Obsolete rows request [storage mode]

[Ilia Kantor]

Memcached could be very useful for session handling and a bunch of other
problems if it allowed "external garbage collecting".

So to say: I put memcached into "return error on memory exhausted" mode(so
it is storage, not cache any more!) and can send a command to
delete-and-return all items last used >3600 sec ago (or similar).

Then I can perform any operations on obsolete rows.. Like copy
last-visit/logs/aggregate information into DB.

Such garbage collection issue seem to link well with memcached
"storage-mode(-M)", how do you think ?