undoredologging
Undoredologging is a database technique used to facilitate undo operations. It involves recording information about changes made to data in a way that allows for the reversal of those changes. When a transaction modifies data, the original state of that data is written to a special log file, often referred to as the undo log. This log is distinct from the redo log, which records changes to allow for reapplication during recovery.
The primary purpose of the undo log is to support transaction rollback. If a transaction fails or
When a rollback occurs, the database reads the undo log records corresponding to the uncommitted transaction.
Undoredologging is crucial for maintaining data integrity in environments with frequent transactions and the possibility of