Best approach for upgrading from 6.0 to 9i

This is a tough question because I haven't actually tried an upgrade from Oracle 6 to 9.2. I would suggest creating a new Oracle 9.2 database, exporting the Oracle 6 database and importing it into the newly created 9.2 database. Another method you might be able to try is the CTAS (create table as select …) method between the two databases.

Whichever method you choose, the key word to remember here is "test." Make sure you and the application support teams do lots of it. There were many, many changes made to the Oracle kernel between version 6 and 9.2 that are bound to affect your applications – some will improve performance but others may require some work or code changes. You may also want to open a TAR with Oracle Support and ask for their expertise on how best to proceed with this upgrade.