Package org.apache.beam.sdk.transforms

Interface CombineFnBase.GlobalCombineFn<InputT,AccumT,OutputT>

Type Parameters:
InputT - type of input values
AccumT - type of mutable accumulator values
OutputT - type of output values
All Superinterfaces:
HasDisplayData, Serializable
All Known Implementing Classes:
ApproximateDistinct.ApproximateDistinctFn, ApproximateQuantiles.ApproximateQuantilesCombineFn, ApproximateUnique.ApproximateUniqueCombineFn, ArrayAgg.ArrayAggArray, BeamBuiltinAggregations.BitXOr, BeamBuiltinAnalyticFunctions.PositionAwareCombineFn, Combine.AccumulatingCombineFn, Combine.BinaryCombineDoubleFn, Combine.BinaryCombineFn, Combine.BinaryCombineIntegerFn, Combine.BinaryCombineLongFn, Combine.CombineFn, Combine.IterableCombineFn, Combine.SimpleCombineFn, CombineFns.ComposedCombineFn, CombineFns.ComposedCombineFnWithContext, CombineWithContext.CombineFnWithContext, CountIf.CountIfFn, CovarianceFn, DefaultSequenceCombiner, FlinkStreamingAggregationsTranslators.ConcatenateAsIterable, LazyAggregateCombineFn, Sample.FixedSizedSampleFn, SketchFrequencies.CountMinSketchFn, SnowflakeIO.Concatenate, StringAgg.StringAggByte, StringAgg.StringAggString, TDigestQuantiles.TDigestQuantilesFn, Top.TopCombineFn, TypedCombineFnDelegate, VarianceFn
Enclosing class:
CombineFnBase
@Internal public static interface CombineFnBase.GlobalCombineFn<InputT,AccumT,OutputT> extends Serializable, HasDisplayData
For internal use only; no backwards-compatibility guarantees.

A GloballyCombineFn<InputT, AccumT, OutputT> specifies how to combine a collection of input values of type InputT into a single output value of type OutputT. It does this via one or more intermediate mutable accumulator values of type AccumT.

Do not implement this interface directly. Extends Combine.CombineFn and CombineWithContext.CombineFnWithContext instead.

  • Method Details

    • getAccumulatorCoder

      Coder<AccumT> getAccumulatorCoder(CoderRegistry registry, Coder<InputT> inputCoder) throws CannotProvideCoderException
      Returns the Coder to use for accumulator AccumT values, or null if it is not able to be inferred.

      By default, uses the knowledge of the Coder being used for InputT values and the enclosing Pipeline's CoderRegistry to try to infer the Coder for AccumT values.

      This is the Coder used to send data through a communication-intensive shuffle step, so a compact and efficient representation may have significant performance benefits.

      Throws:
      CannotProvideCoderException

    • getDefaultOutputCoder

      Coder<OutputT> getDefaultOutputCoder(CoderRegistry registry, Coder<InputT> inputCoder) throws CannotProvideCoderException
      Returns the Coder to use by default for output OutputT values, or null if it is not able to be inferred.

      By default, uses the knowledge of the Coder being used for input InputT values and the enclosing Pipeline's CoderRegistry to try to infer the Coder for OutputT values.

      Throws:
      CannotProvideCoderException

    • getIncompatibleGlobalWindowErrorMessage

      String getIncompatibleGlobalWindowErrorMessage()
      Returns the error message for not supported default values in Combine.globally().

    • defaultValue

      OutputT defaultValue()
      Returns the default value when there are no values added to the accumulator.