Redis is a data structure store. It is popular with WordPress sites because it offers large performance boosts due to its optimized approach at caching. A popular alternative for Redis is Memcached, but Redis can currently do about everything Memcached can do and more.
This tutorial assumes that you have a server running WordPress and that you want to boost its performance.
Step 1: Install Redis
We are going to be installing both the Redis server itself (
redis-server) and a PHP extension that will allow applications to communicate with Redis (such as WordPress):
apt-get install php5-redis redis-server
Step 2: Setup Redis as a cache
We are going to be using Redis for a cache. In order to achieve this, there are a number of changes that we need to make in the configuration. Edit the
After the last line, add:
maxmemory 128mb maxmemory-policy allkeys-lru
maxmemory should be set according to the amount of RAM available on your server. Create a swap file if you are worried about running out of RAM.
Step 3: Change the WordPress configuration file
wp-config.php file to add settings that will allow caching:
At the end of the
Authentication Unique Keys and Salts section, add the following lines. Note that
string can be anything you want, as long as it’s unique.
define('WP_CACHE_KEY_SALT', 'string'); define('WP_CACHE', true);
Step 4: Use the Redis Object Cache
Redis Object Cache is a script which will allow your WordPress installation to use Redis. The original script written by Eric Mann can be found on GitHub. Upload this script to your server to
Warning: Do not place this script in your
wp-content/plugins folder, but in your
Step 5: Restart services
Restart the Redis server, then restart Apache.
service redis-server restart service apache2 restart
Now, test that Redis and WordPress are integrated. Navigate around your WordPress admin area while viewing the Redis monitor.
If you see log entries appear, that means WordPress is communicating with Redis. You can now enjoy the performance boosts of using Redis as cache for WordPress!
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