Memcache
PHP 手册

预定义常量

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

Memcache
PHP 手册