[FLINK-10343] Expose setCurrentKey method to streamRuntimeContext

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Won't Fix
• Affects Version/s: 1.7.0
• Assignee: WenJun Min
• Reporter: WenJun Min
• Created: 13/Sep/18 15:33
• Updated: 28/Feb/19 11:15
• Resolved: 25/Feb/19 12:35

Description

when we use reducing state / aggregating keyed state and so on , we have to read value from state backend and update the value with userFunction and then put back to state backend. If we can just cache certain data in heap with a map, and update once in snapshot method with

snapshot() {
 for(Map.Entry<String, String> entry : map.entrySet()){
     setCurrentKey(entry.getKey());
     valueState.update(entry.getValue()); // put value back to state backend
}}

we just have to expose the setCurrentKey to userFunction and the will enable the ability to cache partitial keyedState in memory by userself.

what's your opinion [e-mail] azagrebin ?