Plugin / WP Redis

Installation

This assumes you have a PHP environment with the required PhpRedis extension and a working Redis server (e.g. Pantheon). WP Redis also works with Predis via humanmade/wp-redis-predis-client.

1. Install object-cache.php to wp-content/object-cache.php with a symlink or by copying the file.

2. If you’re not running on Pantheon, edit wp-config.php to add your cache credentials, e.g.:

   $redis_server = array(
       'host'     => '127.0.0.1',
       'port'     => 6379,
       'auth'     => '12345',
       'database' => 0, // Optionally use a specific numeric Redis database. Default is 0.
   );
   

3. Engage thrusters: you are now backing WP’s Object Cache with Redis.

4. (Optional) To use the wp redis WP-CLI commands, activate the WP Redis plugin. No activation is necessary if you’re solely using the object cache drop-in.
5. (Optional) To use the same Redis server with multiple, discreet WordPress installs, you can use the WP_CACHE_KEY_SALT constant to define a unique salt for each install.
6. (Optional) To use true cache groups, with the ability to delete all keys for a given group, register groups with wp_cache_add_redis_hash_groups(), or define the WP_REDIS_USE_CACHE_GROUPS constant to true to enable with all groups. However, when enabled, the expiration value is not respected because expiration on group keys isn’t a feature supported by Redis.
7. (Optional) On an existing site previously using WordPress’ transient cache, use WP-CLI to delete all (%_transient_%) transients from the options table: wp transient delete-all. WP Redis assumes responsibility for the transient cache.