Re: Bug in nbtree optimization to skip > operator comparisons (or < comparisons in backwards scans)

On Wed, Dec 6, 2023 at 8:27 AM Matthias van de Meent
<boekewurm+postgres@gmail.com> wrote:
> I feel that Peter refered to these two distinct optimizations:
>
> 1. When scanning an index in ascending order using scankey a > 1 (so,
> one that defines a start point of the scan), we don't need to check
> items for consistency with that scankey once we've found the first
> value that is consistent with the scankey, as all future values will
> also be consistent with the scankey (if we assume no concurrent page
> deletions).
>
> 2. When scanning an index in ascending order using scankey a < 10 (one
> that defines an endpoint of the scan), we can look ahead and check if
> the last item on the page is consistent. If so, then all other items
> on the page will also be consistent with that scankey.

Oh, interesting. Thanks.

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