Query Rewriting On Path Views Without Integrity Constraints

TL;DR

This paper introduces a new class of query rewriting plans for path views that do not rely on integrity constraints, providing practical guarantees and applicable algorithms for real-world Web services.

Contribution

It presents a novel class of plans with guarantees without requiring integrity constraints and offers a complete algorithm to enumerate these plans.

Findings

The method can find valid plans on real-world Web Services.

The proposed plans provide guarantees even without integrity constraints.

A complete and correct algorithm for plan enumeration is developed.

Abstract

A view with a binding pattern is a parameterised query on a database. Such views are used, e.g., to model Web services. To answer a query on such views, one has to orchestrate the views together in execution plans. The goal is usually to find equivalent rewritings, which deliver precisely the same results as the query on all databases. However, such rewritings are usually possible only in the presence of integrity constraints - and not all databases have such constraints. In this paper, we describe a class of plans that give practical guarantees about their result even if there are no integrity constraints. We provide a characterisation of such plans and a complete and correct algorithm to enumerate them. Finally, we show that our method can find plans on real-world Web Services.