Horton

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

Pavel Stehule <pavel.stehule@gmail.com>

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From: Pavel Stehule <pavel.stehule@gmail.com>
To: "James Pang (chaolpan)" <chaolpan@cisco.com>
Cc: "pgsql-performance@lists.postgresql.org" <pgsql-performance@lists.postgresql.org>
Date: 2023-06-13T09:29:49Z
Lists: pgsql-hackers, pgsql-performance 
Hi

út 13. 6. 2023 v 11:21 odesílatel James Pang (chaolpan) <chaolpan@cisco.com>
napsal:

> Hi,
>
>      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

Regards

Pavel


>
>
> Thanks,
>
>
>
> James
>
>
>

Commits

  1. Doc: mention that extended stats aren't used for joins