From 9i, Oracle introduced Automatic Segment Space Management (ASSM) as a replacement of freelists management.In a locally managed tablespace, there are two methods by which Oracle manages the Segment Space:- Automatic and Manual.Manual segment space management uses "FREELISTS" to  manage the free space in the segment whereas the Automatic segment space management uses "BITMAPS".From 10g … Continue reading ASSM and PCTFREE