From: | Heikki Linnakangas <hlinnaka(at)iki(dot)fi> |
---|---|
To: | Andy Fan <zhihui(dot)fan1213(at)gmail(dot)com>, "Hou, Zhijie" <houzj(dot)fnst(at)cn(dot)fujitsu(dot)com> |
Cc: | Michael Paquier <michael(at)paquier(dot)xyz>, Floris Van Nee <florisvannee(at)optiver(dot)com>, David Rowley <dgrowleyml(at)gmail(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: | 2020-11-30 10:04:34 |
Message-ID: | 0e4ecefb-17b2-fbe1-7c3e-e7d68a744b9b@iki.fi |
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Lists: | pgsql-hackers |
On 26/11/2020 16:58, Andy Fan wrote:
> This patch has stopped moving for a while, any suggestion about
> how to move on is appreciated.
The question on whether UniqueKey.exprs should be a list of
EquivalenceClasses or PathKeys is unresolved. I don't have an opinion on
that, but I'd suggest that you pick one or the other and just go with
it. If it turns out to be a bad choice, then we'll change it.
Quickly looking at the patches, there's one thing I think no one's
mentioned yet, but looks really ugly to me:
> + /* Make sure the path->parent point to current joinrel, can't update it in-place. */
> + foreach(lc, outer_rel->pathlist)
> + {
> + Size sz = size_of_path(lfirst(lc));
> + Path *path = palloc(sz);
> + memcpy(path, lfirst(lc), sz);
> + path->parent = joinrel;
> + add_path(joinrel, path);
> + }
Copying a Path and modifying it like that is not good, there's got to be
a better way to do this. Perhaps wrap the original Paths in
ProjectionPaths, where the ProjectionPath's parent is the joinrel and
dummypp=true.
- Heikki
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