Hello, I recently read the paper ‘SPARQL Basic Graph Pattern Optimisation Using Selectivity Estimation’ by Markus Stocker et al. from WWW 2008. This paper proposes a new method based on graph statistics and heuristics for estimating the result size of a simple SPARQL query (simple = conjunction of BGPs). As far as I know, this approach was implemented and was part of ARQ.
I have a couple of questions regarding static query optimisation in JENA/ARQ: Does JENA/ARQ query optimiser still follow the approach by Markus Stocker et al? If no, is there a place where I can read about query optimisation in JENA/ARQ? Given a SPARQL query q, is it possible to obtain the estimated size of the result set of q? I tried following this example (https://jena.apache.org/documentation/query/explain.html <https://jena.apache.org/documentation/query/explain.html>), however, the result of explaining the query does not include the cardinality estimation. Best regards, Giorgio
