On Sat, 2003-10-04 at 11:22, Andrew Sullivan wrote:
> Also, a vacuum pretty much destroys your shared buffers, so you have
> to be aware of that trade-off too.
True, although there is no reason that this necessary needs to be the
case (at least, as far as the PostgreSQL shared buffer goes). As has
been pointed out numerous times on -hackers and in the literature, using
LRU for a DBMS shared buffer cache is far from optimal, and better
algorithms have been proposed (e.g. LRU-K, ARC). We could even have the
VACUUM command inform the bufmgr that the pages it is in the process of
reading in are part of a seqscan, and so are unlikely to be needed in
the immediate future.
-Neil