On Mon, Oct 16, 2006 at 05:59:05PM +0930, Shane Ambler wrote: > > Registering each cache entry by the tables included in the query and > >invalidating the cache during on a committed update or insert > >transaction to any of the tables would, transparently, solve the > >consistency problem. > That was part of my thinking when I made the suggestion of adding > something like memcached into postgres.
There is a valid suggestion in here, but I think it's the caching of query plans, and caching of query plan results that the PostgreSQL gain would be at. The query to query plan cache could map SQL statements (with parameters specified) to a query plan, and be invalidated upon changes to the statistical composition of any of the involved tables. The query plan to query results cache would keep the results and first and last transaction ids that the results are valid for. Although it sounds simple, I believe the above to be very complicated to pursue. The real PostgreSQL hackers (not me) have talked at length about it over the last while that I've read their mailing lists. They've come up with good ideas, that have not all been shot down. Nobody is willing to tackle it, because it seems like a lot of effort, for a problem that can be mostly solved by application-side caching. It's a subject that interests me - but it would take a lot of time, and that's the thing that few of us have. Time sucks. :-) Cheers, mark -- [EMAIL PROTECTED] / [EMAIL PROTECTED] / [EMAIL PROTECTED] __________________________ . . _ ._ . . .__ . . ._. .__ . . . .__ | Neighbourhood Coder |\/| |_| |_| |/ |_ |\/| | |_ | |/ |_ | | | | | | \ | \ |__ . | | .|. |__ |__ | \ |__ | Ottawa, Ontario, Canada One ring to rule them all, one ring to find them, one ring to bring them all and in the darkness bind them... http://mark.mielke.cc/ ---------------------------(end of broadcast)--------------------------- TIP 3: Have you checked our extensive FAQ? http://www.postgresql.org/docs/faq