A)AWR data is stored in the SYSTEM tablespace.
B)By default, AWR snapshots are taken every 60 minutes.
C)It is the foundation for the self-managing infrastructure.
D)The taking of AWR snapshots cannot be disabled.
E)Its collection level is determined by the value of the STATISTICS_LEVEL database parameter.
F)It is used by the Optimizer to determine optimal execution plans.
Answer: BCE
赵：F 错，优化器使用的是统计信息，不是 AWR。
原文：https://blog.51cto.com/13854012/2425154