Re: Extending my question. Was: The relational model and relational algebra - why did SQL become the industry standard?
Date: 12 Mar 2003 21:45:06 -0800
Message-ID: <e9d83568.0303122145.4e5f3158_at_posting.google.com>
jan.hidders_at_REMOVE.THIS.ua.ac.be (Jan Hidders) wrote in message news:<3e6da66b.0_at_news.ruca.ua.ac.be>...
> >>So, what is your point exactly?
> >>
> >If nobody needs them (bags) why support them? Even if the cost is zero?
>
> I'm not convinced that bags are never needed. There's a reason that
> mathematicians introduced it; they needed it to model certain things. What
> about Petri nets, for example? And if you are then going to simulate them
> with sets then the cost might become negative because the set-based
> optimizer might miss certain optimizations that would have been easier to
> spot for a bag-based optimizer.
Boy! What foresight by Chamberline et al for them to use bags instead of (just) sets in SQL back in 1975 against Codd's advice! Or was is just a happy coincidence. Think, if we had adhered to Codd's original ideas we would now be stuck!
regards,
Lauri Pietarinen
Received on Thu Mar 13 2003 - 06:45:06 CET