Can someone help me with the following problem, please?

I'm attempting to merge two XML documents with similar structures. I would like to use an XSL transformation to accomplish this.

The first document looks like this:

<RECORDS>
   <DETAIL INDEX="1">
      <FIELD01>record 1 data</FIELD01>
      <FIELD02>record 1 data</FIELD02>
   </DETAIL>
   <DETAIL INDEX="3">
      <FIELD01>record 3 data</FIELD01>
      <FIELD02>record 3 data</FIELD02>
   </DETAIL>
   <DETAIL INDEX="999">
      <FIELD01>record 999 data</FIELD01>
      <FIELD02>record 999 data</FIELD02>
   </DETAIL>
</RECORDS>

The second file looks like this:

<RECORDS>
   <RECORD INDEX="3">
      <FIELD03>record 3 data</FIELD03>
      <FIELD04>record 3 data</FIELD04>
      <FIELD05>record 3 data</FIELD05>
   </RECORD>
   <RECORD INDEX="999">
      <FIELD03>record 999 data</FIELD03>
      <FIELD04>record 999 data</FIELD04>
      <FIELD05>record 999 data</FIELD05>
   </RECORD>
   <RECORD INDEX="1">
      <FIELD03>record 1 data</FIELD03>
      <FIELD04>record 1 data</FIELD04>
      <FIELD05>record 1 data</FIELD05>
   </RECORD>
</RECORDS>

and the output should look like this:

<RECORDS>
   <DETAIL INDEX="1">
      <FIELD01>record 1 data</FIELD01>
      <FIELD02>record 1 data</FIELD02>
      <FIELD03>record 1 data</FIELD03>
      <FIELD04>record 1 data</FIELD04>
      <FIELD05>record 1 data</FIELD05>
   </DETAIL>
   <DETAIL INDEX="3">
      <FIELD01>record 3 data</FIELD01>
      <FIELD02>record 3 data</FIELD02>
      <FIELD03>record 3 data</FIELD03>
      <FIELD04>record 3 data</FIELD04>
      <FIELD05>record 3 data</FIELD05>
   </DETAIL>
   <DETAIL INDEX="999">
      <FIELD01>record 999 data</FIELD01>
      <FIELD02>record 999 data</FIELD02>
      <FIELD03>record 999 data</FIELD03>
      <FIELD04>record 999 data</FIELD04>
      <FIELD05>record 999 data</FIELD05>
   </DETAIL>
</RECORDS>

The merge must be performed by matching the values in the Index attribute of both files. Notice that in the second file, the index values are out of order. The index values in both files can be non-sequential.

Both files with have the same number of records with a maximum of 50,000 records per file.

Any help will be greatly appreciated.

David Walker
Memphis, TN

If every index value appears each file, then this isn't too difficult. Keys make it much more efficient:

<xsl:variable name="doc1" select="/">
<xsl:variable name="doc2" select="document('doc2.xml')"/>

<xsl:key name="k" match="DETAIL" use="@INDEX"/>

<xsl:template match="/">
  <RECORDS>
  <xsl:apply-templates select="RECORDS/DETAIL"/>
  </RECORDS>
</xsl:template>

<xsl:template match="DETAIL">
  <DETAIL>
   <xsl:copy-of select="@*|*"/>
   <xsl:copy-of select="key('k', @INDEX, $doc2)/*"/>
  </DETAIL>
</xsl:template>

The 3-argument form of key() is XSLT 2.0 only, on 1.0 you have to write the circumlocution

   <xsl:variable name="this" select="."/>
   <xsl:for-each select="$doc2">
     <xsl:copy-of select="key('k', $this/@INDEX)/*"/>
   </xsl:for-each>

because key() only works when the node you want is in the same document as the context node.

Michael Kay
http://www.saxonica.com/
Author, XSLT Programmer's Reference and XPath 2.0 Programmer's Reference