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https://issues.apache.org/jira/browse/FLINK-3714?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Aljoscha Krettek updated FLINK-3714:
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Description:
As mentioned in
https://docs.google.com/document/d/1Xp-YBf87vLTduYSivgqWVEMjYUmkA-hyb4muX3KRl08/edit#
we should add support for an allowed lateness setting.
This includes several things:
- API for setting allowed lateness
- Dropping of late elements
- Garbage collection of windows state/timers
Depending on whether the {{WindowAssigner}} assigns windows based on event time
or processing time we have to adjust the GC behavior. For event-time windows
"allowed lateness" makes sense and we should garbage collect after this
expires. For processing-time windows "allowed lateness" does not make sense and
we should always GC window state/timers at the end timestamp of a
processing-time window. I think that we need a method for this on
{{WindowAssigner}} that allows to differentiate between event-time windows and
processing-time windows: {{boolean WindowAssigner.isEventTime()}}.
was:
As mentioned in
https://docs.google.com/document/d/1Xp-YBf87vLTduYSivgqWVEMjYUmkA-hyb4muX3KRl08/edit#
we should add support for an allowed lateness setting.
This includes several things:
- API for setting allowed lateness
- Dropping of late elements
- Garbage collection of event-time windows
Lateness only makes sense for event-time windows. So we also have to figure out
what the API for this should look like and especially what should happen with
the "stream-time characteristic" switch. For example in this:
{code}
env.setStreamTimeCharacteristic(ProcessingTime)
...
DataStream in = ...
result = in
.keyBy()
.timeWindow()
.allowedLateness()
.apply()
{code}
I think the setting can be silently ignored when doing processing-time
windowing.
> Add Support for "Allowed Lateness"
> ----------------------------------
>
> Key: FLINK-3714
> URL: https://issues.apache.org/jira/browse/FLINK-3714
> Project: Flink
> Issue Type: Sub-task
> Components: Streaming
> Reporter: Aljoscha Krettek
> Assignee: Kostas Kloudas
>
> As mentioned in
> https://docs.google.com/document/d/1Xp-YBf87vLTduYSivgqWVEMjYUmkA-hyb4muX3KRl08/edit#
> we should add support for an allowed lateness setting.
> This includes several things:
> - API for setting allowed lateness
> - Dropping of late elements
> - Garbage collection of windows state/timers
> Depending on whether the {{WindowAssigner}} assigns windows based on event
> time or processing time we have to adjust the GC behavior. For event-time
> windows "allowed lateness" makes sense and we should garbage collect after
> this expires. For processing-time windows "allowed lateness" does not make
> sense and we should always GC window state/timers at the end timestamp of a
> processing-time window. I think that we need a method for this on
> {{WindowAssigner}} that allows to differentiate between event-time windows
> and processing-time windows: {{boolean WindowAssigner.isEventTime()}}.
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