[xsl] Efficient XPath 2.0 expression to return each <row> element for which there are other <row> elements having the same navaid?

["Costello, Roger L. costello@xxxxxxxxx" <xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx>]

Hi Folks,

I have a large XML document containing data about airports around the world:

<airports>
    <row>
        <navaid>A</navaid>
    </row>
    <row>
        <navaid>B</navaid>
    </row>
    <row>
        <navaid>A</navaid>
    </row>
</airports>

Notice that there is only one <row> element having the B navaid, but two <row>
elements having the A navaid.

I want an XPath 2.0 expression to return each <row> element for which there
are other <row> elements having the same navaid. For the above example, I want
the XPath expression to return the first and third <row> elements.

Here is one way to do it:

//row[navaid = (preceding-sibling::row/navaid,
following-sibling::row/navaid)]

Eek! That is horribly inefficient. I ran that XPath expression on my XML
document and it took a long time to finish.

Is there an efficient XPath 2.0 expression to solve this problem?

Note: I am running the XPath expression from Oxygen's XPath evaluator, not
from an XSLT program.

/Roger