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.