November 21, 2014

Using UNION to implement loose index scan in MySQL

One little known fact about MySQL Indexing, however very important for successfull MySQL Performance Optimization is understanding when exactly MySQL is going to use index and how it is going to do them. So if you have table people with KEY(age,zip) and you will run query something like SELECT name FROM people WHERE age BETWEEN […]

Mess with innodb_thread_concurrency

In MySQL 5.0.19 the meaning of innodb_thread_concurrency variable was changed (yeah, again). Now innodb_thread_concurrency=0 means unlimitied count of concurrent threads inside InnoDB. It’s logical, but there was long way. In MySQL versions below 5.0.8 for unlimited threads you had to set innodb_thread_concurrency over 500 (and default value for innodb_thread_concurrency was 8 ). Starting with MySQL […]