Re: Returning PK of first insert for second insert use. - Mailing list pgsql-sql

From Ken Corey
Subject Re: Returning PK of first insert for second insert use.
Date
Msg-id 1027973100.2360.278.camel@kenlinux.bithub.org
Whole thread Raw
In response to Re: Returning PK of first insert for second insert use.  (Peter Atkins <peter.atkins@NXCD.com>)
List pgsql-sql
On Mon, 2002-07-29 at 20:52, Peter Atkins wrote:
> Is there a possibility of another application accessing the DB and using the
> id before my function has completed the transaction? I'm concerned with the
> possibility of cross-over of ID's if the insert hangs.
> 
> There's no way to return the id of that insert inherently, and then use it
> for the second insert? I think SQL uses something like ADD_ID, not sure.

That's the beauty of the nextval statement. The database internally
sequences requests to it so that you're kept out of harm's way.

Say process A called the function,and nextval returns 16.  The function
now continues on its way, but is not finished when process B then calls
the function (before A is done), and nextval returns 17.

So, then function called by process A returns 16, and the function
called by process B returns 17.

That means that unless the results of process B depend in some way upon
the results of process A, there's no problem.

-Ken

-- 
Ken Corey  CTO  http://www.atomic-interactive.com  07720 440 731



pgsql-sql by date:

Previous
From: ROUWEZ Stephane
Date:
Subject: Re: Change size of a field
Next
From: Peter Atkins
Date:
Subject: Returning PK of first insert for second insert use.