[basex-talk] Efficient query for duplicates

I'm running out of memory (1.5 GB allocated) when querying for duplicate node values over a fairly flat XML database of approximately 450 MB. Can anyone suggest a more memory-efficient approach to framing this query than iterating over distinct-values as I do below? I'm hoping that there are some Basex tips and tricks to help out here. for $val in distinct-values(/dataset/item/pii) let $cnt := count(/dataset/item/pii[. = $val]) return if ($cnt > 1) then <duplicate>{$val}</duplicate> else null Thanks in advance, Constantine ________________________________ Elsevier B.V. Registered Office: Radarweg 29, 1043 NX Amsterdam, The Netherlands, Registration No. 33156677, Registered in The Netherlands.