tracking online user count under memcached

[Xuefer]

> So say your code gets cookie 332233, if memcached doesn't have data,
> it yanks from DB..  Otherwise, it yanks data from memcached for
> relevant needs.  at some point during the request it checks exist of
> sky-STORED - if it doesn't exist, it dumps any changes/updates as
> relevant into the database, and recreates sky-STORED with another 60
> second expiration.
> 
> You cut DB hits mostly, and you still have minute-resolution on
> session activity.  Performance from memcached, reliability from db.
> 
> Skylos
> 
great, that's what i need.
(i was hoping there is a way to do something like
session_onstart/onend, as doing a "select count(*) from table where
location=..." is a bit slow)
i'll look into it