Re: consistent random order

[Shane Ambler <pgsql(at)007Marketing(dot)com>]

Jeff Herrin wrote:
> I don't think cursors are going to help in this case. The order by random() is still going to give different result sets on different pages.
>
> Jeff

A cursor will maintain the order it was created with until it is 
disposed of.

It won't work with a web app though as each page will come from a 
different connection in the available pool (or created for each page) 
meaning you will loose the cursor between pages.

I would think you want to look at having a sort column that has a random 
number in it that is used for sorting.

mysortcol integer default random()

or maybe update the column a couple of times a day to keep the variety 
you seem to be after.


> ----- Original Message -----
> From: Andreas Kretschmer <akretschmer(at)spamfence(dot)net>
> To: pgsql-sql(at)postgresql(dot)org
> Sent: Wednesday, November 29, 2006 12:27:42 PM GMT-0500 US/Eastern
> Subject: Re: [SQL] consistent random order
>
> Jeff Herrin <jeff(at)alternateimage(dot)com> schrieb:
>
> > I am returning results ordered randomly using 'order by random()'. My issue has
> > to do with page numbers in our web application. When I hit the 2nd page and
> > retrieve results with an offset, ordering by random() isn't really what I want
> > since I will often receive results that were on the 1st page (they get re-
> > randomized).
> >
> > I'm looking for a way to order in a controled random order. Maybe a UDF.
>
> I think you are searching for CURSORs.
>
> 18:25 < akretschmer> ??cursor
> 18:25 < rtfm_please> For information about cursor
> 18:25 < rtfm_please> see http://www.postgresql.org/docs/current/static/plpgsql-cursors.html
> 18:25 < rtfm_please> or http://www.postgresql.org/docs/current/static/sql-declare.html
>
> With a CURSOR, you get one result-set and can walk through this result.
>
>
> Andreas


--

Shane Ambler
pgSQL(at)007Marketing(dot)com

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