example of how you'd specify multiple repos in a database.yml for DataMapper

1_sample_database.yml

development:
    repositories:
        default: &balls_defaults
            adapter: mysql
            host: localhost
            database: balls
            username: root
            password: ""
        dongs: &dongs_defaults
            adapter: mysql
            host: localhost
            database: dongs
            username: root
            password: ""
        foo: &foo_defaults
            adapter: mysql
            host: localhost
            database: foo
            username: root
            password: ""

test:
    repositories:
        default:
            <<: *balls_defaults
            database: balls_test
        dongs:
            <<: *dongs_defaults
            database: dongs_test
        foo:
            <<: *foo_defaults
            database: foo_test

production:
    repositories:
        default:
            <<: *balls_defaults
        dongs:
            <<: *dongs_defaults
        foo:
            <<: *foo_defaults