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Answering Queries Using Views with Arithmetic Comparisons


Foto N. Afrati, Chen Li, and Prasenjit Mitra

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Return to Queries and Views


Abstract

We consider the problem of answering queries using views, where queries and views are conjunctive queries with arithmetic comparisons (CQACs) over dense orders. Previous work only considered limited variants of this problem, without giving a complete solution. We have developed a novel algorithm to obtain maximally-contained rewritings (MCRs) for queries having left (or right) semi-interval-comparison predicates. For semi-interval queries, we show that the language of finite unions of CQAC rewritings is not sufficient to find a maximally-contained solution, and identify cases where datalog is sufficient. Finally, we show that it is decidable to obtain equivalent rewritings for CQAC queries.


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