Re: [tutoriald-design] Design Goals

[<reh...@t-...>]

On 12 Aug 2003, Leandro Guimarães Faria Corsetti Dutra wrote:

> Em Ter, 2003-08-12 às 20:48, Rene Hartmann escreveu:
>
> > We might want to have some statement that changes the current database,
> > as Tutorial D doesn't provide that. But again this could be easily
> > added to the language. For the beginning, the current database
> > could be provided to the interpreter through command line arguments .
>
> 	AFAIR (without checking the books) that is because D&D want us to think
> distributed.  That is, there would be only one namespace that would be
> "THE" database; where it would reside would fall outside D, that must
> remain entirely logic.
>

Well, RM prescription 17 states that distinct databases shall not
be necessarily disjoint. As I understand it, this means that several
databases may exist within one namespace, sharing relvars.
Duro supports this by allowing the creation of several databases
within one "database environment", and these databases may share tables,
though there is currently no function that performs sharing user
tables between two databases - the only tables shared are the catalog tables.

It migth turn out to be helpful to have statements for creating additional
databases and sharing tables between these databases, for example,
to support the creation of application-specific databases
(I think there is some article from Date or Darwen which mentions
application-spcific databases, but I don't have it at hand).

But it's true that statements which deal with databases would be
outside of D - outside the "D part" of the language, so to say.

--
Rene´