larry@zeek.UUCP (Larry Podmolik) (03/17/89)
In some magazine (PC Week?) recently there was an interview with some consultant from Codd & Date. He was asked which products on the market were really relational databases. He mentioned Oracle and a few others. He then said Informix had "honorary mention" in that group because it was a relational interface built on top of a non- relational (C-ISAM) engine. (BTW, neither Unify nor Ingres was mentioned at all.) I guess I don't understand what a truly "relational engine" is in that sense (i.e. why Informix doesn't qualify). And what about Ingres and Unify? Any enlightenment appreciated. Larry
davek@rtech.rtech.com (Dave Kellogg) (03/20/89)
In article <217@zeek.UUCP> larry@zeek.UUCP (Larry Podmolik) writes: > He then said Informix had "honorary mention" in that >group because it was a relational interface built on top of a non- >relational (C-ISAM) engine. (BTW, neither Unify nor Ingres was >mentioned at all.) > >I guess I don't understand what a truly "relational engine" is in that >sense (i.e. why Informix doesn't qualify). And what about Ingres >and Unify? > >Any enlightenment appreciated. > I'm not sure what they guy is talking about and would appreciate a solid reference to the article so I can check it out. Fundamentally, the guy seems off the mark. (Especially since he works at Codd and Date because his own boss defines things differently...) The bottom line is that relational is as relational appears. At the lowest level of abstraction it's all 1's and 0's on some disk anyway. The relational model is concerned at how the data APPEARS to its users. My guess is you could make a relational "engine" on top of a bunch of file clerks and manila folders if the clerks PRESENTED the data relationally to its end users. Quoting Date (Guide to DB2): ... the relational model is a way of looking at data-- that is, a prescription for how to represent data and how to manipulate that representation... Thus, in my book, to determine whether a DBMS is relational or not you don't look at how it stores things or how it internally works. Rather, you look at the way the data is presented to you and the query language and its operators. David Kellogg Relational Technology New York As usual, these thoughts are mine (or Date's) and not necessarily those of my employer.
dan@speedy.wisc.edu (Dan Frank) (03/22/89)
In article <2739@rtech.rtech.com> davek@rtech.UUCP (Dave Kellogg) writes: >In article <217@zeek.UUCP> larry@zeek.UUCP (Larry Podmolik) writes: >> He then said Informix had "honorary mention" in that >>group because it was a relational interface built on top of a non- >>relational (C-ISAM) engine. (BTW, neither Unify nor Ingres was >>mentioned at all.) >> >I'm not sure what they guy is talking about and would appreciate a solid >reference to the article so I can check it out. I believe the article was in PC Week, the weekly offering of the PC Cargo Cult. The interviewee (Fabian Pascal, I think) felt that Informix was non-relational because a progammer could utilize the C-ISAM interface to circumvent security and integrity constraints of the relational schema. It's a good thing we have consultants to warn us of such things. -- Dan