Virtual graph query conversion

Hi Stardog team,

I have used virtual graph to query relational database directly using SPARQL. My question is about query conversion.

During queries, are all SPARQL queries being converted to SQL queries which are then operated on the original relational database? Are there SPARQL queries, which are not supported on virtual graphs? What is the level of optimization of SQL statements? Are hints being used?


Hi Ju Yang,

Thank you for your inquiry. The fragment of the SPARQL query which operates over the virtual graph is being translated to SQL. The supported SPARQL features are documented here. We are optimizing SQL statements locally but depending on the RDBMS to perform join optimization. We are not sending query hints to remote servers. Please let us know if you’re running into a situation that requires it.


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