(PECL memcache >= 1.0.0)
Memcache::flush — Flush all existing items at the server
Memcache::flush() immediately invalidates all existing items. Memcache::flush() doesn't actually free any resources, it only marks all the items as expired, so occupied memory will be overwritten by new items. Also you can use memcache_flush() function.
Returns TRUE on success or FALSE on failure.
Example #1 Memcache::flush() example
<?php
/* procedural API */
$memcache_obj = memcache_connect('memcache_host', 11211);
memcache_flush($memcache_obj);
/* OO API */
$memcache_obj = new Memcache;
$memcache_obj->connect('memcache_host', 11211);
$memcache_obj->flush();
?>