[FLINK-19438] Queryable State needs to support both read-uncommitted and read-committed

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Won't Do
• Component/s: Runtime / Queryable State
• Assignee: Unassigned
• Reporter: sheep
• Created: 28/Sep/20 02:21
• Updated: 13/Apr/21 20:30
• Resolved: 15/Jan/21 10:31

Description

Flink exposes its managed keyed (partitioned) state to the outside world and allows the user to query a job’s state from outside Flink. From a traditional database isolation-level viewpoint, the queries access uncommitted state, thus following the read-uncommitted isolation level.

I fully understand Flink provides read-uncommitted state query in order to query real-time state. But the read-committed state is also important (I cannot fully explain). From Flink 1.9, querying even modifying the state in Checkpoint has been implemented. The state in Checkpoint is equivalent to read-committed state.  So, users can query read-committed state via the state processor api.

Flink should provide users  for configuration of isolation level of Queryable State by integration of the two levels of state query.