NOLOGGING

NOLOGGING is an option in Oracle Database that reduces the amount of redo and undo generated by certain operations to improve performance. It is applied as an attribute on database objects (such as tables or indexes) or specified during operations (for example, NOLOGGING for bulk loads or index creation). When an operation is performed with NOLOGGING, Oracle minimizes the generation of redo for the data blocks involved. However, metadata and control information still require some logging, and the operation is not fully recoverable from redo alone.

In practice, NOLOGGING is commonly used for bulk data loads, direct-path inserts, index builds, or table creation with large data volumes, where performance is critical and a backup-based recovery is acceptable.

Recovery implications: Because the operation is minimally logged, a failure after the operation may result in data blocks that cannot be restored from archived redo if you rely only on redo; full recoverability requires a backup taken before the operation. If a tablespace is configured with FORCE LOGGING, all operations on that tablespace are forced to generate redo even if the NOLOGGING attribute is specified, reducing the benefit.

Best practices: Use NOLOGGING only when you have a robust backup and recovery strategy, and you can tolerate potential data loss on the affected blocks. Always test restore scenarios; consider using NOLOGGING for non-critical data or temporary staging areas, and use FORCE LOGGING to guarantee logging when needed.