RDF is a data representation format for schema-free structured information
that is gaining momentum in the context of Semantic-Web corpora,
life sciences, and also Web 2.0 platforms. The ``pay-as-you-go'' nature of RDF
and the flexible pattern-matching capabilities of its query language SPARQL
entail efficiency and scalability challenges for complex queries.
This talk concentrates on the query processing and optimization techniques
required for managing very large RDF graphs that contain
hundreds of millions of RDF triples.