RE: Using key to group large documents

------------------------------

Date: Wed, 17 Mar 2004 10:01:11 -0000
From: "Michael Kay" <mhk@xxxxxxxxx>
Subject: RE:  Using key to group large documents

You've only shown us one line of your code. It's almost certainly possible
to improve it, but you will have to publish it first.

Michael Kay 
---------------------------------
The detail is quite a lot - i trimmed the input to only contain enough to
get the idea accross.
I include my attempt at grouping the information using many keys. The result
is correctly grouped (Category, Member, Contract, Benefit) but I still have
some performance problems on large (2Meg+) files.

XML:
==============================================================[XML start]
<?xml version='1.0' ?>
<bulk-benefit-statement>
    <bulk-benefit>
        <bulk-benefit-items>
            <bulk-benefit-item>
                <person>
                    <person-number>20108</person-number>
                    <contract-number>100</contract-number>
                    <class-number>1</class-number>
                    <firstname>Jack</firstname>
                </person>
                <benefit>
                    <lots-of-elements>foo</lots-of-elements>
                </benefit>
            </bulk-benefit-item>

            <bulk-benefit-item>
                <person>
                    <person-number>20108</person-number>
                    <contract-number>100</contract-number>
                    <class-number>1</class-number>
                    <firstname>Jack</firstname>
                </person>
                <benefit>
                    <lots-of-elements>foo</lots-of-elements>
                </benefit>
            </bulk-benefit-item>
        
            <bulk-benefit-item>
                <person>
                    <person-number>20108</person-number>
                    <contract-number>100</contract-number>
                    <class-number>2</class-number>
                    <firstname>Jill</firstname>
                </person>
                <benefit>
                    <lots-of-elements>foo</lots-of-elements>
                </benefit>
            </bulk-benefit-item>
        
         </bulk-benefit-items>
    </bulk-benefit>
</bulk-benefit-statement>
==============================================================[XML stop]
And then the XSL:
==============================================================[XSL start]
<xsl:stylesheet version="1.0"
xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
   <xsl:output method="xml" encoding="UTF-8" version="1.0"
omit-xml-declaration="no" standalone="yes" indent="yes" />

   <xsl:key name="cat" match="//person" use="class-number" />

   <xsl:key name="per" match="//person"
use="concat(class-number,concat(person-number, contract-number))" />

   <xsl:key name="membersByCat" match="//person"
use="concat(person-number,class-number)" />

   <xsl:key name="contracts" match="//person" use="contract-number" />

   <xsl:variable name="uniqueMembersByCat"
select="//person[generate-id(.)=generate-id(key('membersByCat',concat(person
-number,class-number))[1])]" />

   <xsl:variable name="uniqueContracts"
select="//person[generate-id(.)=generate-id(key('contracts',contract-number)
[1])]" />

   <xsl:variable name="contractsByMemberAndCat"
select="//person[generate-id(.)=generate-id(key('per',concat(class-number,co
ncat(person-number, contract-number)))[1])]" />

   <xsl:template match="bulk-benefit-statement">
      <display>
         <categories>
            <xsl:for-each
select="//person[generate-id(.)=generate-id(key('cat',class-number)[1])]">
               <xsl:variable name="theCat" select="class-number" />
               <category>
                  <xsl:attribute name="category">
                     <xsl:value-of select="class-number" />
                  </xsl:attribute>
                  <xsl:for-each
select="$uniqueMembersByCat[class-number=$theCat]">
                     <xsl:variable name="thePerson" select="person-number"
/>
                     <member>
                        <xsl:attribute name="number">
                           <xsl:value-of select="person-number" />
                        </xsl:attribute>
                        <contracts>
                           <xsl:for-each
select="$contractsByMemberAndCat[class-number=$theCat and
person-number=$thePerson]">
                              <xsl:variable name="theContract"
select="contract-number" />
                              <contract>
                                 <xsl:attribute name="number">
                                    <xsl:value-of select="contract-number"
/>
                                 </xsl:attribute>
                                 <!-- Now keep the stuf I need for the items
-->
                                 <xsl:apply-templates
select="//bulk-benefit-item[person/class-number=$theCat and
person/person-number=$thePerson and person/contract-number=$theContract]" />
                              </contract>
                           </xsl:for-each>
                        </contracts>
                     </member>
                  </xsl:for-each>
               </category>
            </xsl:for-each>
         </categories>
      </display>
   </xsl:template>


   <xsl:template match="bulk-benefit-item">
      <xsl:if test="position() = 1">
          <!-- here I copy all the elements that are repeated in the input
for all benefits -->
      </xsl:if>
      <!--Then I grab the benefit -->
      <xsl:copy-of select="benefit" />
   </xsl:template>
   

</xsl:stylesheet>
==============================================================[XSL start]

Any suggestions will be happily received!!

Regards,
Heinz Seldte

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