Re: A Logical Model for Lists as Relations

Marshall Spight wrote:

> What about imperative operations? This is a bit more complicated.

Not really. The only imperative operations in an RDBMS map to relation variable assignment. Lists, if you have them at all, are necessarily just values.

> Anyway, comments, suggestions, criticisms welcome. Although
> note I'm not much interested in the question of whether ordered
> data is useful or not.

I think you are getting way ahead of yourself. Why do you need a list type? What do you intend to accomplish with your index attribute that one cannot accomplish with quota queries and relations? How does list differ from array? How does array differ from relation? Wouldn't a list have a candidate key and a successor self-referencing foreign key? Wouldn't a double-linked list also have a predecessor self-referencing foreign key? Or do I have those reversed? If one links lists using foreign keys, can one specify the ordered relation using a closure? What about circular lists? If it is a type, shouldn't a list have multiple possible representations? If it has multiple possible representations, doesn't physical independence suggest the dbms can use any of them? What sorts of payloads can one put in lists? Received on Wed May 10 2006 - 07:54:45 CEST