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6 | <title>Web Page Caching : CodeIgniter User Guide</title> | |
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29 | <table cellpadding="0" cellspacing="0" border="0" style="width:100%"> | |
30 | <tr> | |
31 | <td><h1>CodeIgniter User Guide Version 2.1.3</h1></td> | |
32 | <td id="breadcrumb_right"><a href="../toc.html">Table of Contents Page</a></td> | |
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43 | <a href="http://codeigniter.com/">CodeIgniter Home</a> › | |
44 | <a href="../index.html">User Guide Home</a> › | |
45 | Page Caching | |
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54 | ||
55 | <!-- START CONTENT --> | |
56 | <div id="content"> | |
57 | ||
58 | ||
59 | <h1>Web Page Caching</h1> | |
60 | ||
61 | <p>CodeIgniter lets you cache your pages in order to achieve maximum performance.</p> | |
62 | ||
63 | <p>Although CodeIgniter is quite fast, the amount of dynamic information you display in your pages will correlate directly to the | |
64 | server resources, memory, and processing cycles utilized, which affect your page load speeds. | |
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> | |
66 | ||
67 | ||
68 | <h2>How Does Caching Work?</h2> | |
69 | ||
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. | |
71 | When a page is loaded for the first time, the cache file will be written to your <dfn>application/cache</dfn> folder. On subsequent page loads the cache file will be retrieved | |
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> | |
73 | ||
74 | <p>Note: The Benchmark tag is not cached so you can still view your page load speed when caching is enabled.</p> | |
75 | ||
76 | <h2>Enabling Caching</h2> | |
77 | ||
78 | <p>To enable caching, put the following tag in any of your controller functions:</p> | |
79 | ||
80 | <code>$this->output->cache(<var>n</var>);</code> | |
81 | ||
82 | <p>Where <var>n</var> is the number of <strong>minutes</strong> you wish the page to remain cached between refreshes.</p> | |
83 | ||
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 | |
85 | most logical to you. Once the tag is in place, your pages will begin being cached.</p> | |
86 | ||
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> | |
88 | <p class="important"><strong>Note:</strong> Before the cache files can be written you must set the file permissions on your | |
89 | <dfn>application/cache</dfn> folder such that it is writable.</p> | |
90 | ||
91 | <h2>Deleting Caches</h2> | |
92 | ||
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: | |
94 | Removing the tag will not delete the cache immediately. It will have to expire normally. If you need to remove it earlier you | |
95 | will need to manually delete it from your cache folder.</p> | |
96 | ||
97 | ||
98 | ||
99 | </div> | |
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105 | Previous Topic: <a href="errors.html">Error Handling</a> | |
106 | · | |
107 | <a href="#top">Top of Page</a> · | |
108 | <a href="../index.html">User Guide Home</a> · | |
109 | Next Topic: <a href="profiling.html">Profiling Your Application</a> | |
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111 | <p><a href="http://codeigniter.com">CodeIgniter</a> · Copyright © 2006 - 2012 · <a href="http://ellislab.com/">EllisLab, Inc.</a></p> | |
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