[FLINK-6034] Add KeyedStateHandle for the snapshots in keyed streams

• Type: Sub-task
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 1.3.0
• Component/s: Runtime / State Backends
• Assignee: Xiaogang Shi
• Reporter: Xiaogang Shi
• Created: 14/Mar/17 03:37
• Updated: 29/Mar/17 01:38
• Resolved: 28/Mar/17 18:10

Description

Currently, the only type of the snapshots in keyed streams is KeyGroupsStateHandle which is full and store the states one group after another. With the introduction of incremental checkpointing, we need a higher level abstraction of keyed snapshots to allow flexible snapshot formats.

The implementation of KeyedStateHandle s may vary a lot in different backends. The only information needed in KeyedStateHandle s is their key group range. When recovering the job with a different degree of parallelism, KeyedStateHandle s will be assigned to those subtasks whose key group ranges overlap with their ranges.

Issue Links

• links to: GitHub Pull Request #3531