This may be a question for -hackers, but I don't like disturbing them unnecessarily. I've been having a look at memcached. I would like to ask, is there any reason that, theoretically, a similar caching system could be built right into the db serving daemon? I.e., the hash tables and libevent could sit on top of postmaster as an optional component caching data on a per-query basis and only hitting the actual db in the event of a cache miss? Such a mechanism could be a) transparent to any and all APIs accessing the back end thus instantly providing the benefits of caching to all apps transparently, and b) assist with replication by providing a way for a setup to have n serving daemons (effectively db caches) on different machines accessing <n replicated DBs. Such a setup would be far easier to set up than n fully fledged DB servers, and would likely scale better anyway. Thoughts?
