SQLite Cache vs SQLite Object Cache

On first request to a given URL whole html code of a page is being stored in the SQLite database. On next requests to the same page WordPress core will not be loaded at all but the content of a page will be retrieved from the the SQLite storage therefore duration of PHP execution decreases in dozen of times. Many sites on the same webserver may use common SQLite storage. Compatible with WordPress Multisite. Requires PHP SQLite PDO. In comparison with plugins generating static html pages this plugin does not create multiple directories and html files but stores all generated pages in one file. Moreover, many wordpress sites on the same webserver may use common SQLite storage. Keeps 404, 301, 302, 304 HTTP statuses, optionally supports ETag, Expires, Content-Length, Content-Type (with charset) headers. As the cache script doesn’t load the WordPress core where does it save it’s settings? To get the plugin working you need to define the SQLite storage location in the index.php of the wordpress installation directory (note, not in wp-config.php but index.php). Besides of the SQLite file, this directory contains general settings file (compression setting) and a subfolder for per domain settings. In the admin area (plugin setting page) and to remember after deactivation where the cache located, litecache_path WordPress option is used. How the plugin handles URLs with and without `www.` prefix? The presence of www. prefix is defined in Settings – General. The plugin stores with_www parameter in domains/yourdomain.ini file in the cache directory and redirects requests correspondingly; these redirects are being processed before cache usage. Is it WordPress Multisite compatible? Yes, but for subdomains mode only (blogname.example.com), not for example.com/blogname. A superadmin of a multisite network has access to the first setting form (cache location), blog admins have access to the second form and purge form.

A persistent object cache helps your site perform well. This one uses the widely available SQLite3 extension, and optionally the igbinary and APCu extensions to php. Many hosting services offer those extensions, and they are easy to install on a server you control. What is this about? It’s about making your site’s web server perform better. An object cache does that by reducing the workload on your MariaDB or MySQL database. This is not a page cache; these persistent objects go into a different kind of cache. These objects aren’t chunks of web pages ready for people to view in their browsers, they are data objects for use by the WordPress software. Caches are ubiquitous in computing, and WordPress has its own caching subsystem. Caches contain short-term copies of the results of expensive database lookups or computations, and allow software to use the copy rather than repeating the expensive operation. This plugin (like other object-caching plugins) extends WordPress’s caching subsystem to save those short-term copies from page view to page view. WordPress’s cache happens to be a memoization cache. Without a persistent object cache, every WordPress page view must use your MariaDB or MySQL database server to retrieve everything about your site. When a user requests a page, WordPress starts from scratch and loads everything it needs from your database server. Only then can it deliver content to your user. With a persistent object cache, WordPress immediately loads much of the information it needs. This lightens the load on your database server and delivers content to your users faster. Who should use this? If your site runs on a single web server machine, and that server provides the SQLite3 and igbinary extensions to php, this plugin will almost certainly make your site work faster. And if that server provides the APCu extension, this plugin uses it too. Some hosting providers offer redis cache servers. If your provider offers redis, it may be a good choice. You can use it via the Redis Object Cache plugin. Sites using redis have one SQL database and another non-SQL storage server: redis. Other hosting providers offer memcached, which has the Memcached Object Cache plugin. And some large multipurpose cache plugins, such as the LiteSpeed Cache, also offer object caching based on one of those cache server software packages. The cache-server approach to object caching comes into its own when you have multiple load-balanced web server machines handling your site. SQLite doesn’t work correctly in a multiple-web-server environment. But, for single-server site configurations, SQLite, possibly assisted by APCu, performs well. And the vast majority of sites are single-server. APCu APCu is an in-memory storage medium. It lets php programs, like WordPress, store data in shared memory so it’s very fast to retrieve when needed. If APCu is available on your host server, you can configure this plugin to use it. It reduces the typical cache lookup time to one-fifth or less of the SQLite lookup time, which is itself a few tens of microseconds. Performance counts, especially on busy web sites. Please look at Installation to learn how to configure this plugin to use APCu. The plugin works fast without it, and faster with it. WP-CLI: Even if APCu is in use, caching with SQLite is necessary when your web site uses WP-CLI, because WP-CLI programs do not have access to the APCu cache. This plugin writes all cached data both to APCu and to SQLite and makes sure the two are synchronized. WP-CLI You can control this plugin via WP-CLI once you activate it. Please type this command into your shell for details. wp help sqlite-object-cache Credits Thanks to Till Krüss. His Redis Object Cache plugin serves as a model for this one. And thanks to Ari Stathopoulos and Jonny Harris for reviewing this. Props to Matt Jones for finding and fixing a bug that appeared on a heavily loaded system. Thanks to Massimo Villa for testing help, and to nickchomey for a comprehensive code review. All defects are, of course, entirely the author’s responsibility. And thanks to Jetbrains for the use of their software development tools, especially PhpStorm. It’s hard to imagine how a plugin like this one could be developed without PhpStorm’s tools for exploring epic code bases like WordPress’s. How can I learn more about making my WordPress site more efficient? We offer several plugins to help with your site’s database efficiency. You can read about them here.