Re: CODASYL-like databases

On Apr 2, 4:10 pm, Rob <rmpsf..._at_gmail.com> wrote:
> Sorry. After rereading your post and my response, I realize my effort
> to be concise resulted in confusion. Here are 3 statements:
>
> 1. > > RDBMSes are sometimes described as a reaction against network-/
> hierarchical databases. ("Troels Arvin" <tro..._at_arvin.dk>)
>
> I agree with this wrt hierarchcial dbms's, not network. In 1970,
> hierarchical dbms products were everywhere, network dbms products
> hardly existed. Codd's relational model and the CODASYL/DBTG network
> proposals were both reactions to maintenance/management problems with
> hierarchical products. The relational model prevailed.
>
> 2. > I would describe the introduction of the relational model of data
> for DBMS
> work as forward progress rather than as a reaction against something.
> ("David Cressey" <cresse..._at_verizon.net>)
>
> Here I do disagree. The relational model was revolutionary thinking.
> Before 1970, database management wasn't even a computer science
> concept. Until at least 1974, SIGMOD was SIGFIDET-- Special Interest
> Group on File Description & Translation. Perhaps my "disagreement" is
> based on my personal experience of that time: IMS and all it's
> lookalikes were uninteresting data processing products; the relational
> model was a giant leap forward that was worthy of interest to a
> computer scientist. You imply "evolutionary" -- I need
> "revolutionary".
>
> 3. > The early RDBMS products were, to some extent, an attempt to
> obtain the power and simplicity of the relational model without
> discarding a code base that had been based on hierarchical or network
> models of databases. ("David Cressey" <cresse..._at_verizon.net>)
>
> Wrt codebases, the only contribution from hierarchical systems were
> the Access Methods (ISAM, VSAM, ...). Wrt network systems, the only
> reused code I know of (from your postings) were the DEC products. In
> the grand scheme of things, these hardly appeared on the radar screen.
> (That is not meant to disparage your knowledge or experience: I was
> the system architect on a RDBMS in 1980-84 and designed the optimizing
> compiler for another RDBMS in 1985. I guarantee you nobody remembers
> either!)
>
> Not really that much disagreement here, just differences in
> perspective.
>
> Cheers, Rob

I concur. The innovative aspect was that before RM, there was no direct relationship between mathematical concepts and database management. Received on Wed Apr 02 2008 - 18:34:57 CEST