The data and schema migration procedure described at
did not work for UC Berkeley and U. Michigan, and it seems likely that other Oracle installations will have similar problems. Symptoms might include SchemaConversionController errors or null pointer exceptions.
Jim Eng has worked around Michigan's issues in his branch for
SAK-12239, but that's a mix of 2.4.x and 2.5.x code and he doesn't have time scheduled to merge the relevant fixes into the trunk or 2.5.x. Moreover, at UC Berkeley we found a couple of minor tweaks that needed to be made even in that code before we could complete a upgrade.
Any officially supported change to Sakai DB schemas should be maintainable via officially released code. All Oracle fixes need to be moved into 2.5.x and included in future releases.