Re: [PATCH] Keeps tracking the uniqueness with UniqueKey
| От | Andy Fan |
|---|---|
| Тема | Re: [PATCH] Keeps tracking the uniqueness with UniqueKey |
| Дата | |
| Msg-id | CAKU4AWpUSpOS1YCt6zhZsNYpD2NkTUDVv+HLOvewbHnADtAb0g@mail.gmail.com обсуждение исходный текст |
| Ответ на | Re: [PATCH] Keeps tracking the uniqueness with UniqueKey (David Rowley <dgrowleyml@gmail.com>) |
| Ответы |
Re: [PATCH] Keeps tracking the uniqueness with UniqueKey
|
| Список | pgsql-hackers |
On Mon, May 25, 2020 at 2:34 AM David Rowley <dgrowleyml@gmail.com> wrote:
On Sun, 24 May 2020 at 04:14, Dmitry Dolgov <9erthalion6@gmail.com> wrote:
>
> > On Fri, May 22, 2020 at 08:40:17AM +1200, David Rowley wrote:
> > I imagine we'll set some required UniqueKeys during
> > standard_qp_callback()
>
> In standard_qp_callback, because pathkeys are computed at this point I
> guess?
Yes. In particular, we set the pathkeys for DISTINCT clauses there.
Actually I have some issues to understand from here, then try to read index
skip scan patch to fully understand what is the requirement, but that doesn't
get it so far[1]. So what is the "UniqueKeys" in "UniqueKeys during
standard_qp_callback()" and what is the "pathkeys" in "pathkeys are computed
at this point” means? I tried to think it as root->distinct_pathkeys, however I
didn't fully understand where root->distinct_pathkeys is used for as well.
Best Regards
Andy Fan
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