Re: Sorting and Paging in one pass with XSLT 2

Michael,
Thanks for your help.

I was able to implement your solution with two small changes.
1. Closing quote on as="element(row)*"
2. Small change in group-adjacent="(position() - 1) idiv $perPage">

Thanks again for your expertise!
Kyle

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@xxxxxxxxxxxx] Sent: 19 November 2004 03:26
To: xsl-list@xxxxxxxxxxxxxxxxxxxxxx
Subject: 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