Review Comment:
This manuscript was submitted as 'full paper' and should be reviewed along the usual dimensions for research contributions which include (1) originality, (2) significance of the results, and (3) quality of writing.
I appreciate the effort made by the authors to fill important gaps in the the article, particularly with relation to the size of the data used in the experiments.
However, I am still sceptical about the value of the contribution. The UFO-indexing approach is not a novel contribution and the benchmark presented does not seem to make sense outside the specific case of testing a number of triple stores with that. In other words, who else would need this benchmark? Future UFO users would just use one of the best triple stores in your results (e.g. Virtuoso), without bothering of performing the bench ark again, right?
Don't get me wrong, it is useful to know which triple store performs better with UFO-shaped data, it's just that the resulting benchmark does not generalise outside UFO and therefore is of limited use.
The claim that existing benchmarks do not pay attention to the shape of data seems not accurate. The shape of data is taken into account at the RDF level, with complex graph patterns, etc… The presented work has a point on generating an ontology-specific benchmark (and this is the most interesting part of the article) but this aspect should be generalised to other ontologies (shapes) and evaluated for its capacity of generating useful and high-quality queries, to be a contribution.
What is the take-away message of the article? The performance of the tested triple stores is comparable to previous research, nothing new on that side. The indexing mechanism makes the queries faster. OK, but this is not surprising (and already published).
I feel appropriate to leave a decision to the editors.
|