Difference between revisions of "MySQL Query logging"
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*'<tt>log_slow_queries</tt>' is used to log all queries which take more than '<tt>long_query_time</tt>' seconds to execute. The minimum value of this parameter is 2, as mysql measures time with second accuracy. | *'<tt>log_slow_queries</tt>' is used to log all queries which take more than '<tt>long_query_time</tt>' seconds to execute. The minimum value of this parameter is 2, as mysql measures time with second accuracy. | ||
*'<tt>log_long_format</tt>' will log additional information like which queries are not using indexes at all or not using indexes properly, etc. | *'<tt>log_long_format</tt>' will log additional information like which queries are not using indexes at all or not using indexes properly, etc. | ||
In newer versions use: | |||
<pre> | |||
long_query_time = 5 | |||
slow_query_log = 1 | |||
slow_query_log_file = /tmp/mysql_slow.log | |||
</pre> | |||
Revision as of 05:35, 29 July 2015
<yambe:breadcrumb>Mysql configuration</yambe:breadcrumb>
Query logging
Logging all queries
We can log all queries that are received by server (even that have incorrect syntax) using 'log' option in '[mysqld]' section
[mysqld] log
This can be very helpful on development machines for debugging.
Logging slow queries
Logging all queries can be problematic on production servers. Hence on production servers we can use:
long_query_time = 5 log_slow_queries log_long_format
Here:
- 'log_slow_queries' is used to log all queries which take more than 'long_query_time' seconds to execute. The minimum value of this parameter is 2, as mysql measures time with second accuracy.
- 'log_long_format' will log additional information like which queries are not using indexes at all or not using indexes properly, etc.
In newer versions use:
long_query_time = 5 slow_query_log = 1 slow_query_log_file = /tmp/mysql_slow.log
More information about configurable parameters of mysql can be found in '/usr/share/doc/mysql-server-<version>'.
<yambe:breadcrumb>Mysql configuration</yambe:breadcrumb>
