instance method migrate_all

# File activerecord/lib/active_record/tasks/database_tasks.rb, line 241
      def migrate_all
        db_configs = ActiveRecord::Base.configurations.configs_for(env_name: ActiveRecord::Tasks::DatabaseTasks.env)
        db_configs.each { |db_config| initialize_database(db_config) }

        if db_configs.size == 1 && db_configs.first.primary?
          ActiveRecord::Tasks::DatabaseTasks.migrate(skip_initialize: true)
        else
          mapped_versions = ActiveRecord::Tasks::DatabaseTasks.db_configs_with_versions

          mapped_versions.sort.each do |version, db_configs|
            db_configs.each do |db_config|
              ActiveRecord::Tasks::DatabaseTasks.with_temporary_connection(db_config) do
                ActiveRecord::Tasks::DatabaseTasks.migrate(version, skip_initialize: true)
              end
            end
          end
        end
      end