Re: constraints in algebra instead of calculus
From: Vadim Tropashko <vadimtro_invalid_at_yahoo.com>
Date: Mon, 18 Jun 2007 11:42:46 -0700
Message-ID: <1182192166.260352.77510_at_o11g2000prd.googlegroups.com>
Date: Mon, 18 Jun 2007 11:42:46 -0700
Message-ID: <1182192166.260352.77510_at_o11g2000prd.googlegroups.com>
On Jun 18, 12:15 am, Jon Heggland <jon.heggl..._at_idi.ntnu.no> wrote:
> I think all this indicates that GROUP is such a difficult operator that
> using it to express constraints is a bad idea. :)
Grouping is has much in common with set equality join, and set joins were are known to be difficult operators: http://fie.engrng.pitt.edu/fie2003/papers/1057.pdf
More important, however, is that the attempt to express such a fundamental constraint as functional dependency via some obscure operator doesn't seem right to begin with. Received on Mon Jun 18 2007 - 20:42:46 CEST