Split data in different buckets

Hi, after reading this post ==> network-performance-using-couchbase-20 a new question arose:

PROBLEM:
If I put all data in one bucket and, after some time, I want to split the data in different buckets... grouping by a specific JSON field...

Ex: grouping by "to" field:

{
"type" : "mail",
"from" : "someone",
"to" : "user01",
"message" : "some message text"
}

QUESTION:
1) Is this possible? How can I do it?

Thanks