642 lines
44 KiB
HTML
642 lines
44 KiB
HTML
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<title>Database Caching Class — CodeIgniter 3.1.11 documentation</title>
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<li class="toctree-l2"><a class="reference internal" href="../general/hooks.html">Hooks - Extending the Framework Core</a></li>
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<li class="toctree-l2"><a class="reference internal" href="../general/compatibility_functions.html">Compatibility Functions</a></li>
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<li class="toctree-l2"><a class="reference internal" href="../general/routing.html">URI Routing</a></li>
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<li class="toctree-l2"><a class="reference internal" href="../general/errors.html">Error Handling</a></li>
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<li class="toctree-l2"><a class="reference internal" href="../general/caching.html">Caching</a></li>
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<li class="toctree-l2"><a class="reference internal" href="../general/profiling.html">Profiling Your Application</a></li>
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<li class="toctree-l2"><a class="reference internal" href="../libraries/benchmark.html">Benchmarking Class</a></li>
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<li class="toctree-l2"><a class="reference internal" href="../libraries/caching.html">Caching Driver</a></li>
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<li class="toctree-l2"><a class="reference internal" href="../libraries/calendar.html">Calendaring Class</a></li>
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<li class="toctree-l2"><a class="reference internal" href="../libraries/cart.html">Shopping Cart Class</a></li>
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<li class="toctree-l2"><a class="reference internal" href="../libraries/config.html">Config Class</a></li>
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<li class="toctree-l2"><a class="reference internal" href="../libraries/email.html">Email Class</a></li>
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<li class="toctree-l2"><a class="reference internal" href="../libraries/encrypt.html">Encrypt Class</a></li>
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<li class="toctree-l2"><a class="reference internal" href="../libraries/encryption.html">Encryption Library</a></li>
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<li class="toctree-l2"><a class="reference internal" href="../libraries/file_uploading.html">File Uploading Class</a></li>
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<li class="toctree-l2"><a class="reference internal" href="../libraries/form_validation.html">Form Validation</a></li>
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<li class="toctree-l2"><a class="reference internal" href="../libraries/ftp.html">FTP Class</a></li>
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<li class="toctree-l2"><a class="reference internal" href="../libraries/image_lib.html">Image Manipulation Class</a></li>
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<li class="toctree-l2"><a class="reference internal" href="../libraries/input.html">Input Class</a></li>
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<li class="toctree-l2"><a class="reference internal" href="../libraries/javascript.html">Javascript Class</a></li>
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<li class="toctree-l2"><a class="reference internal" href="../libraries/language.html">Language Class</a></li>
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<li class="toctree-l2"><a class="reference internal" href="../libraries/loader.html">Loader Class</a></li>
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<li class="toctree-l2"><a class="reference internal" href="../libraries/migration.html">Migrations Class</a></li>
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<li class="toctree-l2"><a class="reference internal" href="../libraries/output.html">Output Class</a></li>
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<li class="toctree-l2"><a class="reference internal" href="../libraries/pagination.html">Pagination Class</a></li>
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<li class="toctree-l2"><a class="reference internal" href="../libraries/parser.html">Template Parser Class</a></li>
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<li class="toctree-l2"><a class="reference internal" href="../libraries/security.html">Security Class</a></li>
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<li class="toctree-l2"><a class="reference internal" href="../libraries/sessions.html">Session Library</a></li>
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<li class="toctree-l2"><a class="reference internal" href="../libraries/table.html">HTML Table Class</a></li>
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<li class="toctree-l2"><a class="reference internal" href="../libraries/trackback.html">Trackback Class</a></li>
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<li class="toctree-l2"><a class="reference internal" href="../libraries/typography.html">Typography Class</a></li>
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<li class="toctree-l2"><a class="reference internal" href="../libraries/unit_testing.html">Unit Testing Class</a></li>
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<li class="toctree-l2"><a class="reference internal" href="../libraries/uri.html">URI Class</a></li>
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<li class="toctree-l2"><a class="reference internal" href="../libraries/user_agent.html">User Agent Class</a></li>
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<li class="toctree-l2"><a class="reference internal" href="../libraries/xmlrpc.html">XML-RPC and XML-RPC Server Classes</a></li>
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<li class="toctree-l2"><a class="reference internal" href="../libraries/zip.html">Zip Encoding Class</a></li>
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</ul>
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</li>
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</ul>
