Data Caching and Performance¶

Tag Caching¶

The Tag Caching system lets you cache the output of individual tags. This enables you to display sections of your pages completely dynamically while leaving others to display statically. By caching individual tags you will reduce the amount of scripting and server resources needed to display any given page while maintaining a fully dynamic presentation for things that require it.

Tag caching is time-based, meaning the cache is used for a user-definable time interval. When the time expires, the cache is automatically refreshed.

To enable tag caching, add these two parameters to any tag:

cache="yes" refresh="10"

For example, to cache your channel tag in 30 minute intervals you’ll do this:

{exp:channel:entries cache="yes" refresh="30"}

Template Caching¶

Template Caching (or Dynamic Page Caching) lets you cache entire templates, making your pages much more light-weight. Because ExpressionEngine requires some scripting and a few database queries in order to manage core resources, we can’t achieve 100% static pages, but we can get close.

Template caching, like tag caching, is time-based. To enable Template caching, click the “Preferences” link in your Templates page. There you will enable caching as well as set the time interval of the refreshes.

We call it Dynamic Page Caching because the system will clear itself automatically when certain events happen. For example, if you cache your comments page, when someone submits a comment, the cache will be cleared, momentarily overriding the normal caching preferences.

Dynamic Channel Query Caching¶

This feature is found under Admin ‣ Channel Administration ‣ Global Preferences. This feature will improve the speed at which the {exp:channel:entries} tag is rendered by caching queries that are normally executed dynamically. This option cannot be used for all people, though.

Enable this feature only if you do not use future entries, expiring entries, or random entries.

Query Disabling¶

The disable= parameter is available in the {exp:channel:entries} tag. It allows you to turn off aspects of the tag that you might not be using in order to improve performance. The channel tag is designed to fetch a lot of information by default: Categories, fields, member data, etc. Depending on how you use the tag, some of this data may not be needed. Through the use of the “disable” parameter you can turn off aspects of the tag in order to make it more lightweight.

The syntax for the disable parameter is this: disable=”ITEM YOU WANT TO DISABLE”. There are five items that can be turned off:

• categories
• category_fields
• custom_fields
• member_data
• pagination

You may specify multiple items to disable by separating them with the pipe character:

disable="categories|member_data"

The best approach is to examine the data you are showing in each instance of the tag. If there is a type of data you are not utilizing, turn it off.

For example, let’s say you are using an instance of your channel tag to show your 10 most recent entry titles:

{exp:channel:entries orderby="date" sort="desc" limit="10"}
        <h1 href="{title_permalink='channel/comments'}">{title}</h1>
{/exp:channel:entries}

In this example you are only showing the title of your entries and nothing else; yet, the channel tag automatically fetches categories and other data automatically. Using the disable= parameter you can turn off the unneeded features from being queried. In this case, you don’t need any of the features that can be disabled.

{exp:channel:entries orderby="date" sort="desc" limit="10" disable="categories|custom_fields|member_data|pagination"}
        <h1 href="{title_permalink='channel/comments'}">{title}</h1>
{/exp:channel:entries}