http://sequel.jeremyevans.net/rdoc/files/doc/transactions_rdoc.html

sequel_array_db_multi_commit.rb

  def multi_db_commit(tx_id, dbs)
    prepared = []
    dbs.each do |db, pr|
      db.transaction(:prepare=>tx_id, &pr)
      prepared << db
    end
  rescue
    prepared.each do |db|
      begin
        db.rollback_prepared_transaction(tx_id)
      rescue Sequel::DatabaseError
        # ...
      end
    end
  else
    prepared.each do |db|
      begin
        db.commit_prepared_transaction(tx_id)
      rescue Sequel::DatabaseError
        # ...
      end
    end
  end
  multi_db_commit('foo', DB1=>proc{...}, DB2=>proc{...}, DB3=>proc{...})

sequel_multi_commit.rb

  DB1.transaction(:prepare => 'foo')
    # ...
  end
  begin
    DB2.transaction(:prepare => 'foo')
      # ...
    end
    begin
      DB3.transaction(:prepare => 'foo')
        # ...
      end
    rescue
      DB2.rollback_prepared_transaction('foo')
      raise
    else
    end
  rescue Sequel::DatabaseError
    DB1.rollback_prepared_transaction('foo')
    raise
  else
    DB1.commit_prepared_transaction('foo')
    DB2.commit_prepared_transaction('foo')
    DB3.commit_prepared_transaction('foo')
  end