Online rebuilds don't use existing index for
creating new. They do full table scan on the table.
However, in both cases, old index segment is
kept until new one is ready to use and switch to it is done. Also the journal
IOTs used for online rebuilds are stored in the target tablespace, so if
you've got lots of transactions going on while you are rebuilding the index
online, you need additional space in target tablespace.
----- Original Message -----
Sent: Monday, January 23, 2006 2:38
Subject: RE: ORA-01652: unable to extend
For rebuild operations, twice the index space is used during the rebuild,
as Oracle constructs the new index from the old one.
The space is released once the index is rebuilt.