| From: | David Rowley <dgrowleyml(at)gmail(dot)com> |
|---|---|
| To: | Andy Fan <zhihui(dot)fan1213(at)gmail(dot)com> |
| Cc: | Heikki Linnakangas <hlinnaka(at)iki(dot)fi>, Jesper Pedersen <jesper(dot)pedersen(at)redhat(dot)com>, "Hou, Zhijie" <houzj(dot)fnst(at)cn(dot)fujitsu(dot)com>, Michael Paquier <michael(at)paquier(dot)xyz>, Floris Van Nee <florisvannee(at)optiver(dot)com>, PostgreSQL Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Ashutosh Bapat <ashutosh(dot)bapat(dot)oss(at)gmail(dot)com>, "rushabh(dot)lathia(at)gmail(dot)com" <rushabh(dot)lathia(at)gmail(dot)com>, Dmitry Dolgov <9erthalion6(at)gmail(dot)com> |
| Subject: | Re: [PATCH] Keeps tracking the uniqueness with UniqueKey |
| Date: | 2020-12-09 06:13:48 |
| Message-ID: | CAApHDvoVhZwgEkCgdzAS+52v2KndNf81yk7E68Rno6bJ-TO8WQ@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Sun, 6 Dec 2020 at 04:10, Andy Fan <zhihui(dot)fan1213(at)gmail(dot)com> wrote:
> For anyone who is interested with these patchsets, here is my plan about this
> now. 1). I will try EquivalenceClass rather than Expr in UniqueKey and add opfamily
> if needed.
I agree that we should be storing them in EquivalenceClasses. Apart
from what was mentioned already it also allow the optimisation to work
in cases like:
create table t (a int not null unique, b int);
select distinct b from t where a = b;
David
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