'unbalanced' indexes

I've worked with other RDBMS's before but am new to Oracle. I've heard a few people mention the need to rebuild indexes occasionally becuase they are 'unbalanced'?? I thought BTree indixes were by definition balanced. I can see the benefit of re-building if indexes are fragmented, i.e. spread too much across disks, but a doesn't a BTree idx ALWAYS have the same number of levels from root to ANY leaf.

TIA,
-Lin Received on Fri Jul 16 1999 - 12:36:39 CDT