Re: DB cache size strategies

On Tuesday February 10 2004 3:48, scott.marlowe wrote:
> On Tue, 10 Feb 2004, Ed L. wrote:
> > Interesting.  Why leave very large tables to the kernel instead of the
> > db cache?  Assuming a dedicated DB server and a DB smaller than
> > available RAM, why not give the DB enough RAM to get the entire DB into
> > the DB cache? (Assuming you have the RAM).
>
> Because the kernel is more efficient (right now) at caching large data
> sets.
>
> With the ARC cache manager that will likely wend it's way into 7.5, it's
> quite a likely possibility that postgresql will be able to efficiently
> handle a larger cache, but it will still be a shared memory cache, and
> those are still usually much slower than the kernel's cache.

Hmmm.  Others have asserted/assumed they'd be roughly equivalent.  It'd be
interesting to see some real data measuring the performance of the shared
mem cache vs. kernel cache.  Anyone know of existing benchmarks?