I run a Virtuoso Server and missed a number of results when making a SPARQL-Select request. I tracked it down and find a really strange behaviour, that I cannot explain.
But to start from the beginning.
The endpoint I query can be found at http://creativeartefact.org/sparql
I) Check for a specific triple:
ASK WHERE {
<http://creativeartefact.org/mbrainzImport/f18e677a-4051-486a-aa64-d9a3bfef90af>
<http://creativeartefact.org/ontology/represents>
<http://creativeartefact.org/mbrainzImport/35ed9f2a-6ce4-44ca-9c7a-967377b0e007>. }
The query returns TRUE
II) Now getting a bit more unspecific:
ASK WHERE {
?s
<http://creativeartefact.org/ontology/represents>
<http://creativeartefact.org/mbrainzImport/35ed9f2a-6ce4-44ca-9c7a-967377b0e007>. }
If the first returns true, the second shall do as well, shouldn't it? But it doesn't. It return FALSE!
If I replace the predicate or the object with a variable, it returns true as expected. Only when setting a variable for the subject, it returns false.
That the data really exists in the triple store can be tested by running the query
SELECT * WHERE {
?s
?p
<http://creativeartefact.org/mbrainzImport/35ed9f2a-6ce4-44ca-9c7a-967377b0e007>. }
You will see, that both results comw with p = http://creativeartefact.org/ontology/represents - which is exactly the predicate I am asking for in the former query.
To make it even more strange, there ARE triples with the aforementioned format, that return the triples:
select * {
?s
<http://creativeartefact.org/ontology/represents>
<http://creativeartefact.org/mbrainzImport/e4003568-5645-4ee1-abd0-2e8156272e59>. }
Any idea, what is happening here?
Thanks in advance,
Frank
The Virtuoso being used is an original 07.00.3203 build from 2013.
I would suggest upgrading to the latest Virtuoso 07.10.3211, open source or commercial, depending on which is in use here, and see if the problem persists ...
Related
I have a data source file that one of its properties is an actual class instance:
<clinic:Radiology rdf:ID="rad1234">
<clinic:diagnosis>Stage 4</clinic:diagnosis>
<clinic:ProvidedBy rdf:resource="#MountSinai"/>
<clinic:ReceivedBy rdf:resource="#JohnSmith"/>
<clinic:patientId>7890123</clinic:patientId>
<clinic:radiologyDate>01-01-2017</clinic:radiologyDate>
</clinic:Radiology>
so clinic:ProvidedBy is pointing to this:
<clinic:Radiologists rdf:ID="MountSinai">
<clinic:name>Mount Sinai</clinic:name>
<clinic:npi>1234567</clinic:npi>
<clinic:specialty>Oncology</clinic:specialty>
</clinic:Radiologists>
How do I query using the property clinic:providedBy (which is of type clinic:Radiologists)? Whatever I have tried does not bring back results.
It's also not clear what exactly you want to have, so my answer will return "all radiology resources that are provided by MountSinai":
PREFIX clinic: <THE NAMESPACE OF_THE_CLINIC_PREFIX>
PREFIX : <THE_BASE_NAMESPACE_OF_YOUR_RDF_DOCUMENT>
SELECT DISTINCT ?s WHERE {
?s clinic:ProvidedBy :MountSinai
}
But, I really suggest to start with an RDF and SPARQL tutorial, since form your comment your query
SELECT * WHERE { ?x rdf:resource "#MountSinai" }
is missing fundamental SPARQL basics. And for writing a matching SPARQL query it'S always good to have a look at the data in Turtle resp. N-Triples format both of which being closer to the SPARQL syntax.
Consider the following snippet
ASK WHERE { wd:Q734774 wdt:P31 wd:Q3918. }
This works fine in Wikidata. I want to use some of the path syntax in the this snippet. Specifically I want to limit the number of the times "wdt:P31" used in the path. According to the guidelines this should be the right syntax:
ASK WHERE { wd:Q734774 wdt:P31{,3} wd:Q3918. }
But it's giving me weird error messages. Any ideas?
The final version of SPARQL 1.1 Property Paths lets you do this with the following query --
ASK WHERE
{ wd:Q734774
wdt:P31? / wdt:P31? / wdt:P31?
wd:Q3918
}
For clarity, I've put the full Property Path Predicate (wdt:P31? / wdt:P31? / wdt:P31?) on a separate line between Subject (wd:Q734774) and Object (wd:Q3918). The trailing ? asks for one-or-zero instances of the wdt:P31 predicate, and the / asks for a sequence, so this full path asks for a sequence of zero-or-one-or-two-or-three instances.
