Preparing multiple MySQL databases with Rails 2.3

db.rake

namespace :db do
  namespace :test do
    task :prepare => :environment do
      abcs = ActiveRecord::Base.configurations

      [ "", "_data_warehouse" ].each do |db|
        # Dump the development database
        config = abcs["development#{db}"]
        cmd = "mysqldump -u#{config["username"]} -p#{config["password"]} #{config["database"]} --no-data > #{RAILS_ROOT}/db/development#{db}_structure.sql"
        `#{cmd}`

        # Recreate an empty test database
        config = abcs["test#{db}"]
        ActiveRecord::Base.establish_connection("test#{db}")
        ActiveRecord::Base.connection.recreate_database(config["database"], config)

        # Import the dump
        cmd = "mysql -u#{config["username"]} -p#{config["password"]} #{config["database"]} < #{RAILS_ROOT}/db/development#{db}_structure.sql"
        `#{cmd}`
      end
    end
  end
end