Troubleshooting Linked Data Views generated from a Relational Database

What?

Virtuoso provides powerful options for generating 5-Star Linked Data from ODBC and JDBC accessible RDBMS based data sources. It provides you with the ability to produce transient and materialized Linked Data views using its native Metaschema Language or the W3C's R2RML.

Why?

Being able to diagnose problems associated with Linked Data views generation is vital for sustainable usage of this powerful Virtuoso feature.

How?

The following steps guide you through the process of generating Linked Data Views and isolating problems that might arise during the process:

  1. Pick an example script building your view, in this case we use one that builds Linked Data Views from the DB2 hosted data.
  2. It might happen that while running the script you receive output errors such as: 

    22023 The quad storage "http://www.openlinksw.com/schemas/virtrdf#DefaultQuadStorage" is edited by other client, started 2011-12-19 16:20:48

  3. The error above means that a manipulation was started at 2011-12-19 16:20:48, but it never completed. The default remedy is to use Virtuoso's DB.DBA.RDF_AUDIT_METADATA() function, as follows: 

    SQL> DB.DBA.RDF_AUDIT_METADATA(1, '*');

  4. The resulting output should contain no errors.
  5. Some demo links from the created Linked Data Views:

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