Re: Oracle and PICK

From: Jan Hidders <>
Date: Sat, 17 Apr 2004 11:32:35 GMT
Message-ID: <nB8gc.74564$>

Dawn M. Wolthuis wrote:
> [...] I'm coming from trying to figure out why
> relational theory is taught and marketed big time when my way-too-many-years
> of practice have given me the impression (not the proof) that other
> approaches work better.

As far as teaching theory goes, the answer is quite simple. It is because we have a formal description of the relational model that it is possible to do develop theory around it. And because it is based on other theories with a long pedigree such as set theory and logic we can re-use the already known results of those fields. So there is a big corpus of theory concerning all kinds of issues such as complexity theory, query optimization, concurrency theory, logical deduction, constraint checking, et cetera, that can be taught.

I haven't seen such a formal description for Pick, and in fact most of its proponents I have spoken to, don't even seem to realize its importance. So there you go. We cannot teach theory that we do not have.

> [...] It was quite amusing to me to see that the XML model looked like
> the old PICK products I'm accustomed to -- makes me think that perhaps
> theory and practice might actually come to the same conclusion once we have
> a better theory.

Not even the staunchest defenders of native XML databases are claiming that they will replace RDBMSs. See for example the remarks by Dana Florescu at SD2004:

There's a very simple reason for that. Many of these people used to do research on relational databases and know very well what their advantages can be.

Also interesting in that respect is the fact that if you look at the current research on query optimization for XML the bigger successes in scalability and performance such as demonstrated in

Efficient Algorithms for Processing XPath Queries. Georg Gottlob, Christoph Koch, and Reinhard Pichler. In Proc. VLDB 2002


T. Grust, J. Teubner, M. van Keulen. Accelerating XPath Evaluation in Any RDBMS, in ACM Transactions on Database Systems (TODS), 29(1), pages 91-131, March 2004.

are applying / extending techniques that were already known from relational research. This suggests that even if you have data that has a typical XML structure and is accessed in a typical XML way (XPath expressions) the relational model is very often still an excellent choice for your underlying logical data model.

  • Jan Hidders
Received on Sat Apr 17 2004 - 13:32:35 CEST

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