Current State of RDF Storage and Querying
Query Languages: ICS-FORTH RQL, ILRT SquishQL, Intellidimension RDFQL, RDFPath, VERSA RDF Query Language, TRIPLE, DAML+OIL Query Language, TMQL, Ontopia Tolog.
Interesting TRIPLE is the only that supports reification. Versa is the only one that supports nested queries. Most of them do not support grouping, sorting and aggregate functions.
RDF Stores: ICS-FORTH RDF Suite, Sesame, Inkling, RDFdb, RDFStore, EOR, Redland, Jena, RDF Gateway, Triple, KAON, Cereba, Emplois K24, Ontopia Knowledge Storage.
Around half of these are Java based. Cereba and Emplois look like the only commercial offerings. One of them uses OODB, most of them use PostgreSQL. The two commercial ones look like they have their own persistance. They also give a list of the performance and scalability characteristics where available.
Cereba is an RDF Inference Engine (an automated reasoner) developed by Network Inference. Its supporting facilities are similar to the University of Manchester’s FaCT Description Logics engine, with the difference that it supports instances and concrete datatypes. Cerebra allows for collaboration and has been reported to collaborate successfully with OilEd (version 2.0 and above) and Protegé-2000 with the OIL plug-in. Demonstration versions of Cerebra® for all major platforms (Windows and Linux) are available from the download section of the Network Inference website.
The full PDF is here: