redolog

A redolog, short for redo log, is a component of some database management systems that helps maintain the integrity and consistency of data in the event of a system failure or unexpected shutdown. It is a sequential record of all data modifications made to the database, including insertions, updates, and deletions.

The primary purpose of a redolog is to ensure that all committed transactions are safely stored on disk and can be recovered in case of a database crash or shutdown. The redolog acts as a temporary buffer, holding a record of all transactions that have been executed against the database. When the database comes back online after a failure, the redolog is used to replay these transactions, effectively bringing the database back to a consistent state.

In many database systems, the redolog is used in conjunction with a write-ahead log, which ensures that all transactions are written to the log before they are applied to the database. This helps to prevent data loss in the event of a system failure, as the log can be used to recover the last known good state of the database.

Redologs are commonly used in enterprise database management systems, such as those used in financial and healthcare applications, where data integrity and consistency are critical. The use of a redolog provides an additional layer of protection against data loss and ensures that the database can be recovered to a consistent state in the event of an unexpected failure.