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Re: Lucid statement of the MV vs RM position?

From: Pickie <keith.johnson_at_datacom.co.nz>
Date: 26 Apr 2006 20:57:27 -0700
Message-ID: <1146110247.495974.84970@i39g2000cwa.googlegroups.com>


People can collaborate (and exchange data in a meaningful, formal fashion) without a DBMS. In practice, using a DBMS involves much more than just providing the database(s). You have to be able to evolve the database structure for new circumstances, which means you run into a different set of problems. But I understand where you are coming from.

The original request was for a lucid statement of the MV vs RM position. In my reply I tried to describe Pick-MV a bit, because there are a few misconceptions about it. The basic position I took with respect to the request was that I didn't think it could be compared with RM because they are different things. Moreover Pick-MV doesn't have some of the key things required of a DBMS, so it can't be compared with RDBMSs either. You are, however, left with the fact that one can build a system which acts as if it was built with a DBMS. People can access information, update it, report on it, etc. without getting in each others way. Of course, this does depend on the application programmer. Similarly you depend on your DBA when you have a DBMS. These people need to be skilled, and an undestanding of normalisation, etc. is necessary to both.

The only theory I have any knowledge at all about in the database world is the RM. The major DBMS's (I mean the ones that call themselves RDBMSs) are based on SQL which doesn't follow the RM. In fact, given that the RM does not have nulls, Codd's rules for a RDBMS don't seem to follow the RM either. There are DBMS's that are said to follow the RM but I have my doubts if SQL is supported.

The truest answer to the request seems to be that the Relational Model is a theory that has no practical example and Multi-Value (at least the Pick version) is a practical example that has no theory. Received on Wed Apr 26 2006 - 22:57:27 CDT

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