Tag Archives: innodb

Read ahead…

Posted on January 2, 2010 by Domas Mituzas

Mark wrote about how to find situations where InnoDB read-ahead is a bottleneck. What he didn’t disclose, though, is his trick to disable read-ahead without restart or recompile of MySQL. See, there’s no internal “disable read ahead knob”. But there … Continue reading →

Posted in mysql | Tagged , | 4 Comments

Opening tables!

Posted on December 26, 2009 by Domas Mituzas

There’s one bottleneck in MySQL/InnoDB that ultimately sucks. It sucked in 4.0, sucked in 5.0, sucks in 5.1 with newest InnoDB plugin. Opening tables has been a bottleneck on machines that have thousands of tables all the time (as LOCK_open … Continue reading →

Posted in mysql | Tagged | 3 Comments

On deadlock detection

Posted on December 21, 2009 by Domas Mituzas

InnoDB detects deadlocks. Deadlocks are those nasty situations, when transaction 1 tries to acquire locks A and B, whereas transaction 2 tries to acquire locks B and A at the same time. As both are stubborn, InnoDB will decide simply … Continue reading →

Posted in mysql | Tagged | 2 Comments

Crash recovery, again

Posted on December 8, 2009 by Domas Mituzas

There’s one stage in InnoDB crash recovery where it reads log file, you know, this one: InnoDB: Doing recovery: scanned up to log sequence number 354164119040 InnoDB: Doing recovery: scanned up to log sequence number 354169361920 On a machine with … Continue reading →

Posted in mysql | Tagged , , | Comments Off

plugin and 5.1

Posted on August 18, 2009 by Domas Mituzas

You can check it yourself – 5.1 seems to be shipped with InnoDB plugin in future :-) (oh the joy of open source repositories, always ready to spoil the surprise, eh?:)

Posted in mysql | Tagged , | 1 Comment

Checksums again, some I/O too

Posted on May 28, 2009 by Domas Mituzas

When I was doing data loading tests, I realized that usually low checksum calculation CPU percentage is actually the blocking factor. See, usually when background writers do the flushing, it gets parallelized, but if active query is forcing a checkpoint, … Continue reading →

Posted in mysql | Tagged , , | 3 Comments

stop messing with the tablespace

Posted on May 21, 2009 by Domas Mituzas

People keep loving and endorsing the –innodb-file-per-table. Then poor new users read about that, get confused, start using –innodb-file-per-table, and tell others to. Others read then, get confused even more, and start using –innodb-file-per-table, then write about it. Then… Oh … Continue reading →

Posted in mysql | Tagged | 13 Comments

after the conference, mydumper, parallelism, etc

Posted on May 18, 2009 by Domas Mituzas

Though slides for my MySQL Conference talks were on the O’Reilly website, I placed them in my talks page too, for both dtrace and security presentations. I also gave a lightning talk about mydumper. Since my original announcement mydumper has … Continue reading →

Posted in mysql | Tagged , , , | 6 Comments

Eyecandy mutexes!

Posted on February 15, 2009 by Domas Mituzas

In my quest of making MySQL usable, I managed to hit contention that wasn’t spotted by performance masters before. Meet most useless mutex ever (this is actual contention event, not just a hold): Count nsec Lock 1451 511364 mysqld`ut_list_mutex nsec … Continue reading →

Posted in mysql | Tagged , , | 3 Comments

Charsets mutex meets InnoDB

Posted on February 6, 2009 by Domas Mituzas

When InnoDB compares data (like, when looking up in indexes), it actually asks help from MySQL – character sets may provide different rules for evaluation. MySQL then looks up character set information. This is where the fun begins – if … Continue reading →

Posted in mysql | Tagged , | 1 Comment