Mapping Semantic Web Data with RDBMSes
http://www.w3.org/2001/sw/Europe/reports/scalable_rdbms_mapping_report/
A public report on mapping triple stores and RDBMS concentrating on surveying the schemas used and discussing mapping approaches to and from relational schemas. It describes current best practice for using such systems for Semantic Web data including feature comparisons, recommendations for particular applications and advice on tradeoffs.