Magento 2: log slow queries

Question

Back in M1 you could log the slow queries by modifying the following variables in lib/Varien/Db/Adapter/Pdo/Mysql.php :

/**
  * Write SQL debug data to file
  *
  * @var bool
  */
 protected $_debug               = false;
 /**
  * Minimum query duration time to be logged
  *
  * @var unknown_type
  */
 protected $_logQueryTime        = 0.05;
 /**
  * Log all queries (ignored minimum query duration time)
  *
  * @var bool
  */
 protected $_logAllQueries       = false;
 /**
  * Add to log call stack data (backtrace)
  *
  * @var bool
  */
 protected $_logCallStack        = false;
 /**
  * Path to SQL debug data log
  *
  * @var string
  */
 protected $_debugFile           = 'var/debug/sql.txt';

So I'm wondering how can I do that in M2? I've found some interesting stuff in lib/internal/Magento/Framework/DB/Logger/LoggerAbstract as well as lib/internal/Magento/Framework/DB/Logger/File but I ain't 100% sure how to tackle this.

Answer 1

app/etc/di.xml has the following preference set

<preference for="Magento\Framework\DB\LoggerInterface" type="Magento\Framework\DB\Logger\Quiet"/>

Add your own module to change the preference to the file logger you mentioned with

<preference for="Magento\Framework\DB\LoggerInterface" type="Magento\Framework\DB\Logger\File"/>

You should also be able to change the params via the same di.xml

<type name="Magento\Framework\DB\Logger\File">
    <arguments>
        <argument name="debugFile" xsi:type="string">debug/db-custom.log</argument>
        <argument name="logAllQueries" xsi:type="boolean">false</argument>
        <argument name="logQueryTime" xsi:type="number">0.01</argument>
        <argument name="logCallStack" xsi:type="boolean">false</argument>
    </arguments>
</type>