Composition and Inversion of Schema Mappings

TL;DR

This paper reviews formal approaches to the semantics, expression languages, and algorithms for composing and inverting schema mappings, focusing on data exchange and tuple-generating dependencies.

Contribution

It provides a comprehensive analysis of existing proposals for schema mapping composition and inversion, highlighting their formal semantics and computational aspects.

Findings

Analyzes various semantics for schema mapping operators.

Examines language requirements for expressing composition and inversion.

Discusses algorithmic challenges in computing these operators.

Abstract

In the recent years, a lot of attention has been paid to the development of solid foundations for the composition and inversion of schema mappings. In this paper, we review the proposals for the semantics of these crucial operators. For each of these proposals, we concentrate on the three following problems: the definition of the semantics of the operator, the language needed to express the operator, and the algorithmic issues associated to the problem of computing the operator. It should be pointed out that we primarily consider the formalization of schema mappings introduced in the work on data exchange. In particular, when studying the problem of computing the composition and inverse of a schema mapping, we will be mostly interested in computing these operators for mappings specified by source-to-target tuple-generating dependencies.