I never quite understand this:

The previous DBA created DBs with export/import. However, when he did export from DB#1, he specified compress=y and import it into DB#2. Thus in the subsequent exports from DB#2, they all have big initial extents. I notice even if I export only schema from DB#2 with compress=n and import into other DBs, the result is still big tablespace, just like the source DB DB#2 (even though there is no data in it).

How do people actually reoganize the tablespace and shrink down the size if the tablespace doesn't really have much data in it?

thanks,