On 29/11/13 11:18, Florent Georges wrote:
> Hi,
>
> I have a few millions entities in a collection, and would like to
> find duplicates in it. There are several possible root element
> names (all documents do not have the same root element).
>
> By duplicates, I mean any document where the value of the element
> /*/foobar is the same. Foo is declared as a string in the schema.
> So what I am looking for, really, is the value of all the values of
> /*/foobar that appear in more than one document in that collection.
>
> Because there are several millions documents in the collection,
> it is not possible to use the naive query that would look something
> like the following:
>
> for $f in fn:collection('coll')/*/foobar
> where fn:exists(fn:collection('coll')[/*/foobar eq $f][2])
> return
> <dup>{ $f }</dup>
>
> There is a range element index configured for the element foobar.
>
> Any idea how I can optimize the query (so it actually completes)?
>
> Regards,
Use an element lexicon lookup:
cts:elememt-values(xs:QName("foobar"))[cts:frequency(.)>1]
This will give you all the values of the foobar element for which there
are duplicates. Then you'll need to look up the documents for those values.
John
--
John Snelson, Lead Engineer http://twitter.com/jpcs
MarkLogic Corporation http://www.marklogic.com
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