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https://issues.apache.org/jira/browse/FLINK-7337?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16114891#comment-16114891
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Fabian Hueske commented on FLINK-7337:
--------------------------------------
Hi [~xccui], no worries about your questions. They are all very valid.
1) The {{ProcessFunction}} copies the {{StreamRecord}} timestamp (this is the
one set with the assigner) into the {{Row}} and removes the {{StreamRecord}}
timestamp. So it's an exact copy. The watermarks are not affected by this.
Watermarks are special records and not directly exposed to {{ProcessFunction}}.
2) We use the watermarks to trigger computations when the result is assumed to
be complete. They are a mechanism to control out-of-order data. So, yes. We
could compute results without watermarks, but then we would have to sent many
updates because we do not know at which point in time we received enough data
for a good first result. This is the approach of Kafka Streams.
> Refactor handling of time indicator attributes
> ----------------------------------------------
>
> Key: FLINK-7337
> URL: https://issues.apache.org/jira/browse/FLINK-7337
> Project: Flink
> Issue Type: Improvement
> Components: Table API & SQL
> Affects Versions: 1.4.0
> Reporter: Fabian Hueske
> Assignee: Fabian Hueske
>
> After a [discussion on the dev mailing
> list|https://lists.apache.org/thread.html/735d55f9022df8ff73566a9f1553e14be94f8443986ad46559b35869@%3Cdev.flink.apache.org%3E]
> I propose the following changes to the current handling of time indicator
> attributes:
> * Remove the separation of logical and physical row type.
> ** Hold the event-time timestamp as regular Long field in Row
> ** Represent the processing-time indicator type as a null-valued field in Row
> (1 bit overhead)
> * Remove materialization of event-time timestamps because timestamp is
> already accessible in Row.
> * Add {{ProcessFunction}} to set timestamp into the timestamp field of a
> {{StreamRecord}}.
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