Affects Version/s: None
Fix Version/s: 0.12.0
MapJoin is an essential component for high performance joins in Hive and the current code has done great service for many years. However, the code is showing it's age and currently suffers from the following issues:
- Uses static state via the MapJoinMetaData class to pass serialization metadata to the Key, Row classes.
- The api of a logical "Table Container" is not defined and therefore it's unclear what apis HashMapWrapper
needs to publicize. Additionally HashMapWrapper has many used public methods.
- HashMapWrapper contains logic to serialize, test memory bounds, and implement the table container. Ideally these logical units could be seperated
- HashTableSinkObjectCtx has unused fields and unused methods
- CommonJoinOperator and children use ArrayList on left hand side when only List is required
- There are unused classes MRU, DCLLItemm and classes which duplicate functionality MapJoinSingleKey and MapJoinDoubleKeys