[FLINK-4856] Add MapState for keyed streams

• Type: New Feature
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 1.3.0
• Component/s: API / DataStream, Runtime / State Backends
• Assignee: Xiaogang Shi
• Reporter: Xiaogang Shi
• Created: 19/Oct/16 02:00
• Updated: 24/Feb/17 01:41
• Resolved: 23/Feb/17 16:07

Description

Many states in keyed streams are organized as key-value pairs. Currently, these states are implemented by storing the entire map into a ValueState or a ListState. The implementation however is very costly because all entries have to be serialized/deserialized when updating a single entry. To improve the efficiency of these states, MapStates are urgently needed.

Issue Links

• links to: GitHub Pull Request #3336