It’s good way reclaim WASTED space from tables and index using the Segment Advisor.
To perform an database reclaim procedure using Automatic Segment Space Management (ASSM) it is preferred to create tablespaces with below option:
grepdb> CREATE TABLESPACE HR DATAFILE '+GREPORADG/' SIZE 10M EXTENT MANAGEMENT LOCAL SEGMENT SPACE MANAGEMENT AUTO;
Only tablespaces with segment space auto are eligible to Segment Advisor.
To manually run the Segment Advisor on OEM:
It will save some database storage area, and make it more effective cause by LHWM/HHWM.
Maiquel.