Hi Paul,
Why would the outer query need any graph patterns other than the
subquery? You ought to be able to do exactly what you have below without
anything in the "what goes here" spot.
Lee
On 1/23/2013 3:56 PM, Paul Tyson wrote:
Hi all,
I'm wondering if there is a simple solution to this problem.
I have a rather complicated query, consisting of several union
clauses, which by its nature will return duplicates. I need to get a
unique solution set so I can group them and sum a couple of fields.
Simply wrapping the union query in a nested SELECT DISTINCT doesn't
work, because the outer query has no graph pattern to match the
variables projected from the subquery.
I tried adding a series of BIND statements to simply rename the
subquery variables for use by the aggregate outer query, but that
didn't work (with jena, at least).
The source dataset is nearly 500M triples. I'm using Jena 2.7.3. The
subquery will return anywhere from a few dozen to a few hundred
solutions, and by itself runs very quickly.
Here's a skeleton view of the query. Is there something to fill "what
goes here" that will pass the subquery results up to the grouping
function?
select ?var1 ?var2 (sum(?var3) as ?var3_total)
where {
{ ??? what goes here ??? }
{select distinct ?var1 ?var ?var3
where { ... complicated union query ... }}
}
group by ?var1 ?var2
Or any other suggestions on how to tackle this problem?
Thanks,
--Paul
