Re: Dreaming About Redesigning SQL - Mailing list pgsql-hackers

Anthony,

> And don't other databases have both theory and model?

Actually, no, the "new" databases do not.  

The relational model is backed by relational algebra and relational calculus, 
plus a series of postulates and laws which have been refined and tested over 
20 years.   

Not Object-Oriented databases nor XML "databases", nor Multi-Value databases 
have any body of theory behind them, mathematical or otherwise.   I defy you 
to post a single paper that has a mathematical theory for MV or OODB, or even 
a firm set of laws that govern such a database.   Nor is the industry moving 
toward developing such a theory; instead the marketeers of commercial OODB 
and XMLDB use a lot of ink to denigrate the idea of mathematical theory as 
antiquated and stuffy, and in one case even using their advertising clout to 
drive critical theorists off the pages of IT magazines (see Fabian Pascal's 
web page).

Actually, amusingly enough, there is a body of theory backing XML databases, 
but it's not one any current devloper would want to admit to: the XML 
database is functionally identical to the Network Databases of the 1960's.   
Of course, Network Databases gave way, historically, to Relational for good 
reason.  

And MV databases, despite decades of existence, never developed any theory 
behind them at all, possibly because one is not possible; MV databases are 
entirely an ad-hoc creation designed to work around decade-old limits in 
computer processing.  Pick is merely TextMagic revived and put on the web.

Now, OODB could certainly *develop* a model and theory, and I think it's high 
time it did.   The Zope project has amply demonstrated the usefulness of OODB 
for certain applications.   But as long as there is no OODB calculus, and no 
industry-agreed model, and no ANSI standard language or interface, each and 
every OODB will be 100% incompatible with every other one ... severely 
limiting their utility.

The importance of theory, model, and standards is *not* to be overstated in an 
industry where every year the industry-favorite commerical databases get more 
ad-hoc, further from the theory, and more callous in their disregard of 
international standards.

FWIW, I share your dissatisfaction with SQL, but because it's not relational 
enough rather than the other way around.

-- 
Josh Berkus
Aglio Database Solutions
San Francisco