into a temporary table, and apply the LIKE filter to that temporary table.

Use this instead:

SELECT @@session.tx_isolation

This will just fetch the tx_isolation variable from memory directly. This is much more efficient and to-the-point.

1 Like, say, 8,000 per second. Creating so many temporary tables burns up a pretty big chunk of CPU time for nothing.

MySQL Conference & Expo Free Ride Winners

It was a tough decision, but after much deliberation, the Proven Scaling Free Ride panel has made their decision, and the MySQL Conference & Expo 2007 Free Ride winners have been chosen. To recap, each of the winners will receive:

  • Round-trip airfare from their location to SJC, SFO, or OAK airport
  • Transportation from the airport to hotel/conference
  • Hotel accommodations
  • A meal stipend
  • A full conference pass, provided by MySQL AB (Thanks, MySQL!)

Without further ado, here are the winners and their stories:

Jan Lehnardt, a student from Münster, Germany

Asked why we should choose him, Jan says: “I’m not a one trick pony. I’m a computer science student, but I attend classes in English literature and linguistics. I’m a freelancing open-source consultant by night, so I can pay for my studies. I like to improve user-interfaces by making them more humane. I want to make the web accessible and good looking to not only the 14 to 40 generation.”

J.R. Bullington, from a non-profit in Sterling Heights, Michigan, USA

J.R. had this to say about the opportunity: “I know that this section isn’t long, but it really does come down to money. I can get the time off and I have the support of my superiors. However, as we do not gain a profit and only gain enough capital to keep the lights on and the water running, training and conferences are not in the budget unless I pay for them myself.”

Carlos Proal Aguilar, from a non-profit in Puebla, Mexico

Carlos is concerned about the community in Latin America, and wonders why there is so little action on an international scale coming from the area. Carlos also says: “I have been a big MySQL fan for several years and have contributed with the mailing list and some bugs/patches and right now i have a couple of tutorials that I want to share with the community (after translating from Spanish to English).”

Thanks for all the entries, and I look forward to meeting Jan, Sean, and Carlos at the conference in just about three weeks.

Update: Sean Walberg couldn’t make it to the conference due to some scheduling conflicts, so we have chosen J.R. Bullington to replace him.