Re: index prefetching

On Tue, Jan 16, 2024 at 11:25 AM Tomas Vondra
<tomas(dot)vondra(at)enterprisedb(dot)com> wrote:
> > 3. It doesn't perform prefetch of leave pages for IOS, only referenced
> > heap pages which are not marked as all-visible. It seems to me that if
> > optimized has chosen IOS (and not bitmap heap scan for example), then
> > there should be large enough fraction for all-visible pages. Also index
> > prefetch is most efficient for OLAp queries and them are used to be
> > performance for historical data which is all-visible. But IOS can be
> > really handled separately in some other PR. Frankly speaking combining
> > prefetch of leave B-Tree pages and referenced heap pages seems to be
> > very challenged task.
>
> I see prefetching of leaf pages as interesting / worthwhile improvement,
> but out of scope for this patch. I don't think it can be done at the
> executor level - the prefetch requests need to be submitted from the
> index AM code (by calling PrefetchBuffer, etc.)

+1. This is a good feature, and so is that, but they're not the same
feature, despite the naming problems.

--
Robert Haas
EDB: http://www.enterprisedb.com