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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_at_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 - 18:34:19 CET












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