| Derek Allard | 39b622d | 2008-01-16 21:10:09 +0000 | [diff] [blame] | 1 | <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
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| Derek Allard | afd99ac | 2008-01-19 19:59:14 +0000 | [diff] [blame] | 2 | <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
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| Derek Allard | 39b622d | 2008-01-16 21:10:09 +0000 | [diff] [blame] | 3 | <head>
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| 4 |
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| 5 | <title>CodeIgniter User Guide : Web Page Caching</title>
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| 6 |
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| 7 | <style type='text/css' media='all'>@import url('../userguide.css');</style>
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| 8 | <link rel='stylesheet' type='text/css' media='all' href='../userguide.css' />
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| 10 | <script type="text/javascript" src="../nav/nav.js"></script>
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| 15 | <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
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| 17 | <meta http-equiv= 'pragma' content='no-cache' />
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| Derek Allard | 3d879d5 | 2008-01-18 19:41:32 +0000 | [diff] [blame] | 19 | <meta name='author' content='ExpressionEngine Dev Team' />
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| Derek Allard | 39b622d | 2008-01-16 21:10:09 +0000 | [diff] [blame] | 20 | <meta name='description' content='CodeIgniter User Guide' />
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| 21 |
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| 22 | </head>
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| 23 | <body>
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| 24 |
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| 25 | <!-- START NAVIGATION -->
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| 26 | <div id="nav"><div id="nav_inner"><script type="text/javascript">create_menu('../');</script></div></div>
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| 27 | <div id="nav2"><a name="top"></a><a href="javascript:void(0);" onclick="myHeight.toggle();"><img src="../images/nav_toggle.jpg" width="153" height="44" border="0" title="Toggle Table of Contents" alt="Toggle Table of Contents" /></a></div>
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| 28 | <div id="masthead">
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| 29 | <table cellpadding="0" cellspacing="0" border="0" style="width:100%">
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| 30 | <tr>
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| Derek Allard | 067f2cc | 2008-02-04 22:12:03 +0000 | [diff] [blame] | 31 | <td><h1>CodeIgniter User Guide Version 1.6.1</h1></td>
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| Derek Allard | 39b622d | 2008-01-16 21:10:09 +0000 | [diff] [blame] | 32 | <td id="breadcrumb_right"><a href="../toc.html">Table of Contents Page</a></td>
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| 33 | </tr>
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| 34 | </table>
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| 35 | </div>
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| 36 | <!-- END NAVIGATION -->
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| 37 |
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| 38 |
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| 39 | <!-- START BREADCRUMB -->
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| 40 | <table cellpadding="0" cellspacing="0" border="0" style="width:100%">
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| 41 | <tr>
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| 42 | <td id="breadcrumb">
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| Derek Jones | 7a9193a | 2008-01-21 18:39:20 +0000 | [diff] [blame] | 43 | <a href="http://codeigniter.com/">CodeIgniter Home</a> ›
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| Derek Allard | 39b622d | 2008-01-16 21:10:09 +0000 | [diff] [blame] | 44 | <a href="../index.html">User Guide Home</a> ›
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| 45 | Page Caching
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| 46 | </td>
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| 47 | <td id="searchbox"><form method="get" action="http://www.google.com/search"><input type="hidden" name="as_sitesearch" id="as_sitesearch" value="codeigniter.com/user_guide/" />Search User Guide <input type="text" class="input" style="width:200px;" name="q" id="q" size="31" maxlength="255" value="" /> <input type="submit" class="submit" name="sa" value="Go" /></form></td>
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| 48 | </tr>
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| 49 | </table>
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| 50 | <!-- END BREADCRUMB -->
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| 51 |
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| 52 | <br clear="all" />
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| 53 |
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| 54 |
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| 55 | <!-- START CONTENT -->
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| 56 | <div id="content">
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| 57 |
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| 58 |
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| 59 | <h1>Web Page Caching</h1>
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| 60 |
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| 61 | <p>CodeIgniter lets you cache your pages in order to achieve maximum performance.</p>
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| 62 |
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| 63 | <p>Although CodeIgniter is quite fast, the amount of dynamic information you display in your pages will correlate directly to the
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| 64 | server resources, memory, and processing cycles utilized, which affect your page load speeds.
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| 65 | By caching your pages, since they are saved in their fully rendered state, you can achieve performance that nears that of static web pages.</p>
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| 66 |
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| 67 |
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| 68 | <h2>How Does Caching Work?</h2>
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| 69 |
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| 70 | <p>Caching can be enabled on a per-page basis, and you can set the length of time that a page should remain cached before being refreshed.
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| 71 | When a page is loaded for the first time, the cache file will be written to your <dfn>system/cache</dfn> folder. On subsequent page loads the cache file will be retrieved
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| 72 | and sent to the requesting user's browser. If it has expired, it will be deleted and refreshed before being sent to the browser.</p>
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| 73 |
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| 74 | <p>Note: The Benchmark tag is not cached so you can still view your page load speed when caching is enabled.</p>
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| 75 |
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| 76 | <h2>Enabling Caching</h2>
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| 77 |
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| 78 | <p>To enable caching, put the following tag in any of your controller functions:</p>
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| 79 |
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| 80 | <code>$this->output->cache(<var>n</var>);</code>
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| 81 |
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| 82 | <p>Where <var>n</var> is the number of <strong>minutes</strong> you wish the page to remain cached between refreshes.</p>
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| 83 |
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| 84 | <p>The above tag can go anywhere within a function. It is not affected by the order that it appears, so place it wherever it seems
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| 85 | most logical to you. Once the tag is in place, your pages will begin being cached.</p>
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| 86 |
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| 87 | <p class="important"><strong>Warning:</strong> Because of the way CodeIgniter stores content for output, caching will only work if you are generating display for your controller with a <a href="./views.html">view</a>.</p>
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| 88 | <p class="important"><strong>Note:</strong> Before the cache files can be written you must set the file permissions on your
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| 89 | <dfn>system/cache</dfn> folder such that it is writable.</p>
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| 90 |
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| 91 | <h2>Deleting Caches</h2>
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| 92 |
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| 93 | <p>If you no longer wish to cache a file you can remove the caching tag and it will no longer be refreshed when it expires. Note:
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| 94 | Removing the tag will not delete the cache immediately. It will have to expire normally. If you need to remove it earlier you
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| 95 | will need to manually delete it from your cache folder.</p>
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| 96 |
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| 97 |
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| 98 |
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| 99 | </div>
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| 100 | <!-- END CONTENT -->
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| 101 |
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| 102 |
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| 103 | <div id="footer">
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| 104 | <p>
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| 105 | Previous Topic: <a href="errors.html">Error Handling</a>
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| 106 | ·
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| 107 | <a href="#top">Top of Page</a> ·
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| 108 | <a href="../index.html">User Guide Home</a> ·
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| 109 | Next Topic: <a href="profiling.html">Profiling Your Application</a>
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| 110 | </p>
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| Derek Jones | 7a9193a | 2008-01-21 18:39:20 +0000 | [diff] [blame] | 111 | <p><a href="http://codeigniter.com">CodeIgniter</a> · Copyright © 2007 · <a href="http://ellislab.com/">Ellislab, Inc.</a></p>
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| Derek Allard | 39b622d | 2008-01-16 21:10:09 +0000 | [diff] [blame] | 112 | </div>
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| 113 |
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| 114 | </body>
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| 115 | </html> |