[FLINK-8384] Session Window Assigner with Dynamic Gaps

• Type: Improvement
• Status: Closed
• Priority: Minor
• Resolution: Fixed
• Fix Version/s: 1.5.0
• Component/s: API / DataStream
• Assignee: Dyana Rose
• Reporter: Dyana Rose
• Created: 08/Jan/18 10:27
• Updated: 28/Feb/19 11:14
• Resolved: 05/Feb/18 15:49

Description

Reason for Improvement

Currently both Session Window assigners only allow a static inactivity gap.
Given the following scenario, this is too restrictive:

• Given a stream of IoT events from many device types
• Assume each device type could have a different inactivity gap
• Assume each device type gap could change while sessions are in flight

By allowing dynamic inactivity gaps, the correct gap can be determined in the assignWindows function by passing the element currently under consideration, the timestamp, and the context to a user defined function. This eliminates the need to create unwieldy work arounds if you only have static gaps.

Dynamic Session Window gaps should be available for both Event Time and Processing Time streams.

(short preliminary discussion: https://lists.apache.org/thread.html/08a011c0039e826343e9be0b1bb4e0000cfc2e12976bc65f8a43ee88@%3Cdev.flink.apache.org%3E)

Issue Links

• links to: GitHub Pull Request #5295