Redmine

We were using Redmine 1.3 with sqlite for a year with no problems.
After upgrading to 2.2, it frequently locks up (need to restart webserver), also the official doc now discourages usage of sqlite in multiuser environment. Thus I need to migrate the DB.

I found a simple solution:
Add

gem 'yaml_db'

to Gemfile, then

bundle install
RAILS_ENV=production rake db:dump

now switch config in database.yml to MySQL, then

RAILS_ENV=production rake db:load

Done and works.

Looks too easy, doesn't it?
In fact an issue popped up: Plugin migration is broken.
While I can do

rake db:migrate RAILS_ENV=production 

(finishes without output, thus I assume without error), running

rake db:plugins:migrate RAILS_ENV=production

fails:

# rake redmine:plugins:migrate RAILS_ENV=production
Migrating redmine_contacts (Redmine CRM plugin)...
==  CreateContacts: migrating =================================================
-- create_table(:contacts)
rake aborted!
An error has occurred, all later migrations canceled:

Mysql::Error: Table 'contacts' already exists: ...

That's not pretty. While it's not an instant issue (Redmine works), it blocks future updates.

Since I don't have any Ruby/Rails knowledge apart from what I learned from Redmine administration, I don't know the inner workings of the migration scripts and hereby kindly ask for help.