silverstripe-framework/docs/en/02_Developer_Guides/00_Model/12_Indexes.md

title: Indexes summary: Add Indexes to your Data Model to optimize database queries.

Indexes

It is sometimes desirable to add indexes to your data model, whether to optimize queries or add a uniqueness constraint to a field. This is done through the DataObject::$indexes map, which maps index names to descriptor arrays that represent each index. There're several supported notations:

:::php
<?php

class MyObject extends DataObject {

	private static $indexes = array(
		'<column-name>' => true,
		'<index-name>' => array('type' => '<type>', 'value' => '"<column-name>"'),
		'<index-name>' => 'unique("<column-name>")'
	);
}

The <index-name> can be an arbitrary identifier in order to allow for more than one index on a specific database column. The "advanced" notation supports more <type> notations. These vary between database drivers, but all of them support the following:

• index: Standard index
• unique: Index plus uniqueness constraint on the value
• fulltext: Fulltext content index

In order to use more database specific or complex index notations, we also support raw SQL as a value in the $indexes definition. Keep in mind that using raw SQL is likely to make your code less portable between DBMSs.

mysite/code/MyTestObject.php

:::php
<?php

class MyTestObject extends DataObject {

	private static $db = array(
		'MyField' => 'Varchar',
		'MyOtherField' => 'Varchar',
	);

	private static $indexes = array(
		'MyIndexName' => array(
			'type' => 'index', 
			'value' => '"MyField","MyOtherField"'
		)
	);
}

API Documentation

• [api:DataObject]