Re: distinct on doesn't fail without order by? why?

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От Tom Lane
Тема Re: distinct on doesn't fail without order by? why?
Дата
Msg-id 2750.1242687460@sss.pgh.pa.us
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Ответ на distinct on doesn't fail without order by? why?  (hubert depesz lubaczewski <depesz@depesz.com>)
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hubert depesz lubaczewski <depesz@depesz.com> writes:
> I was under impression that select distinct on (xx) ...
> will fail if xx doesn't match the left most part of order by. i.e. it
> requires order by xx, while allowing order by xx, something, else.

No, it requires that *if* you specify an ORDER BY, it agrees with
the DISTINCT ON.

            regards, tom lane

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