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find out slow sql of mysql
Recent days, I should do a sql tuning for a mysql database, and I know a bit of mysql db. In order to find the slow sql, i do the slow_query_log on to collect the slow sql.
[sql]mysql> show variables like 'slow%'; +---------------------+-------------------------------------------+ | Variable_name | Value | +---------------------+-------------------------------------------+ | slow_launch_time | 2 | | slow_query_log | ON | | slow_query_log_file | /opt/mysql_data/mysql/mysql-test-slow.log | +---------------------+-------------------------------------------+ 3 rows in set (0.00 sec) mysql> set global slow_launch_time=5; Query OK, 0 rows affected (0.00 sec) mysql> show variables like 'slow%'; +---------------------+-------------------------------------------+ | Variable_name | Value | +---------------------+-------------------------------------------+ | slow_launch_time | 5 | | slow_query_log | ON | | slow_query_log_file | /opt/mysql_data/mysql/mysql-test-slow.log | +---------------------+-------------------------------------------+ 3 rows in set (0.00 sec) We can read /opt/mysql_data/mysql/mysql-test-slow.log to find slow sql.
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