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<ul class="current">
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<li class="toctree-l1 current"><a class="reference internal" href="index.html">Database Reference</a><ul class="current">
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<li class="toctree-l2"><a class="reference internal" href="examples.html">Quick Start: Usage Examples</a></li>
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<li class="toctree-l2"><a class="reference internal" href="configuration.html">Database Configuration</a></li>
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<li class="toctree-l2"><a class="reference internal" href="connecting.html">Connecting to a Database</a></li>
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<li class="toctree-l2"><a class="reference internal" href="queries.html">Running Queries</a></li>
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<li class="toctree-l2"><a class="reference internal" href="results.html">Generating Query Results</a></li>
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<li class="toctree-l2"><a class="reference internal" href="helpers.html">Query Helper Functions</a></li>
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<li class="toctree-l2"><a class="reference internal" href="query_builder.html">Query Builder Class</a></li>
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<li class="toctree-l2"><a class="reference internal" href="transactions.html">Transactions</a></li>
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<li class="toctree-l2"><a class="reference internal" href="metadata.html">Getting MetaData</a></li>
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<li class="toctree-l2"><a class="reference internal" href="call_function.html">Custom Function Calls</a></li>
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<li class="toctree-l2 current"><a class="current reference internal" href="#">Query Caching</a></li>
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<li class="toctree-l2"><a class="reference internal" href="forge.html">Database Manipulation with Database Forge</a></li>
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<li class="toctree-l2"><a class="reference internal" href="utilities.html">Database Utilities Class</a></li>
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<li class="toctree-l2"><a class="reference internal" href="db_driver_reference.html">Database Driver Reference</a></li>
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</ul>
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</li>
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</ul>
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<ul>
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<li class="toctree-l1"><a class="reference internal" href="../helpers/index.html">Helpers</a><ul>
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<li class="toctree-l2"><a class="reference internal" href="../helpers/array_helper.html">Array Helper</a></li>
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<li class="toctree-l2"><a class="reference internal" href="../helpers/captcha_helper.html">CAPTCHA Helper</a></li>
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<li class="toctree-l2"><a class="reference internal" href="../helpers/cookie_helper.html">Cookie Helper</a></li>
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<li class="toctree-l2"><a class="reference internal" href="../helpers/date_helper.html">Date Helper</a></li>
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<li class="toctree-l2"><a class="reference internal" href="../helpers/directory_helper.html">Directory Helper</a></li>
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<li class="toctree-l2"><a class="reference internal" href="../helpers/download_helper.html">Download Helper</a></li>
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<li class="toctree-l2"><a class="reference internal" href="../helpers/email_helper.html">Email Helper</a></li>
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<li class="toctree-l2"><a class="reference internal" href="../helpers/file_helper.html">File Helper</a></li>
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<li class="toctree-l2"><a class="reference internal" href="../helpers/form_helper.html">Form Helper</a></li>
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<li class="toctree-l2"><a class="reference internal" href="../helpers/html_helper.html">HTML Helper</a></li>
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<li class="toctree-l2"><a class="reference internal" href="../helpers/inflector_helper.html">Inflector Helper</a></li>
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<li class="toctree-l2"><a class="reference internal" href="../helpers/language_helper.html">Language Helper</a></li>
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<li class="toctree-l2"><a class="reference internal" href="../helpers/number_helper.html">Number Helper</a></li>
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<li class="toctree-l2"><a class="reference internal" href="../helpers/path_helper.html">Path Helper</a></li>
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<li class="toctree-l2"><a class="reference internal" href="../helpers/security_helper.html">Security Helper</a></li>
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<li class="toctree-l2"><a class="reference internal" href="../helpers/smiley_helper.html">Smiley Helper</a></li>
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<li class="toctree-l2"><a class="reference internal" href="../helpers/string_helper.html">String Helper</a></li>
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<li class="toctree-l2"><a class="reference internal" href="../helpers/text_helper.html">Text Helper</a></li>
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<li class="toctree-l2"><a class="reference internal" href="../helpers/typography_helper.html">Typography Helper</a></li>
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<li class="toctree-l2"><a class="reference internal" href="../helpers/url_helper.html">URL Helper</a></li>
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<li class="toctree-l2"><a class="reference internal" href="../helpers/xml_helper.html">XML Helper</a></li>
