| From: | Alvaro Herrera <alvherre(at)2ndquadrant(dot)com> |
|---|---|
| To: | David Rowley <david(dot)rowley(at)2ndquadrant(dot)com> |
| Cc: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Marko Tiikkaja <marko(at)joh(dot)to>, PostgreSQL mailing lists <pgsql-bugs(at)lists(dot)postgresql(dot)org> |
| Subject: | Re: BUG #15383: Join Filter cost estimation problem in 10.5 |
| Date: | 2019-09-05 23:20:14 |
| Message-ID: | 20190905232014.GA32014@alvherre.pgsql |
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| Thread: | |
| Lists: | pgsql-bugs pgsql-hackers |
On 2019-Jul-01, David Rowley wrote:
> One thing we could look at would be to charge an additional
> cpu_tuple_cost per outer row for all joins except semi, anti and
> unique joins. This would account for the additional lookup for
> another matching row which won't be found and cause the planner to
> slightly favour keeping the unique rel on the inner side of the join,
> when everything else is equal.
So does this proposal fix the problem that David was describing earlier?
If it does, Tom, would you like to get this finalized and pushed?
I've bcc'ed someone who might be interested in chiming in and/or helping
out. Please look here:
https://postgr.es/m/153683552113.22350.18441286362867559841@wrigleys.postgresql.org
Thanks,
--
Álvaro Herrera https://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
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