Initially, for the Automatic Workload Repository (AWR) statistics, the retention period is set to 7 days, the collection interval is set to 30 minutes and the collection level is set to Typical in your production database.
You have been using the Memory Advisor for the last three months to generate recommendations for tuning memory components.
However, when you observe the Memory Advisor on a Friday, you find that the statistics are available only for two days, Thursday and Friday, of that week.
What would have caused the statistics to be removed?
A. On Wednesday, the statistics have been purged.
B. On Wednesday, the retention period has been set to zero.
C. On Wednesday, the collection interval has been set to zero.
D. On Wednesday, the collection level has been changed to All.
E. On Wednesday, the retention period has been set to one day.
F. On Wednesday, the retention period has been set to two days.
G. On Wednesday, the collection level has been changed to Typical.
H. On Wednesday, the collection interval has been set to 1440 minutes.
Answer: F
只剩下2天的说明保留时间变成2天了。
Note:
Timed statistics are automatically collected for the database if the initialization parameter STATISTICS_LEVEL is set to TYPICAL or ALL. If STATISTICS_LEVEL is set to BASIC, then you must set TIMED_STATISTICS to TRUE to enable collection of timed statistics. Note that setting STATISTICS_LEVEL to BASIC disables many automatic features and is not recommended.
If you explicitly set DB_CACHE_ADVICE, TIMED_STATISTICS, or TIMED_OS_STATISTICS, either in the initialization parameter file or by using ALTER_SYSTEM or ALTER SESSION, the explicitly set value overrides the value derived from STATISTICS_LEVEL.