Re: Random not so random

Bruno Wolff III <bruno@wolff.to>

From: Bruno Wolff III <bruno@wolff.to>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Arnau Rebassa <arebassa@hotmail.com>, pgsql-general@postgresql.org
Date: 2004-10-04T15:57:42Z
Lists: pgsql-general
On Mon, Oct 04, 2004 at 10:14:19 -0400,
  Tom Lane <tgl@sss.pgh.pa.us> wrote:
> 
> It occurs to me that you might be seeing predictability as an indirect
> result of something else you are doing that somehow tends to synchronize
> the backend start times.  Are you connecting from a cron script that
> would tend to be launched at the same relative instant within a second?
> 
> It might improve matters to make the code do something like
> 
> 	srandom((unsigned int) (now.tv_sec ^ now.tv_usec));

Using /dev/urandom, where available, might be another option. However, some
people may not want their entropy pool getting 4 bytes used up on every
connection start up.