Re: random

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От Bruce Momjian
Тема Re: random
Дата
Msg-id 200103052129.QAA03712@candle.pha.pa.us
обсуждение исходный текст
Ответ на Re: random  (Tom Lane <tgl@sss.pgh.pa.us>)
Ответы Re: random  (Tom Lane <tgl@sss.pgh.pa.us>)
Список pgsql-sql
> Bruce Momjian <pgman@candle.pha.pa.us> writes:
> >> Jelle Ouwerkerk <jelle@openface.ca> writes:
> > Also, is there a way to randomize the order of a result set?
> >> 
> >> There's always
> >> SELECT * FROM foo ORDER BY random();
> 
> > However:
> >     test=> select * from pg_class order by random();
> > does return some output.  Is it random, and if so, how?
> 
> Sure.  The function is marked noncachable, so it gets evaluated
> afresh at each row --- but only once per row, as the sort step doesn't
> recompute any values.  Should work just peachy, and it seems to do
> so in a couple quick tests.

But random returns a random value from 0-1, right?  How does that work
in ORDER BY?

--  Bruce Momjian                        |  http://candle.pha.pa.us pgman@candle.pha.pa.us               |  (610)
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