Re: CODASYL-like databases
Date: Wed, 02 Apr 2008 08:14:34 GMT
> I would describe the introduction of the relational model of data for
> work as forward progress rather than as a reaction against something.
< Disagree. Codd was a doer as well as a thinker. In his 1970 paper, he < perceived that data dependencies in present systems (ordering < dependence, indexing dependence and access path dependence) implied
> that "changes to the characteristics of data representation logically
< impaired some application programs".
However Codd did not introduce the notion of avoiding those physical dependencies. In his first paper on the relational model, Codd cited the work of David L. Childs on Set Theoretic Data Structures.
Childs' 1968 papers and Codd's 1970 paper discussed structure
(independent sets, no fixed structure, access by name instead of by
pointers) and operations (union, restriction, etc.). Childs' papers
included benchmark times for doing set operations on an IBM 7090. Codd's
1970 paper introduced normal forms, and his subsequent papers introduced
the integrity rules.
What's interesting is the University of Michigan connection. Codd, Bing Yao, and Michael Stonebraker were graduates. Some of the work done at University of Michigan during that time (Childs' STDS, Ash and Sibley's TRAMP relational memory) was for the CONCOMP project. It was funded by the US government and the research was available only to "qualified requesters".
- Ken North =========== www.KNComputing.com
www.WebServicesSummit.com www.SQLSummit.com www.GridSummit.comReceived on Wed Apr 02 2008 - 10:14:34 CEST