item expiration

[Dustin Sallings]

On Jun 11, 2008, at 21:59, Grant Maxwell wrote:

> Dustin In this particular case to do that would completely negate  
> the benefit of the cache because better than 99% would fail in the  
> cache lookup AND the database lookup. In effect we would be using  
> the cache as a virtual table and only refer to the database on  
> startup. There is method in our "madness" uhahaha. The number of  
> "rogue" actions requested that would be blocked may only represent  
> 10% of our total action requests, but would reduce server load  
> significantly.

	Sounds like a bloom filter (or a variant like a counting filter)  
would help you tremendously, then.

> I take the point of some folk who have suggested running a 2nd  
> instance of memcached and I am thinking about that. The single  
> downside is calculation of the memory requirement and getting it  
> right so that we don't lose entries and don't waste memory.
>
> I've not heard of dynamo etc and will look into them.


	AFAIK, dynamo is just a paper -- but it describes something that  
sounds like the kind of thing you'd want as far as a persistent and  
fault tolerant kv storage.

	Perhaps we can get a counter filter backend.  Toru?  :)

-- 
Dustin Sallings