On Fri, 2007-09-21 at 12:08 +0200, Csaba Nagy wrote:
> On Fri, 2007-09-21 at 10:43 +0100, Gregory Stark wrote:
> > The other possibility is that Postgres just hasn't even touched a large part
> > of its shared buffers.
> >
>
> But then how do you explain the example I gave, with a 5.5GB table
> seq-scanned 3 times, shared buffers set to 12 GB, and top still showing
> almost 100% memory as cached and no SWAP "used" ? In this case you can't
> say postgres didn't touch it's shared buffers - or a sequential scan
> won't use the shared buffers ?
Well, 6.5GB of shared_buffers could be swapped out and need not be
swapped back in to perform those 3 queries.
--
Simon Riggs
2ndQuadrant http://www.2ndQuadrant.com