Study and comparison of schema versioning and database conversion techniques for bi-temporal databases

Schema evolution and schema versioning are two techniques used for managing database evolution. Schema evolution keeps only the current version of a schema and database after applying schema changes. Schema versioning creates new schema versions and converts the corresponding data while preserving the old schema versions and data. To provide the most generality, bi-temporal databases can be used to realize schema versioning, since they allow both retroactive and proactive updates to the schema and database. We first study two proposed database conversion approaches for supporting schema evolution and schema versioning: single table version approach and multiple table version approach. We then propose the partial table version approach to solve the problems encountered in these approaches when applied to bi-temporal databases.