1

Why can I use a UUID to sort rows:

SELECT uuid_nil()
ORDER BY 1;

But I cannot compute the maximum value:

SELECT max(uuid_nil());

[42883] ERROR: function max(uuid) does not exist
Hint: No function matches the given name and argument types. You might need to add explicit type casts.

I know that I can cast to a character type or ORDER BY and LIMIT 1. I'm just curious as to why I have to use a workaround.

2

I'd say that nobody saw any use in calculating the maximum of UUIDs, and I cannot see one either.

That said, it is easy to use CREATE AGGREGATE to define your own max, if you really need that.

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