Description:

Generate the migrations like the migration generator from rails but
create the files in the multiple_dbs databases.

You can use it as you usually use the rails migration generator

You can use the options:
--only and pass the name of the databases space separated. This only create
       the migration in the specified databases
--skip and pass the name of the databases space separated. This not create
       the migration in the specified databases

Example:

rails g multiple_dbs_migration add_password_to_users password:string --only=db1 db3 --skip=db3