Sandeep Gupta wrote:
Hi,
Our institution is hosting an sparql endpoint which was populated
using sponger feature. Due to this we have several named graphs
(roughly 30-40). Sometimes we aren't sure which graphs would be
relevant for the query so we list all the graphs in a one from clause.
Something like this :
Select *
from <graph1>
from <graph2>
from <graph3>
...
....
30 such lines
where
{
few-simple-predicates
}
//////////////////////////
The predicates aren't too fancy simple relationship chain of size 2-3.
The problem is now is that virtuoso estimates the query time to be 551
secs and doesn't execute the query.
Is there a simple fix for this problem.
Is it possible to query in two stages first finding the graphs where
the constants in predicate occurs and then running the original
query only those graphs.
P.S. I have tried using bit-map indices but it doesn't help with our
query significantly.
Appreciate any help in this regard.
What version of Virtuoso are you running?
Later release do not require you to specify named graphs or build any
specific indices.
Also look at you INI file for the current Query Timeout which is
affecting your queries. Basically look at the [SPARQL] section [1].
Links:
1. http://docs.openlinksw.com/virtuoso/dbadm.html#ini_SPARQL
Kingsley
Thanks
Sandeep
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OpenLink Software
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