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.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

A checkpoint records the highest SCN written to data files. During recovery, only redo records with SCNs higher than the checkpoint SCN need to be applied - changes below that point are already persisted. This dramatically reduces recovery time. Option A is wrong because checkpoint doesn't define SCN, B is wrong because redo above checkpoint is NOT written to data files yet, and D refers to a different parameter.

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