On Mon, 2002-08-12 at 11:52, Curt Sampson wrote: > On Sun, 11 Aug 2002, Don Baccus wrote: > > > Obviously it would require extending SQL, but since you in part argue > > that SQL sucks in regard to the relational model this shouldn't matter, > > right? > > Well, if we're going to go so far as to get rid of SQL, we can go all > the way with the D&D thing, and VIEWs will no longer be syntatic sugar > because views and tables will be the same thing. (I'll leave you how > specify physical storage as an exercise for the reader. :-)) > > But anyway, I have no particularly huge objection to syntatic sugar > alone. I do have objections to it when it's not saving much typing. (It > is in this case, but that could be fixed with better automatic support > of view updates.) > > But my real objection is when it makes things more confusing, rather > than less, which I think is definitely happening here.
What makes things more confusing is poor understanding of a feature, not the feature itself. > I've never > seen a rigourous explanation of our model of table inheritance, > nor any model that was more obviously correct than another. And > the parallel drawn with inheritance in OO languages is a false > parallel that adds to the confusion. Are you saying that inheritance in SQL is something fundamentally different than inheritance in OO languages ? > (For example, the distinction > between types and instances of types is critical in OO theory. What are > the TI equivalants of this?) If by TI you mean type instance then the equivalent of of an instance is a relation (i.e. one row in an (inherited) table). > All this is borne out by the regular questions one sees about > inheritance in the mailing lists. I'll admit a good part of it is > due to the broken implementation of inheritance, but all of the > problems I've ever seen are easily solved with very simple relational > solutions. All _simple_ inheritance problems are easily solved by simple relational solutions. The general problem of much more typing and debugging, less clues for optimiser etc. are not solved by _simple_ relational solutions. > Maybe the inheritance thing is causing people to turn off the relational > parts of their brain or something. Of maybe people are diversifying, using inheritance for is-a relationships and relational model for has-a relationships. --------------- Hannu ---------------------------(end of broadcast)--------------------------- TIP 4: Don't 'kill -9' the postmaster
