| From: | Andy Fan <zhihui(dot)fan1213(at)gmail(dot)com> |
|---|---|
| To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | Andrew Gierth <andrew(at)tao11(dot)riddles(dot)org(dot)uk>, David Rowley <dgrowleyml(at)gmail(dot)com>, pavelsivash(at)gmail(dot)com, PostgreSQL mailing lists <pgsql-bugs(at)lists(dot)postgresql(dot)org> |
| Subject: | Re: BUG #16585: Wrong filtering on a COALESCE field after using GROUPING SETS |
| Date: | 2020-08-21 01:19:57 |
| Message-ID: | CAKU4AWrbKtXEzwMogaJTTK_xovoesrb6ERNHQB5dFMWQngHXGQ@mail.gmail.com |
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| Lists: | pgsql-bugs |
>
> The scheme I've been thinking about for clarifying the nullability
> semantics of Vars might eventually provide a nicer answer for this,
> but we haven't got it today.
>
> regards, tom lane
>
>
>
With this direction, how about maintaining a
RelOptInfo->notnullattrs (BitmapSet *)
attrs, which might be accessed in a more efficient way? We should set it
to nullattrs
if it exists in groupSet clause. I introduced this attribute in UniqueKey
patch [1]
(patch 0001), but it is not maintained in baserelonly now. I think we can
expand it
for other types of rel as well.
However both implementations can avoid the issue here, but still make it
impossible
to push down an qual even if it references all the exprs in the groupset,
am I right?
--
Best Regards
Andy Fan
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