Dear Virtuoso Team,
I installed Virtuoso 5.09 and i use it as TripleStore for a semantic
WebApplication . ;-)
All works fine and also really performant, but now i have detect a
little problem while using the following query:
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
PREFIX model: <http://myModel.org/resources#>
PREFIX wgs84: <http://www.w3.org/2003/01/geo/wgs84_pos#>
SELECT ?resource FROM <http://myModel.org/resources>
WHERE
{
?resource rdf:type model:POI .
?resource model:hasPoint ?point .
?point wgs84:long ?longitude .
?point wgs84:lat ?latitude .
FILTER (?longitude >= 0) .
FILTER (?longitude <= 10) .
FILTER (?latitude >= 45) .
FILTER (?latitude <= 55)
}
LIMIT 10 OFFSET 0
The TripleStore consists of 500.000 triples and if i use this query i
get a response between 1 second and 2 minutes (different values for
longitude and latitude) . If i use instead of OFFSET 0 the OFFSET 10
(LIMIT = OFFSET) or a greater value, a result returns in ca. 30 ms. The
problem also exists if i increase both values like LIMIT 20 OFFSET 10.
So all Queries are quiet performant if the OFFSET is greater than or
equal to the LIMIT.
In addition to the use of this query via ODBC i tested it with the
Virtuoso-Conductor and via isql. The results are similar.
All the Very Best
Michael Martin
