[FLINK-2107] Add OuterJoin strategy with HashTable on inner side

• Type: New Feature
• Status: Closed
• Priority: Minor
• Resolution: Fixed
• Fix Version/s: 0.10.0
• Component/s: Runtime / Task
• Assignee: Chiwan Park
• Reporter: Fabian Hueske
• Created: 28/May/15 14:44
• Updated: 02/Oct/19 17:50
• Resolved: 19/Oct/15 16:11

Description

Flink does not natively support outer joins at the moment.
This issue proposes to implement a hash outer join algorithm that can cover left and right outer joins.

The implementation can be based on the regular hash join iterators (for example `ReusingBuildFirstHashMatchIterator` and `NonReusingBuildFirstHashMatchIterator`, see also `MatchDriver` class)

The Reusing and NonReusing variants differ in whether object instances are reused or new objects are created. I would start with the NonReusing variant which is safer from a user's point of view and should also be easier to implement.