Re: RM and abstract syntax trees
From: Jonathan Leffler <jleffler_at_earthlink.net>
Date: Wed, 31 Oct 2007 21:31:32 -0700
Message-ID: <13iill2q6gusd6c_at_corp.supernews.com>
>
> I think if we are clear about it being an analogy we are on solid
> ground. But as soon as we start thinking pointers and references
> are the *same* thing we are in trouble, because now we can't
> see the differences anymore.
>
> I think Date actually nails this issue. He says (roughly) that
> pointers add complexity but don't add any expressive power.
Date: Wed, 31 Oct 2007 21:31:32 -0700
Message-ID: <13iill2q6gusd6c_at_corp.supernews.com>
Marshall wrote:
> On Oct 31, 7:50 pm, David BL <davi..._at_iinet.net.au> wrote:
>> Isn't it helpful to see the analogy with a pointer dereference? >> >> I'll leave it up to you as to whether you dislike the analogy between >> node identifiers and pointer values, and the idea that a join can be >> compared to a pointer dereference. Perhaps you are right and the >> analogy creates confusion.
>
> I think if we are clear about it being an analogy we are on solid
> ground. But as soon as we start thinking pointers and references
> are the *same* thing we are in trouble, because now we can't
> see the differences anymore.
>
> I think Date actually nails this issue. He says (roughly) that
> pointers add complexity but don't add any expressive power.
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.
-- Jonathan Leffler #include <disclaimer.h> Email: jleffler_at_earthlink.net, jleffler_at_us.ibm.com Guardian of DBD::Informix v2007.0914 -- http://dbi.perl.org/ publictimestamp.org/ptb/PTB-1677 whirlpool 2007-11-01 03:00:04 136EC3850C6A351ABA4F75728C29638E5FD3A94DFC10470DA9FC9E7EC2E70EA48251A6 CEFD27B053762ABE7BC69C403990C43628769C2162BA5FAB540097F23Received on Thu Nov 01 2007 - 05:31:32 CET