Not much that can be done just by changing the query I think.
If you can modify the dataset, then one approach would be to precompute the
results of the afn:namespace call. So, add an additional triple of this form to
each subject in the dataset:
<http://mynamespace#foo> my:namespace "http://mynamespace#"; .
Then you can query for
GRAPH <http://mygraph> {
?s my:namespace "http://mynamespace#"; .
?s ?p ?o .
}
and that should be much faster.
Richard
> On 31 Aug 2018, at 17:13, Steve Ray (CMU) <[email protected]> wrote:
>
> Hi,
> I’m putting out this request to the community at large to see if
> there are ideas that I’m unaware of. I have a fairly large database of
> roughly 1.5 million triples. It is populated with many sets of roughly 450
> triples which share the same namespace. Many of my operations involve
> retrieving one of those sets of triples, but I’m finding it takes about 7
> seconds to execute on TBL, installed on a 16GB AWS instance. Here is the
> SPARQL query I’m using to get a set of triples:
>
>
> PREFIX afn: <http://jena.hpl.hp.com/ARQ/function#
> <http://jena.hpl.hp.com/ARQ/function#>>
> SELECT ?s ?p ?o
> WHERE {
> GRAPH <http://mygraph <http://mygraph/>> {
> ?s ?p ?o .
> FILTER (afn:namespace(?s) = "http://mynamespace# <http://mynamespace/#>")
> .
> }}
>
>
> Is there some clever way to pull just the triples in a single namespace that
> doesn’t involve using ?s ?p ?o followed by a FILTER?
> Brilliant ideas welcome!
>
>
> - Steve
>
> Steven R. Ray, Ph.D.
> Distinguished Research Fellow
> Carnegie Mellon University
> NASA Research Park
> Building 23 (MS 23-11)
> P.O. Box 1
> Moffett Field, CA 94305-0001
> Email: [email protected] <mailto:[email protected]>
> Phone: (650) 587-3780
> Cell: (202) 316-6481
> Skype: steverayconsulting
> <image001.png>
>
>
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