Triplestore

A triplestore is a purpose-built database for the storage and retrieval of Resource Description Framework (RDF) metadata.^[1]

Much like a relational database, one stores information in a triplestore and retrieves it via a query language. Unlike a relational database, a triplestore is optimized for the storage and retrieval of many short statements called triples, in the form of subject-predicate-object, like "Bob is 35" or "Bob knows Fred".

Some triplestores can store billions of triples.^[2] The performance of a particular triplestore can be measured with the Lehigh University Benchmark (LUBM), or with real data from UniProt.

Implementation

Some triplestores have been built as database engines from scratch, while others have been built on top of existing commercial relational database engines (i.e. SQL-based).^[3] Like the early development of OLAP databases, this intermediate approach allowed large and powerful database engines to be constructed for little programming effort in the initial phases of triplestore development. Long-term though it seems likely that native triplestores will have the advantage for performance. A difficulty with implementing triplestores over SQL is that although "triples" may thus be "stored", implementing efficient querying of a graph-based RDF model (i.e. mapping from SPARQL) onto SQL queries is difficult.^[4]

See also

• Freebase, uses a triplestore called graphd.^[5]

References

External links

• A list of large triplestores
• Lehigh University Benchmark (LUBM)
• Semantic Systems Biology
• ARC's RDF Store is built using PHP with MySQL as the backend for the triplestore. It also provides a SPARQL endpoint for access and updating of stored triples.