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UBC Theses and Dissertations

On detecting and repairing inconsistent schema mappings Ho, Terence Cheung-Fai


Huge amount of data flows around the Internet every second, but for the data to be useful at its destination, it must be presented in a way such that the target has little problem interpreting it. Current data exchange technologies may rearrange the structure of data to suit expectations at the target. However, there may be semantics behind data (e.g. knowing the title of a book can determine its #pages) that may be violated after data translation. These semantics are expressed as integrity constraints (IC) in a database. Currently, there is no guarantee that the exchanged data conforms to the target’s ICs. As a result, existing applications (e.g. user queries) that assume such semantics will no longer function correctly. Current constraint repair techniques deal with data after it has been translated; thus take no consideration of the integrity constraints at the source. Moreover, such constraint repair methods usually involve addition/deletion/modification of data, which may yield incomplete or false data. We consider the constraints of both source and target schemas; together with the mapping, we can efficiently detect which constraint is violated and suggest ways to correct the mappings.

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