Database 10g introduces a non-intrusive, efficient and timely monitoring of database space, built right into the database server. Proactive tablespace management is available by default with no measurable performance impact, and it is uniformly available across all tablespace types.
The Oracle Database 10g also introduces the ability to reclaim space from a segment by shrinking it online and in-place. Shrinking of a segment makes unused space available to other segments in the tablespace and can improve the performance of queries and DML operations. The Segment Advisor analyzes a specified tablespace or a schema for objects that may be candidates for shrinking. It also performs growth trend analysis on individual objects to determine if there will be any additional space left in the object and uses this information to select candidate objects to shrink.