Aggregator (Google Cloud Dataflow SDK 1.9.1 API)

Google Cloud Dataflow SDK for Java, version 1.9.1

Warning: Dataflow SDK 1.x for Java is unsupported as of October 16, 2018. After August 12, 2020, you can use unsupported SDKs temporarily while you upgrade your pipelines. For more information, see Using an unsupported SDK.

For information on migrating from the 1.x SDK, see Migrating from Dataflow SDK 1.x for Java.

Note: If you are using Cloud Dataflow SDK version 2.x, see the Apache Beam API reference documentation.

com.google.cloud.dataflow.sdk.transforms

Interface Aggregator<InputT,OutputT>

• Type Parameters:

  InputT - the type of input values

  OutputT - the type of output values

  ---

  
  

  public interface Aggregator<InputT,OutputT>

  An Aggregator<InputT> enables monitoring of values of type InputT, to be combined across all bundles.

  Aggregators are created by calling DoFn.createAggregator(java.lang.String, com.google.cloud.dataflow.sdk.transforms.Combine.CombineFn<? super AggInputT, ?, AggOutputT>), typically from the DoFn constructor. Elements can be added to the Aggregator by calling addValue(InputT).

  Aggregators are visible in the monitoring UI, when the pipeline is run using DataflowPipelineRunner or BlockingDataflowPipelineRunner, along with their current value. Aggregators may not become visible until the system begins executing the ParDo transform that created them and/or their initial value is changed.

  Example:

   
   class MyDoFn extends DoFn {
     private Aggregator myAggregator;
  
     public MyDoFn() {
       myAggregator = createAggregator("myAggregator", new Sum.SumIntegerFn());
     }

• • Method Summary

    All Methods Instance Methods Abstract Methods 

    Modifier and Type	Method and Description
    void	addValue(InputT value) Adds a new value into the Aggregator.
    Combine.CombineFn<InputT,?,OutputT>	getCombineFn() Returns the Combine.CombineFn, which combines input elements in the aggregator.
    String	getName() Returns the name of the Aggregator.

• • Method Detail

    • addValue

      void addValue(InputT value)

      Adds a new value into the Aggregator.

    • getName

      String getName()

      Returns the name of the Aggregator.

    • getCombineFn

      Combine.CombineFn<InputT,?,OutputT> getCombineFn()

      Returns the Combine.CombineFn, which combines input elements in the aggregator.