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Questions tagged [d2rq]

The D2RQ Platform is a system for accessing relational databases as virtual, read-only RDF graphs. It offers RDF-based access to the content of relational databases without having to replicate it into an RDF store.

The D2RQ Platform is a system for accessing relational databases as virtual, read-only RDF graphs. It offers -based access to the content of relational databases without having to replicate it into an RDF store.

The main features of D2RQ are:

  • query a non-RDF database using SPARQL
  • access the content of the database as Linked Data over the Web
  • create custom dumps of the database in RDF formats for loading into an RDF store
  • access information in a non-RDF database using the Apache Jena API

The D2RQ Platform consists of:

  • The D2RQ Mapping Language a declarative mapping language for describing the relation between an ontology and an relational data model.
  • The D2RQ Engine a plug-in for the Jena Semantic Web toolkit, which uses the mappings to rewrite Jena API calls to SQL queries against the database and passes query results up to the higher layers of the frameworks.
  • D2R Server an HTTP server that provides a Linked Data view, a HTML view for debugging and a SPARQL Protocol endpoint over the database.

The currently supported databases are

You should be using this tag if your question is related to the use of D2RQ platform or its integration with other databases.

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In D2RQ, I run d2r-server.bat kg_movie.ttl,but got an error: "Exception in thread "main" java.lang.ExceptionInInitializerError"

I want to use D2RQ to start a service,so I run d2r-server.bat kg_movie.ttl, but got the following error: Exception in thread "main" java.lang.ExceptionInInitializerError at com.ibm.icu.impl.UPropertyAliases.(UPropertyAliases.java:87) …
pfwl
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Database connection problem encountered using d2rq

When I convert the data in MySQL into RDF, when using generate-mapping -u root -p 123456 -o kg_demo_movie_mapping.ttl "jdbc:mysql:///kg_demo_movie?useSSL=false&serverTimezone=UTC" I report an error.Loading class com.mysql.jdbc.Driver'. This is…
Felixgjh
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How to get response time on d2r-query of D2RQ?

I'm using d2r-query of D2RQ to make some SPARQL Query, I'm using commande line. Please, how can I get a response time? d2r-query myMappedData.ttl "SELECT * {?s ?p ?o} LIMIT 1000" Is there other tools to use to get the response time?
kebir
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Login failed for user 'XYZ' Error: 18456, Severity: 14, State: 5

I'm trying to map the content of a relational database to RDF using D2RQ. To generate-mapping I'm using Command Prompt. I’m trying to access the SQL Server database but I’m getting the error: Database Connection to…
Buni
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Compiling D2RQ with ant

D2RQ is shipped with an ant build script, which works fine. I can compile on a linux box, where the default ant version is 1.8.2 and the javac version is 1.7.0_121. I want to compile D2RQ with Java 8. I've downloaded ant 1.10, which requires Java 8…
ChrisW
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Filtering with options in SPARQL

I've got a dataset (exposed via D2RQ) from which I can run the following SPARQL query SELECT ?index ?freetext ?label WHERE { ?s a prov:Agent ; skos:notation ?index. ?s skos:description ?freetext . OPTIONAL {…
ChrisW
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Modify Jena model returned by D2RQ

D2RQ creates a RDF representation of the DB using a Jena model. Model m = new ModelD2RQ("file:outfile2.ttl"); I know that the returned model is a "read-only" model. Hence, if I try to add a resource to the model I get a…
user3579222
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how to set oracle JDBC database URL

I am using an application which needs to access my oracle database to do some tasks with my data. That application needs two properties, which are: d2rq:jdbcDSN The JDBC database URL. This is a string of the form jdbc:subprotocol:subname. For a…
Ania David
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Openlink Virtuoso does not apply FILTER using SERVICE clause

I am trying to run the following query both from Virtuoso and Fuseki-server. I use the SERVICE clause to connect to the SPARQL endpoint of D2R. The problem is that while Fuseki correctly applies the FILTER, Virtuoso doesn't do the same and returns…
Francesco
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Data property with d2rq

I am using the D2RQ Language to create the mapping file. I have a class Persona with this defination: # Table persone map:Persona a d2rq:ClassMap; d2rq:dataStorage map:database; d2rq:uriPattern "persona/@@persona.cognome_persona@@"; …
user3563844
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Mapping database with D2RQ

I am trying to do the mapping between with my database. I am using Jena and the D2RQ Engine. I do not know how I can configure the file .ttl with information about the connection with the database. Here my code: public class CreateOntModel5 { …
user3563844
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Error java.lang.IncompatibleClassChangeError: Implementing class

I have a Dynamic Web Project in Java and I use Jena and D2RQ libraries. When I start my project as "Java Application", I have this problem: Exception in thread "main" java.lang.IncompatibleClassChangeError: Implementing class at …
user3582433
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Generate mapping for SQL database to RDF with D2RQ

I'm trying to convert a MySQL database from MAMP to an RDF graph using D2RQ (on a Mac). I've unpacked d2rq server and I've run the generate mapping tool from terminal like this: sh generate-mapping -o mapping.ttl -u root -p passw…
Tum
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enclose table name containing spaces - d2rq language

How do I enclose table name (sql server) containing space while mapping files using d2rq language? table name is Compression Stats So in my mapping file I have among other things: d2rq:condition "Compression Stats.VelocityID = '2145C'" ; I tried…
Angelina
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Unable to query d2rq ttl file from Jena

I am trying to query from a d2rq-generated ttl file. Following is my code snippet: ModelD2RQ m = new ModelD2RQ("file:C:\\Users\\599782\\Downloads\\d2rq-0.8.1\\northwind.ttl"); String sparql = "PREFIX vocab:…
Kaushik Shrestha
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