On Thu, 2004-11-04 at 19:34, Tom Lane wrote: > Simon Riggs <simon@xxxxxxxxxxxxxxx> writes: > > On Thu, 2004-11-04 at 15:47, Chris Browne wrote: > >> Something like a "read_uncached()" call... > >> > >> That would mean that a seq scan or a vacuum wouldn't force useful data > >> out of cache. > > > ARC does almost exactly those two things in 8.0. > > But only for Postgres' own shared buffers. The kernel cache still gets > trashed, because we have no way to suggest to the kernel that it not > hang onto the data read in. I guess a difference in viewpoints. I'm inclined to give most of the RAM to PostgreSQL, since as you point out, the kernel is out of our control. That way, we can do what we like with it - keep it or not, as we choose. -- Best Regards, Simon Riggs
