After more than four years of using a theme that can charitably be described as rustic, we’ve updated our look. We’re using the News theme from StudioPress, which is a bargain; their themes and theme framework are an engineering marvel. We’re still using the amazing Sphinx search plugin from Ivinco for fast and relevant searches. [...]
Ultimate MySQL variable and status reference list
January 8, 2011 By 4 Comments
I am constantly referring to the amazing MySQL manual, especially the option and variable reference table. But just as frequently, I want to look up blog posts on variables, or look for content in the Percona documentation or forums. So I present to you what is now my newest Firefox toolbar bookmark: an option and [...]
MySQL 5.5.8 – in search of stability
January 3, 2011 By 11 Comments
A couple of days ago, Dimitri published a blog post, Analyzing Percona’s TPCC-like Workload on MySQL 5.5, which was a response to my post, MySQL 5.5.8 and Percona Server: being adaptive. I will refer to Dimitri’s article as article [1]. As always, Dimitri has provided a very detailed and thoughtful article, and I strongly recommend reading if [...]
Sharing an auto_increment value across multiple MySQL tables
October 4, 2010 By 9 Comments
The title is SEO bait – you can’t do it. We’ve seen a few recurring patterns trying to achieve similar – and I thought I would share with you my favorite two: Option #1: Use a table to insert into, and grab the insert_id:
1 2 3 4 5 | CREATE TABLE option1 (id int not null primary key auto_increment) engine=innodb; # each insert does one operations to get the value: INSERT INTO option1 VALUES (NULL); # $connection->insert_id(); |
Option #2: Use a table with one just row:
1 2 3 4 5 6 | CREATE TABLE option2 (id int not null primary key) engine=innodb; INSERT INTO option2 VALUES (1); # start from 1 # each insert does two operations to get the value: UPDATE option2 SET id=@id:=id+1; SELECT @id; |
Why you should ignore MySQL’s key cache hit ratio
February 28, 2010 By 28 Comments
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 [...]
Introducing tpce-like workload for MySQL
February 8, 2010 By 6 Comments
We have been using tpcc-mysql benchmark for long time, and there many results published in our blog, but that’s just single workload. That’s why we are looking into different benchmarks, and one of them is TPCE. Yasufumi made some efforts to make TPCE working with MySQL, and we are making it available for public consideration. [...]
Finding your MySQL High-Availability solution – The questions
October 16, 2009 By 36 Comments
After having reviewed the definition my the previous post (The definitions), the next step is to respond to some questions. Do you need MySQL High-Availability? That question is quite obvious but some times, it is skipped. It can also be formulated “What is the downtime cost of the service?”. In the cost, you need to [...]
How (not) to find unused indexes
October 16, 2009 By 2 Comments
I’ve seen a few people link to an INFORMATION_SCHEMA query to be able to find any indexes that have low cardinality, in an effort to find out what indexes should be removed. This method is flawed – here’s the first reason why:
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 | CREATE TABLE `sales` ( `id` int(11) NOT NULL AUTO_INCREMENT, `customer_id` int(11) DEFAULT NULL, `status` enum('archived','active') DEFAULT NULL, PRIMARY KEY (`id`), KEY `status` (`status`) ) ENGINE=MyISAM AUTO_INCREMENT=65691 DEFAULT CHARSET=latin1; mysql> SELECT count(*), status FROM sales GROUP by status; +----------+---------+ | count(*) | status | +----------+---------+ |   65536 | archived | |     154 | active | +----------+---------+ 2 rows in set (0.17 sec) mysql> EXPLAIN SELECT * FROM sales WHERE status='active'; # query 1 +----+-------------+-------+------+---------------+--------+---------+-------+------+-------------+ | id | select_type | table | type | possible_keys | key   | key_len | ref  | rows | Extra      | +----+-------------+-------+------+---------------+--------+---------+-------+------+-------------+ | 1 | SIMPLE     | sales | ref | status       | status | 2      | const | 196 | Using where | +----+-------------+-------+------+---------------+--------+---------+-------+------+-------------+ 1 row in set (0.06 sec) mysql> EXPLAIN SELECT * FROM sales WHERE status='archived'; # query 2 +----+-------------+-------+------+---------------+------+---------+------+-------+-------------+ | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra      | +----+-------------+-------+------+---------------+------+---------+------+-------+-------------+ | 1 | SIMPLE     | sales | ALL | status       | NULL | NULL   | NULL | 65690 | Using where | +----+-------------+-------+------+---------------+------+---------+------+-------+-------------+ 1 row in set (0.01 sec) |
The cardinality of status index is woeful, but provided that the application [...]
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 [...]
Sphinx Technologies launches Sphinx Support
March 24, 2009 By 1 Comment
A couple of weeks ago Sphinx Technologies, a company behind Sphinx Full Text Search Engine launched Sphinx Support Packages which I think is a great value for everyone using Sphinx in Production. This is also a great way to support the project and get something in return – even if you’re not actively using support [...]
