I would think, from a Windows perspective at least, that it would =
be
possible to update an XML "database" at the field and row level. =
It
would possibly be a question of search and replace functions, and
there I could see problems. If, however, you used unique keys for=
all
of your XML "tables", that shouldn't be too much of an issue.
I would think it's feasible - whether it's as easy to use as a reg=
ular
relational or object oriented DB, is another thing. I would want =
to
test the speed of access also. Without any data, I'd have to say =
that
a binary level database would probably perform faster, perhaps muc=
h
faster, than a human readable ASCII document combined with a XML
database app.
______________________________ Reply Separator ________________________=
_________
Subject: Re: Relational Tables and structured document
Author: owner-xml-dev@ic.ac.uk at INTERNET
Date: 03/23/98 09:59 PM
I've been following the comments about using XML as a database, and
I have a question -- The discussion of ODMG and using XML as a
database suggests that you will be able to update the database.
But, if you have a large XML file, how do you update fields within
that file without copying or re-writting the whole file? That
sounds very awkward.
Or am I missing a step in this process? Are we assuming that the
XML file has been sucked into an OODBMS such as one for which there
are ODMG language bindings? I think this would be very powerful.
However, it is no longer XML, is it? Or is the goal to store the
data in a RDBMS or OODBMS and then export it to XML so we can send
it across the wire and around the Web?
I guess I am asking whether there is a model this kind of use of
XML as a database.
Dave
> Peter Murray-Rust:
>
> >I have been spending the last two weeks working on a molecular appli=
cation
> >which essentially consists of relational tables. The application is=
> >largely hierarchical (a protein molecule) so that it benefits from b=
eing
> >recast into structured document form. I have therefore found it usef=
ul to
> >create routines which generate nodes in a tree as a result of joinin=
g
> tables.
>
>
> I think there are several things that one could usefully do.
>
> (1) define a recommended way of representing a relational table in XM=
L.
> (There
> are a number of ways of doing this, the biggest decision is whether t=
o use a
> standard DTD for all tables or a DTD that reflects the specific table=
> definition.)
>
> (2) extend this to a richer data model, e.g. the nested relational mo=
del,
> that
> allows you to represent hierarchic structures, or the ODMG model whic=
h
> allows
> to to represent arbitrary graphs. (Note that the problem then becomes=
> analogous to the one of using XML as a serialisation format for CORBA=
> objects)
>
> (3) provide a toolkit that allows you to perform transformations on t=
hese
> XML
> documents that reflect the operators of the relevant data model, e.g.=
> relational
> selection, projection, and join; sorting and grouping; flattening of =
nested
> relations.
> Of course one way to implement such operations would be to load the d=
ata
> into
> a database, but many of the operations can be implemented directly wi=
thout
> too
> much effort.
>
> I think the key thing is to keep the set of structures and operations=
very
> clean:
> base it on a data model with an established formal basis rather than
> inventing
> something new.
>
> Mike Kay, ICL
>
>
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