Move window baseline

Oracle Database automatically maintains a system-defined mobile window baseline. The default window size for the system-defined mobile window baseline is the current AWR retention period (default is eight days). If you plan to use adaptive thresholds, consider using a larger movement window (such as 30 days) to accurately calculate the threshold. You can resize the mobile window baseline by changing the number of days in the mobile window to be equal to or less than the number of days in the AWR retention period. Therefore, to increase the size of the mobile window, you need to increase the AWR retention period accordingly.

This system-defined baseline provides a ready-made default baseline, and EM's performance screen compares performance against current database performance.

Note: in Oracle Database 11g, the default retention period for snapshot data has been changed from seven days to eight days to ensure that performance data for the entire week is captured.