[FLINK-2105] Implement Sort-Merge Outer Join algorithm

• Type: Sub-task
• Status: Closed
• Priority: Minor
• Resolution: Fixed
• Fix Version/s: 0.10.0
• Component/s: Runtime / Task
• Assignee: Ricky Pogalz
• Reporter: Fabian Hueske
• Created: 28/May/15 12:02
• Updated: 04/Aug/15 22:44
• Resolved: 04/Aug/15 22:43

Description

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

The implementation can be based on the regular sort-merge join iterator (ReusingMergeMatchIterator and NonReusingMergeMatchIterator, 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.