Memcache
PHP Manual

예약 상수

Memcache Constants
Name Description
MEMCACHE_COMPRESSED (integer) Used to turn on-the-fly data compression on with Memcache::set(), Memcache::add() 그리고 Memcache::replace().
MEMCACHE_HAVE_SESSION (integer) 1 if this Memcache session handler is available, 0 otherwise.

Memcache
PHP Manual