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https://issues.apache.org/jira/browse/FLINK-4266?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17456215#comment-17456215
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Yun Tang commented on FLINK-4266:
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[~foxss] What's the progress of thie ticket, can we close it now?
> Cassandra SplitOver Statebackend
> --------------------------------
>
> Key: FLINK-4266
> URL: https://issues.apache.org/jira/browse/FLINK-4266
> Project: Flink
> Issue Type: New Feature
> Components: Runtime / State Backends
> Affects Versions: 1.3.0
> Reporter: Chen Qin
> Assignee: Chen Qin
> Priority: Not a Priority
> Labels: stale-assigned
>
> Current FileSystem statebackend limits whole state size to disk space.
> Dealing with scale out checkpoint states beyond local disk space such as long
> running task that hold window content for long period of time. Pipelines
> needs to split out states to durable remote storage even replicated to
> different data centers.
> We draft a design that leverage checkpoint id as mono incremental logic
> timestamp and perform range query to get evicited state k/v. we also
> introduce checkpoint time commit and eviction threshold that reduce "hot
> states" hitting remote db per every update between adjacent checkpoints by
> tracking update logs and merge them, do batch updates only when checkpoint;
> lastly, we are looking for eviction policy that can identify "hot keys" in
> k/v state and lazy load those "cold keys" from remote storage(e.g Cassandra).
> For now, we don't have good story regarding to data retirement. We might have
> to keep forever until manually run command and clean per job related state
> data. Some of features might related to incremental checkpointing feature, we
> hope to align with effort there also.
> Welcome comments, I will try to put a draft design doc after gathering some
> feedback.
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