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RE: Validation, Versioning and RDF [Was Re: WSDL WG request for adding multiple version extensibility into Schema 1.1]

From: <paul.downey@bt.com>
Date: Wed, 3 Mar 2004 17:04:47 -0000
Message-ID: <2B7789AAED12954AAD214AEAC13ACCEF0FFF201C@i2km02-ukbr.domain1.systemhost.net>
To: <dbooth@w3.org>, <bparsia@isr.umd.edu>
Cc: <www-ws-desc@w3.org>, <dorchard@bea.com>, <distobj@acm.org>
David Booth wrote:
> IMO, this is the main reason
>relational databases won the database wars 20 years ago when they were
> introduced: you can easily add new tables (i.e., new relations) to a
> relational database without breaking existing application code.  
> However,
> if you add new data to an XML schema for a tree-structured data format (for
> example by inserting siblings or by inserting new levels of hierarchy) you
> are much more likely to break existing application code.  It is possible to
> avoid, but it's harder than in the relational world.

i do like the analogy with relational (v) hierarchical databases, 
but one view of an RDBMS is as a loosely connected graph with 
joins between columns and views. 

I agree, the success of relational databases was in no small part due 
to their making  touchless versioning possible - the query language 
/by default/ ignores new columns and tables, and missing data can
be easily recognised and given a default value.

Paul

Received on Wednesday, 3 March 2004 12:05:20 GMT

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