Re: RM and abstract syntax trees
Date: Thu, 01 Nov 2007 01:27:17 -0700
On Nov 1, 3:18 pm, Marshall <marshall.spi..._at_gmail.com> wrote:
> On Oct 31, 9:52 pm, David BL <davi..._at_iinet.net.au> wrote:
> > On Nov 1, 1:31 pm, Jonathan Leffler <jleff..._at_earthlink.net> wrote:
> > > Isn't the other 'point' that 'pointers point somewhere' but values
> > > stored in a relation don't - that relational database bases work on
> > > associative addressing. In particular, even in a foreign key, the value
> > > doesn't point to the referenced primary key; it merely contains the same
> > > value as some entry in the referenced table. It may also contain the
> > > same value as a large number of other places in the database.
> > That's quite right, but note in the special case of using RM to
> > represent an AST, a foreign key node identifier ends up uniquely
> > referencing precisely one tuple in one relation elsewhere in the DB.
> You say that like it's a bad thing.
I hate to say this for fear of more discussion about the pointer analogy...
I was (yet again) drawing attention to the idea that in this special case a foreign key value can be regarded as analogous to a "pointer" that can be "dereferenced" to obtain another tuple in the DB. Received on Thu Nov 01 2007 - 09:27:17 CET