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Impact Analysis of Database Schema Changes

Andy Maule

Abstract

When database schemas require change, it is typical to predict the effects of the change, first to gauge if the change is worth the expense, and second, to determine what must be reconciled once the change has taken place. Current techniques to predict the effects of schema changes upon applications that use the database can be expensive and error-prone, making the change process expensive and difficult. Our thesis is that an automated approach for predicting these effects, known as an impact analysis, can create a more informed schema change process, allowing stakeholders to obtain beneficial information, at lower costs than currently used industrial practice. This is an interesting research problem because modern data-access practices make it difficult to create an automated analysis that can identify the dependencies between applications and the database schema. In this dissertation we describe a novel analysis that overcomes these difficulties.

We present a novel analysis for extracting potential database queries from a program, called query analysis. This query analysis builds upon related work, satisfying the additional requirements that we identify for impact analysis.

The impacts of a schema change can be predicted by analysing the results of query analysis, using a process we call impact calculation. We describe impact calculation in detail, and show how it can be practically and efficiently implemented.

Due to the level of accuracy required by our query analysis, the analysis can become expensive, so we describe existing and novel approaches for maintaining an efficient and computational tractable analysis.

We describe a practical and efficient prototype implementation of our schema change impact analysis, called SUITE. We describe how SUITE was used to evaluate our thesis, using a historical case study of a large commercial software project. The results of this case study show that our impact analysis is feasible for large commercial software applications, and likely to be useful in real-world software development.

Details

Publication typePhdThesis
InstitutionUniversity College London
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