I ran into an issue earlier where adding a sub project to an already existing Redmine project produced an error and after a little bit of troubleshooting determined that upgrading Redmine would resolve the issue. During the upgrade process I ran into some other issues including a specific migration error using rake that is noted below. The upgrade process involved upgrading Redmine 0.8.3 to Redmine 0.9.3.
The other day I did some optimization work on a PostgreSQL database and at the end needed to create migrations so the changes I was going to make could be deployed on multiple servers. It was my first shot at migrations so I wanted to note for myself and anyone else that may find it useful how to create Ruby migrations for dropping and adding Indexes on PostgreSQL tables. Below you will find the basic concept for creating a migration that adds a Postgres table index and information on removing a table index which is just the reverse of adding.