From: Tom Lane <tgl@sss.pgh.pa.us>
To: Richard Guo <guofenglinux@gmail.com>
Cc: Andrey Lepikhov <a.lepikhov@postgrespro.ru>
Cc: PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Subject: Re: Optimization issue of branching UNION ALL
Date: Wed, 21 Dec 2022 22:48:55 -0500
Message-ID: <1800456.1671680935@sss.pgh.pa.us> (raw)
In-Reply-To: <CAMbWs49fj701dxtmo9A7e+Bu_aR1xyLNPL4dPG+W0cT43QKgyg@mail.gmail.com>
References: <703c09a2-08f3-d2ec-b33d-dbecd62428b8@postgrespro.ru>
<1788831.1671673839@sss.pgh.pa.us>
<CAMbWs49fj701dxtmo9A7e+Bu_aR1xyLNPL4dPG+W0cT43QKgyg@mail.gmail.com>
Richard Guo <guofenglinux@gmail.com> writes:
> I noticed we also check 'parse->hasSubLinks' when we fix PHVs and
> AppendRelInfos in pull_up_simple_subquery. I'm not sure why we have
> this check. It seems not necessary.
Yeah, I was wondering about that too ... maybe it was important
in some previous state of the code? I didn't do any archeology
though.
> In remove_result_refs, I don't think we need to check 'lastPHId' again
> before calling substitute_phv_relids, since it has been checked a few
> lines earlier.
Oh, duh ...
regards, tom lane
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Cc: tgl@sss.pgh.pa.us, guofenglinux@gmail.com, a.lepikhov@postgrespro.ru, pgsql-hackers@lists.postgresql.org
Subject: Re: Optimization issue of branching UNION ALL
In-Reply-To: <1800456.1671680935@sss.pgh.pa.us>
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