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Posted to issues@beam.apache.org by "Alexey Romanenko (Jira)" <ji...@apache.org> on 2021/12/22 17:15:00 UTC
[jira] [Commented] (BEAM-13320) KafkaIO: inconsistent behaviour with Beam Row coders
[ https://issues.apache.org/jira/browse/BEAM-13320?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17463971#comment-17463971 ]
Alexey Romanenko commented on BEAM-13320:
-----------------------------------------
CC: [~lcwik]
> KafkaIO: inconsistent behaviour with Beam Row coders
> ----------------------------------------------------
>
> Key: BEAM-13320
> URL: https://issues.apache.org/jira/browse/BEAM-13320
> Project: Beam
> Issue Type: Bug
> Components: io-java-kafka
> Reporter: Yaroslav Tkachenko
> Priority: P2
>
> We've been using KafkaIO's _withValueDeserializerAndCoder_ method to provide a Beam Row Coder for many versions of Beam, however, it stopped working in 2.30 after _ReadFromKafkaViaSDF_ implementation was made the default in BEAM-12114.
> As far as I can see, _ReadFromKafkaViaUnbounded_ simply uses the key and the value coders that were passed with _withValueDeserializerAndCoder._
> But _ReadFromKafkaViaSDF_ relies on an internal _ReadSourceDescriptors_ class, which, for some reason, doesn't receive the provided coders directly. Instead, it leverages _DeserializerProvider_ which uses the _CoderRegistry_ to get the coders. BEAM-9569 added a [check|https://github.com/apache/beam/pull/10990/files#diff-fbe73e228ab8f76836ebfa899382731fe93c739f8cdb84ba9841b8f9591df175] that practically prevents using CoderRegistry with Beam Row objects. {*}The prevents us from using Beam Rows with KafkaIO{*}.
> As a workaround, we can use _--experiments=beam_fn_api_use_deprecated_read_ to force _ReadFromKafkaViaUnbounded_ implementation, but I'm afraid it'll be eventually deleted.
> So, I feel like either:
> * The existing KafkaIO documentation or examples needs to be updated to show how to rely on schemas when using Beam Rows, as was suggested in BEAM-9569. But I don't see how it can work with the existing implementation of KafkaIO.
> * Or _ReadFromKafkaViaSDF_ needs to use the provided coders and not fallback to {_}DeserializerProvider{_}.
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