Re: foundations of relational theory? - some references for the truly starving

"daveb" <davebest_at_SuPsAaM.net> wrote in message news:<zyxrb.5926$Cj1.1446_at_fed1read07>...
> "Database Guy" <dbguy101_at_hotmail.com> wrote in message
> news:7fdee71c.0311081524.77d4fc78_at_posting.google.com...
> > davebest_at_usa.net (Dave Best) wrote in message
> > >In Pick, the primary key of a MV element is the primary key
> > > of the record plus its array index.
> >
> > Really? So how does PK persistence work when you insert or delete
> > values in the array?
> >
> >
> > DG
> It doesn't. Pick is not relational. I was just showing a mapping between
> the relational model and Pick's physical model, thereby exposing a weakness
> in the physical model. To preserve "PK persistence" as you call it, one
> would need to actually have a PK for the MV columns. This would be
> problematic, since it's really a collection of MV columns synchronized
> together that form a nested relation, and Pick itself doesn't know about the
> multi-column association; it's up to the application to maintain this.
>

Isn't the PK preserved anyway? The position of a multivalue is inherent - if the datum changes its position so does it's PK change. Received on Mon Nov 10 2003 - 07:12:56 CET