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</ul>
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</li>
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</ul>
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</div>
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<img src="data:image/jpeg;base64,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" title="Toggle Table of Contents" alt="Toggle Table of Contents" />
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<nav data-toggle="wy-nav-shift" class="wy-nav-side">
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<div class="wy-side-nav-search">
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<a href="../index.html" class="fa fa-home"> CodeIgniter</a>
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<div role="search">
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<form id="rtd-search-form" class="wy-form" action="../search.html" method="get">
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<input type="text" name="q" placeholder="Search docs" />
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<input type="hidden" name="check_keywords" value="yes" />
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</form>
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<div class="wy-menu wy-menu-vertical" data-spy="affix" role="navigation" aria-label="main navigation">
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<ul>
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<li class="toctree-l1"><a class="reference internal" href="../general/welcome.html">Welcome to CodeIgniter</a></li>
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</ul>
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<ul>
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<li class="toctree-l1"><a class="reference internal" href="../installation/index.html">Installation Instructions</a><ul>
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<li class="toctree-l2"><a class="reference internal" href="../installation/downloads.html">Downloading CodeIgniter</a></li>
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<li class="toctree-l2"><a class="reference internal" href="../installation/index.html">Installation Instructions</a></li>
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<li class="toctree-l2"><a class="reference internal" href="../installation/upgrading.html">Upgrading From a Previous Version</a></li>
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<li class="toctree-l2"><a class="reference internal" href="../installation/troubleshooting.html">Troubleshooting</a></li>
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</ul>
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</li>
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</ul>
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<ul>
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<li class="toctree-l1"><a class="reference internal" href="../overview/index.html">CodeIgniter Overview</a><ul>
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<li class="toctree-l2"><a class="reference internal" href="../overview/getting_started.html">Getting Started</a></li>
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<li class="toctree-l2"><a class="reference internal" href="../overview/at_a_glance.html">CodeIgniter at a Glance</a></li>
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<li class="toctree-l2"><a class="reference internal" href="../overview/features.html">Supported Features</a></li>
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<li class="toctree-l2"><a class="reference internal" href="../overview/appflow.html">Application Flow Chart</a></li>
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<li class="toctree-l2"><a class="reference internal" href="../overview/mvc.html">Model-View-Controller</a></li>
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<li class="toctree-l2"><a class="reference internal" href="../overview/goals.html">Architectural Goals</a></li>
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</ul>
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</li>
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</ul>
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<ul>
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<li class="toctree-l1"><a class="reference internal" href="../tutorial/index.html">Tutorial</a><ul>
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<li class="toctree-l2"><a class="reference internal" href="../tutorial/static_pages.html">Static pages</a></li>
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<li class="toctree-l2"><a class="reference internal" href="../tutorial/news_section.html">News section</a></li>
|
|||
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<li class="toctree-l2"><a class="reference internal" href="../tutorial/create_news_items.html">Create news items</a></li>
|
|||
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<li class="toctree-l2"><a class="reference internal" href="../tutorial/conclusion.html">Conclusion</a></li>
|
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</ul>
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</li>
|
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</ul>
|
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<ul>
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<li class="toctree-l1"><a class="reference internal" href="../contributing/index.html">Contributing to CodeIgniter</a><ul>
|
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<li class="toctree-l2"><a class="reference internal" href="../documentation/index.html">Writing CodeIgniter Documentation</a></li>
|
|||
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<li class="toctree-l2"><a class="reference internal" href="../DCO.html">Developer’s Certificate of Origin 1.1</a></li>
|
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</ul>
|
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</li>
|
|||
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</ul>
|
|||
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<ul>
|
|||
|
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<li class="toctree-l1"><a class="reference internal" href="../general/index.html">General Topics</a><ul>
|
|||
