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Comprehensive Overview of Recovery Mechanisms in ARIES Logging System

This article delves deep into the ARIES logging system, covering undo and redo logging, checkpointing, physiological log records, failures during recovery, and truncating the log. Learn about the importance of CLR, log record retention, and steps for redo and undo log recovery.

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Comprehensive Overview of Recovery Mechanisms in ARIES Logging System

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Presentation Transcript

  1. Section 7: Recovery Undo logging Redo logging ARIES

  2. Checkpointing • START_CKPT • END_CKPT • MASTER_LOG_RECORD

  3. Questions • What happens if a second begin_checkpoint record is encountered during the Analysis phase? • Can a second end_checkpoint record be encountered during the Analysis phase?

  4. Physiological Log Records • Why is the use of CLRs important for the use of undo actions that are not the physical inverse of the original update?

  5. Aries: Failures During Recovery • If the system fails repeatedly during recovery, what is the maximum number of log records that can be written before restart completes successfully?

  6. Failures During Recovery

  7. Truncating the Log • What is the oldest log record we need to retain in the following systems: • Redo logging • Undo logging • Aries

  8. Truncating the Log

  9. Questions about the previous logs • One of these is an undo log, the other is a redo log. Identify the correct one. • What are the missing transactions in BEGIN CHECKPOINT? • What steps do we take to recover from the REDO log? • What steps do we take to recover from the UNDO log?

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