I have a query to get some similar instances for a specific instance, which is owbes:Dies_Irae instance. This is the query:
CONSTRUCT { ?recommendable0 ?predicate0 ?similarity0 } WHERE {
?recommendable0 ?predicate0 ?object0.
owbes:Dies_Irae ?predicate0 ?object0.
?predicate0 owbes:hasSimilarityValue ?similarity0.
?recommendable0 rdf:type ?someType.
?someType rdfs:subClassOf owbes:Recommendable.
}
It works fine, I get in the results what I'm supposed to. However, I also get the same instance owbes:Dies_Irae. Is there a way to exclude it from the result?
Well, I'm sure there is. I tried to search, I found that there is a filter, I tried to use it, but no succeed. This is the filter that I apply FILTER (?recmmendable0 != owbes:Dies_Irae)
I also tried to check if both of them have the same rdf:about but it didn't work.
Here you go the result:
<http://www.welovethesemanticweb.com/recommendation-systems#Requiem:_Sequentia>
recommendation-systems:hasArtist
"0.4"^^xsd:double .
recommendation-systems:Le_nozze_di_Figaro
recommendation-systems:hasArtist
"0.4"^^xsd:double .
recommendation-systems:Dies_Irae
recommendation-systems:hasArtist
"0.4"^^xsd:double .
as you see, the last instance is the one that I'd like to exclude
FILTER (?recmmendable0 != owbes:Dies_Irae)
You didn't spell recommendable0 correctly in your filter. Since the variable isn't used anywhere else, it never has a value, so the filter doesn't have anything to compare.
I use this sparql query to get as much cities as possible:
select * where {
?city rdf:type dbo:PopulatedPlace
}
However, some expected ones are missing e.g.
http://dbpedia.org/resource/Heidelberg
(neither that nor one of its wikiRedirects)
which is of a dbo:PopulatedPlace as this query returns true (in JSON):
ask {
:Heidelberg a dbo:PopulatedPlace
}
I need that list to be exhaustiv because later I will add constraints based on user input.
I use http://dbpedia.org/snorql/ to test the queries.
Any help is appreciated.
UPDATE:
One of the Devs told me the public endpoint is limited ( about 1K ).
I'll come up with a paginated solution and see if it contains the 'outlier'.
UPDATE2:
The outlier is definitly in the resultset of rdf:type dbo:Town.
Using dbo:PopulatedPlace yields too many results to check per hand, though.
The public endpoint limits results to about 1K. Pagination or use of a smaller subclass of dbo:PopulatedPlace yields the result.
I am trying to perform a simple update of the value of a property that that has a given resource as its subject.
Here is my query:
WITH <http://127.0.0.1:3000/dendro_graph>
DELETE { <http://127.0.0.1:3000/project/datanotes/records/teste/filho%20do%20teste> <http://purl.org/dc/elements/1.1/creator> ?o0 .
}
INSERT
{
<http://127.0.0.1:3000/project/datanotes/records/teste/filho%20do%20teste> <http://purl.org/dc/elements/1.1/creator> "creator1" .
}
WHERE { <http://127.0.0.1:3000/project/datanotes/records/teste/filho%20do%20teste> <http://purl.org/dc/elements/1.1/creator> ?o0 .
}
The result of this is that the delete is executed, but the insert is not; I end up destroying all instances of the property, but no new value is added.
If I remove the WHERE clause, I end up with duplicate triples, because it seems the DELETE is not executed.
What am I doing wrong?
EDIT:
This code produces the duplicates:
WITH <http://127.0.0.1:3000/dendro_graph>
DELETE
{
<http://127.0.0.1:3000/project/datanotes/records/teste/filho%20do%20teste> <http://purl.org/dc/elements/1.1/creator> ?o0 .
}
INSERT
{
<http://127.0.0.1:3000/project/datanotes/records/teste/filho%20do%20teste> <http://purl.org/dc/elements/1.1/creator> "creator1" .
}
The query without the WHERE clause is not a legal SPARQL expression, and should have resulted in a syntax error. If the engine you're using accepts this, then that is a bug in that engine.
At first glance, ditto for the earlier operation, which you say deletes but does not insert: as far as I can see the SPARQL expression is correct, and if as you say the insert part does not get executed, that means you've discovered a bug in the engine that executes it. I recommend you get in touch with the developers directly.
Here is a workaround I used to get this working (finally thank God). It seems you can specify several operations to be executed over the graph in a single operation using the semicolon ;.
I ended up specifying the DELETE statement and then the UPDATE one
Check this out for code sample : SPARQL Update example for updating more than one triple in a single query