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Time- and Space-Efficient Regular Path Queries

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Diego Arroyuelo, Aidan Hogan, Gonzalo Navarro, and Javiel Rojas-Ledesma

We introduce a time- and space-efficient technique
to solve regular path queries over labeled (RDF) graphs. We
combine a bit-parallel simulation of the Glushkov automaton
of the regular expression with the ring index introduced by
Arroyuelo et al., exploiting its wavelet tree representation in order
to efficiently reach relevant states of the product graph. Our
algorithm is able to simultaneously process several automaton
states, as well as several graph nodes/labels. Our experiments
show that our approach uses 3-5 times less space than the
alternatives in the literature, while generally outperforming them
in query times (1.67 times faster than the next best).