Date: Tue, 19 Apr 2005 15:16:41 +0200 From: Alexandr Savinov User-Agent: Mozilla Thunderbird 1.0 (Windows/20041206) X-Accept-Language: de-DE, de, en-us, en MIME-Version: 1.0 Newsgroups: comp.databases.theory Subject: Re: the relational model of data objects *and* program objects References: <425ce2a2$1@news.fhg.de> <425e6687$1@news.fhg.de> <60l3j2-g8s.ln1@pluto.downsfam.net> <425f83b6$1@news.fhg.de> <1113835006.499144.59960@l41g2000cwc.googlegroups.com> <4263d82f$1@news.fhg.de> <4264f062$0$539$ed2e19e4@ptn-nntp-reader04.plus.net> In-Reply-To: <4264f062$0$539$ed2e19e4@ptn-nntp-reader04.plus.net> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Message-ID: <426504b8$1@news.fhg.de> Organization: Fraunhofer Gesellschaft (http://www.fraunhofer.de/) Lines: 29 Path: dp-news.maxwell.syr.edu!spool.maxwell.syr.edu!drn.maxwell.syr.edu!news.maxwell.syr.edu!newsfeed.media.kyoto-u.ac.jp!newsfeed.icl.net!newsfeed.fjserv.net!news.tele.dk!news.tele.dk!small.news.tele.dk!news-fra1.dfn.de!news-koe1.dfn.de!usenet-feed.fhg.de!news.fhg.de!not-for-mail Xref: dp-news.maxwell.syr.edu comp.databases.theory:30564 Paul schrieb: > This relies on the fact that domain names are a hierarchy, so I'm not > sure how a similar idea would work with the standard relational model > though. The relational model does not have hierarchies and it is obviously a serious drawback (one of many, actually). The worst problem however is that the relational model does not want to have hierarchies because this theory is in a frozen state and simply does not recognize that there could be any problems in use of this model. Having hierarchies is only one thread leading to a new model. Indeed, why we have to store (to model) all our tables in one space/scope? We never do it with our own files or other things so why do we do it with tables? Because there are no other means. Let us assume that there exist several departments so why not to model their data structure separately in their own spaces which are subspaces of one common space? It would absolutely natural and we could avoid very serious problems frequently encountered in complex systems. But we prefer to cheat ourselves by repeating that the relational model is the ultimate model and it can model any possible situation and if not then you are have low qualification. So hierarchies in data modeling are not simply desirable. They must exist because any system has a hierarchical natural (fundamental principle). But if we introduce them then it will be already a completely new model. alex http://conceptoriented.com