Supporting a new DMBS (GeoSpark)

[Huy Tran]

Hello,

I want to use Apache Spark/Sedona as a RDBMS within Ontop. For this purpose, I forked a Spark JDBC driver and made it work with Ontop. 

The tools work perfectly with normal queries, but not GeoSPARQL ones. The resultset is empty and no exception thrown.

Here is an extract of the log when a GeoSPARQL function is used:

================================================================

23:30:19.796 |-INFO  in i.u.i.o.r.query.impl.OntopTupleQuery - ==> evaluate()

23:30:19.796 |-INFO  in i.u.i.o.r.query.impl.OntopTupleQuery - ==> Query String=PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>

PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>

PREFIX : <http://melodi.irit.fr/ontologies/mtd>

PREFIX ais: <http://melodi.irit.fr/ontologies/ais/>

PREFIX geof:<http://www.opengis.net/def/function/geosparql/> 

prefix geo:  <http://www.opengis.net/ont/geosparql#>

SELECT *

WHERE {

 

?stop ais:geometry ?geom.

?stop2 ais:geometry ?geom2.

filter(geof:sfWithin(?geom, ?geom2)). 

} 

limit 100

23:30:19.796 |-INFO  in i.u.i.o.r.query.impl.OntopTupleQuery - ==> Parsed query=Slice (limit=100)

   Projection

      ProjectionElemList

         ProjectionElem "stop"

         ProjectionElem "geom"

         ProjectionElem "stop2"

         ProjectionElem "geom2"

      Filter

         FunctionCall (http://www.opengis.net/def/function/geosparql/sfWithin)

            Var (name=geom)

            Var (name=geom2)

         Join

            StatementPattern

               Var (name=stop)

               Var (name=_const_147068b3_uri, value=http://melodi.irit.fr/ontologies/ais/geometry, anonymous)

               Var (name=geom)

            StatementPattern

               Var (name=stop2)

               Var (name=_const_147068b3_uri, value=http://melodi.irit.fr/ontologies/ais/geometry, anonymous)

               Var (name=geom2)

23:30:19.823 |-INFO  in i.u.i.o.r.query.impl.OntopTupleQuery - ==> stm.execute getRewritingRendering=ans1(stop,geom,stop2,geom2)

SLICE limit=100

   JOIN RDF_2_DB_BOOL(GEOF_SF_WITHIN(geom,geom2))

      INTENSIONAL triple(stop,<http://melodi.irit.fr/ontologies/ais/geometry>,geom)

      INTENSIONAL triple(stop2,<http://melodi.irit.fr/ontologies/ais/geometry>,geom2)

23:30:19.882 |-INFO  in i.u.i.o.r.query.impl.OntopTupleQuery - ==> stm.execute getExecutableQuery=ans1(stop,geom,stop2,geom2)

EMPTY [stop, geom, stop2, geom2]

23:30:19.884 |-INFO  in i.u.i.o.a.c.impl.QuestStatement - ==> executeSelectQuery

23:30:19.884 |-INFO  in i.u.i.o.a.c.impl.QuestStatement - ==> executableQuery=ans1(stop,geom,stop2,geom2)

EMPTY [stop, geom, stop2, geom2]

23:30:19.884 |-INFO  in i.u.i.o.a.c.impl.SQLQuestStatement - ++++ extractSQLQuery EMPTY [stop, geom, stop2, geom2]

23:30:19.887 |-INFO  in i.u.i.o.r.query.impl.OntopTupleQuery - ==> result.hasNext()=false

23:30:19.888 |-INFO  in i.u.i.o.r.query.impl.OntopTupleQuery - ==> endQueryResult

=====================================================================

Because there is a problem with the executable query, it isn't sent to the DMBS (I made logs to trace the sql queries received inside the JDBC) . 

Thanks a lot for your help,

Ba Huy

[Guohui Xiao]

Hi Ba Huy,

Your messages have been classified by Google as spam. That's why we did not see them earlier. Now we have seen them and take them out. In the future, your messages should go through.

Could you share your setup so that we can reproduce your problem?

Best regards,

Guohui