Hi everyone,
Does anyone have comments on this question?
CCing user ML
ThanksEtienne
Le mardi 11 décembre 2018 à 19:02 +0100, Etienne Chauchot a écrit :
> Hi Spark guys,
> I'm Etienne Chauchot and I'm a committer on the Apache Beam project.
> We have what we call runners. They are pieces of software that translate
> pipelines written using Beam API into
> pipelines that use native execution engine API. Currently, the Spark runner
> uses old RDD / DStream APIs. I'm writing a
> new runner that will use structured streaming (but not continuous processing,
> and also no schema for now).
> I am just starting. I'm currently trying to map our sources to yours. I'm
> targeting new DataSourceV2 API. It maps
> pretty well with Beam sources but I have a problem with instanciation of the
> custom source.I searched for an answer in
> stack-overflow and user ML with no luck. I guess it is a too specific
> question:
> When visiting Beam DAG I have access to Beam objects such as Source and
> Reader that I need to map to MicroBatchReader
> and InputPartitionReader.As far as I understand, a custom DataSourceV2 is
> instantiated automatically by spark thanks
> to sparkSession.readStream().format(providerClassName) or similar code. The
> problem is that I can only pass options of
> primitive types + String so I cannot pass the Beam Source to DataSourceV2. =>
> Is there a way to do so ?
>
> Also I get as an output a Dataset<Row>. The Row contains an instance of Beam
> WindowedValue<T>, T is the type parameter
> of the Source. I do a map on the Dataset to transform it to a
> Dataset<WindowedValue<T>>. I have a question related to
> the Encoder: => how to properly create an Encoder for the generic type
> WindowedValue<T> to use in the map?
> Here is the
> code:https://github.com/apache/beam/tree/spark-runner_structured-streaming
> And more specially:
> https://github.com/apache/beam/blob/spark-runner_structured-streaming/runners/spark-structured-streaming/src/main/java/org/apache/beam/runners/spark/structuredstreaming/translation/batch/ReadSourceTranslatorBatch.javahttps://github.com/apache/beam/blob/spark-runner_structured-streaming/runners/spark-structured-streaming/src/main/java/org/apache/beam/runners/spark/structuredstreaming/translation/io/DatasetSource.java
> Thanks,
> Etienne
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