In a method, data is partitioned into partitions, which are divided into
levels. The levels are ordered by creation times of the levels. A request
is received at a current partition, which includes a key that identifies
a field in a record and a value for the key. A determination is made
whether the value exists in the field in the current partition. If the
determination is false, a message is sent from the current partition to a
next-older partition, and the message instructs the next-older partition
to move the record with the value from the next-older partition to the
current partition. If the determination is true, the record with the
value in the field is moved from the current partition to a next-newer
partition if the next-newer partition sent the request, and the record is
deleted from the current partition.