In the most general sense (master-master) yes, but in a more detailed sense... not really.
Cassandra and Riak have a similar replication model -- the are deployed into a "ring" and the data in the ring distributed across some (or all) of the nodes depending on your ReplicationFactor (how many nodes to copy each piece of data to).
If you query for a piece of data that a node doesn't have, it hashes the query and routes you to the node that does have it.
CouchDB is a bit different, in that by default it treats every node as a master and replicates it in its entirety to any other nodes registered as a replication target.
You can shard with something like BigCouch, but that is 3rd party.
This is different than Mongo which is master-slave-slave-* or Redis which I believe is master-slave as well (I never got a clear answer on how "slave" nodes in Redis resolve or push changes back upstream to the master).
Cassandra and Riak have a similar replication model -- the are deployed into a "ring" and the data in the ring distributed across some (or all) of the nodes depending on your ReplicationFactor (how many nodes to copy each piece of data to).
If you query for a piece of data that a node doesn't have, it hashes the query and routes you to the node that does have it.
CouchDB is a bit different, in that by default it treats every node as a master and replicates it in its entirety to any other nodes registered as a replication target.
You can shard with something like BigCouch, but that is 3rd party.
This is different than Mongo which is master-slave-slave-* or Redis which I believe is master-slave as well (I never got a clear answer on how "slave" nodes in Redis resolve or push changes back upstream to the master).