Re: Extending my question. Was: The relational model and relational algebra - why did SQL become the industry standard?

Home -> Community -> Usenet -> comp.databases.theory -> Re: Extending my question. Was: The relational model and relational algebra - why did SQL become the industry standard?

From: Paul Vernon <paul.vernon_at_ukk.ibmm.comm>
Date: Thu, 13 Feb 2003 17:34:19 -0000
Message-ID: <b2gl27$nds$1@sp15at20.hursley.ibm.com>

"Jan Hidders" <jan.hidders_at_REMOVE.THIS.ua.ac.be> wrote in message news:3e4bca2b.0_at_news.ruca.ua.ac.be...
[snip]
> >and better optimisations would be obtained without duplicates"
>
> No. In fact, in theory, all optimizations that can be done in a set-based
> algebra can also be done in a bag-based algebra but not the other way
> around.

Obviously, I guess. A bag algebra being a superset of a set alegbra.

However it does not follow that a dbms where users were exposed to a bag-based algebra would be overall more efficient than one with users 'restricted' to a set-based alegbra. Not by a long shot.

Regards
Paul Vernon
Business Intelligence, IBM Global Services Received on Thu Feb 13 2003 - 11:34:19 CST