Date: Fri, 3 Aug 2012 15:50:53 -0400
From: Wayne Cuddy <lists-pgsql@useunix.net>
To: PostgreSQL <pgsql-sql@postgresql.org>
Subject: Re: can this be done with a check expression?
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	<88520F99-849D-438C-9CCD-F80700636A2A@excoventures.com>
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Thanks for the input.

I don't insert into this table that often so I'll just prevent overlaps
at the application level since I'm running 9.0.X and not really in a
position to upgrade right now.

Thanks again,

Wayne

On Fri, Aug 03, 2012 at 11:50:13AM -0400, Jonathan S. Katz wrote:
> On Aug 2, 2012, at 7:10 PM, Wayne Cuddy wrote:
> 
> > I have a table with 3 columns:
> > 
> > name text
> > start_id integer
> > end_id integer
> > 
> > start_id and end_id are ranges which must not overlap but can have gaps
> > between them. Is it possible to formulate a table check constraint that
> > can verify that either id does not fall within an existing range at
> > insert time? IE prevent overlaps during insert?
> > 
> > Thanks,
> > Wayne
> 
> So this answer will not help you for the here-and-now, but Postgres 9.2 is going to be released in the near future (though the beta is available) and contains "range types" which have check constraints on them:
> 
> http://www.postgresql.org/docs/9.2/static/rangetypes.html#RANGETYPES-CONSTRAINT
> 
> You could formulate a check constraint right now to do the equivalent, albeit it will involve a lot of conditions.
> 
> Jonathan