Data redundancy refers to the storage of the same data in multiple places within a database or data storage system. This can occur accidentally but is also done deliberately for backup and recovery purposes.
Accidental data redundancy can happen when data is entered into multiple systems or databases without being properly synchronized. This can lead to inconsistencies and errors in the data, as well as making it difficult to keep track of changes.
Deliberate data redundancy is often used as a way to improve performance and availability. For example, a database may store a copy of its data on a backup server in case the primary server fails. This way, users can still access the data even if the primary server is unavailable.