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RE: XML Database Decision Tree?

• From: Nicolas LEHUEN <nicolas.lehuen@u...>
• To: "'Champion, Mike'" <Mike.Champion@S...>,"'xml-dev@l...'" <xml-dev@l...>
• Date: Wed, 24 Oct 2001 15:09:57 +0200

See my old post [1] :

<self-quote>
I don't think a node-labeled tree (the XML model is a tree, more restricted
than a graph) structure can model all kind of data easily and efficiently.
Likewise, relational and object model cannot model all kind of data easily
and efficiently. The key word here are "easily" and "efficiently" : okay,
for any given data to model, you can find a hierarchical (e.g. XML)
representation, a network representation (the node-labeled graph model), a
relational representation, an object representation, or more exotic
representations (e.g. the Caché model). But depending on your data, one of
these models will rise out at the "best" one, in terms of ease of
implementation and of efficiency in queries and updates.

So I believe there is a whole set of problems that will benefit from XML
databases (which are I believe based on the hierarchical database model*,
maybe Mike can confirm/infirm). The storage, indexation and querying of a
set of document-oriented data is a good example. 

But XML databases isn't or (won't) be a revolution, blasting all other
storage models. We could even say that the XML database model is just a come
back of the hierarchical model that was supposedly "killed" by the
relational model back in the 80s. I don't think XML databases are the "next
thing".
</self-quote>

[1] http://lists.xml.org/archives/xml-dev/200106/msg00990.html

>-----Message d'origine-----
>De : Champion, Mike [mailto:Mike.Champion@S...]
>Envoyé : samedi 20 octobre 2001 15:36
>À : xml-dev@l...
>Objet : RE:  XML Database Decision Tree?
>
>
>
>
>> -----Original Message-----
>> From: Eric van der Vlist [mailto:vdv@d...]
>> Sent: Saturday, October 20, 2001 3:16 AM
>> To: XML Everywhere
>> Cc: xml-dev@l...
>> Subject: Re:  XML Database Decision Tree?
>
>I agree with Eric's point that the RDBMS systems faced the same uphill
>battle against the conventional wisdom 10-15 years ago that 
>XML DBMS systems
>do today.  
>
>> As you know, at this  point, it took only a couple of years to wipe
>hierarchical 
>> databases out.
>
>BUT for the record, the hierarchical DBSMS have not exactly been "wiped
>out." They lost most of their *mindshare* in the trade press 
>in a couple of
>years, but still keep on truckin' in the back offices of 
>almost all large
>enterprises.
>According to
>http://www-4.ibm.com/software/data/ims/highlights/experform.html
>"More than ninety-percent of the Fortune 1000 companies use 
>IMS. IMS serves
>200 million end users, managing over 15 billion Gigabytes of 
>production data
>and processing over 50 billion transactions every day. IMS 
>still owns the
>high-volume on-line transaction and database management environment."
>Adabas is not precisely a hierarchical DBMS, but is usually 
>lumped in with
>IMS. It has 3000 customers, mostly large enterprises; I can't find hard
>figures, but I will guess that there's something like 1 or 2 billion
>gigabytes of production data managed by Adabas.  
>
>In any event, if either IMS or Adabas suddenly went away 
>(e.g., on 1 January
>2000), the world economy would come to a standstill: the banks 
>couldn't send
>money around, most big companies couldn't keep track of who 
>owed what to
>whom, the credit card system would collapse, the telephone companies
>couldn't track who called whom when via which intermediaries, 
>many airlines
>couldn't schedule their people and equipment ... and on and 
>on.  RDBMS could
>pick up the slack, eventually, and after a massive investment in the
>hardware infrastructure  -- ever wonder why the big hardware 
>companies are
>such good buddies with the RDBMS vendors?.
>
>Anyway, the RDBMS swiftly displaced the hierarchical DBMS in 
>the collective
>mindset because they addressed a new set of needs -- affordable data
>processing in smaller organizations, more flexible queries, 
>methodologies
>for database design, independence of logical and physical 
>design, etc.  XML
>DBMS will not displace RDBMS in the back offices of the world, 
>but they will
>gain mindshare because they address a new set of needs: to handle
>semi-structured documents efficiently, demands to build new e-business
>applications in "internet time", the need to cache and log transactions
>performed via XML messages, the need to maintain the state of complex
>multi-way transactions involving high-latency, unreliable internet and
>wireless  connections (see my comments on XML "tuple spaces"), 
>and so and so
>on. 
>
>
>
>
>
> 
>
>
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