From: | "bucoo" <bucoo(at)sohu(dot)com> |
---|---|
To: | "'Robert Haas'" <robertmhaas(at)gmail(dot)com> |
Cc: | "'Richard Guo'" <guofenglinux(at)gmail(dot)com>, "'pgsql-hackers'" <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: fix cost subqueryscan wrong parallel cost |
Date: | 2022-04-22 03:35:43 |
Message-ID: | 058201d855fa$0ca3dc80$25eb9580$@sohu.com |
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Thread: | |
Lists: | pgsql-hackers |
> > > Suppose parallelism is not in use and that param_info is NULL. Then,
> > > is path->subpath->rows guaranteed to be equal to baserel->rows? If
> > > yes, then we don't need to a three-part if statement as you propose
> > > here and can just change the "else" clause to say path->path.rows =
> > > path->subpath->rows. If no, then your change gives the wrong answer.
> >
> > I checked some regress test, Sometimes subquery scan have filter,
> > so path->subpath->row guaranteed *not* to be equal to baserel->rows.
> > If the first patch is false, I don't known how to fix this,
> > looks like need someone's help.
>
> Please fix your mailer so that it doesn't send me a bounce message
> every time I reply to one of your messages on list.
This message send using Outlook.
> I don't know how to fix this right now either, then; maybe I or
> someone else will have a good idea later.
I don't known too.
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