Answering Tree Pattern Queries Using Views, a revisit
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We revisit the problem of answering tree pattern queries using views. We first show that, for queries and views that do not have nodes labeled with the wildcard *, there is an alternative to the approach of query rewriting which does not require us to find any rewritings explicitly yet which produces the same answers as the maximal contained rewriting. Then, using the new approach, we give a simple criterion and a corresponding algorithm for identifying redundant view answers, which are view answers that can be ignored when evaluating the maximal contained rewriting. Finally, for queries and views that do have nodes labeled *, we provide a method to find the maximal contained rewriting and show how to answer the query using views without explicitly finding the rewritings.
EDBT/ICDT 2011 Joint Conference Electronic Conference Proceedings
Copyright ACM 2011. This is the author's version of the work. It is posted here by permission of ACM for your personal use. Not for redistribution. The definitive version was published in EDBT/ICDT '11 Proceedings of the 14th International Conference on Extending Database Technology , ISBN 978-1-4503-0528-0, dx.doi.org/10.1145/1951365.1951386