Recently I tried running my RoR applications on Oracle.
I noticed that when I ran rake db:migrate it would hang. Specifically it would hang during the schema dump phase.
E:\work\sandbox>rake db:migrate --trace -v (in E:/work/sandbox) ** Invoke db:migrate (first_time) ** Invoke environment (first_time) ** Execute environment ** Execute db:migrate ** Invoke db:schema:dump (first_time) ** Invoke environment ** Execute db:schema:dump
I realized later that this was because the schema dump phase is very slow and the database I was using had many other tables from other applications. When I left it running it finally completed after 10 minutes.
You can see the slow progress of the schema dump phase by tailing schema.rb in the db directory.