From: Tom Lane <tgl@sss.pgh.pa.us>
To: Andrew Gierth <andrew@tao11.riddles.org.uk>
cc: pgsql-hackers@lists.postgresql.org, kes-kes@yandex.ru
Subject: Re: mark/restore failures on unsorted merge joins
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Comments: In-reply-to Andrew Gierth <andrew@tao11.riddles.org.uk>
	message dated "Tue, 24 Nov 2020 20:45:33 +0000"
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Date: Tue, 24 Nov 2020 15:49:33 -0500
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Andrew Gierth <andrew@tao11.riddles.org.uk> writes:
> "Tom" == Tom Lane <tgl@sss.pgh.pa.us> writes:
>  Tom> Looks about right. Not sure if we need to bother with a regression
>  Tom> test case; once that's in, it'd be hard to break it.

> We could check the EXPLAIN output (since the Materialize node would show
> up), but it's not easy to get stable plans since the choice of which
> path to put on the outside is not fixed. Based on what I found when
> actually testing the code, it probably wouldn't be worth the effort.

If it's not easy to test, I agree it's not worth it.

(Given how long it took anyone to notice this, the difficulty of
making a stable test case is unsurprising, perhaps.)

			regards, tom lane