問題文
A DBA wants to compare the behavior of a database between two hours of last week. Which statement describes what the workload repository provides for that?
選択肢
- It copies the dynamic performance views into permanent tables at the end of each day, so the difference between two hours has to be computed from the values that the views held at those times.
- It samples the active sessions once a second and maintains the samples for a retention period, so the difference between two hours is described by the sessions that were active in just one of them.
- It records every statement that the database ran during the period and keeps the text for a retention period, so the difference between two hours is described by the statements that appear in just one of them.
- It takes snapshots of the accumulated statistics at intervals and maintains them for a retention period, so the difference between two snapshots describes the activity of the period between them.