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| <h1>Web Page Caching</h1> | |
| <p>CodeIgniter lets you cache your pages in order to achieve maximum performance.</p> | |
| <p>Although CodeIgniter is quite fast, the amount of dynamic information you display in your pages will correlate directly to the | |
| server resources, memory, and processing cycles utilized, which affect your page load speeds. | |
| 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> | |
| <h2>How Does Caching Work?</h2> | |
| <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. | |
| 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 | |
| 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> | |
| <p>Note: The Benchmark tag is not cached so you can still view your page load speed when caching is enabled.</p> | |
| <h2>Enabling Caching</h2> | |
| <p>To enable caching, put the following tag in any of your controller functions:</p> | |
| <code>$this->output->cache(<var>n</var>);</code> | |
| <p>Where <var>n</var> is the number of <strong>minutes</strong> you wish the page to remain cached between refreshes.</p> | |
| <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 | |
| most logical to you. Once the tag is in place, your pages will begin being cached.</p> | |
| <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> | |
| <p class="important"><strong>Note:</strong> Before the cache files can be written you must set the file permissions on your | |
| <dfn>system/cache</dfn> folder such that it is writable.</p> | |
| <h2>Deleting Caches</h2> | |
| <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: | |
| Removing the tag will not delete the cache immediately. It will have to expire normally. If you need to remove it earlier you | |
| will need to manually delete it from your cache folder.</p> | |
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