More than 30 (Maximum) Buckets per cluster

Document goes into specific collection.

Same JSON document can be stored in different collection with same key. If need to store in same collection you must use different key (key is unique in the collection).

bucket1.scope1.coll1    Key "k01"     doc {"a":1}
bucket1.scope1.coll1    Key "k01"     doc {"a":1}   -- not allowed violates key  (you can change key it allowed)

bucket1.scope1.coll2    Key "k01"     doc {"a":1}  -- Allowed
bucket1.scope2.coll1    Key "k01"     doc {"a":1}  -- Allowed
bucket2.scope1.coll1    Key "k01"     doc {"a":1}  -- Allowed