Marc-Alexandre Nolin wrote:
Hello,
When I do the following query:
select distinct
?s
where
{
?s rdf:type <http://biology.com/Protein> .
}
limit 100
Lets say I have 20000 objects of type protein in the triplestore. I
will receive a results containing 100 rows of 100 distinct proteins.
If I run the same query again, I will receive the same 100 distinct
proteins.
Is there a way to receive a RANDOM set 100 proteins everytime I run
the query? I bet its not possible in Sparql itself, but could it be
with the Virtuoso toolset of bif:_something_ ? If its not there, how
can I expand the bif toolset ?
For example, it could be a query like this:
select distinct
?s
where
{
?s rdf:type <http://biology.com/Protein> .
bif:random(?s, 100) .
}
USE : bif:random(<variable you want a random set>, <the amount you want>)
Implemented that way, I could expand the query with other attribute.
select distinct
?s
where
{
?s rdf:type <http://biology.com/Protein> .
bif:random(?s, 100) .
?s <http://biology.com/chromosomeNumber> ?cn .
filter(?cn == 10) .
}
Thanks,
Marc-Alexandre Nolin
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Marc,
You've answered the question :-)
Just make a Stored Procedure and surface it as a magic/function predicate.
Links:
1. http://docs.openlinksw.com/virtuoso/rdfsparql.html#rdfsqlfromsparql
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Regards,
Kingsley Idehen Weblog: http://www.openlinksw.com/blog/~kidehen
President & CEO
OpenLink Software Web: http://www.openlinksw.com
