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https://issues.apache.org/jira/browse/FLINK-7799?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Flink Jira Bot updated FLINK-7799:
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Labels: stale-assigned stale-minor (was: stale-minor)
> Improve performance of windowed joins
> -------------------------------------
>
> Key: FLINK-7799
> URL: https://issues.apache.org/jira/browse/FLINK-7799
> Project: Flink
> Issue Type: Improvement
> Components: Table SQL / Legacy Planner
> Affects Versions: 1.4.0
> Reporter: Fabian Hueske
> Assignee: Xingcan Cui
> Priority: Minor
> Labels: stale-assigned, stale-minor
>
> The performance of windowed joins can be improved by changing the state
> access patterns.
> Right now, rows are inserted into a MapState with their timestamp as key.
> Since we use a time resolution of 1ms, this means that the full key space of
> the state must be iterated and many map entries must be accessed when joining
> or evicting rows.
> A better strategy would be to block the time into larger intervals and
> register the rows in their respective interval. Another benefit would be that
> we can directly access the state entries because we know exactly which
> timestamps to look up. Hence, we can limit the state access to the relevant
> section during joining and state eviction.
> The good size for intervals needs to be identified and might depend on the
> size of the window.
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