This illustration shows a LogMiner data dictionary at two points in time (Time 3 and Time 4). At Time 3, the first SCN is set to 423667 and the start SCN is set to 479502. At Time 4, the first SCN has been reset to 502631 and the LogMiner data dictionary information prior to this SCN has been purged. In addition, start SCN is set to 502631 automatically.