Recently I had a chance to take a look at Redis project, which is semi-persistent in memory database with idea somethat similar to memcache but richer feature set. Redis has simple single process event driven design, which means it does not have to deal with any locks which is performance killer for a lot of [...]
Converting Character Sets
March 17, 2009 By 21 Comments
The web is going the way of utf8. Drizzle has chosen it as the default character set, most back-ends to websites use it to store text data, and those who are still using latin1 have begun to migrate their databases to utf8. Googling for “mysql convert charset to utf8″ results in a plethora of sites, [...]
XtraDB storage engine release 1.0.2-3 (Spring edition) codename Sapporo
March 2, 2009 By 10 Comments
Today we announce release 1.0.2-3 of our XtraDB storage engine. Here is a list of enhancements: Move to MySQL 5.1.31 Scalability fix — ability to use several rollback segments Increasing the number of rseg may be helpful for CPU scale of write-intentional workloads. See benchmark results. Scalability fix — replaced page_hash mutex to page_hash read-write [...]
Updated msl (microslow) patch, installation walk-through!
April 20, 2008 By 17 Comments
For a couple of months there have been no updates to our msl patch, however recently I managed some time to change this. The functionality was extended a little bit and what’s even more important the patch is available for all the recent MySQL releases. To remind anyone who has not yet come across this [...]
Idea: Couple of more string types
April 18, 2008 By 12 Comments
MySQL has a lot of string data types – CHAR, VARCHAR, BLOB, TEXT, ENUM and bunch of variants such as VARBINARY but I think it is not enough I would also like to see type HEXCHAR which would be able to store hex strings, such as those returned as MD5() and SHA1() efficiently. With little [...]
Fixing column encoding mess in MySQL
December 18, 2007 By 32 Comments
Just had an interesting issue with an encoding mess on a column containing non-ASCII (Russian) text. The solution was not immediately obvious so I decided it’s worth sharing. The column (actually the whole table) was created with DEFAULT CHARSET cp1251. Most of the data was in proper cp1251 national encoding indeed. However, because of web [...]
Be careful when joining on CONCAT
October 16, 2007 By 15 Comments
The other day I had a case with an awful performance of a rather simple join. It was a join on tb1.vid = CONCAT(‘prefix-’, tb2.id) with tb1.vid – indexed varchar(100) and tb2.id – int(11) column. No matter what I did – forced it to use key, forced a different join order, it did not want [...]
Handling big result sets
June 26, 2006 By 13 Comments
Sometime it is needed to handle a lot of rows on client side. Usual way is send query via mysql_query and than handle the result in loop mysql_fetch_array (here I use PHP functions but they are common or similar for all APIs, including C). Consider table:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 | CREATE TABLE `longf` ( `f1` int(11) NOT NULL auto_increment, `f2` date default NULL, `f3` date default NULL, `f4` varchar(14) default NULL, `f5` varchar(6) default NULL, `f6` date default NULL, `f7` smallint(6) default NULL, `f8` smallint(6) default NULL, `f9` varchar(13) default NULL, `f10` varchar(39) default NULL, `f11` int(11) default NULL, `f12` float default NULL, `f13` int(11) default NULL, `f14` smallint(6) default NULL, `f15` varchar(39) default NULL, `f16` date default NULL, `f17` smallint(6) default NULL, `f18` int(11) NOT NULL, `f19` date default NULL, `f20` date default NULL, `f21` varchar(14) default NULL, `f22` varchar(6) default NULL, `f23` date default NULL, `f24` smallint(6) default NULL, `f25` smallint(6) default NULL, `f26` varchar(13) default NULL, `f27` varchar(39) default NULL, `f28` int(11) default NULL, `f29` float default NULL, `f30` int(11) default NULL, `f31` smallint(6) default NULL, `f32` varchar(39) default NULL, `f33` date default NULL, `f34` smallint(6) default NULL, `f35` int(11) NOT NULL, PRIMARY KEY (`f1`) ); select count(*) from longf; +----------+ | count(*) | +----------+ | 5242880 | +----------+ |
To pack or not to pack – MyISAM Key compression
May 13, 2006 By 4 Comments
MyISAM storage engine has key compression which makes its indexes much smaller, allowing better fit in caches and so improving performance dramatically. Actually packed indexes not a bit longer rows is frequent reason of MyISAM performing better than Innodb. In this article I’ll get in a bit more details about packed keys and performance implications [...]
