This plugin hasn’t been tested with the latest 3 major releases of WordPress. It may no longer be maintained or supported and may have compatibility issues when used with more recent versions of WordPress.

Memcached Object Cache


Memcached Object Cache provides a persistent backend for the WordPress object cache. A memcached server and the PECL memcache extension are required.


  1. Install memcached on at least one server. Note the connection info. The default is

  2. Install the PECL memcache extension

  3. Copy object-cache.php to wp-content


How can I manually specify the memcached server(s)?

Add something similar to the following to wp-config.php above /* That's all, stop editing! Happy blogging. */:

$memcached_servers = array(     'default' => array(         '',         ''     ) ); 

The top level array keys, are cache groups, where ‘default’ corresponds to any cache group that is not explicitly defined. This allows for specifying memcached servers that only handle certain cache groups. The most common use is only specifying ‘default’.

Possible cache groups are:

{$taxonomy}_relationships {$meta_type}_meta {$taxonomy}_relationships blog-details blog-id-cache blog-lookup bookmark calendar category comment counts general global-posts options plugins post_ancestors post_meta posts rss site-lookup site-options site-transient terms themes timeinfo transient user_meta useremail userlogins usermeta users userslugs widget 


Apparently Perfect functioning, Out-Of-The-Box.

For my purposes, that assume a default configuration (of ‘memcached’), this little plugin just works. And it seems to cache a wide variety of objects by design.

It’s important to follow the instructions carefully though, as this is a drop-in, the installation of which is not that, of a standard plugin.


Works perfectly!


It works out-of-box, just added the file and done! Awesome work here!

Only had to replace the constructor name at 424 to -> function __construct() – so we avoid a Warning at PHP7, for example.

Kind Regards,

Nothing but Fatal

Getting consistent fatal errors upon activation of plugin

Fatal error: Cannot redeclare wp_cache_add() (previously declared in /home/urbschool/public_html/wp-includes/cache.php:27) in /home/urbschool/public_html/wp-content/plugins/memcached/object-cache.php on line 22

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Contributors & Developers

“Memcached Object Cache” is open source software. The following people have contributed to this plugin.



  • Fix key generation error in switch_to_blog()


  • Flush site cache by rotating keys
  • Flush global cache when flushing main site


  • Flush the local cache on wp_cache_flush()


  • Fix missing global in switch_to_blog


  • Remove deprecated constructor


  • Support for unix sockets


  • Break references by cloning objects
  • Keep local cache in sync with memcached when using incr and decr
  • Handle limited environments where is_multisite() is not defined
  • Fix setting and getting 0
  • PHP 5.2.4 is now required
  • Use the WP_CACHE_KEY_SALT constant if available to gaurantee uniqueness of keys