GraphDB Users Ask: Can I Use the Standard Ontop Configurations?

ONTOTEXT ANSWER:

GraphDB virtualization is built on the open source Ontop tool. Ontop is under active development and often gets improvements and updates. The GraphDB team doesn’t always catch up to that development. For example, with Ontop 4.1.0, query logging was introduced that allows you to check the translated query. However, the GraphDB configuration does not allow you to set that configuration parameter. Does this mean you can’t use query logging?

When you are creating a repository, you can do it by passing along a turtle configuration file, in a specific repository folder. The same can, of course, be done with Ontop. When the Ontop repository is created, a special folder and configuration file are created. This file is located within data\repositories\{{name}}\ontop_jdbc.properties. The name of the file is telling – this literally contains the system properties for Ontop!

Of course, once you know where the file is located, the next step is quite easy – simply adding the Ontop parameters in the file will lead to them being applied. This would require restarting the database, though. So, if you want to skip this step, you’ll have to provide the contents of the repository directory, named after the repository, yourself. This includes the config.ttl, the mapping.obda or mapping.r2rml and the Ontop configuration. For your convenience, we have provided you with a sample Ontop properties configuration.

By default, this would be created for you automatically, but you can pass it on manually, adding lines like:

And that’s how you can set all Ontop configurations.

Note: when it comes to logging, the logs are produced in the standard output console and NOT in the log itself. So, if you need to check the Ontop logs, you will need access to the standard output console – for example, the Docker logs or the service logs.