How to log slow queries

How can I enable slow query logging?

Problem

You may need to test and review slow queries on a database. By default slow queries are not logged.

Solution

To enable slow query logging, add 'logslow' => 1  to the dboptions array in config.php. This will cause queries over one second (the '1' can be changed to any number of seconds) to be logged in the 'log_queries' table in the database.

$CFG->dboptions = array (                                                                                                                                                                                      
  'dbpersist' => 0,
  'dbport' => '',
  'dbsocket' => '',
  'logslow' => 1
 ;

The log_queries table can be exported and sent to Totara Support.

Most database administrations tools (such as MySQL Workbench, PHPMyAdmin, etc.) have a graphical user interface for this. You can also do this from the command line on the server.

MySQL
PostgreSQL
MSSQL