(PECL memcached >= 2.0.0)
Memcached::deleteMultiByKey — Delete multiple items from a specific server
$server_key
   , array $keys
   [, int $time = 0
  ] )
    Memcached::deleteMultiByKey() is functionally equivalent to
    Memcached::deleteMulti(), except that the free-form
   server_key can be used to map the
   keys to a specific server.
  
server_key
     The key identifying the server to store the value on or retrieve it from. Instead of hashing on the actual key for the item, we hash on the server key when deciding which memcached server to talk to. This allows related items to be grouped together on a single server for efficiency with multi operations.
keys
     The keys to be deleted.
time
     The amount of time the server will wait to delete the items.
   Returns TRUE on success or FALSE on failure.
   The  Memcached::getResultCode() will return
   Memcached::RES_NOTFOUND if the key does not exist.