Re: [PATCHES] ARC Memory Usage analysis

On Mon, 2004-10-25 at 23:53, Tom Lane wrote:
> Greg Stark <gsstark(at)mit(dot)edu> writes:
> > Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> writes:
> >> Another issue is what we do with the effective_cache_size value once we
> >> have a number we trust. We can't readily change the size of the ARC
> >> lists on the fly.
>
> > Huh? I thought effective_cache_size was just used as an factor the cost
> > estimation equation.
>
> Today, that is true. Jan is speculating about using it as a parameter
> of the ARC cache management algorithm ... and that worries me.

Because it's so often set wrong I take it. But if it's set right, and
it makes the the database faster to pay attention to it, then I'd be in
favor of it. Or at least having a switch to turn on the ARC buffer's
ability to look at it.

Or is it some other issue, having to do with the idea of knowing
effective cache size cause a positive effect overall on the ARC
algorhythm?