[FLINK-3336] Add Semi-Rebalance Data Shipping for DataStream

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 1.0.0
• Assignee: Aljoscha Krettek
• Reporter: Aljoscha Krettek
• Created: 04/Feb/16 17:28
• Updated: 28/Feb/19 11:14
• Resolved: 08/Feb/16 12:14

Description

This feature has recently been requested on the ML: http://apache-flink-user-mailing-list-archive.2336050.n4.nabble.com/Distribution-of-sinks-among-the-nodes-td4640.html

The new data shipping pattern would allow to rebalance data only to a subset of downstream operations.

The subset of downstream operations to which the upstream operation would send
elements depends on the degree of parallelism of both the upstream and downstream operation.
For example, if the upstream operation has parallelism 2 and the downstream operation
has parallelism 4, then one upstream operation would distribute elements to two
downstream operations while the other upstream operation would distribute to the other
two downstream operations. If, on the other hand, the downstream operation had parallelism
2 while the upstream operation has parallelism 4 then two upstream operations would
distribute to one downstream operation while the other two upstream operations would
distribute to the other downstream operations.

In cases where the different parallelisms are not multiples of each other one or several
downstream operations would have a differing number of inputs from upstream operations.