Null To Unset
Use unset instead of NULL in CQL query when performing INSERT operations.
In Cassandra 2.2 and above, when executing an INSERT query, a parameter value can be set to unset. Cassandra does not consider unset field values which helps to avoid tombstones.
When NULL values are inserted, it is possible to reach the tombstone threshold limits which causes an exception to be thrown when querying the data. Setting this property to true and submitting unset values avoids these tombstones from being created.
Note: This option is only available on INSERT operations as Cassandra does not support changing existing values to unset.