Many Open Source software solutions use database per user (or set of tables per user) which starts to cause problems if it is used on massive scale (blog hosting, forum hosting etc), resulting of hundreds of thousands if not millions of tables per server which can become really inefficient. It is especially inefficient with Innodb [...]
InnoDB in self-compiled MySQL 5.1
September 13, 2007 By 9 Comments
If you like to compile MySQL from sources by yourself, for different needs, like debugging, testing etc, you probably can face this issue. What I usually do to fast compile and test is
1 2 3 | ./configure --prefix=/dir/to/mysql make make install |
and then, for example, load the dump of InnoDB from previous version:
1 | mysql testdatabase < dump.sql |
I bet you will not notice all your [...]
What exactly is read_rnd_buffer_size
July 24, 2007 By 4 Comments
Looking for documentation for read_rnd_buffer_size you would find descriptions such as “The read_rnd_buffer_size is used after a sort, when reading rows in sorted order. If you use many queries with ORDER BY, upping this can improve performance” which is cool but it does not really tell you how exactly read_rnd_buffer_size works as well as which [...]
Implementing efficient counters with MySQL
July 1, 2007 By 16 Comments
On many web sites you would see a counter how many time given object – blog post, forum thread, image, movie etc was viewed. This is sometimes handy feature but it can be rather expensive from performance point of view. The nasty thing with counters as they are implemented the most trivial way – they [...]
Using CHAR keys for joins, how much is the overhead ?
June 18, 2007 By 18 Comments
I prefer to use Integers for joins whenever possible and today I worked with client which used character keys, in my opinion without a big need. I told them this is suboptimal but was challenged with rightful question about the difference. I did not know so I decided to benchmark. The results below are for [...]
Pitfalls of converting to InnoDB
February 25, 2007 By 16 Comments
We often recommend to our clients to convert their current database from MyISAM tables to InnoDB. The transfer by itself in most cases is almost plain, however the application can be broken by new unexpected errors 1205 (ER_LOCK_WAIT_TIMEOUT) Lock wait timeout expired. Transaction was rolled back. 1213 (ER_LOCK_DEADLOCK) Transaction deadlock. You should rerun the transaction.
MySQL Error control changes
February 19, 2007 By 4 Comments
In MySQL 5.0 mainly error control was improved, such as strict mode was added to change famous MySQL behavior of cutting too large strings, too big numbers and allowing you to use dates such as February 31st. In one case however reverse change was done – in regards to storage engine initialization. Previously if you [...]
Using MyISAM in production
June 17, 2006 By 36 Comments
There were recently number of posts about MyISAM, for example Arjen wrote pretty nice article about MyISAM features so I thought I would share my own view on using MyISAM in production. For me it is not only about table locks. Table locks is only one of MyISAM limitations you need to consider using it [...]
MySQL Server Variables – SQL layer or Storage Engine specific.
June 8, 2006 By 14 Comments
MySQL Server has tons of variables which may be adjusted to change behavior or for performance purposes. They are documented in the manual as well as on new page Jay has created. Still I see constant confusion out where which of variables apply to storage engines only and which are used on SQL layer and [...]
