Обсуждение: About sorting rows randomly

Hi all

It's possible to return rows randomly sorted?

Something like this:

Select * from table order by random

Thanks
--
Marc Soler

On Fri, 2003-03-28 at 00:32, Marc Soler wrote:
> It's possible to return rows randomly sorted?
> Something like this:
> Select * from table order by random

The way I've accomplished this in the past is to create an extra column,
call it "randNum," populate it with random numbers, then order by that
column.

If you don't care how strong the "randomness" is, you can sort by an
arbitrary column that has a lot of variation, say a foreign key column
ID.

I've also seen the logic moved into the application: select the values
into an array, and randomly traverse the array.

--
Tim Ellis
Senior Database Architect and author, tedia2sql (http://tedia2sql.tigris.org)
If this helped you, http://svcs.affero.net/rm.php?r=philovivero

H,

Is there a simple way to know how many request per second
(average) my PG database is currently handling ??

thank you !

jean-arthur silve






Jean-Arthur Silve
EuroVox
4, Place Félix Eboué
75583 Paris Cedex 12
T : +33 1 44670505
F : +33 1 44670519

Marc Soler writes:

> It's possible to return rows randomly sorted?

select * from table order by random();

--
Peter Eisentraut   peter_e@gmx.net

Don't remember what I wrote this for, but IIRC it outputs the current
transaction counter every 1 sec, which you can then use to determine the
number of transactions per second.

#!/bin/bash

while true
do sleep 1; psql -U postgres mydb -c "SELECT age(datfrozenxid) FROM
pg_database where datname='mydb'";
done;

I'm sure you can use this to come up with something more robust.

Robert Treat


On Fri, 2003-03-28 at 05:39, jeanarthur@eurovox.fr wrote:
> H,
>
> Is there a simple way to know how many request per second
> (average) my PG database is currently handling ??
>
> thank you !
>
> jean-arthur silve

On Friday 28 March 2003 09:32, Marc Soler wrote:
> Hi all
>
> It's possible to return rows randomly sorted?
>
> Something like this:
>
> Select * from table order by random

SELECT foo, bar, random() AS rand FROM my_table ORDER BY rand

Ian Barwick
barwick@gmx.net