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https://issues.apache.org/jira/browse/FLINK-12005?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17121272#comment-17121272
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Yu Li commented on FLINK-12005:
-------------------------------
Hi [~lyee], sorry but I'm not actively working on this issue at the moment. We
ever had a [discussion in
ML|http://apache-flink-mailing-list-archive.1008284.n3.nabble.com/Discuss-Semantics-of-event-time-for-state-TTL-td28113.html]
about the semantic of event time in state TTL but it seems to be no explicit
conclusion.
OTOH, I think it's better to look back at it after
[FLIP-27|https://cwiki.apache.org/confluence/display/FLINK/FLIP-27%3A+Refactor+Source+Interface]
is done. Will ping here once we revive the job, or please let me know if any
suggestions. Thanks.
> [State TTL] Event time support
> ------------------------------
>
> Key: FLINK-12005
> URL: https://issues.apache.org/jira/browse/FLINK-12005
> Project: Flink
> Issue Type: New Feature
> Components: API / DataStream, Runtime / State Backends
> Reporter: Andrey Zagrebin
> Assignee: Yu Li
> Priority: Major
>
> The event time is opted for in StateTtlConfig by setting
> TtlTimeCharacteristic.EventTime.
> To enable event time support, the updated watermark needs to be passed to the
> state backend, shared with TTL state wrappers and additional cleanup
> strategies (snapshot transformers and compaction filter).
> h3. Event time provider
> Additional implementation of TtlTimeProvider, which holds current watermark,
> needs to be passed to the state backend at the moment of its creation in
> StreamTaskStateInitializerImpl. There several ways to update watermark in
> this implementation of TtlTimeProvider:
> * in InternalTimeServiceManager.advanceWatermark explicitly
> * InternalTimeServiceManager/InternalTimerServiceImpl could be refactored to
> use shared EventTimeService which holds current updatable watermark and
> wrapped by TtlTimeProvider
> The TTL state wrapping factory should create TTL state wrappers and snapshot
> transformers with TtlTimeProvider selected by TtlTimeCharacteristic.
> h3. RocksDB TTL compaction filter
> The RocksDB TTL compaction filter factory needs to get selected
> TtlTimeProvider when it gets configured. There are two ways:
> * make it volatile and settable in
> RocksDbTtlCompactFiltersManager.TimeProviderWrapper, track it in
> RocksDbTtlCompactFiltersManager along with FlinkCompactionFilterFactory to
> configure later before configuring FlinkCompactionFilterFactory.
> * Move FlinkCompactionFilter.TimeProvider from FlinkCompactionFilterFactory
> to ConfigHolder and set selected TtlTimeProvider with the Config.
> The second option does not use volatile variable and should be more
> performant but needs changing RocksDB java client and either releasing new
> version FRocksDB or Flink RocksDB extensions.
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