establish_temporary_connection

# File activerecord/lib/active_record/migration/pending_migration_connection.rb, line 5
    def self.establish_temporary_connection(db_config, &block)
      pool = ActiveRecord::Base.connection_handler.establish_connection(db_config, owner_name: self)

      yield pool.connection
    ensure
      ActiveRecord::Base.connection_handler.remove_connection_pool(self.name)
    end