Reference Guide

Zend Server Reference Manual
Zend Page Cache
The Zend Page Cache component is used to cache the entire output of PHP scripts, without changing the
PHP code.
The Zend Page Cache improves PHP application performance by caching the entire output of PHP
scripts (HTML, XML, etc.), while still maintaining dynamic capabilities through an elaborate rules system.
Rules are configured in the Administration Interface.
Page caching extends the concept of caching files and applies it to pages. Caching by page facilitates the
ability to eliminate situations where the same file is used in multiple instances, such as when the same file
is used to redirect to several pages.
When to Cache Pages
Pages should be cached when their content is stable and does not require frequent changes. You can
cache any PHP generated output including, HTML, XML, and images (if the images are generated by
PHP, such as graphs and charts).
Compression should be used to cache content such as HTML, XML and plain text, but is not
recommended for caching binary output.
When Not to Cache Pages
Caching is not recommended for files that have constantly changing output, such as clocks, timers and
database queries.
Compression should not be used for images, PDF files, .exe files, ZIP files or any other compressed
binary formats.
Note:
Zend Page Cache only caches GET and HEAD HTTP requests. To comply with the HTTP RFC, POST
requests are never cached.
All cached content is stored in a hashed directory structure on disk. The location is defined by the
directive zend_pagecache.save_path.
Caching Alternatives
Web pages that contain sections that continuously change can also be cached. This partial page caching
solution can be accomplished by applying the Data Cache API to the portions of code that do not change.
Data caching is an intermediate solution to provide a partial performance boost that can sustain the
accuracy of changing content.
To find out more about this alternative, go to Data Cache
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