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<li class="toctree-l2"><a class="reference internal" href="../general/urls.html">CodeIgniter URLs</a></li>
|
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<li class="toctree-l2"><a class="reference internal" href="../general/controllers.html">Controllers</a></li>
|
|||
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<li class="toctree-l2"><a class="reference internal" href="../general/reserved_names.html">Reserved Names</a></li>
|
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<li class="toctree-l2"><a class="reference internal" href="../general/views.html">Views</a></li>
|
|||
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<li class="toctree-l2"><a class="reference internal" href="../general/models.html">Models</a></li>
|
|||
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<li class="toctree-l2"><a class="reference internal" href="../general/helpers.html">Helpers</a></li>
|
|||
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<li class="toctree-l2"><a class="reference internal" href="../general/libraries.html">Using CodeIgniter Libraries</a></li>
|
|||
|
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<li class="toctree-l2"><a class="reference internal" href="../general/creating_libraries.html">Creating Libraries</a></li>
|
|||
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<li class="toctree-l2"><a class="reference internal" href="../general/drivers.html">Using CodeIgniter Drivers</a></li>
|
|||
|
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<li class="toctree-l2"><a class="reference internal" href="../general/creating_drivers.html">Creating Drivers</a></li>
|
|||
|
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<li class="toctree-l2"><a class="reference internal" href="../general/core_classes.html">Creating Core System Classes</a></li>
|
|||
|
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<li class="toctree-l2"><a class="reference internal" href="../general/ancillary_classes.html">Creating Ancillary Classes</a></li>
|
|||
|
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<li class="toctree-l2"><a class="reference internal" href="../general/hooks.html">Hooks - Extending the Framework Core</a></li>
|
|||
|
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<li class="toctree-l2"><a class="reference internal" href="../general/autoloader.html">Auto-loading Resources</a></li>
|
|||
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<li class="toctree-l2"><a class="reference internal" href="../general/common_functions.html">Common Functions</a></li>
|
|||
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<li class="toctree-l2"><a class="reference internal" href="../general/compatibility_functions.html">Compatibility Functions</a></li>
|
|||
|
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<li class="toctree-l2"><a class="reference internal" href="../general/routing.html">URI Routing</a></li>
|
|||
|
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<li class="toctree-l2"><a class="reference internal" href="../general/errors.html">Error Handling</a></li>
|
|||
|
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<li class="toctree-l2"><a class="reference internal" href="../general/caching.html">Caching</a></li>
|
|||
|
|
<li class="toctree-l2"><a class="reference internal" href="../general/profiling.html">Profiling Your Application</a></li>
|
|||
|
|
<li class="toctree-l2"><a class="reference internal" href="../general/cli.html">Running via the CLI</a></li>
|
|||
|
|
<li class="toctree-l2"><a class="reference internal" href="../general/managing_apps.html">Managing your Applications</a></li>
|
|||
|
|
<li class="toctree-l2"><a class="reference internal" href="../general/environments.html">Handling Multiple Environments</a></li>
|
|||
|
|
<li class="toctree-l2"><a class="reference internal" href="../general/alternative_php.html">Alternate PHP Syntax for View Files</a></li>
|
|||
|
|
<li class="toctree-l2"><a class="reference internal" href="../general/security.html">Security</a></li>
|
|||
|
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<li class="toctree-l2"><a class="reference internal" href="../general/styleguide.html">PHP Style Guide</a></li>
|
|||
|
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</ul>
|
|||
|
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</li>
|
|||
|
|
</ul>
|
|||
|
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<ul>
|
|||
|
|
<li class="toctree-l1"><a class="reference internal" href="../libraries/index.html">Libraries</a><ul>
|
|||
|
|
<li class="toctree-l2"><a class="reference internal" href="../libraries/benchmark.html">Benchmarking Class</a></li>
|
|||
|
|
<li class="toctree-l2"><a class="reference internal" href="../libraries/caching.html">Caching Driver</a></li>
|
|||
|
|
<li class="toctree-l2"><a class="reference internal" href="../libraries/calendar.html">Calendaring Class</a></li>
|
|||
|
|
<li class="toctree-l2"><a class="reference internal" href="../libraries/cart.html">Shopping Cart Class</a></li>
|
|||
|
|
<li class="toctree-l2"><a class="reference internal" href="../libraries/config.html">Config Class</a></li>
|
|||
|
|
<li class="toctree-l2"><a class="reference internal" href="../libraries/email.html">Email Class</a></li>
|
|||
|
|
<li class="toctree-l2"><a class="reference internal" href="../libraries/encrypt.html">Encrypt Class</a></li>
|
|||
|
|
<li class="toctree-l2"><a class="reference internal" href="../libraries/encryption.html">Encryption Library</a></li>
|
|||
|
|
<li class="toctree-l2"><a class="reference internal" href="../libraries/file_uploading.html">File Uploading Class</a></li>
|
|||
|
|
<li class="toctree-l2"><a class="reference internal" href="../libraries/form_validation.html">Form Validation</a></li>
|
|||
|
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<li class="toctree-l2"><a class="reference internal" href="../libraries/ftp.html">FTP Class</a></li>
|
|||
|
|
<li class="toctree-l2"><a class="reference internal" href="../libraries/image_lib.html">Image Manipulation Class</a></li>
|
|||
|
|
<li class="toctree-l2"><a class="reference internal" href="../libraries/input.html">Input Class</a></li>
|
|||
|
|
<li class="toctree-l2"><a class="reference internal" href="../libraries/javascript.html">Javascript Class</a></li>
|
|||
|
