From: scott.marlowe <scott.marlowe@ihs.com>
To: Iain <iain@mst.co.jp>
Cc: Enver ALTIN <enver.altin@frontsite.com.tr>
Cc: pgsql-sql@postgresql.org
Subject: Re: randomized order in select?
Date: Thu, 11 Mar 2004 09:28:43 -0700 (MST)
Message-ID: <Pine.LNX.4.33.0403110924161.11329-100000@css120.ihs.com> (raw)
In-Reply-To: <009301c4072a$19b28fd0$7201a8c0@mst1x5r347kymb>
On Thu, 11 Mar 2004, Iain wrote:
> If you have a lot of tips, you could create a unique indexed tip number
> column. Select the highest tip number using:
>
> select tip_number from tips order by tip_number desc limit 1;
>
> Then generate a random number and select using that tip_number.
>
> Of course, you would have to allow for the possibility of missing tip
> numbers, by repeating the random number generation/read sequence until you
> find something. Since the tip_number isn't the PK of the table, you can
> regenerate the tip numbers to eliminate holes from deletions any time you
> like. Just reset the sequence to 1 and update all rows with the
> nextval(tipnumber_seq).
>
> Sounds like a lot of work to me though...
Assuming there are ten rows, you can use this:
select * from table limit 1 offset random()*10;
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To: pgsql-sql@postgresql.org
Cc: scott.marlowe@ihs.com, iain@mst.co.jp, enver.altin@frontsite.com.tr
Subject: Re: randomized order in select?
In-Reply-To: <Pine.LNX.4.33.0403110924161.11329-100000@css120.ihs.com>
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