Re: random - Mailing list pgsql-sql

From Tom Lane
Subject Re: random
Date
Msg-id 20854.983827417@sss.pgh.pa.us
Whole thread Raw
In response to Re: random  (Bruce Momjian <pgman@candle.pha.pa.us>)
Responses Re: random
List 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.
        regards, tom lane


pgsql-sql by date:

Previous
From: Bruce Momjian
Date:
Subject: Re: Optimizing Query
Next
From: Stephan Szabo
Date:
Subject: Re: random