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<li class="toctree-l2"><a class="reference internal" href="../libraries/language.html">Language Class</a></li>
|
|||
|
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<li class="toctree-l2"><a class="reference internal" href="../libraries/loader.html">Loader Class</a></li>
|
|||
|
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<li class="toctree-l2"><a class="reference internal" href="../libraries/migration.html">Migrations Class</a></li>
|
|||
|
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<li class="toctree-l2"><a class="reference internal" href="../libraries/output.html">Output Class</a></li>
|
|||
|
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<li class="toctree-l2"><a class="reference internal" href="../libraries/pagination.html">Pagination Class</a></li>
|
|||
|
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<li class="toctree-l2"><a class="reference internal" href="../libraries/parser.html">Template Parser Class</a></li>
|
|||
|
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<li class="toctree-l2"><a class="reference internal" href="../libraries/security.html">Security Class</a></li>
|
|||
|
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<li class="toctree-l2"><a class="reference internal" href="../libraries/sessions.html">Session Library</a></li>
|
|||
|
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<li class="toctree-l2"><a class="reference internal" href="../libraries/table.html">HTML Table Class</a></li>
|
|||
|
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<li class="toctree-l2"><a class="reference internal" href="../libraries/trackback.html">Trackback Class</a></li>
|
|||
|
|
<li class="toctree-l2"><a class="reference internal" href="../libraries/typography.html">Typography Class</a></li>
|
|||
|
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<li class="toctree-l2"><a class="reference internal" href="../libraries/unit_testing.html">Unit Testing Class</a></li>
|
|||
|
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<li class="toctree-l2"><a class="reference internal" href="../libraries/uri.html">URI Class</a></li>
|
|||
|
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<li class="toctree-l2"><a class="reference internal" href="../libraries/user_agent.html">User Agent Class</a></li>
|
|||
|
|
<li class="toctree-l2"><a class="reference internal" href="../libraries/xmlrpc.html">XML-RPC and XML-RPC Server Classes</a></li>
|
|||
|
|
<li class="toctree-l2"><a class="reference internal" href="../libraries/zip.html">Zip Encoding Class</a></li>
|
|||
|
|
</ul>
|
|||
|
|
</li>
|
|||
|
|
</ul>
|
|||
|
|
<ul class="current">
|
|||
|
|
<li class="toctree-l1 current"><a class="reference internal" href="index.html">Database Reference</a><ul class="current">
|
|||
|
|
<li class="toctree-l2"><a class="reference internal" href="examples.html">Quick Start: Usage Examples</a></li>
|
|||
|
|
<li class="toctree-l2"><a class="reference internal" href="configuration.html">Database Configuration</a></li>
|
|||
|
|
<li class="toctree-l2"><a class="reference internal" href="connecting.html">Connecting to a Database</a></li>
|
|||
|
|
<li class="toctree-l2"><a class="reference internal" href="queries.html">Running Queries</a></li>
|
|||
|
|
<li class="toctree-l2"><a class="reference internal" href="results.html">Generating Query Results</a></li>
|
|||
|
|
<li class="toctree-l2"><a class="reference internal" href="helpers.html">Query Helper Functions</a></li>
|
|||
|
|
<li class="toctree-l2"><a class="reference internal" href="query_builder.html">Query Builder Class</a></li>
|
|||
|
|
<li class="toctree-l2"><a class="reference internal" href="transactions.html">Transactions</a></li>
|
|||
|
|
<li class="toctree-l2"><a class="reference internal" href="metadata.html">Getting MetaData</a></li>
|
|||
|
|
<li class="toctree-l2"><a class="reference internal" href="call_function.html">Custom Function Calls</a></li>
|
|||
|
|
<li class="toctree-l2 current"><a class="current reference internal" href="#">Query Caching</a></li>
|
|||
|
|
<li class="toctree-l2"><a class="reference internal" href="forge.html">Database Manipulation with Database Forge</a></li>
|
|||
|
|
<li class="toctree-l2"><a class="reference internal" href="utilities.html">Database Utilities Class</a></li>
|
|||
|
|
<li class="toctree-l2"><a class="reference internal" href="db_driver_reference.html">Database Driver Reference</a></li>
|
|||
|
|
</ul>
|
|||
|
|
</li>
|
|||
|
|
</ul>
|
|||
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|
<ul>
|
|||
|
|
<li class="toctree-l1"><a class="reference internal" href="../helpers/index.html">Helpers</a><ul>
|
|||
|
|
<li class="toctree-l2"><a class="reference internal" href="../helpers/array_helper.html">Array Helper</a></li>
|
|||
|
|
<li class="toctree-l2"><a class="reference internal" href="../helpers/captcha_helper.html">CAPTCHA Helper</a></li>
|
|||
|
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<li class="toctree-l2"><a class="reference internal" href="../helpers/cookie_helper.html">Cookie Helper</a></li>
|
|||
|
|
<li class="toctree-l2"><a class="reference internal" href="../helpers/date_helper.html">Date Helper</a></li>
|
|||
|
|
<li class="toctree-l2"><a class="reference internal" href="../helpers/directory_helper.html">Directory Helper</a></li>
|
|||
|
|
<li class="toctree-l2"><a class="reference internal" href="../helpers/download_helper.html">Download Helper</a></li>
|
|||
|
|
<li class="toctree-l2"><a class="reference internal" href="../helpers/email_helper.html">Email Helper</a></li>
|
|||
|
|
<li class="toctree-l2"><a class="reference internal" href="../helpers/file_helper.html">File Helper</a></li>
|
|||
|
|
<li class="toctree-l2"><a class="reference internal" href="../helpers/form_helper.html">Form Helper</a></li>
|
|||
|
|
<li class="toctree-l2"><a class="reference internal" href="../helpers/html_helper.html">HTML Helper</a></li>
|
|||
|
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<li class="toctree-l2"><a class="reference internal" href="../helpers/inflector_helper.html">Inflector Helper</a></li>
|
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<li class="toctree-l2"><a class="reference internal" href="../helpers/language_helper.html">Language Helper</a></li>
