[XSL-LIST Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message] Re: Advantages of using key()?
> What are the advantages of using xsl:key and key()? key() is _always_ equivalent to an Xpath that doesn't use it , as you have shown, but typically an xpath to find the nodes matching the key are of the form //*[@foo='value'] and // is very expensive causing a search of the entire document. an implementtation may implment key() just by rewriuting it to the equivalent xpath but in practice it is a hint that the stylesheet author would rather the system save (a lot) of time at the cost of some (perhaps non-negligable) amount of memory space, and build some kind of index or hash table doing a one-off pass over the whole document and then hashing the locations of the nodes that match the key values. this can make orders of magnitute speed improvements for some kinds of problem. David ________________________________________________________________________ This e-mail has been scanned for all viruses by Star. The service is powered by MessageLabs. For more information on a proactive anti-virus service working around the clock, around the globe, visit: http://www.star.net.uk ________________________________________________________________________
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