Package org.apache.beam.sdk.io

Class BoundedReadFromUnboundedSource<T>

java.lang.Object
org.apache.beam.sdk.transforms.PTransform<PBegin,PCollection<T>>
org.apache.beam.sdk.io.BoundedReadFromUnboundedSource<T>
All Implemented Interfaces:
Serializable, HasDisplayData
public class BoundedReadFromUnboundedSource<T> extends PTransform<PBegin,PCollection<T>>
PTransform that reads a bounded amount of data from an UnboundedSource, specified as one or both of a maximum number of elements or a maximum period of time to read.
See Also:

  • Method Details

    • withMaxNumRecords

      public BoundedReadFromUnboundedSource<T> withMaxNumRecords(long maxNumRecords)
      Returns a new BoundedReadFromUnboundedSource that reads a bounded amount of data from the given UnboundedSource. The bound is specified as a number of records to read.

      This may take a long time to execute if the splits of this source are slow to read records.

    • withMaxReadTime

      public BoundedReadFromUnboundedSource<T> withMaxReadTime(Duration maxReadTime)
      Returns a new BoundedReadFromUnboundedSource that reads a bounded amount of data from the given UnboundedSource. The bound is specified as an amount of time to read for. Each split of the source will read for this much time.

    • expand

      public PCollection<T> expand(PBegin input)
      Description copied from class: PTransform
      Override this method to specify how this PTransform should be expanded on the given InputT.

      NOTE: This method should not be called directly. Instead apply the PTransform should be applied to the InputT using the apply method.

      Composite transforms, which are defined in terms of other transforms, should return the output of one of the composed transforms. Non-composite transforms, which do not apply any transforms internally, should return a new unbound output and register evaluators (via backend-specific registration methods).

      Specified by:
      expand in class PTransform<PBegin,PCollection<T>>

    • getKindString

      public String getKindString()
      Description copied from class: PTransform
      Returns the name to use by default for this PTransform (not including the names of any enclosing PTransforms).

      By default, returns the base name of this PTransform's class.

      The caller is responsible for ensuring that names of applied PTransforms are unique, e.g., by adding a uniquifying suffix when needed.

      Overrides:
      getKindString in class PTransform<PBegin,PCollection<T>>

    • populateDisplayData

      public void populateDisplayData(DisplayData.Builder builder)
      Description copied from class: PTransform
      Register display data for the given transform or component.

      populateDisplayData(DisplayData.Builder) is invoked by Pipeline runners to collect display data via DisplayData.from(HasDisplayData). Implementations may call super.populateDisplayData(builder) in order to register display data in the current namespace, but should otherwise use subcomponent.populateDisplayData(builder) to use the namespace of the subcomponent.

      By default, does not register any display data. Implementors may override this method to provide their own display data.

      Specified by:
      populateDisplayData in interface HasDisplayData
      Overrides:
      populateDisplayData in class PTransform<PBegin,PCollection<T>>
      Parameters:
      builder - The builder to populate with display data.
      See Also: