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Redis Object Cache

A persistent object cache backend powered by Redis. Supports Predis, PhpRedis, HHVM, replication, clustering and WP-CLI.

A persistent object cache backend powered by Redis. Supports Predis, PhpRedis (PECL), HHVM, replication, clustering and WP-CLI.

To adjust the connection parameters, prefix cache keys or configure replication/clustering, please see Other Notes.

Forked from Eric Mann's and Erick Hitter's Redis Object Cache.

Author Till Krüss
Contributors tillkruess
Tags cache, caching, clustering, hhvm, load, object cache, optimize, pecl, performance, redis, replication, server, speed, WP Object Cache
  1. redis-cache screenshot 1

    Plugin settings, connected to a single Redis server.

  2. redis-cache screenshot 2

    Plugin settings, not connected to a Redis cluster.

For detailed installation instructions, please read the standard installation procedure for WordPress plugins.

  1. Make sure Redis is installed and running.
  2. Install and activate plugin.
  3. Enable the object cache under Settings -> Redis.
  4. If necessary, adjust connection parameters.

If your server doesn't support the WordPress Filesystem API, you have to manually copy the object-cache.php file from the /plugins/redis-cache/includes/ directory to the /wp-content/ directory.


  • Added basic diagnostics to admin interface
  • Added WP_REDIS_DISABLED constant to disable cache at runtime
  • Prevent "Invalid plugin header" error
  • Return integer from increment() and decrement() methods
  • Prevent object cache from being instantiated more than once
  • Always separate cache key prefix and group by semicolon
  • Improved performance of build_key()
  • Only apply redis_object_cache_get filter if callbacks have been registered
  • Fixed add_or_replace() to only set cache key if it doesn't exist
  • Added redis_object_cache_flush action
  • Added redis_object_cache_enable action
  • Added redis_object_cache_disable action
  • Added redis_object_cache_update_dropin action


  • Added WP-CLI support
  • Show host and port unless scheme is unix
  • Updated default global and ignored groups
  • Do a cache flush when activating, deactivating and uninstalling


  • Updated Predis to v1.1.1
  • Added redis_instance() method
  • Added incr() method alias for Batcache compatibility
  • Added redis_object_cache_delete action
  • Use WP_PLUGIN_DIR with WP_CONTENT_DIR as fallback
  • Set password when using a cluster or replication
  • Show Redis client in stats()
  • Change visibility of $cache to public
  • Use old array syntax, just in case


  • Make sure $result is not false in WP_Object_Cache::get()


  • Fixed connection issue


  • New admin interface
  • Added support for wp_cache_get()'s $force and $found parameter
  • Added support for clustering and replication with Predis


  • UI improvements


  • Added redis_object_cache_set action
  • Added redis_object_cache_get action and filter
  • Prevented duplicated admin status messages
  • Load bundled Predis library only if necessary
  • Load bundled Predis library using WP_CONTENT_DIR constant
  • Updated stats() method output to be uniform with WordPress


  • Added composer.json
  • Added deactivation and uninstall hooks to delete object-cache.php
  • Added local serialization functions for better advanced-cache.php support
  • Updated bundled Predis version to 1.0.3
  • Updated heading structure to be semantic


  • Added Multisite support
  • Moved admin menu under Settings menu
  • Fixed PHP notice in get_redis_client_name()


  • Call select() and optionally auth() if HHVM extension is used


  • Added support for HHVM's Redis extension
  • Added support for PECL Redis extension
  • Added WP_REDIS_CLIENT constant, to set preferred Redis client
  • Added WP_REDIS_MAXTTL constant, to force expiration of cache keys
  • Improved add_or_replace(), get(), set() and delete() methods
  • Improved admin screen styles
  • Removed all internationalization/localization from drop-in


  • Added "Flush Cache" button
  • Added support for UNIX domain sockets
  • Improved cache object retrieval performance significantly
  • Updated bundled Predis library to version 1.0.1


  • Load plugin translations
  • Hide global admin notices from non-admin users
  • Prevent direct file access to redis-cache.php and admin-page.php
  • Colorize "Disable Object Cache" button
  • Call Predis\Client->connect() to avoid potential uncaught Predis\Connection\ConnectionException


  • Initial release

Connection Parameters

By default the object cache drop-in will connect to Redis over TCP at and select database 0.

