Re: Design question regarding arrays

That is exactly what I had in mind but wasn't clear on.

Sean
----- Original Message -----
From: "Stephan Szabo" <sszabo@megazone.bigpanda.com>
To: "Oliver Fromme" <olli@lurza.secnetix.de>
Cc: "Sean Davis" <sdavis2@mail.nih.gov>; "Michael Glaesemann"
<grzm@myrealbox.com>; <pgsql-novice@postgresql.org>; "A Gilmore"
<agilmore@shaw.ca>
Sent: Monday, August 09, 2004 10:22 AM
Subject: Re: [NOVICE] Design question regarding arrays


> On Mon, 9 Aug 2004, Oliver Fromme wrote:
>
> > Sean Davis wrote:
> >  > I'm a novice, too, but why not look up the value in the sequence and
> >  > increment it before doing any inserting?  If you are doing all the
inserts
> >  > at the same time (more or less), then you can just use this value in
the
> >  > insert into both tables.  Put all of this inside one transaction.
> >
> > That won't work if another process is trying to do the same
> > thing at the same time.  They both get the same value when
> > they look it up, so there will be an ID collision.
>
> It should be safe if you're using a sequence and using nextval() to get
> the value that you are using in both insert statements. A second session
> will not get the same value you just got from nextval barring a cycling
> sequence generator that wraps back to the same number between the nextval
> and insert.
>