RDF and Databases "Some RDF research dropped me to a nice paper (PDF) from IBM discussing RDF with relational databases. This combination can replace half-baked application data mechanisms. These crop up regularly in my consulting work. Think nested directories of Windows INI files and brittle, binary files breaking on minor design iterations. The pain, the pain."
"There are several projects in this domain. My favorite so far is OpenRDF Sesame. It supports querying at the semantic level. It seems more mature than others, having derived from previous efforts, and works with both PostgreSQL and MySQL as well as Oracle. An abstraction layer called SAIL makes Sesame database-agnostic. Sesame even sports a stand-alone b-tree system, or in-memory operation, if you don't want an external database."