From: Tom Lane <tgl@sss.pgh.pa.us>
To: Andrey Rachitskiy <pl0h0yp1@gmail.com>
cc: i.portnov@compassplus.com, pgsql-bugs@lists.postgresql.org
Subject: Re: BUG #19487: Error while executing SQL query involving XML parsing
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Comments: In-reply-to Andrey Rachitskiy <pl0h0yp1@gmail.com>
	message dated "Sun, 30 Aug 2026 23:35:13 +0500"
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Date: Tue, 01 Sep 2026 12:21:27 -0400
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Andrey Rachitskiy <pl0h0yp1@gmail.com> writes:
> вс, 30 авг. 2026 г. в 23:04, Tom Lane <tgl@sss.pgh.pa.us>:
>> I've got mixed emotions about back-patching this.  It's not really
>> a bug fix, because we already disclaim the safety of relying on
>> CASE for this purpose, cf [1].  I think it might still be reasonable
>> to sneak into v19, but I'm unsure that putting it into 18 is a good
>> idea.

> On back-patching: I share the hesitation about 18. At the same time,
> SQL-language functions with this pattern did work on earlier branches and
> broke for some users after the plan-cache change in 18. I would be fine
> with putting it into 19 and master. If we back-patch to 18, I would treat
> it as a narrow regression fix rather than a semantic promise about CASE.
> Either way works for me.

After thinking about it for a day or so, I elected to push just as far
as 19.  While it's true that this fixes the reported problem, it seems
possible that it de-optimizes somebody else's query.  People don't
like that in minor releases...

			regards, tom lane