Semantics and implementation of schema evolution in object-oriented databases
SIGMOD '87 Proceedings of the 1987 ACM SIGMOD international conference on Management of data
Schema evolution and the relational algebra
Information Systems
Temporally oriented data definitions: managing schema evolution in temporally oriented databases
Data & Knowledge Engineering
Schema evolution in database systems: an annotated bibliography
ACM SIGMOD Record
Schema evolution in OODBs using class versioning
ACM SIGMOD Record
ACM SIGMOD Record
Schema versioning for multitemporal relational databases
Information Systems
The Historical Relational Data Model (HRDM) and Algebra Based on Lifespans
Proceedings of the Third International Conference on Data Engineering
Versions of Schema for Object-Oriented Databases
VLDB '88 Proceedings of the 14th International Conference on Very Large Data Bases
Management Of Schema Evolution In Databases
VLDB '91 Proceedings of the 17th International Conference on Very Large Data Bases
Schema and Database Evolution in the O2 Object Database System
VLDB '95 Proceedings of the 21th International Conference on Very Large Data Bases
On Schema Versioning in Temporal Databases
Proceedings of the International Workshop on Temporal Databases: Recent Advances in Temporal Databases
A Taxonomy for Schema Versioning Based on the Relational and Entity Relationship Models
ER '93 Proceedings of the 12th International Conference on the Entity-Relationship Approach: Entity-Relationship Approach
Defining Metrics for Conceptual Schema Evolution
FoMLaDO/DEMM 2000 Selected papers from the 9th International Workshop on Foundations of Models and Languages for Data and Objects, Database Schema Evolution and Meta-Modeling
Reduce, reuse, recycle: practical approaches to schema integration, evolution and versioning
CoMoGIS'06 Proceedings of the 2006 international conference on Advances in Conceptual Modeling: theory and practice
| Hi-index | 0.00 |
This paper presents a framework for evolving relation schemas that is based on conditional schema changes and tuple versioning. With each tuple a recorded schema and a conceptual schema is associated. This allows for a simple and semantically clean solution to the problem of schema mismatches that arise when the schema of a database is changed and some data no longer fits the schema. Specifically, no data needs to be migrated to the new schema, and no special null values are required. We precisely define evolving schemas in terms of schema segments and corresponding attribute mappings, present an algorithm to compute answers to queries over evolving schemas, and prove that the query answers consider the maximal set of schema segments consistent with the evolving schema.