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Jonathan Robie wrote: > Joe English wrote: > >I wouldn't go that far either; the structure of XQuery does look > >to me like it's more amenable to optimization than XSLT. > >But the '..' axis is definitely problematic. > [...] > Now the question - if a user chooses to write recursive functions to do > this sort of thing, does that user have the right to expect that we will > optimize such queries well? I think that '..' may turn out to be one of those features that you have to pay for even if you don't use it. Since an XQuery engine _might_ need to evaluate '..', it rules out many implementation strategies that would be more space-efficient than those used by conventional XSLT processors. It will be interesting to see what XQuery implementors come up with though. I have a hard time envisioning a space-efficient query evaluation framework which also supports '..', but that's no doubt due to a lack of imagination on my part. (OTOH, I can think of several that don't or can't support '..'.) I also notice that none of the example queries in the WD, and only one in the "Use Cases" document, require '..'. Is this feature really essential for XQuery? --Joe English jenglish@f...
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