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RE: FW: DN-FO-09: 15.1.11 fn:distinct-values

From: Dimitre Novatchev <dnovatchev@yahoo.com>
Date: Mon, 4 Aug 2003 09:00:06 -0700 (PDT)
Message-ID: <20030804160006.89548.qmail@web41115.mail.yahoo.com>
To: "Kay, Michael" <Michael.Kay@softwareag.com>, public-qt-comments@w3.org
Cc: dnovatchev@europe.com

As usual, Mike expressed the problem in the most precise manner.

Please, just note that exactly the same argumentation applies to any other function
returning a sequence, the order of results of which is "implementation defined".

Please, therefore modify these to return a sequence in "order of first appearance".

Thank you!

Dimitre Novatchev.

--- "Kay, Michael" <Michael.Kay@softwareag.com> wrote:
> For the record, I am in favour of distinct-values being defined to retain
> the first occurrence of each set of of duplicates, and for the result to be
> in "order of first appearance".
> 
> I think that making this implementation-defined will lead to
> interoperability problems. People will discover that their favourite
> implementation returns results in a predictable order, and they will come to
> rely on it, which will give them problems moving to a different product.
> 
> Our data model provides sequences of values, not sets of values, and we
> should therefore assume that by default, the order of the values is
> significant. They can always wrap the result in a call to fn:unordered() if
> they want a higher-performance implementation that doesn't retain order. 
> 
> Michael Kay
> 
> 
> > -----Original Message-----
> > From: Dimitre Novatchev [mailto:dnovatchev@yahoo.com] 
> > Sent: 25 July 2003 22:34
> > To: public-qt-comments@w3.org
> > Cc: dnovatchev@europe.com
> > Subject: Re: FW: DN-FO-09: 15.1.11 fn:distinct-values
> > 
> > 
> > 
> > > We have clarified the text to indicate that order of the output 
> > > sequence if implementation dependent.  We have also changed the 
> > > wording of the example as you suggested.
> > 
> > Thank you.
> > 
> > > 
> > > If the user wants the output in a particular order, he can sort the 
> > > values by document order by using $x/. or in any other 
> > order by using 
> > > the order-by clause.
> > > 
> > > Please let us know if this is satisfactory.
> > 
> > Document order is defined for nodes. We may want to preserve 
> > the *sequence order* between the distinct elements that would 
> > be returned. 
> > 
> > The example I gave before:
> > 
> > I have the following sequence of random numbers:
> > 
> > 3, 5, 2, 8, 6, 4, 9, 7, 1, 5, 2, 10, 9, 3
> > 
> > I want to get only the (first occuring) distinct numbers with 
> > their ordering
> > preserved:
> > 
> > 3, 5, 2, 8, 6, 4, 9, 7, 1, 10
> > 
> > This could be possible if the distinct-values() function was 
> > defined with an additional argument "preserve-order" 
> > (possibly with default value of false).
> > 
> > 
> > fn:distinct-values($srcval as xs:anyAtomicType*,
> >                    $preserve-order as xs:boolean? ) as 
> > xs:anyAtomicType*
> > 
> > 
8> > Cheers,
> > Dimitre Novatchev.
> > 
> > 
> > 
> > __________________________________
> > Do you Yahoo!?
> > Yahoo! SiteBuilder - Free, easy-to-use web site design 
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> > 
> 


=====
Cheers,

Dimitre Novatchev.
http://fxsl.sourceforge.net/ -- the home of FXSL

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Received on Monday, 4 August 2003 12:00:12 UTC

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