[xsl] Sum of multiple elements

["Chad Gorshing" <gorshing@xxxxxxxxx>]

I have an instance document, input.xml below, that I have to perform a
sum on multiple elements.  As you can see in my instance document, I
perform the sum function with the 'count' element.  I believe this is
going to mainly be a grouping problem.

I need to sum all of:
* Sex, Grade, Race - (All males, in grade 01, of race HI)
* Sex, Grade - (All males in grade 01)
* Sex, Race - (All males of race HI)
* Grade, Race - (Everybody of race HI in grade 01)

These totals are repeated for about 15 grades, and 6 races, and of
course once for male and another time for females.  So 15 * 6 = 90 ...
90 * 2 = 180 combinations.  You can see where my concern lies.

But these sums need to be group within their 'local' parent element.

My instance document can be as large as (or possibly even larger than)
20MB.  So with a document that big and with all the combinations ...
well ... I'm just plain scared :)

I would like to open the door for suggestions on the best way to
handle this.  I would assume this is best left up to something such as
a DBMS, but I am currently stuck with this scenario.  I do also have
access to the schema, so reading the possible values from a schema is
also an option instead of traversing the document.

The project will be a C# 2.0 app, but for testing and developing of
the transform I am using xalan 1.10.0 with xerces 2.7.0 ... so no XSLT
2.0 possible.

Thanks

input.xml
====================
<?xml version="1.0" ?>
<data xmlns="http://schemas.somewhere.com/class.xsd";>
<district num="1234">
  <local num="1234-12">
    <class>
      <grade>01</grade>
      <race>HI</race>
      <gender>M</gender>
      <count>26</count>
    </class>
    <class>
      <grade>PK</grade>
      <race>AM</race>
      <gender>M</gender>
      <count>2</count>
    </class>
  </local>
  <local num="1234-12">
    <class>
      <grade>KG</grade>
      <race>HI</race>
      <gender>F</gender>
      <count>21</count>
    </class>
    <class>
      <grade>KG</grade>
      <race>HI</race>
      <gender>F</gender>
      <count>7</count>
    </class>
  </local>
</district>
</data>