[jira] [Closed] (FLINK-17099) Refactoring State TTL solution in Group Agg、Deduplication、TopN operators replace Timer with StateTtlConfig

["Jark Wu (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/FLINK-17099?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Jark Wu closed FLINK-17099.
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    Fix Version/s:     (was: 1.13.0)
       Resolution: Duplicate

This has been fixed by FLINK-17096. But note that TopN is not migrated to the StateTtlConfig becuase it holds multiple states and needs to sync with each other. 

> Refactoring State TTL solution in Group Agg、Deduplication、TopN operators replace Timer with StateTtlConfig
> ----------------------------------------------------------------------------------------------------------
>
>                 Key: FLINK-17099
>                 URL: https://issues.apache.org/jira/browse/FLINK-17099
>             Project: Flink
>          Issue Type: Improvement
>          Components: Table SQL / Runtime
>    Affects Versions: 1.9.0, 1.10.0
>            Reporter: dalongliu
>            Assignee: dalongliu
>            Priority: Major
>
> At the moment, there are 2 ways to cleanup states.
> 1) registering a processing-time timer, and cleanup entries when the timer is callback.
>  - pros: can cleanup multiple states at the same time (state consistent)
>  - cons: timer space depends on the key size, which may lead to OOM (heap timer).
>  - used in Group Aggregation, Over Aggregation, TopN
> 2) using the {{StateTtlConfig}} provided by DataStream [1].
>  - pros: decouple the logic of state ttl with the record processing, easy to program (take a look at old planner NonWindowJoin which bundles ttl timestamp with records in MapState).
>  - cons: can't cleanup multiple states at the same time.
>  - useed in Sream-Stream Joins.
> For timer solution, although it can cleanup multiple states at the same time, but it also will lead to OOM when there have a great many state keys, besides, StateTtlConfig is used in stream-stream join case, and will be used in more operator. Therefore，in order to unify the state ttl solution, simplify the code implemention, and improve the readability of codes, so we should refactor state cleanup way which use StateTtlConfig to replace processing-time timer in Group Aggregation、Deduplication、TopN operators.



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