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Recovery techniques

Idea 2: Log redo information

  • Log redo records for committed changes.
  • Changed pages get to disk after commit.

Recovery from crash

  • A: was not committed, skip the redo.
  • B: was committed, is present on disk, nothing to redo.
  • C: was committed, is NOT on disk, redo the change.
  • D: was not committed, skip the redo.

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