Memcached
PHP Manual

Memcached::getAllKeys

(PECL memcached >= 2.0.0)

Memcached::getAllKeysGets the keys stored on all the servers

Description

public array Memcached::getAllKeys ( void )

Memcached::getAllKeys() queries each memcache server and retrieves an array of all keys stored on them at that point in time. This is not an atomic operation, so it isn't a truly consistent snapshot of the keys at point in time. As memcache doesn't guarantee to return all keys you also cannot assume that all keys have been returned.

Parameters

This function has no parameters.

Return Values

Returns the keys stored on all the servers on success or FALSE on failure.


Memcached
PHP Manual