So What does memcached offer pgsql users? It would still seem to offer
the benefit of a multi-machined cache.

Ack, I totally missed this thread. Sorry for jumping in late.

Basically, memcached and pgmemcache offer a more technically correct way of implementing query caching. MySQL's query caching is a disaster, IMHO. memcached alleviates this load from the database and puts it elsewhere in a more optimized form. The problem with memcached by itself is that you're relying on the application to invalidate the cache. How many different places have to be kept in sync? Using memcached, in its current form, makes relying on the application to be developed correctly with centralized libraries and database access routines. Bah, that's a cluster f#$@ waiting to happen.

pgmemcache fixes that though so that you don't have to worry about invalidating the cache in every application/routine. Instead you just centralize that logic in the database and automatically invalidate via triggers. It's working out very well for me.

I'd be interested in success stories, fwiw. In the next week or so I'll probably stick this on pgfoundry and build a proper make/release structure. -sc

Sean Chittenden

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