| From: | Andy Fan <zhihui(dot)fan1213(at)gmail(dot)com> |
|---|---|
| To: | PostgreSQL Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org> |
| Subject: | Re: [PATCH] Erase the distinctClause if the result is unique by definition |
| Date: | 2020-02-06 06:01:27 |
| Message-ID: | CAKU4AWqi8_N+13+msrDOK1HZhLppSY0RN9gxESYFKzjKmX4E1w@mail.gmail.com |
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| Lists: | pgsql-hackers |
update the patch with considering the semi/anti join.
Can anyone help to review this patch?
Thanks
On Fri, Jan 31, 2020 at 8:39 PM Andy Fan <zhihui(dot)fan1213(at)gmail(dot)com> wrote:
> Hi:
>
> I wrote a patch to erase the distinctClause if the result is unique by
> definition, I find this because a user switch this code from oracle
> to PG and find the performance is bad due to this, so I adapt pg for
> this as well.
>
> This patch doesn't work for a well-written SQL, but some drawback
> of a SQL may be not very obvious, since the cost of checking is pretty
> low as well, so I think it would be ok to add..
>
> Please see the patch for details.
>
> Thank you.
>
| Attachment | Content-Type | Size |
|---|---|---|
| 0001-Erase-the-distinctClause-if-the-result-is-unique-by-.patch | application/octet-stream | 27.7 KB |
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