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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' => true to 1  to the 'dboptions' array  array in config.php.This  This will cause slow queries to 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. This table can also be export and sent to Totara Support.

$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