Re: extended statistics n-distinct on multiple columns not used when join two tables

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От Pavel Stehule
Тема Re: extended statistics n-distinct on multiple columns not used when join two tables
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Msg-id CAFj8pRCQ5bXt_kDtoQRk=D0voVo_Wwj70SfrS19+dZHbAr3hsw@mail.gmail.com
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Ответ на Re: extended statistics n-distinct on multiple columns not used when join two tables  (David Rowley <dgrowleyml@gmail.com>)
Ответы RE: extended statistics n-distinct on multiple columns not used when join two tables  ("James Pang (chaolpan)" <chaolpan@cisco.com>)
Re: extended statistics n-distinct on multiple columns not used when join two tables  (David Rowley <dgrowleyml@gmail.com>)
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út 13. 6. 2023 v 13:26 odesílatel David Rowley <dgrowleyml@gmail.com> napsal:
(moving to -hackers)

On Tue, 13 Jun 2023 at 21:30, Pavel Stehule <pavel.stehule@gmail.com> wrote:
> út 13. 6. 2023 v 11:21 odesílatel James Pang (chaolpan) <chaolpan@cisco.com> napsal:
>>      When join two table on multiple columns equaljoin, rows estimation always use selectivity = multiplied by distinct multiple individual columns, possible to use  extended n-distinct statistics on multiple columns?
>>
>>     PG v14.8-1, attached please check test case with details.
>
> There is not any support for multi tables statistic

I think it's probably worth adjusting the docs to mention this. It
seems like it might be something that could surprise someone.

Something like the attached, maybe?

+1

Pavel


David

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