Louis Jachiet will give a talk on Friday 11th January, at 2pm.
The relational model has benefited from a huge body of research in
the last half century. Since its introduction, the relational model
has seen various attempts to extend it with recursion and it is now
possible to use recursion in several SQL or Datalog database systems.
The optimization of recursive queries remains, however, a challenge.
In this talk, we introduce μ-RA, a variation of the Relational Algebra
that allows for the expression of relational queries with recursion.
μ-RA can express unions of conjunctive regular path queries as well as
certain non-regular properties. We present its syntax, semantics and
the rewriting rules we specifically devised to tackle the optimization
of recursive queries. We will also present our experiment to compare
our prototype implementation of these rewriting rules with respect to