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<li class="toctree-l2"><a class="reference internal" href="../helpers/number_helper.html">Number Helper</a></li>
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<li class="toctree-l2"><a class="reference internal" href="../helpers/path_helper.html">Path Helper</a></li>
|
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<li class="toctree-l2"><a class="reference internal" href="../helpers/security_helper.html">Security Helper</a></li>
|
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<li class="toctree-l2"><a class="reference internal" href="../helpers/smiley_helper.html">Smiley Helper</a></li>
|
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<li class="toctree-l2"><a class="reference internal" href="../helpers/string_helper.html">String Helper</a></li>
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<li class="toctree-l2"><a class="reference internal" href="../helpers/text_helper.html">Text Helper</a></li>
|
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<li class="toctree-l2"><a class="reference internal" href="../helpers/typography_helper.html">Typography Helper</a></li>
|
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<li class="toctree-l2"><a class="reference internal" href="../helpers/url_helper.html">URL Helper</a></li>
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<li class="toctree-l2"><a class="reference internal" href="../helpers/xml_helper.html">XML Helper</a></li>
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</ul>
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</li>
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</ul>
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</div>
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</nav>
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<section data-toggle="wy-nav-shift" class="wy-nav-content-wrap">
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<nav class="wy-nav-top" role="navigation" aria-label="top navigation">
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<i data-toggle="wy-nav-top" class="fa fa-bars"></i>
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<a href="../index.html">CodeIgniter</a>
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</nav>
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<div class="wy-nav-content">
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<div class="rst-content">
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<div role="navigation" aria-label="breadcrumbs navigation">
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<ul class="wy-breadcrumbs">
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<li><a href="../index.html">Docs</a> »</li>
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<li><a href="index.html">Database Reference</a> »</li>
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|
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<li>Database Caching Class</li>
|
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<li class="wy-breadcrumbs-aside">
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</li>
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<div style="float:right;margin-left:5px;" id="closeMe">
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<img title="Classic Layout" alt="classic layout" src="data:image/gif;base64,R0lGODlhFAAUAJEAAAAAADMzM////wAAACH5BAUUAAIALAAAAAAUABQAAAImlI+py+0PU5gRBRDM3DxbWoXis42X13USOLauUIqnlsaH/eY6UwAAOw==" />
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</div>
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</ul>
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<hr/>
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</div>
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<div role="main" class="document">
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<div class="section" id="database-caching-class">
|
|||
|
|
<h1>Database Caching Class<a class="headerlink" href="#database-caching-class" title="Permalink to this headline">¶</a></h1>
|
|||
|
|
<p>The Database Caching Class permits you to cache your queries as text
|
|||
|
|
files for reduced database load.</p>
|
|||
|
|
<div class="admonition important">
|
|||
|
|
<p class="first admonition-title">Important</p>
|
|||
|
|
<p class="last">This class is initialized automatically by the database
|
|||
|
|
driver when caching is enabled. Do NOT load this class manually.</p>
|
|||
|
|
</div>
|
|||
|
|
<div class="admonition important">
|
|||
|
|
<p class="first admonition-title">Important</p>
|
|||
|
|
<p class="last">Not all query result functions are available when you
|
|||
|
|
use caching. Please read this page carefully.</p>
|
|||
|
|
</div>
|
|||
|
|
<div class="section" id="enabling-caching">
|
|||
|
|
<h2>Enabling Caching<a class="headerlink" href="#enabling-caching" title="Permalink to this headline">¶</a></h2>
|
|||
|
|
<p>Caching is enabled in three steps:</p>
|
|||
|
|
<ul class="simple">
|
|||
|
|
<li>Create a writable directory on your server where the cache files can
|
|||
|
|
be stored.</li>
|
|||
|
|
<li>Set the path to your cache folder in your
|
|||
|
|
application/config/database.php file.</li>
|
|||
|
|
<li>Enable the caching feature, either globally by setting the preference
|
|||
|
|
in your application/config/database.php file, or manually as
|
|||
|
|
described below.</li>
|
|||
|
|
</ul>
|
|||
|
|
<p>Once enabled, caching will happen automatically whenever a page is
|
|||
|
|
loaded that contains database queries.</p>
|
|||
|
|
</div>
|
|||
|
|
<div class="section" id="how-does-caching-work">
|
|||
|
|
<h2>How Does Caching Work?<a class="headerlink" href="#how-does-caching-work" title="Permalink to this headline">¶</a></h2>
|
|||
|
|
<p>CodeIgniter’s query caching system happens dynamically when your pages
|
|||
|
|
are viewed. When caching is enabled, the first time a web page is
|
|||
|
|
loaded, the query result object will be serialized and stored in a text
|
|||
|
|
file on your server. The next time the page is loaded the cache file
|
|||
|
|
will be used instead of accessing your database. Your database usage can
|
|||
|
|
effectively be reduced to zero for any pages that have been cached.</p>
|
|||
|
|
<p>Only read-type (SELECT) queries can be cached, since these are the only
|
|||
|
|
type of queries that produce a result. Write-type (INSERT, UPDATE, etc.)
