Re: select random order by random

> -----Original Message-----
> From: pgsql-general-owner(at)postgresql(dot)org [mailto:pgsql-general-
> owner(at)postgresql(dot)org] On Behalf Of piotr_sobolewski
> Sent: Thursday, November 01, 2007 9:25 AM
> To: pgsql-general(at)postgresql(dot)org
> Subject: [GENERAL] select random order by random
>
> Dear sirs,
>
> I was very surprised when I executed such SQL query (under PostgreSQL
> 8.2):
> select random() from generate_series(1, 10) order by random();
>
> I thought I would receive ten random numbers in random order. But I
> received
> ten random numbers sorted numerically:
> random
> -------------------
> 0.102324520237744
> 0.17704638838768
> 0.533014383167028
> 0.60182224214077
> 0.644065519794822
> 0.750732169486582
> 0.821376844774932
> 0.88221683120355
> 0.889879426918924
> 0.924697323236614
> (10 rows)
>
> I don't understand - why the result is like that? It seems like in each
> row
> both random()s were giving the same result. Why is it like that? What
> caused
> it?
>
> --
> Piotr Sobolewski
> http://www.piotrsobolewski.w.pl
>
>
> ---------------------------(end of broadcast)---------------------------
> TIP 9: In versions below 8.0, the planner will ignore your desire to
> choose an index scan if your joining column's datatypes do not
> match
[Lee Keel]

Would this not have to do with the 'order by' you added to the end of the
statement? If you remove the order by clause, then it works for me...

-LK

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