Re: Index Skip Scan - Mailing list pgsql-hackers

From James Coleman
Subject Re: Index Skip Scan
Date
Msg-id CAAaqYe9ELb1rKx06fuKom7aBLCoZ0-mB9FkojijXnucoV95WQQ@mail.gmail.com
Whole thread Raw
In response to Re: Index Skip Scan  (Dmitry Dolgov <9erthalion6@gmail.com>)
Responses Re: Index Skip Scan  (Andy Fan <zhihui.fan1213@gmail.com>)
List pgsql-hackers
On Mon, Mar 9, 2020 at 3:56 PM Dmitry Dolgov <9erthalion6@gmail.com> wrote:
>
> Assuming we'll implement it in a way that we do not know about what kind
> of path type is that in create_distinct_path, then it can also work for
> ProjectionPath or anything else (if UniqueKeys are present). But then
> still EquivalenceMember are used only to figure out correct
> distinctPrefixKeys and do not affect whether or not skipping is applied.
> What do I miss?


Part of the puzzle seems to me to this part of the response:

> I think the UniqueKeys may need to be changed from using
> EquivalenceClasses to use Exprs instead.

But I can't say I'm being overly helpful by pointing that out, since I
don't have my head in the code enough to understand how you'd
accomplish that :)

James



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