From: Tom Lane <tgl@sss.pgh.pa.us>
To: Aleksander Alekseev <aleksander@timescale.com>
cc: pgsql-hackers@lists.postgresql.org,
        =?UTF-8?Q?Viliam_=C4=8Eurina?= <viliam.durina@gmail.com>
Subject: Re: MIN/MAX functions for a record
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Comments: In-reply-to Aleksander Alekseev <aleksander@timescale.com>
	message dated "Fri, 22 Mar 2024 18:02:29 +0300"
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Date: Fri, 22 Mar 2024 11:12:55 -0400
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Aleksander Alekseev <aleksander@timescale.com> writes:
>> In my queries I often need to do MIN/MAX for tuples, for example:
>> SELECT MAX(row(year, month))
>> FROM (VALUES(2025, 1), (2024,2)) x(year, month);
>> This query throws:
>> ERROR: function max(record) does not exist
>> Was this ever discussed or is there something preventing the implementa=
tion?

> I believe it would be challenging to implement max(record) that would
> work reasonably well in a general case.

As long as you define it as "works the same way record comparison
does", ie base it on record_cmp(), I don't think it would be much
more than a finger exercise [*].  And why would you want it to act
any differently from record_cmp()?  Those semantics have been
established for a long time.

			regards, tom lane

[*] Although conceivably there are some challenges in getting
record_cmp's caching logic to work in the context of an aggregate.