Hello,
I seem to be having a problem utilizing certain functions inside of a
SPARQL query (specifically, OPTIONAL, BIND, and UNION). FILTER still seems
to be efficient enough, but isn't sufficient for the conditional logic that
needs to be done. The addition of any of these functions, even in very
simple contexts, reduces the speed to a standstill. I am not sure if I am
ordering the triples in an inefficient manner, or whether there is a better
way to use these functions, but they are currently too slow to be
practical.
First of all, this section of code does not use any OPTIONAL:
CONSTRUCT { ?ooo ?predicate1 ?object1 . ?object1 ?predicate2 ?object2 .
?object2 ?predicate3 ?object3}
WHERE{
FILTER (
?ooo = ?temporaryObservationVariable0)
FILTER( ?predicate1 = oboe-core:ofEntity || ?predicate1 =
oboe-core:hasMeasurement || ?predicate1 = oboe-core:hasContext ||
?predicate1 = rdf:type)
?ooo ?predicate1 ?object1.
?ooo oboe-core:hasMeasurement ?mmm .
FILTER( ?predicate2 = oboe-core:hasValue || ?predicate2 =
oboe-core:usesStandard || ?predicate2 = oboe-core:usesProtocol ||
?predicate2 = rdf:type )
?object1 ?predicate2 ?object2.
FILTER (?predicate3 = oboe-core:hasCode || ?predicate3 = rdf:type)
?object2 ?predicate3 ?object3 .
?temporaryObservationVariable0 oboe-core:ofEntity ?temporaryVariable0 .
?temporaryVariable0 rdf:type testing:Fir .
?temporaryObservationVariable0 oboe-core:hasMeasurement
?temporaryMeasurementVariable0 .
?temporaryMeasurementVariable0 oboe-core:ofCharacteristic
?temporaryPlaceholder0 .
?temporaryPlaceholder0 rdf:type testing:Height .
?temporaryMeasurementVariable0 oboe-core:hasValue
?temporaryPlaceholder1 .
?temporaryPlaceholder1 oboe-core:hasCode ?hCode .
?temporaryMeasurementVariable0 oboe-core:usesStandard
?temporaryStandardVariable2 .
?temporaryStandardVariable2 rdf:type ?temporaryStandardType2 .
}
The preceding code executes in just over a second, and returns the proper
results.
This following code, however, does use an OPTIONAL statement (and
constructs the related triple):
CONSTRUCT { ?ooo ?predicate1 ?object1 . ?object1 ?predicate2 ?object2 .
?object2 ?predicate3 ?object3. *?object3 ?predicate4 ?object4*}
WHERE{
FILTER (
?ooo = ?temporaryObservationVariable0)
FILTER( ?predicate1 = oboe-core:ofEntity || ?predicate1 =
oboe-core:hasMeasurement || ?predicate1 = oboe-core:hasContext ||
?predicate1 = rdf:type)
?ooo ?predicate1 ?object1.
?ooo oboe-core:hasMeasurement ?mmm .
FILTER( ?predicate2 = oboe-core:hasValue || ?predicate2 =
oboe-core:usesStandard || ?predicate2 = oboe-core:usesProtocol ||
?predicate2 = rdf:type )
?object1 ?predicate2 ?object2.
FILTER (?predicate3 = oboe-core:hasCode || ?predicate3 = rdf:type)
?object2 ?predicate3 ?object3 .
*OPTIONAL{ ?object3 rdf:type ?object4. ?object3 ?predicate3 ?object4 .}*
?temporaryObservationVariable0 oboe-core:ofEntity ?temporaryVariable0 .
?temporaryVariable0 rdf:type testing:Fir .
?temporaryObservationVariable0 oboe-core:hasMeasurement
?temporaryMeasurementVariable0 .
?temporaryMeasurementVariable0 oboe-core:ofCharacteristic
?temporaryPlaceholder0 .
?temporaryPlaceholder0 rdf:type testing:Height .
?temporaryMeasurementVariable0 oboe-core:hasValue ?temporaryPlaceholder1
.
?temporaryPlaceholder1 oboe-core:hasCode ?hCode .
?temporaryMeasurementVariable0 oboe-core:usesStandard
?temporaryStandardVariable2 .
?temporaryStandardVariable2 rdf:type ?temporaryStandardType2 .
}
The preceding graph (with differences in bold) is unusably slow, with the
only change being the OPTIONAL and the additional triple in CONSTRUCT. I am
not sure why this would be the case, but any help would be greatly
appreciated. Thanks again.
