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https://issues.apache.org/jira/browse/FLINK-8560?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16360414#comment-16360414
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Piotr Nowojski commented on FLINK-8560:
---------------------------------------
[~phoenixjiangnan] why would we have to keep all of the keys in the memory? Can
not we have in KeyedProcessOperator:
{code:java}
@Override
public void onEventTime(InternalTimer<K, VoidNamespace> timer) throws Exception
{
collector.setAbsoluteTimestamp(timer.getTimestamp());
onTime(timer, TimeDomain.EVENT_TIME);
}
@Override
public void onProcessingTime(InternalTimer<K, VoidNamespace> timer) throws
Exception {
collector.eraseTimestamp();
onTime(timer, TimeDomain.PROCESSING_TIME);
}
private void onTime(InternalTimer<K, VoidNamespace> timer, TimeDomain
timeDomain) throws Exception
{
Supplier<K> currentKeyAccessor = () -> (K) getCurrentKey();
onTimerContext.reinitialize(currentKeyAccessor, timeDomain, timer);
userFunction.onTimer(timer.getTimestamp(), onTimerContext, collector);
onTimerContext.reset();
}{code}
Key would be only accessed when a user specifically asks for it, thus it
shouldn't cost us any thing.
> Access to the current key in ProcessFunction after keyBy()
> ----------------------------------------------------------
>
> Key: FLINK-8560
> URL: https://issues.apache.org/jira/browse/FLINK-8560
> Project: Flink
> Issue Type: Wish
> Components: DataStream API
> Reporter: Jürgen Thomann
> Assignee: Bowen Li
> Priority: Minor
>
> Currently it is required to store the key of a keyBy() in the processElement
> method to have access to it in the OnTimerContext.
> This is not so good as you have to check in the processElement method for
> every element if the key is already stored and set it if it's not already set.
> A possible solution would adding OnTimerContext#getCurrentKey() or a similar
> method. Maybe having it in the open() method could maybe work as well.
> http://apache-flink-user-mailing-list-archive.2336050.n4.nabble.com/Getting-Key-from-keyBy-in-ProcessFunction-tt18126.html
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