Hi Rahul,

FYI, that patterns is also available in the Beam docs  ( with updated code
example )
https://beam.apache.org/documentation/patterns/side-input-patterns/.

Please note in the DoFn that feeds the View.asSingleton() you will need to
manually call BigQuery using the BigQuery client.

Regards

Reza

On Tue, 16 Jul 2019 at 14:37, rahul patwari <rahulpatwari8...@gmail.com>
wrote:

> Hi,
>
> we are following [*Pattern: Slowly-changing lookup cache*] from
> https://cloud.google.com/blog/products/gcp/guide-to-common-cloud-dataflow-use-case-patterns-part-1
>
> We have a use case to read slowly changing bounded data as a PCollection
> along with the main PCollection from Kafka(windowed) and use it in the
> query of BeamSql.
>
> Is it possible to design such a use case with Beam Java SDK?
>
> Approaches followed but not Successful:
>
> 1) GenerateSequence => GlobalWindow with Data Trigger => Composite
> Transform(which applies Beam I/O on the
> pipeline[PCollection.getPipeline()]) => Convert the resulting PCollection
> to PCollection<Row> Apply BeamSQL
> Comments: Beam I/O reads data only once even though a long value is
> generated from GenerateSequece with periodicity. The expectation is that
> whenever a long value is generated, Beam I/O will be used to read the
> latest data. Is this because of optimizations in the DAG? Can the
> optimizations be overridden?
>
> 2) The pipeline is the same as approach 1. But, instead of using a
> composite transform, a DoFn is used where a for loop will emit each Row of
> the PCollection.
> comments: The output PCollection is unbounded. But, we need a bounded
> PCollection as this PCollection is used to JOIN with PCollection of each
> window from Kafka. How can we convert an Unbounded PCollection to Bounded
> PCollection inside a DoFn?
>
> Are there any better Approaches?
>
> Regards,
> Rahul
>
>
>

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