- From: Kay, Michael <Michael.Kay@softwareag.com>
- Date: Tue, 24 Jun 2003 15:12:40 +0200
- To: Michael Rys <mrys@microsoft.com>, dnovatchev@yahoo.com, public-qt-comments@w3.org
> Being able to have fn:distinct-values return the values > implementation-dependent provides for better performance for > this often performance critical operation. Thus I would be > strongly against mandating an order. > > If you need to preserve order you have the following options: > > - Write your own function that does so > - Lobby your favorite vendor to provide the functionality > - Lobby for the next version of XQuery/XPath to provide this > functionality. > > In order to do any of the last two, you would need to provide > some compelling use cases. > There is always a danger of course that users will discover that some implementations return results in a predictable and useful order, and become locked-in to this behavior. There are definitely arguments both ways on this one. One approach would be to define the order that distinct-values returns, and advise people to wrap it in a call of unordered() if they don't depend on this order. But that's not a perfect solution either. XSLT users, of course, can always use for-each-group in which the ordering is well defined. Michael Kay
Received on Tuesday, 24 June 2003 09:13:19 UTC