[ https://issues.apache.org/jira/browse/KAFKA-4219?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Guozhang Wang updated KAFKA-4219: --------------------------------- Labels: api (was: api user-experience) > Permit setting of event time in stream processor > ------------------------------------------------ > > Key: KAFKA-4219 > URL: https://issues.apache.org/jira/browse/KAFKA-4219 > Project: Kafka > Issue Type: Improvement > Components: streams > Affects Versions: 0.10.0.1 > Reporter: Elias Levy > Labels: api > > Event time is assigned in stream sources via {{TimestampExtractor}}. Once > the event time has been assigned, it remains the same, regardless of any > downstream processing in the topology. This is insufficient for many > processing jobs, particularly when the output of the job is written back into > a Kafka topic, where the record's time is encoded outside of the record's > value. > For instance: > * When performing windowed aggregations it may be desirable for the timestamp > of the emitted record to be lower or higher limits of the time window, rather > than the timestamp of the last processed element, which may be anywhere > within the time window. > * When joining two streams, it is non-deterministic which of the two record's > timestamps will be the timestamp of the emitted record. It would be either > one depending on what order the records are processed. Even where this > deterministic, it may be desirable for the emitted timestamp to be altogether > different from the timestamp of the joined records. For instance, setting > the timestamp to the current processing time may be desirable. > * In general, lower level processors may wish to set the timestamp of emitted > records to an arbitrary value. > -- This message was sent by Atlassian JIRA (v6.3.4#6332)