Migrating a database from Oracle 8.0.6 to 10gR2 is an enormous step. There have been many enhancements made in the Oracle software and there will likely be some tuning associated with this migration. There are a number of methods to migrate your database but whatever method you choose, be sure to include enough time for testing the migration several times in a non-production environment. This includes testing the migration, as well as application and functional testing by your application and business support teams. Testing is never wasted!
A good source of information is the Oracle Database 10g Release 2 (10.2) Upgrade Guide. There is a section in this guide titled "Determine the Upgrade Path to the New Oracle Database 10g Release" which states that if you wish to upgrade your database in place, you must go from 8.0.6 to 184.108.40.206 and then to 10.2. Your other alternatives are to use export and import from the current 8.0.6 database to a newly created 10.2 database, or to copy the data using a database link. The upgrade guide explains each of these techniques, but you must choose the method you are most comfortable with and that fits within your migration strategy.
This was first published in April 2007