|
|||
|
|
queries, since they don’t generate a result, will not be cached by the
|
|||
|
|
system.</p>
|
|||
|
|
<p>Cache files DO NOT expire. Any queries that have been cached will remain
|
|||
|
|
cached until you delete them. The caching system permits you clear
|
|||
|
|
caches associated with individual pages, or you can delete the entire
|
|||
|
|
collection of cache files. Typically you’ll want to use the housekeeping
|
|||
|
|
functions described below to delete cache files after certain events
|
|||
|
|
take place, like when you’ve added new information to your database.</p>
|
|||
|
|
</div>
|
|||
|
|
<div class="section" id="will-caching-improve-your-site-s-performance">
|
|||
|
|
<h2>Will Caching Improve Your Site’s Performance?<a class="headerlink" href="#will-caching-improve-your-site-s-performance" title="Permalink to this headline">¶</a></h2>
|
|||
|
|
<p>Getting a performance gain as a result of caching depends on many
|
|||
|
|
factors. If you have a highly optimized database under very little load,
|
|||
|
|
you probably won’t see a performance boost. If your database is under
|
|||
|
|
heavy use you probably will see an improved response, assuming your
|
|||
|
|
file-system is not overly taxed. Remember that caching simply changes
|
|||
|
|
how your information is retrieved, shifting it from being a database
|
|||
|
|
operation to a file-system one.</p>
|
|||
|
|
<p>In some clustered server environments, for example, caching may be
|
|||
|
|
detrimental since file-system operations are so intense. On single
|
|||
|
|
servers in shared environments, caching will probably be beneficial.
|
|||
|
|
Unfortunately there is no single answer to the question of whether you
|
|||
|
|
should cache your database. It really depends on your situation.</p>
|
|||
|
|
</div>
|
|||
|
|
<div class="section" id="how-are-cache-files-stored">
|
|||
|
|
<h2>How are Cache Files Stored?<a class="headerlink" href="#how-are-cache-files-stored" title="Permalink to this headline">¶</a></h2>
|
|||
|
|
<p>CodeIgniter places the result of EACH query into its own cache file.
|
|||
|
|
Sets of cache files are further organized into sub-folders corresponding
|
|||
|
|
to your controller functions. To be precise, the sub-folders are named
|
|||
|
|
identically to the first two segments of your URI (the controller class
|
|||
|
|
name and function name).</p>
|
|||
|
|
<p>For example, let’s say you have a controller called blog with a function
|
|||
|
|
called comments that contains three queries. The caching system will
|
|||
|
|
create a cache folder called blog+comments, into which it will write
|
|||
|
|
three cache files.</p>
|
|||
|
|
<p>If you use dynamic queries that change based on information in your URI
|
|||
|
|
(when using pagination, for example), each instance of the query will
|
|||
|
|
produce its own cache file. It’s possible, therefore, to end up with
|
|||
|
|
many times more cache files than you have queries.</p>
|
|||
|
|
</div>
|
|||
|
|
<div class="section" id="managing-your-cache-files">
|
|||
|
|
<h2>Managing your Cache Files<a class="headerlink" href="#managing-your-cache-files" title="Permalink to this headline">¶</a></h2>
|
|||
|
|
<p>Since cache files do not expire, you’ll need to build deletion routines
|
|||
|
|
into your application. For example, let’s say you have a blog that
|
|||
|
|
allows user commenting. Whenever a new comment is submitted you’ll want
|
|||
|
|
to delete the cache files associated with the controller function that
|
|||
|
|
serves up your comments. You’ll find two delete functions described
|
|||
|
|
below that help you clear data.</p>
|
|||
|
|
</div>
|
|||
|
|
<div class="section" id="not-all-database-functions-work-with-caching">
|
|||
|
|
<h2>Not All Database Functions Work with Caching<a class="headerlink" href="#not-all-database-functions-work-with-caching" title="Permalink to this headline">¶</a></h2>
|
|||
|
|
<p>Lastly, we need to point out that the result object that is cached is a
|
|||
|
|
simplified version of the full result object. For that reason, some of
|
|||
|
|
the query result functions are not available for use.</p>
|
|||
|
|
<p>The following functions ARE NOT available when using a cached result
|
|||
|
|
object:</p>
|
|||
|
|
<ul class="simple">
|
|||
|
|
<li>num_fields()</li>
|
|||
|
|
<li>field_names()</li>
|
|||
|
|
<li>field_data()</li>
|
|||
|
|
<li>free_result()</li>
|
|||
|
|
</ul>
|
|||
|
|
<p>Also, the two database resources (result_id and conn_id) are not
|
|||
|
|
available when caching, since result resources only pertain to run-time
|
|||
|
|
operations.</p>
|
|||
|
|
<div class="section" id="function-reference">
