Physical Sciences and Mathematics Commons^™

A Model For Compound Type Changes Encountered In Schema Evolution, Barbara Staudt Lerner

Computer Science Department Faculty Publication Series

Schema evolution is a problem that is faced by long-lived data. When a schema changes, existing persistent data can become inaccessible unless the database system provides mechanisms to access data created with previous versions of the schema. Most existing systems that support schema evolution focus on changes local to individual types within the schema, thereby limiting the changes that the database maintainer can perform. We have developed a model of type changes incorporating changes local to individual types as well as compound changes involving multiple types. The model describes both type changes and their impact on data by defining derivation …