I have not caused a fist fight in a while, so it’s time to take off the gloves. I claim that somewhere around of 99% of advice about tuning MySQL’s key cache hit ratio is wrong, even when you hear it from experts. There are two major problems with the key buffer hit ratio, and [...]
Statistics of InnoDB tables and indexes available in xtrabackup
September 14, 2009 By 6 Comments
If you ever wondered how big is that or another index in InnoDB … you had to calculate it yourself by multiplying size of row (which I should add is harder in the case of a VARCHAR – since you need to estimate average length) on count of records. And it still would be quite [...]
Talking MySQL to Sphinx
April 19, 2009 By 4 Comments
In the recently released Sphinx version 0.9.9-rc2 there is a support for MySQL wire protocol and SphinxQL – SQL-like language to query Sphinx indexes. This support is currently in its early preview stage but it is still fun to play with. A thing to mention – unlike MySQL Storage Engines, some of which as InfoBright [...]
KISS KISS KISS
March 1, 2009 By 7 Comments
When I visit customers quite often they tell me about number of creative techniques they heard on the conferences, read on the blogs, forums and Internet articles and they ask me if they should use them. My advice is frequently – do not. It is fun to be creative but creative solutions also means unproven [...]
Using INFORMATION_SCHEMA instead of shell scripting
November 24, 2008 By 7 Comments
INFORMATION_SCHEMA, in particular by favorite TABLES table is not only helpful to understand tables you have on the system, but I have also found it to be very helpful as a scripting language for variety of database administration tasks. It can be more straightforward compared to using shell or Perl when the operation is database [...]
Unused indexes by single query
September 12, 2008 By 14 Comments
Usually unused indexes are devil, they waste diskspace, cache, they make INSERT / DELETE / UPDATE operations slower and what makes them worse – it is hard to find them. But now ( with userstatsV2.patch) you can find all unused indexes (since last restart of mysqld) by single query
1 2 3 4 5 6 | SELECT DISTINCT s.TABLE_SCHEMA, s.TABLE_NAME, s.INDEX_NAME FROM information_schema.statistics `s` LEFT JOIN information_schema.index_statistics INDXS ON (s.TABLE_SCHEMA = INDXS.TABLE_SCHEMA AND s.TABLE_NAME=INDXS.TABLE_NAME AND s.INDEX_NAME=INDXS.INDEX_NAME) WHERE INDXS.TABLE_SCHEMA IS NULL; |
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 | +--------------+---------------------------+-----------------+ | TABLE_SCHEMA | TABLE_NAME | INDEX_NAME | +--------------+---------------------------+-----------------+ | art100 | article100 | ext_key | | art100 | article100 | site_id | | art100 | article100 | hash | | art100 | article100 | forum_id_2 | | art100 | article100 | published | | art100 | article100 | inserted | | art100 | article100 | site_id_2 | | art100 | author100 | PRIMARY | | art100 | author100 | site_id | ... +--------------+---------------------------+-----------------+ 1150 rows in set (1 min 44.23 sec) |
As you see query [...]
Google’s user_statistics V2 port and changes
September 12, 2008 By 9 Comments
Recently Google published V2 release of patches, one of them user_statistics we use in our releases. New features are quite interesting so we decided to port it to fresh releases of MySQL. Features includes: New statistics per user (Cpu_time, Bytes_received, Bytes_sent, etc) New command SHOW CLIENT_STATISTICS, which shows statistics per client’s hostname, not per user [...]
New patches, new builds
September 5, 2008 By 24 Comments
We made new patches, improved previous and want to announce new builds for 5.0.62, 5.0.67 and 5.1.26 versions. One of biggest changes we separated releases of 5.0 into two branches. First, just “-percona” release is more stable and contains only stable and proven on many installation patches. Second is “-percona-highperf” release, which contains experimental patches [...]
The ultimate tool for generating optimal my.cnf files for MySQL
August 18, 2008 By 34 Comments
There are quite a few “tuning primers” and “my.cnf generators” and “sample my.cnf files” online. The ultimate tool for generating an optimal my.cnf is not a tool. It’s a human with many years of experience, deep knowledge of MySQL and the full application stack, and familiarity with your application and your data. I don’t know [...]
Percona turns two today !
August 1, 2008 By 13 Comments
July 31st 2006 was my last day working for MySQL and August 1st I started what later was incorporated Percona with Vadim joining me September 1st as co-founder. Two years is a significant anniversary for any startup – surviving (and being profitable) for 2 years can be seen as validation of our business model and [...]
