Re: How to create a DBMS from scratch?
Date: Thu, 28 Nov 2002 04:30:26 +0100
Message-Id: <20021128043026.50341077.spam_at_oblomov.org>
On 28 Nov 2002 03:01:15 GMT
> In the last exciting episode, Andy Dingley <dingbat_at_codesmiths.com> wrote::
Christopher Browne <cbbrowne_at_acm.org> wrote:
> > On Mon, 25 Nov 2002 12:45:29 +0000, Rob Tweed
> > <rtweed_at_imtcons.demon.co.uk> wrote:
> >
> >>Its interesting the way XML has brought back new life into the old
> >>hierarchical databases,
> >
> > Interesting, but not a good thing.
> >
> > This commonality between XML and hierarchical DB's isn't a validation
> > of the DB, more a condemnation of XML's rigidly tree-structured data
> > model.
>
> The fact that certain varieties of hierarchical queries are not
> particularly convenient in SQL is a bit of condemnation thereof.
>
> You tend to have two choices:
>
> a) You iterate through the tree, an SQL query for each node, or
> b) Go with some cleverness ala the "Celko nested sets" approach.
Why not just run an LDAP and an RDB at the same time? It's not impossible in any way. Keep heirchial design in heirachial persistency and cross-referenced relations in relation-style persistency.
Or if you ask me, get an OODB and skip the mapping-layers so it's up to you and your design.
karl Received on Thu Nov 28 2002 - 04:30:26 CET