[jira] [Commented] (FLINK-4796) Add new Sink interface with access to more meta data

["Erik van Oosten (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/FLINK-4796?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16160810#comment-16160810 ] 

Erik van Oosten commented on FLINK-4796:
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A workaround is to override {{setRuntimeContext}} (make sure to call {{super.setRuntimeContext}}), and use the passed in context. Possibly store it in a private field for later access.

> Add new Sink interface with access to more meta data
> ----------------------------------------------------
>
>                 Key: FLINK-4796
>                 URL: https://issues.apache.org/jira/browse/FLINK-4796
>             Project: Flink
>          Issue Type: Improvement
>          Components: DataStream API
>    Affects Versions: 1.2.0
>            Reporter: Robert Metzger
>
> The current {{SinkFunction}} cannot access the timestamps of elements which resulted in the (somewhat hacky) {{FlinkKafkaProducer010}}. Due to other limitations {{GenericWriteAheadSink}} is currently also a {{StreamOperator}} and not a {{SinkFunction}}.
> We should add a new interface for sinks that takes a context parameter, similar to {{ProcessFunction}}. This will allow sinks to query additional meta data about the element that they're receiving. 
> This is one ML thread where a user ran into a problem caused by this: http://apache-flink-user-mailing-list-archive.2336050.n4.nabble.com/Why-I-am-getting-Null-pointer-exception-while-accessing-RuntimeContext-in-FlinkKafkaProducer010-td12633.html#a12635
> h3. Original Text (that is still valid but not general)
> The Kafka 0.10 connector supports writing event timestamps to Kafka.
> Currently, the regular DataStream APIs don't allow user code to access the event timestamp easily. That's why the Kafka connector is using a custom operator ({{transform()}}) to access the event time.
> With this JIRA, I would like to provide the event timestamp in the regular DataStream APIs.
> Once I'll look into the issue, I'll post some proposals how to add the timestamp. 



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