Since most of the data that is of likely use for the emerging semantic web is stored in relational databases, the argument for exposing this to SPARQL access is clear. We note that historically, SQL access to relational data has essentially never been given to the public outside of the organization. If programmatic access to corporate IS has been available to partners or the public, it has been through dynamic web pages or more recently web services. There are reasons of performance, security, maintainability and so forth for this.

The culture of the emerging semantic web is however taking a different turn. Since RDF and OWL offer a mergeable and queryable model for heterogeneous data, it is more meaningful and maintainable to expose selected data for outside query than it would be with SQL. Advances in hardware make this also less of a performance issue than it would have been in the client-server database era.

In the context of Virtuoso, since Virtuoso is originally a virtual/federated database, incorporating SPARQL to relational mapping is an evident extension of the product's mission as a multi-protocol, multi-platform connector between information systems.