From: Tom Lane <tgl@sss.pgh.pa.us>
To: Richard Guo <guofenglinux@gmail.com>
cc: Andrey Lepikhov <a.lepikhov@postgrespro.ru>,
        PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Subject: Re: Optimization issue of branching UNION ALL
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Comments: In-reply-to Richard Guo <guofenglinux@gmail.com>
	message dated "Thu, 22 Dec 2022 10:37:35 +0800"
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Date: Wed, 21 Dec 2022 22:48:55 -0500
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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