Re: XQuery and DTD/Schema?
Jonathan Robie wrote: > At 02:30 PM 7/3/2002 -0700, Joe English wrote: > > >I'd even question how relevant the efficiency issue is. > > > >XQuery is designed, principally, to do database queries. > >In this context, it doesn't matter if you can take advantage > >of type information to add two xs:integers in nanoseconds > >instead of microseconds, when it takes milliseconds to retrieve > >the data in the first place. > > Queries on large sets of data *do* need to be efficient - and when you want > to be efficient, you try to avoid actually retrieving the data whenever > possible. Reasoning about types statically is one of the ways we do this. I still don't buy this argument. Static typing can help optimize low-level operations that are close to the machine (for instance this is why as a rule SML is more efficient than Scheme), but languages that do heroic optimizations -- APL, SQL, and Common Lisp for instance -- tend to be dynamically typed. Static typing is neither necessary nor sufficient. What optimization strategies does the XQuery type system enable? Has anyone implemented, or even just designed, a database access optimizer that takes advantage of it? --Joe English jenglish@f...
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