On Mon, 2003-09-08 at 11:56, scott.marlowe wrote:
> Basically, Postgresql uses an MVCC locking system that makes massively
> parallel operation possible, but costs in certain areas, and one of those
> areas is aggregate performance over large sets. MVCC makes it very hard
> to optimize all but the simplest of aggregates, and even those
> optimzations which are possible would wind up being quite ugly at the
> parser level.
As was pointed out in a thread a couple days ago, MIN/MAX() optimization
has absolutely nothing to do with MVCC. It does, however, make
optimizing COUNT() more difficult.
-Neil
