How to extend Memcached item lifetime without getting it?

Can I extend a lifetime of a Memcached item without actually getting it?

Sure, I can开发者_JS百科 get the item, set it again and increase a lifetime. However, this way I'll have to copy the object to script's memory first, which is not good from the perfomance prospective.

It sounds like you probably just want to not set a TTL at all (use 0) and let the LRU evict things that you aren't accessing. If you don't intend to access the items at all, then why do you care if they're there?