SQLite Object Cache vs wao.io Cache Control

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.

wao.io Cache Control is a free plugin to clear your WordPress site’s cache at wao.io. Cache Control Use this plugin to control your site’s cache at wao.io. Click on the Invalidate Origin Content button to clear your optimized WordPress website’s cache at wao.io to make sure that you and your customers will see the latest version of your content. Cache invalidation will automatically be triggered after publishing or updating a post or a page, and after switching a theme. Cache invalidation treats all content in the cache as if it was outdated. This means that wao.io will check on the next request if the content changed on the origin server. If so, it will be requested. Otherwise wao.io will continue to use the cached resource. This is especially useful if you changed only a few images and the majority of content remained unmodified. Settings In the wao.io Cache Control Settings section of your general WordPress settings, please enter your Site ID, and the API key that you obtained from wao.io’s support team. If you do not have an API key yet, please contact wao.io support. In future versions of this plugin, you can disable or enable automatic cache invalidation here. Automatic Cache Invalidation Automatic cache invalidation will make WordPress try to invalidate your optimized WordPress website’s cache at wao.io automatically each time your content has changed, e.g. after publishing a page or uploading an image. Known Issues Some WordPress sites reported a bug that the publish / update post event did not fire when using the block editor (Gutenberg issue #17632). This may affect the plugin wao.io Cache Control which depends on the event for automatic cache invalidation. Development and Contribution wao.io Cache Control plugin for WordPress was developed for wao.io by Ingo Steinke, Senior Software Developer at Avenga Germany GmbH. If you want to contribute to this plugin, please contact wao.io product development via our website wao.io.