223Algebraic Optimization of RDF Graph Pattern Queries on MapReduce
6.9.2 Case stuDy: imPaCt oF nesting anD lazy unnesting strategies
For graPh Pattern Queries with multivalueD ProPerties
This section presents a study on the impact of the proposed nesting and unnest-
ing strategies on minimizing the redundancy factor in intermediate results while
processing graph pattern queries. The comparative evaluation included two popular
relational-style systems, Apache Pig (Pig-Opt with COGROUP-based star-join com-
putation) and Hive (Hive), both of which support tuple-based algebra. NTGA-Opt
denotes NTGA with lazy partial unnesting strategy.
Setup and Testbed. Experiments were conducted on a 10-node Hadoop cluster
with Pig release 0.10.0, Hive 0.8.1