Tag Archives: fun

I need a new keyboard

Posted on 2010/09/28 by

Thanks to Jayant, I had to clean coffee off my screen, but keyboard is a bit more tricky. This is Postgres advocacy at its best: The base timings are almost 5 times more in mysql as compared to pgsql. Then … Continue reading →

Posted in mysql | Tagged , | 6 Comments

MySQL processlist phrase book

Posted on 2009/09/27 by

For your convenience, a short phrase book, starting with explanation of process states where MySQL is mostly working to look up data from tables: “Sending data” – reading data from tables (or looking it up) “Copying to tmp table” – … Continue reading →

Posted in mysql | Tagged , , | 13 Comments

query cache tuning

Posted on 2009/07/08 by

For anyone, who has questions about MySQL query cache tuning, try this tuning assistant: http://dom.as/tech/query-cache-tuner/

Posted in mysql | Tagged , , , | 13 Comments

On throttling

Posted on 2009/05/18 by

Seems like nowadays InnoDB crash recovery is much funnier. Please allow me to show you something: while (buf_pool->n_pend_reads >= recv_n_pool_free_frames / 2) { os_aio_simulated_wake_handler_threads(); os_thread_sleep(500000); Translation – if there’re more than 128 outstanding I/O requests, sleep for half a second. … Continue reading →

Posted in mysql | Tagged , | 3 Comments

RESET SLAVE, bash edition

Posted on 2009/03/20 by

Nearly every job advertisement for MySQL DBA positions asks for ‘shell scripting’, so I decided to investigate what it is. I remembered some performance training, where I was told how forking is bad, and one should attempt to use shell … Continue reading →

Posted in mysql | Tagged , | 12 Comments

MySQL password security

Posted on 2009/03/08 by

Simple password authentication schemes are usually guarding against one of two evils – either leaked password tables, or sniffed network traffic. In 4.1 MySQL introduced challenge-response scheme, that is guarding against both, just not both at the same time. How … Continue reading →

Posted in mysql | Tagged | 4 Comments

Rasmus vs me

Posted on 2009/02/09 by

Rasmus (of PHP fame) and me exchanged these nice words on Freenode’s #php (when discussing some PHP execution efficiency issues):   <Rasmus_> if that is your bottleneck, you are the world’s best PHP developer <Rasmus_> domas: then you are writing … Continue reading →

Posted in mysql, wikitech | Tagged , | 2 Comments

Many needles in a haystack

Posted on 2009/02/08 by

This is probably quite useless experiment I’ve been doing, but it all started when someone in #mysql@freenode gave a very simple task: Table A has two million rows Table B has two thousand rows Find all rows in A, which … Continue reading →

Posted in mysql | Tagged , , | 1 Comment

MySQL support fun, multiplication

Posted on 2008/07/03 by

There was a question how to do an aggregate multiplication in MySQL. MySQL does not provide such functionality, so we were looking at various workarounds. We discussed UDF interface that allows to construct custom aggregates, also did look at @a:=@a*field … Continue reading →

Posted in mysql | Tagged , | 3 Comments

TV movie guide for sunday evening

Posted on 2008/01/13 by

Lithuanians have spectacular movie choices on national TV channels this evening: LTV – 21:00 – The Company LNK – 21:00 – Bad Company TV1 – 21:00 – In Good Company

Posted in misc | Tagged , | 5 Comments