select="preceding-sibling::ROW[entered_formatted_day=$curren

I am currently writing a small application using the Apache Cocoon
technology (Cocoon 1.7, Xalan 1.0) , and I am using XSLT to massage
the output from an SQL-request into a list.

My structure looks like this

<list-by-date-query>
<ROW>
  <entered_formatted_data>2000-04-02</entered_formatted_data>
  ....A...
</ROW>
<ROW>
  <entered_formatted_data>2000-04-02</entered_formatted_data>
  ....B...
</ROW>
<ROW>
  <entered_formatted_data>2000-04-01</entered_formatted_data>
  ....C...
</ROW>
</list-by-date-query>

Which I would like rendered as

<h2>2000-04-02</h2>
    A stuff
    B stuff
<h2>2000-04-01</h2>
    C stuff

In e.g. perl I would have had a variable which held the previous
value, so I could output the entered_formatted_data when the value
changed.  Apparently this isn't easy to do in XSLT.

Browsing the list archives, I ended up with this code:

    <xsl:template match="list-by-date-query/ROW">

    <xsl:variable name="currentFruit"><xsl:value-of 
      select="entered_formatted_day"/></xsl:variable>
    <xsl:variable name="others" select="preceding-sibling::ROW[entered_formatted_day=$currentFruit]"/>
    <xsl:if test="count($others) = 0">
    <h2><xsl:value-of select="entered_formatted_day"/></h2>
    </xsl:if>

which works but has the following problems:

1) It is too slow.  With 100 elements in the table it responds in
about 5 seconds, with 300 elements the web browser times out.

2) I do not understand it fully.  After spending quite some time
trying just to get to the entered_formatted_day field in the
preceding-sibling (Xalan is not very helpful in its error messages)
the above worked.  

I am suspecting that the matching code looks over the whole table instead of just the previous element, which might be causing my problems.  I am not running out of memory as such - java takes about 20 Mb - but it runs at full speed for at least 8 minutes (long after the browser timed out).

I would appreciate a hint to how I can speed up the "is this value different from the value of the same tag in the previous tag".  Apparently this list has the expertise :-)

Thanks in advance,
-- 
  Thorbjørn Ravn Andersen               "...plus...Tubular Bells!"
  http://www.mip.sdu.dk/~ravn


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