Re: MDAM techniques and Index Skip Scan patch

> On Tue, Mar 22, 2022 at 04:55:49PM -0400, Tom Lane wrote:
> Peter Geoghegan <pg(at)bowt(dot)ie> writes:
> > Like many difficult patches, the skip scan patch is not so much
> > troubled by problems with the implementation as it is troubled by
> > *ambiguity* about the design. Particularly concerning how skip scan
> > meshes with existing designs, as well as future designs --
> > particularly designs for other MDAM techniques. I've started this
> > thread to have a big picture conversation about how to think about
> > these things.
>
> Peter asked me off-list to spend some time thinking about the overall
> direction we ought to be pursuing here. I have done that, and here
> are a few modest suggestions.

Thanks. To make sure I understand your proposal better, I have a couple
of questions:

> In short: I would throw out just about all the planner infrastructure
> that's been proposed so far. It looks bulky, expensive, and
> drastically undercommented, and I don't think it's buying us anything
> of commensurate value.

Broadly speaking planner related changes proposed in the patch so far
are: UniqueKey, taken from the neighbour thread about select distinct;
list of uniquekeys to actually pass information about the specified
loose scan prefix into nbtree; some verification logic to prevent
applying skipping when it's not supported. I can imagine taking out
UniqueKeys and passing loose scan prefix in some other form (the other
parts seems to be essential) -- is that what you mean?