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RE: [xml-dev] The limitations of XPath and navigation for XML database processing

> The analogy I've used to explain this is contrasting how 
> people use a taxi. The passenger who says "Take me to the 
> airport" and leaves it to the taxi driver to determine the 
> best route is like the SQL user who leaves it to the 
> optimizer to determine the best access plan.
> A different passenger might tell the taxi driver, "Take 
> Interstate 15 to Highway
> 78 and turn west. Then take Interstate 5 South to the San 
> Diego Airport exit". 
> That's navigational, not declarative.

And the passenger who says "take me to the house with a red door that's
opposite the post office on the road that runs from the station to Junction
11 on the M4" is both navigational and declarative. He's describing where it
is by its relationship to other objects. He isn't giving instructions for
how to get there. That's the way XPath works.

Michael Kay

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