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https://issues.apache.org/jira/browse/FLINK-4266?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17329562#comment-17329562
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Flink Jira Bot commented on FLINK-4266:
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This issue is assigned but has not received an update in 7 days so it has been
labeled "stale-assigned". If you are still working on the issue, please give an
update and remove the label. If you are no longer working on the issue, please
unassign so someone else may work on it. In 7 days the issue will be
automatically unassigned.
> 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: Minor
> Labels: stale-assigned, stale-minor
>
> 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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