设置 STATISTICS_LEVEL = BASIC 会禁用一下oracle 的功能特性
Automatic Workload Repository (AWR) Snapshots
Automatic Database Diagnostic Monitor (ADDM)
All server-generated alerts
Automatic SGA Memory Management （ASMM）和自动内存管理
Automatic optimizer statistics collection
Object level statistics
End to End Application Tracing (V$CLIENT_STATS)
Database time distribution statistics (V$SESS_TIME_MODEL and V$SYS_TIME_MODEL)
Service level statistics
Buffer cache advisory
MTTR advisory
Shared pool sizing advisory
Segment level statistics
PGA Target advisory
Timed statistics
Monitoring of statistics