Re: index prefetching

On 8/25/25 16:18, Tomas Vondra wrote:
> ...
> 
> But with more hits, the hit/miss ratio simply determines the "stable"
> distance. Let's say there's 80% hits, so 4 hits to 1 miss. Then the
> stable distance is ~4, because we get a miss, double to 8, and then 4
> hits, so the distance drops back to 4. And again.
> 

I forgot to mention the distance is "stable" only if you already start
at it - then we keep it. But start at a higher value, and the distance
keeps growing. Or start at a lower value, and it collapses to 1. Plus
it's rather sensitive, a minor variation can easily push the distance in
either direction.

So it's more like an "unstable equilibrium" in physics.

regards

-- 
Tomas Vondra