To adjust the connection parameters, define any of the following constants in your wp-config.php file.

  • WP_REDIS_CLIENT (default: not set)

    Specifies the client used to communicate with Redis. Supports hhvm, pecl and predis.

  • WP_REDIS_SCHEME (default: tcp)

    Specifies the protocol used to communicate with an instance of Redis. Internally the client uses the connection class associated to the specified connection scheme. Supports tcp (TCP/IP), unix (UNIX domain sockets), tls (transport layer security) or http (HTTP protocol through Webdis).

  • WP_REDIS_HOST (default:

    IP or hostname of the target server. This is ignored when connecting to Redis using UNIX domain sockets.

  • WP_REDIS_PORT (default: 6379)

    TCP/IP port of the target server. This is ignored when connecting to Redis using UNIX domain sockets.

  • WP_REDIS_PATH (default: not set)

    Path of the UNIX domain socket file used when connecting to Redis using UNIX domain sockets.

  • WP_REDIS_DATABASE (default: 0)

    Accepts a numeric value that is used to automatically select a logical database with the SELECT command.

  • WP_REDIS_PASSWORD (default: not set)

    Accepts a value used to authenticate with a Redis server protected by password with the AUTH command.

Configuration Parameters

To adjust the configuration, define any of the following constants in your wp-config.php file.

  • WP_CACHE_KEY_SALT (default: not set)

    Set the prefix for all cache keys. Useful in setups where multiple installs share a common wp-config.php or $table_prefix, to guarantee uniqueness of cache keys.

  • WP_REDIS_MAXTTL (default: not set)

    Set maximum time-to-live (in seconds) for cache keys with an expiration time of 0.

  • WP_REDIS_GLOBAL_GROUPS (default: ['blog-details', 'blog-id-cache', 'blog-lookup', 'global-posts', 'networks', 'rss', 'sites', 'site-details', 'site-lookup', 'site-options', 'site-transient', 'users', 'useremail', 'userlogins', 'usermeta', 'user_meta', 'userslugs'])

    Set the list of network-wide cache groups that should not be prefixed with the blog-id (Multisite only).

  • WP_REDIS_IGNORED_GROUPS (default: ['counts', 'plugins'])

    Set the cache groups that should not be cached in Redis.

  • WP_REDIS_DISABLED (default: not set)

    Set to true to disable the object cache at runtime.

Replication & Clustering

To use Replication and Clustering, make sure your server is running PHP7, your setup is using Predis to connect to Redis and you consulted the Predis documentation.

For replication use the WP_REDIS_SERVERS constant and for clustering the WP_REDIS_CLUSTER constant. You can use a named array or an URI string to specify the parameters.

For authentication use the WP_REDIS_PASSWORD constant.

Master-Slave Replication Example:

define( 'WP_REDIS_SERVERS', [
] );

Clustering via Client-side Sharding Example:

define( 'WP_REDIS_CLUSTER', [
] );

WP-CLI Commands

To use the WP-CLI commands, make sure the plugin is activated:

wp plugin activate redis-cache

The following commands are supported:

  • wp redis status

    Show the Redis object cache status and (when possible) client.

  • wp redis enable

    Enables the Redis object cache. Default behavior is to create the object cache drop-in, unless an unknown object cache drop-in is present.

  • wp redis disable

    Disables the Redis object cache. Default behavior is to delete the object cache drop-in, unless an unknown object cache drop-in is present.

  • wp redis update-dropin

    Updates the Redis object cache drop-in. Default behavior is to overwrite any existing object cache drop-in.

Version 1.3.5

Requires WordPress version: 3.3 or higher

Compatible up to: 4.7.2

Last Updated 07 Nov 2016

Date Added: 14 Nov 2014

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