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Algorithms for Recovery and Isolation Exploiting Semantics
In computer science, Algorithms for Recovery and Isolation Exploiting Semantics, or ARIES is a recovery algorithm designed to work with a no-force, steal database approach. ARIES is a popular algorithm used by IBM DB2, Microsoft SQL Server and many other database systems.
Three main principles lie behind ARIES:
- Write ahead logging: Any change to an object is first recorded in the log, and the log must be written to stable storage before changes to the object is written to disk.
- Repeating history during Redo: On restart after a crash, ARIES retraces the actions of a database before the crash and brings the system back to the exact state that it was in before the crash. Then it undoes the transactions still active at crash time.
- Logging changes during Undo: Changes made to the database while undoing transactions are logged to ensure such an action isn't repeated in the event of repeated restarts.
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