問題文
A database is about to be upgraded and the team wants to be protected from the plan changes that the new optimizer version might introduce. What does plan management do for them during that upgrade?
選択肢
- The database blocks the upgrade of any object whose plans would change and reports the list of blocked objects to the administrator.
- The database keeps to the plans already in the baseline and puts new plans on one side until they are shown to run with fewer resources.
- The database records the elapsed time of every statement before the upgrade and compares it with the time after the upgrade automatically.
- The database keeps a copy of the statistics from before the upgrade and restores them if any statement becomes slower than it was.