Opinions requested

[Jerome McDonough]

At 02:17 PM 3/5/1999 +1100, Marcelo Cantos wrote:
>>"Jeffrey E. Sussna" wrote:
>>
>> There is not (AFAIK) yet any such thing as an XDBMS (though you could
consider 
>>a file system of XML documements plus a web server to resolve URL's to
those 
>>documents as such a thing).
>
>I am continually surprised to hear remarks such as this.  SIM _is_ an XDBMS 
>(it is also an SGML, MARC, RTF, etc. database with structure and full
content 
>query capabilities).

I think one of the reasons you hear these kinds of remarks is that the
terminology
surrounding these systems is used differently by different folks.  For
instance, 
from what I know of SIM, I wouldn't call it a DBMS system of any kind, as I
don't believe (I could be wrong) it supports referential integrity
constraints, concurrency
control, recoverable transactions, and other features I would expect out of
a reasonable DBMS.  Granted it has hooks that allow you to get it to work with
a DBMS that can provide all that, but that doesn't make SIM itself a DBMS.
I would instead class SIM as an information retrieval system, and a pretty 
damned good one at that.  However, SIM performs as well as it does in great
part because it's not doing the extra work that a DBMS should do, and which 
add greatly to retrieval time from database systems (as well as limiting their
ability to handle complex data formats gracefully).

This isn't to knock SIM; anyone who needs a flexible information retrieval
system should be taking a very serious look at it.  The Z39.50 support alone
puts it way ahead of the market as far as I'm concerned.  But I don't think
SIM is evidence that there are DBMS systems that handle SGML/XML well; I don't
think they do.  Oracle may very well be getting there with its latest release,
but I suspect there's still a lot of work to be done there.




Jerome McDonough -- jmcdonou at library.Berkeley.EDU  |  (......)
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