Path: utzoo!utgpu!news-server.csri.toronto.edu!bonnie.concordia.ca!uunet!pmafire!mica.inel.gov!gem-hy!cdm From: cdm@gem-hy.Inel.GOV (Dale Cook) Newsgroups: comp.databases Subject: Re: Database Comparisons Message-ID: <1991Feb8.162539.6982@inel.gov> Date: 8 Feb 91 16:25:39 GMT References: <10737@pasteur.Berkeley.EDU> <580@opus.NMSU.Edu> Sender: news@inel.gov Reply-To: cdm@gem-hy.Inel.GOV (Dale Cook) Organization: Idaho National Engineering Laboratory, Idaho Falls, Idaho Lines: 110 In article <580@opus.NMSU.Edu>, agonzale@nmsu.edu (Agustin Gonzalez-Tuchmann) writes: |> In article <1991Feb7.190050.449@inel.gov> cdm@gem-hy.Inel.GOV (Dale Cook) writes: |> |> In article <10876@pasteur.Berkeley.EDU>, mao@eden.Berkeley.EDU (Mike |> Olson) makes 3 assertions about the superiority of RDBM systems over |> non-RDBM systems: |> |> |> however, there are several drawbacks: |> |> |> |> + NO ad-hoc queries. if you want to get some data out of the |> |> database, you have to understand its structure and write a |> |> program. |> |> |> |> Excuse me, but this has nothing to do with RDBMS format. I've worked with a |> non-relational DBMS system that has adhoc query capability, you don't have |> to understand the structure any more than you do an RDBMS. The particular |> DBMS I refer to is ADABAS, and I would wager there are others. |> |> There has to be an underlying model, though. In hard-coded application |> the files and application programs very often result in different |> solutions to common problems. This makes it difficult to create an |> ad-hoc query program. |> I still don't see what this has to do with RDBM systems. I can "hard code" an RDBMS application just as easily as a non-RDBMS application. This is more a function of the use of 3GL interfaces to your DBMS than to the fact that you are or are not using an RDBMS. Plus, the applications you build on top of the DBMS are independent of any adhoc queries one might do, at least from the ADABAS point of view. |> |> |> + you're not insulated from changes in the the storage structure. |> |> if i change the way that records are organized on the disk (a |> |> thing that i might do, for example, to speed up certain types |> |> of searches) you have to rewrite all the computer programs that |> |> use the database. |> |> |> |> Nonsense. |> |> If you use a relational data base manager you can achieve data |> independance with less pain than in normal procedural languages. |> Who said anything about "normal procedural languages"??? ADABAS has a "4GL" (whatever that might mean :-) ). The assertion here was insulation from changes to the data. I am no more insulated from changes to the data in say, Oracle than I am in ADABAS. If I delete a field from an Oracle table, any SQL procedures referencing that field will have to be changed. If I delete a field from an ADABAS file, any NATURAL (ADABAS 4GL) procedure referencing it will have to be changed. It doesn't matter if you're using an RDBMS or not. The assertion is nonsense. |> |> + as a corollary to the last point, there's no simple way for you |> |> to speed up a query short of recoding the program that implements |> |> it. on a relational system, i can just define an index and let |> |> the optimizer do the right thing. |> |> |> |> Again, nonsense. |> |> I don't see how you can speed up a query without rewriting the |> program. Thus it makes sense to me. |> In ADABAS, you can create an index on the field(s) in question. |> |> I think the biggest advantages is having a data model ( it enforces |> rigor on design, if that's what you want), data independance, and |> I think the most important -and often most overlooked feature-- |> it gives non-programmers a big chance to ask questions through |> the query manager of the rdbm (or dbm). |> Explain, please, why I can't have a data model unless I use an RDBMS. Explain, please, why a poor data model will perform better on an RDBMS than a non-RDBMS. Explain, please, why one can never achieve data independence with a non-RDBMS. I'm not trying to extoll the virtues of ADABAS. I'm arguing that the reasons people have given so far for choosing an RDBMS over a non-RDBMS are not really reasons at all. ---------------------------------------------------------------------- --- Dale Cook cdm@inel.gov The opinions are mine. 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