Multiple choice technology databases

Which statement is ture regarding checkpoints and recovery ?

  1. A checkpoint defines the highest system change number (SCN)

  2. All redo entries higher or at the SCN are known to be written to the data files.

  3. Only the redo records containing SCNs higher then the checkpoint need to be applied during recovery.

  4. The LOG_CHECKPOINT_INTERVAL initialization paramter specifies the amount of time beteen incremental checkpoints.
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C Correct answer
Explanation

A checkpoint records the SCN up to which all changes have been written to data files. During recovery, only redo records with SCNs higher than the checkpoint SCN need to be applied. This is because all changes at or below the checkpoint are already safely stored in the data files. Checkpoints do not define the highest SCN, they don't guarantee redo entries at the SCN are written, and LOG_CHECKPOINT_INTERVAL specifies redo blocks, not time.

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