SPARQL on SQL Experiences

Hi, i want to set up a SPARQL Endpoint with different RDBMS as a background. Since the data in the RDBMS is updated regulary (and its quite a lot) I wouldn't want to replicate all as RDF. Instead I would like to set up a SPARQL-SQL-Mapper. After reading publications from the W3C on the topic (W3C RDB2RDF) and some research of my own I tried the D2R Server and Virtuoso.
D2R was very easy to configure and is a very nice tool. However it seems to be a little slow (I still want to run some tests on some other DBs that I am currently using)
Virtuoso on the other hand was very uncomfortable to configure i felt. I was so far only able to get a basic example running with the Virtuoso generated mappings. So far that is not useful at all but I was not able to write a custom mapping including all the necessary steps.

So my question (finally) is: What are your experiences with setting up an SPARQL Endpoint on top of (one or many) RDBMS? Is there a best practice? Whats the best software for the task? Any thoughts...


Many approaches use the D2R's SPARQL endpoint ( to expose relational data as SPARQL results. DBLP (, MusicBrainz ( etc., etc. use this approach effectively.

Support for R2RML is planned for Virtuoso to provide a higher level mapping layer between relational and RDF / Linked Data concepts, building on the core Meta Schema mapping language used for creating the current RDF Views supported and exposing is true power.

Spyder from Revelytix implements R2RML standard. It is in Beta. I only know of the product but have not tried it. Hope it helps.