Raw Database Queries

In /lib/Varien/Db/Adapter/Pdo/Mysql.php change this property to true:

/**
 * Write SQL debug data to file
 *
 * @var bool
 */
protected $_debug               = false;

To enable logging for queries slower than a certain ti...

To read:

Mage::getSingleton('core/resource')->getConnection('core_read');

To write:

Mage::getSingleton('core/resource')->getConnection('core_write');

Handy link to a very useful PDF which details how to handle multiple databases in Magento.

This site shows details of the Magento database schema for differing versions - it shows foreign key relationships in a nice drag-and-drop interface

Using the database to inspect EAV-based entity types can be a real pain in the ass, so here are a bunch of queries that let you inspect some popular EAV entity types easily. This practice can be applied to any EAV entity type, however as there are...

You need Cm_Cache_Backend_Redis for this

<config>
    <global>
        <cache>
            <backend>Cm_Cache_Backend_Redis</backend>
            <backend_options>

...

Ever wondered what they do? Basically they disable and then enable foreign key checks, and set the SQL mode to NO_AUTO_VALUE_ON_ZERO, then back to the old SQL mode. Below is the code taken from Varien_Db_Adapter_Pdo_Mysql:

/**
 * Run ad...

Here is a table showing major changes over the Magento version history:

| CE | PE | EE | Year | Major Changes ...