> heavy
> weight RDMS, there is a native XMLType column, and you can do XPath
> querys
> stright to it with SQL.
>
Both SQL Server and Oracle allow you to use proprietary syntax to
access data contained in XML documents, but it is not straight SQL as
defined by ISO. Remember, ISO defines the SQL standard and currently
SQL does not support XML.
> Which makes that wrong too :-)
> However in your other reply you go on to talk about databases with a
> native
> XMLType, so I'm sure you must have been aware of that.
>
All relational databases process data using resultsets. It doesn't
matter what syntactical sugar they add or how things come out at end of
a query being executed; all the data used to produce the result was
processed as resultsets. That means that the XML too has to be in the
form of a resultset in order for a relational database to work with it.
There is simply no other way as relational databases don't have
hierarchical query engines.
Now you can snipe the article all you want, but it was written for IT
managers and as such isn't perfect technically. If you really care
about these issues then I should you read some of the research papers
coming out of Jim Gray's team at Microsoft. Jim Gray was one of the top
database researchers in the world before joining Microsoft and his team
seems to be doing the most innovation in the relational/XML field
currently. You might also be interested in the following. However, it
is patented and as such doesn't seem likely to show up in databases
anytime soon.
http://portal.acm.org/citation.cfm?id=640996&dl=ACM&coll=portal
> I'm also of the view that if you are starting to have to worry about
> one extra
> disk (or more likly memory cache) read, you need to spend some more
> money on
> your database :-)
>
That is flawed logic. Spatial problems in databases can't be overcome
with adding disks. Certainly adding disks can help, but there really is
a finite limit on how many disks you can add. As such scalability will
continue to be a problem as the database grows and you can't add more
disks.
-Matt
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