RE: Sorting and Paging in one pass with XSLT 2

I think that any solution is likely to put the sorted results in memory
before splitting it into multiple result trees, so you shouldn't be worrying
too much about a two-pass solution. If your intermediate result is a
sequence of nodes, rather than a tree, then it should be reasonably
efficient, because the intermediate sequence will contain references to the
original nodes, rather than copies.

Try

    <xsl:template match="result">
        <xsl:variable name="sorted-rows" as="element(row)*>
          <xsl:perform-sort select="row">
            <xsl:sort select="lname"/>
            <xsl:sort select="fname"/>
          </xsl:perform-sort>
        </xsl:variable>
        <xsl:for-each-group select="$sorted-rows"
                            group-adjacent="position()-1 idiv $perPage">
            <xsl:result-document href="out{current-grouping-key()}.xml">
                <result>
                    <xsl:copy-of select="current-group()"/>
                </result>
            </xsl:result-document>
        </xsl:for-each-group>
    </xsl:template>

I'd be interested to know how this performs.

Michael Kay
http://www.saxonica.com/

-----Original Message-----
From: Kyle Himmerick [mailto:kyle(_at_)instabit(_dot_)com] 
Sent: 19 November 2004 03:26
To: xsl-list(_at_)lists(_dot_)mulberrytech(_dot_)com
Subject: [xsl] Sorting and Paging in one pass with XSLT 2

Hello All,

I am trying to use some of the new XSLT 2 functionality to improve my 
sorting and paging performance.

Ideally I would be able to sort and splice a large document 
tree in one 
pass.

So sort the tree and put x # of records in each result document.

Here's a pseudo of what I'm trying to do:

<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet version="1.0" 
xmlns:xsl="http://www.w3.org/1999/XSL/Transform"; 
xmlns:fo="http://www.w3.org/1999/XSL/Format";>
   <xsl:param name="perPage" select="number('10')"/>

   <xsl:template match="result">
       <xsl:for-each select="row">
           <xsl:sort select="lname"/>
           <xsl:sort select="fname"/>
           <xsl:variable name="page" 
select="ceiling(position()/$perPage)"/>
           <xsl:result-document href="out{$page}.xml">
               <result>
                   <xsl:copy-of select="."/>
               </result>
           </xsl:result-document>
       </xsl:for-each>
   </xsl:template>
</xsl:stylesheet>

Obviously this won't work as it would try create a new 
result-document 
on each pass.  Whereas I need the first $perPage rows to go into the 
same result-document.

I was hoping to find a way to use the grouping functionality 
in xslt 2.  
Possibly grouping records by their page and then iterate through 
creating a new result-document for each group of records.  I couldn't 
find a way to do this with one pass through the document, 
which is what 
I'm trying to stick with since I can potentially have very large 
incoming xml.

Any ideas or suggestions for implementing an efficient method 
of sorting 
and then paging the results?

Best Regards,
Kyle

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