Destabilizers and independence of XML updates

Abstract

Independence analysis is the problem of determining whether an update affects the result of a query, e.g. a constraint or materialized view. We develop a new, modular framework for static independence analysis that decomposes the problem into two orthogonal subproblems: approximating the destabilizer, that is, a finite representation of the set of updates that can change the result of the query, and testing whether the update and destabilizer overlap via an intersection analysis. Focusing on XML queries as the view language and the XQuery Update Facility as the update language, we present a syntactic query rewriting algorithm for translating queries to destabilizers, and show that intersection checking can be reduced to satisfiability problems for which efficient checkers already exist. We present an implementation based on an expressive tree satisfiability checker and a Satisfiability Modulo Order package, and give experiments confirming that the resulting analysis is both fast and effective.

XML query-update independence analysis revisited

“…We provide evidence that our approach is more expressive in theory, equally accurate, and provides better performance compared to the various alternatives suggested in [2]. We provide experimental results that back our claims and invalidates Benedikt and Cheney's claims that using such an approach is not competitive.…”

“…In this paper, we revisit query-update independence analysis as proposed by Benedikt and Cheney [2] under the light of the latest developments in intersection testing through a satisfiability checker for an expressive logic, namely the µ-calculus.…”

“…In this section we recall the XML query-update framework introduced by Benedikt and Cheney [2] that we have reimplemented as a prerequisite for developing our approach.…”

“…In [2], Benedikt and Cheney provide a generic framework for independence analysis based on destabilizers and compare different approaches for intersection analysis. The clear separation of concerns in [2] between the representation problem and the problem of intersection analysis provides a good environment for comparison between different independence analysis approaches in addition to the genericity of the framework that can handle any update and query language.…”

“…The clear separation of concerns in [2] between the representation problem and the problem of intersection analysis provides a good environment for comparison between different independence analysis approaches in addition to the genericity of the framework that can handle any update and query language.…”