WithTimestamps (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

Class WithTimestamps<T>

• java.lang.Object
• • com.google.cloud.dataflow.sdk.transforms.PTransform<PCollection<T>,PCollection<T>>
  • • com.google.cloud.dataflow.sdk.transforms.WithTimestamps<T>

• All Implemented Interfaces:

  HasDisplayData, Serializable

  ---

  
  

  public class WithTimestamps<T>
  extends PTransform<PCollection<T>,PCollection<T>>

  A PTransform for assigning timestamps to all the elements of a PCollection.

  Timestamps are used to assign Windows to elements within the Window.into(com.google.cloud.dataflow.sdk.transforms.windowing.WindowFn) PTransform. Assigning timestamps is useful when the input data set comes from a Source without implicit timestamps (such as TextIO).

  See Also:

  Serialized Form

• • Field Summary

    • Fields inherited from class com.google.cloud.dataflow.sdk.transforms.PTransform

      name

  • Method Summary

    All Methods Static Methods Instance Methods Concrete Methods 

    Modifier and Type	Method and Description
    PCollection<T>	apply(PCollection<T> input) Applies this PTransform on the given InputT, and returns its Output.
    Duration	getAllowedTimestampSkew() Returns the allowed timestamp skew duration, which is the maximum duration that timestamps can be shifted backwards from the timestamp of the input element.
    static <T> WithTimestamps<T>	of(SerializableFunction<T,Instant> fn) For a SerializableFunction fn from T to Instant, outputs a PTransform that takes an input PCollection<T> and outputs a PCollection<T> containing every element v in the input where each element is output with a timestamp obtained as the result of fn.apply(v).
    WithTimestamps<T>	withAllowedTimestampSkew(Duration allowedTimestampSkew) Return a new WithTimestamps like this one with updated allowed timestamp skew, which is the maximum duration that timestamps can be shifted backward.

    • Methods inherited from class com.google.cloud.dataflow.sdk.transforms.PTransform

      getDefaultOutputCoder, getDefaultOutputCoder, getDefaultOutputCoder, getKindString, getName, populateDisplayData, toString, validate

    • Methods inherited from class java.lang.Object

      clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

• • Method Detail

    • of

      public static <T> WithTimestamps<T> of(SerializableFunction<T,Instant> fn)

      For a SerializableFunction fn from T to Instant, outputs a PTransform that takes an input PCollection<T> and outputs a PCollection<T> containing every element v in the input where each element is output with a timestamp obtained as the result of fn.apply(v).

      If the input PCollection elements have timestamps, the output timestamp for each element must not be before the input element's timestamp minus the value of getAllowedTimestampSkew(). If an output timestamp is before this time, the transform will throw an IllegalArgumentException when executed. Use withAllowedTimestampSkew(Duration) to update the allowed skew.

      Each output element will be in the same windows as the input element. If a new window based on the new output timestamp is desired, apply a new instance of Window.into(WindowFn).

      This transform will fail at execution time with a NullPointerException if for any input element the result of fn.apply(v) is null.

      Example of use in Java 8:

      
       PCollection<Record> timestampedRecords = records.apply(
           WithTimestamps.of((Record rec) -> rec.getInstant());
       

    • withAllowedTimestampSkew

      public WithTimestamps<T> withAllowedTimestampSkew(Duration allowedTimestampSkew)

      Return a new WithTimestamps like this one with updated allowed timestamp skew, which is the maximum duration that timestamps can be shifted backward. Does not modify this object.

      The default value is Duration.ZERO, allowing timestamps to only be shifted into the future. For infinite skew, use new Duration(Long.MAX_VALUE).

    • getAllowedTimestampSkew

      public Duration getAllowedTimestampSkew()

      Returns the allowed timestamp skew duration, which is the maximum duration that timestamps can be shifted backwards from the timestamp of the input element.

      See Also:

      DoFn.getAllowedTimestampSkew()

    • apply

      public PCollection<T> apply(PCollection<T> input)

      Description copied from class: PTransform
      Applies this PTransform on the given InputT, and returns its Output.

      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).

      The default implementation throws an exception. A derived class must either implement apply, or else each runner must supply a custom implementation via PipelineRunner.apply(com.google.cloud.dataflow.sdk.transforms.PTransform<InputT, OutputT>, InputT).

      Overrides:

      apply in class PTransform<PCollection<T>,PCollection<T>>