Data warehousing and XML

[len bullard]

Paul Prescod wrote:
> 
> Simon St.Laurent wrote:
> >
> > This may be writing it off too quickly; I think the great advantage of XML for
> > a data warehouse would be its ability to ease the inclusion of non-relational
> > data.
> 
> I don't claim to be an expert, but my understanding was that the goal of
> a data warehouse was to make a repository of information that could be
> plumbed through essentially relational queries -- demographic
> information, correlations between dates and so forth. I don't see the
> benefit of including document data in this sort of repository. As
> someone else mentioned, XML may well be a good transfer format for the
> information to move it FROM the regular databases into the data
> warehouse.

Of course XML can be used to create non-ambiguous 
transfer formats (data schlepping).  But Paul, 
a lot of the information that needs to be mined 
is not in relational formats.  Depending on the query 
language and implementation, there is no reason one 
cannot build an industrial strength data repository 
over generalized markup.  Some IETM applications 
(eg, 87269, MID, etc.) are designed to do that.
Even with IADS some years ago, we had some primitive 
capabilities for this although immature then.  Probably 
much improved now.  In those designs it was always 
assumed that the client language (eg, MID) was 
essentially a navigation system over a set of 
notations whose processors are known.  It is also 
assumed that the client language included a query 
language or could call one.  So, data warehouse may 
be in need of further clarification.   Applications 
I work with have to have both document frameworks 
and relational systems as well as all of the 
ad hoc-inTransit data used to interface the 
live data (sensor-derived) to the database that 
is collecting and warehousing.

However, let me ask a technical 
question that you can probably answer with a deeper 
technical perspective than mine?  How well can one query 
data (or convert it for that matter) for which one 
has no rigorous schema (of some kind)?  (Note, 
I consider a self-identifying type (eg, magic number) 
to be a pre-validated file of the notation.)   

len bullard

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