This field displays the sum of the intervals between checkpoints
    due to AIJ growth in block checkpoints for all processes. For
    example, if Process 1 checkpoints at virtual block number (VBN)
    100, then checkpoints again at VBN 250, the AIJ block interval
    category is incremented by 150. If Process 2 checkpoints at VBN
    125, then checkpoints again at VBN 200, the AIJ block interval
    is incremented by an additional 75. Statistics for the other two
    interval categories are displayed in the "interval: tx count" and
    "interval: seconds" fields.

    If CHECKPOINT INTERVAL IS 1000 BLOCKS is specified with the SQL
    ALTER DATABASE statement, each process checkpoints when the .aij
    file has grown 1000 blocks since the process' last checkpoint.

    Keep in mind that checkpointing influences recovery time. The
    main reason to consult checkpoint statistics is to find the
    average interval per checkpoint. You can use the information in
    the total count column to compute this average. For each category
    of checkpoint reason, use the average interval per checkpoint to
    help you decide if a checkpointing interval should be adjusted,
    and by how much.

    If most of the checkpoints for a database are triggered by a
    particular checkpoint limit, that limit may be set too high,
    or the other two limits may be set too low. You can determine
    the average interval per checkpoint for each type of checkpoint
    limit. After you have this information, you can reset the limits
    so that each type of checkpoint limit triggers approximately the
    same number of checkpoints, which results in optimal performance.

    To compute the average interval in AIJ blocks, divide the
    total count for the AIJ block interval by the total number of
    checkpoints minus the number caused by AIJ backups. Although
    checkpoints caused by AIJ backups are counted in the total
    number of checkpoints, they are not counted in the total of AIJ
    block intervals. If the total count of AIJ block intervals is
    70000, the total count of checkpoints is 100, and the number
    of checkpoints caused by AIJ backups is 1, then the average AIJ
    block interval is 707:

          70000/(100 - 1) = 707

    The help for the "interval: tx count" field explains how to
    determine the average interval for transaction checkpoints.

    The help for the "interval: seconds" field explains how to
    determine the average interval for time checkpoints.