|
|||
|
|
<h3>Function Reference<a class="headerlink" href="#function-reference" title="Permalink to this headline">¶</a></h3>
|
|||
|
|
</div>
|
|||
|
|
</div>
|
|||
|
|
<div class="section" id="this-db-cache-on-this-db-cache-off">
|
|||
|
|
<h2>$this->db->cache_on() / $this->db->cache_off()<a class="headerlink" href="#this-db-cache-on-this-db-cache-off" title="Permalink to this headline">¶</a></h2>
|
|||
|
|
<p>Manually enables/disables caching. This can be useful if you want to
|
|||
|
|
keep certain queries from being cached. Example:</p>
|
|||
|
|
<div class="highlight-ci"><div class="highlight"><pre><span></span><span class="c1">// Turn caching on</span>
|
|||
|
|
<span class="nv">$this</span><span class="o">-></span><span class="na">db</span><span class="o">-></span><span class="na">cache_on</span><span class="p">();</span>
|
|||
|
|
<span class="nv">$query</span> <span class="o">=</span> <span class="nv">$this</span><span class="o">-></span><span class="na">db</span><span class="o">-></span><span class="na">query</span><span class="p">(</span><span class="s2">"SELECT * FROM mytable"</span><span class="p">);</span>
|
|||
|
|
|
|||
|
|
<span class="c1">// Turn caching off for this one query</span>
|
|||
|
|
<span class="nv">$this</span><span class="o">-></span><span class="na">db</span><span class="o">-></span><span class="na">cache_off</span><span class="p">();</span>
|
|||
|
|
<span class="nv">$query</span> <span class="o">=</span> <span class="nv">$this</span><span class="o">-></span><span class="na">db</span><span class="o">-></span><span class="na">query</span><span class="p">(</span><span class="s2">"SELECT * FROM members WHERE member_id = '</span><span class="si">$current_user</span><span class="s2">'"</span><span class="p">);</span>
|
|||
|
|
|
|||
|
|
<span class="c1">// Turn caching back on</span>
|
|||
|
|
<span class="nv">$this</span><span class="o">-></span><span class="na">db</span><span class="o">-></span><span class="na">cache_on</span><span class="p">();</span>
|
|||
|
|
<span class="nv">$query</span> <span class="o">=</span> <span class="nv">$this</span><span class="o">-></span><span class="na">db</span><span class="o">-></span><span class="na">query</span><span class="p">(</span><span class="s2">"SELECT * FROM another_table"</span><span class="p">);</span>
|
|||
|
|
</pre></div>
|
|||
|
|
</div>
|
|||
|
|
</div>
|
|||
|
|
<div class="section" id="this-db-cache-delete">
|
|||
|
|
<h2>$this->db->cache_delete()<a class="headerlink" href="#this-db-cache-delete" title="Permalink to this headline">¶</a></h2>
|
|||
|
|
<p>Deletes the cache files associated with a particular page. This is
|
|||
|
|
useful if you need to clear caching after you update your database.</p>
|
|||
|
|
<p>The caching system saves your cache files to folders that correspond to
|
|||
|
|
the URI of the page you are viewing. For example, if you are viewing a
|
|||
|
|
page at example.com/index.php/blog/comments, the caching system will put
|
|||
|
|
all cache files associated with it in a folder called blog+comments. To
|
|||
|
|
delete those particular cache files you will use:</p>
|
|||
|
|
<div class="highlight-ci"><div class="highlight"><pre><span></span><span class="nv">$this</span><span class="o">-></span><span class="na">db</span><span class="o">-></span><span class="na">cache_delete</span><span class="p">(</span><span class="s1">'blog'</span><span class="p">,</span> <span class="s1">'comments'</span><span class="p">);</span>
|
|||
|
|
</pre></div>
|
|||
|
|
</div>
|
|||
|
|
<p>If you do not use any parameters the current URI will be used when
|
|||
|
|
determining what should be cleared.</p>
|
|||
|
|
</div>
|
|||
|
|
<div class="section" id="this-db-cache-delete-all">
|
|||
|
|
<h2>$this->db->cache_delete_all()<a class="headerlink" href="#this-db-cache-delete-all" title="Permalink to this headline">¶</a></h2>
|
|||
|
|
<p>Clears all existing cache files. Example:</p>
|
|||
|
|
<div class="highlight-ci"><div class="highlight"><pre><span></span><span class="nv">$this</span><span class="o">-></span><span class="na">db</span><span class="o">-></span><span class="na">cache_delete_all</span><span class="p">();</span>
|
|||
|
|
</pre></div>
|
|||
|
|
</div>
|
|||
|
|
</div>
|
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<div role="contentinfo">
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<p>
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© Copyright 2014 - 2019, British Columbia Institute of Technology.
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Last updated on Sep 19, 2019.
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