Redis is an open source (BSD licensed) key value store that can operate as both an in-memory store and as cache. A data structure server in it's own right, it can be easily paired with a relational database like MySQL to speed things up by caching database queries.
WordPress uses a MySQL database to cache internal application objects (breadcrumbs, menu items, etc.) which is generally an expensive process. Since the database also handles queries for page requests this can contributes to one of the most common bottlenecks in WordPress, often causing increased load-times.
When a user requests a WordPress page for the first time, a MySQL query is performed on the server. Redis caches this query, so when another user requests the same WordPress page, the results are provided from Redis without the need to query the database again.
If the query is not cached in Redis, the results are provided by MySQL, which are then added to the Redis cache. If a particular value is updated in the database, the corresponding Redis value is invalidated to prevent bad cache data from being served to the user.
All GridPane WordPress sites come deployed with all the server side configurations required to use Redis Object Caching for WordPress, and the necessary plugin already installed. To be able to use this caching is simply a matter of activating a plugin and enabling the caching.
Step 1. Activate the Redis Object Cache Plugin
Log in to your GridPane WordPress site and navigate to the Plugins page in WP Admin.
Step 2. Enable Redis Object Caching
Navigate to the Redis Object Cache Plugin Settings in Settings > Redis
Click the big blue Enable Object Cache button.
In the Overview the Status will change to Connected and object caching will be enabled.
Step 3. Flush Redis Object Cache
To flush the object cache is easy, just click the big blue Flush Cache button.
You will receive a dismissible notification that the cache has been flushed.
Step 4. Disable Redis Object Caching
To disable the object cache click the big orange Disable Object Cache button.
You will receive a dismissible notification that the cache has been disabled.