Currently, partition filtering only handles the first partition key and the type for this partition key must be string. In order to break this limitation, several improvements are required:
1. Change serialization format for partition key. Currently partition keys are serialized into delimited string, which sorted on string order not with regard to the actual type of the partition key. We use BinarySortableSerDe for this purpose.
2. For filter condition not on the initial partition keys, push it into HBase RowFilter. RowFilter will deserialize the partition key and evaluate the filter condition.