Bunch of questions about memcache

[Greg Whalin]

Chris Hartjes wrote:
> I'm evaluating memcache for use where I work (dating site) and needed
> a few questions answered to keep the bosses happy.  I'll be using the
> PHP client.
> 
> 1) how many memcache servers can be up and running before the amount
> of time the client spends more time checking numerous memcache servers
> than it would if it got the results from a very large database
> containing 1.5 million+ records

The client should be determining the server by using a hash of the key 
and modular math to determine the server that contains the object.  No 
problem with scaling as the client will only ever query the "correct" 
server.

> 2) what happens when memcache is full and you ask it to add something
> in?  How does it decide what key/value pair to turf out to make room?

I believe memcached uses a LRU algorithm, so the least requested object 
will fall off.