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Supporting legacy applications when the database schema evolves represents a long-standing challenge of practical and theoretical importance. Recent work has produced algorithms and systems that automate the process of data migration and query adaptation; however, the problems of evolving integrity constraints and supporting legacy updates under schema and integrity constraints evolution are significantly more difficult and have thus far remained unsolved. In this paper, the authors address this issue by introducing a formal evolution model for the database schema structure and its integrity constraints, and use it to derive update mapping techniques akin to the rewriting techniques used for queries.
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