When SHOW SLAVE STATUS and the error log Disagree

When I do a show slave status\G, sometimes mysqld will lie to me and give me a wrong Exec_Master_Log_Pos. Let me explain with a situation from last night. In summary, the slave SQL thread is stuck (in this case because of a problem during the transfer of the binlog data to the slave’s relay log). The show slave status\G command tells me that it is stuck at the master binlog file mysql-bin.000480, position 126.

Don’t Assume Anything

I’ll preface this post with a note that the story itself is not really work- or DBA-related, but the lessons learned certainly are. I consider myself fairly conscientious when it comes to internet security and backing up my most important files (pictures of kids, music, etc), and I am diligent about taking at least a weekly backup of those files so that if (when) something catastrophic happens, I am ready. Once again, as my short life as a DBA has proven, theory and practicality rarely meet.

A Question from OTN Forum

Here is the question that was posted on OTN Forum Grid Control Extensibility. My first reaction was — how stupid one should be to post such absolutely irrelevant question in that forum? I was even more surprised that someone actually tried to provide a sensible response…

The Butterfly Effect

If you check out the “Butterfly Effect” on Wikipedia, you’ll find a rather interesting reference to, “sensitive dependence on initial conditions in chaos theory.” Fascinating use of phrase that probably doesn’t mean much to normal people until it happens to you. I could give you lots of theoretical examples, but perhaps a real-life one will make more sense.

Identifying SQL Execution Bottlenecks Scientifically

A few days ago, a developer and I had an interesting conversation. The developer was trying to tune an expensive SQL statement, using a trial-and-error method. After looking at his method in amusement, I showed him how to identify and tune SQL statements scientifically, and decided to blog about it. Let’s look at a simple case and then proceed to slightly more complex versions.

A Challenge to MySQL Employees

I present a challenge to MySQL employees who have derived tangible benefits from the sale to Sun: what percentage have you put back into the MySQL community, and how? I’d love to see comments on what folks are doing, even without percentages of money and such, because I am willing to wager that most of the folks who work for MySQL give plenty back to the community on non-company time. My theory is based on the fact that most MySQLers that I’ve met do not see working at MySQL as “their job”, they see it as “I get paid to do what I love doing, and would do anyway.”

DBD::Oracle and Instant Client

I have just managed to get DBD::Oracle to successfully compile, install, and test with the Instant Client (IC) on a Linux (32bit) OS. It seems Oracle, in its wisdom, has changed the folder structure yet again, so to get it to compile, try this….

EXPLAIN Cheatsheet

At the 2008 MySQL Conference and Expo, The Pythian Group gave away EXPLAIN cheatsheets. They were very nice, printed in full color and laminated to ensure you can spill your coffee* on it and it will survive.

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