Skip to main content

DML drivers

A number of native drivers are included with Moodle, including those with support for:

  • MySQLi
  • MariaDB
  • PostgreSQL
  • Oracle
  • Microsoft SQL Server

These drivers are supported using DML Database Driver layer, which has a number of discreet benefits:

  • more optimised and probably faster
  • consume less memory
  • better possibility to improve logging, debugging, profiling, etc.
  • less code, easier to fix and maintain
  • and more

Query logging​

The native DML drivers support logging of database queries to database table, which can be enabled in config.php:

config.php
$CFG->dboptions = [
    'dbpersist' => 0,
    //'logall'   => true,
    'logslow'  => 5,
    'logerrors'  => true,
];
  • logall - log all queries - suitable only for developers, causes high server loads
  • logslow - log queries that take longer than specified number of seconds (float values are accepted)
  • logerrors - log all error queries

See also​

  • DML functions: Where all the functions used to handle DB data (DML) are defined.
  • DML exceptions: New DML code is throwing exceptions instead of returning false if anything goes wrong