http://wiki.apache.org/incubator/HeartProposal

• http://www.w3.org/TR/rdf-sparql-query/ - The SPARQL RDF Query Language, a candidate recommendation of W3C as of 14 June 2007.
• A test suit for SPARQL can be found at http://www.w3.org/2001/sw/DataAccess/tests/r2. The web page provides test RDF data, SPARQL queries, and expected results.
• SPARQL Grammer in JavaCC - from Jena ARQ
• Large triple stores
• Scalable Semantic Web Data Management Using Vertical Partitioning Good summary of techniques storing RDF in RDBMS.
• RDF Store Benchmarks with DBpedia