Package org.apache.beam.sdk.values
Class PBegin
- java.lang.Object
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- org.apache.beam.sdk.values.PBegin
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- All Implemented Interfaces:
PInput
public class PBegin extends java.lang.Object implements PInput
PBegin
is the "input" to a rootPTransform
, such asRead
orCreate
.Typically elided by simply calling
Pipeline.apply(String, PTransform)
orPipeline.apply(PTransform)
, but one can be explicitly created by callingPipeline.begin()
on a Pipeline.
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Method Summary
All Methods Static Methods Instance Methods Concrete Methods Modifier and Type Method Description <OutputT extends POutput>
OutputTapply(java.lang.String name, PTransform<? super PBegin,OutputT> t)
Applies the givenPTransform
to thisPBegin
, usingname
to identify this specific application of the transform.<OutputT extends POutput>
OutputTapply(PTransform<? super PBegin,OutputT> t)
Likeapply(String, PTransform)
but defaulting to the name of thePTransform
.java.util.Map<TupleTag<?>,PValue>
expand()
Pipeline
getPipeline()
static PBegin
in(Pipeline pipeline)
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Constructor Detail
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PBegin
protected PBegin(Pipeline pipeline)
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Method Detail
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apply
public <OutputT extends POutput> OutputT apply(PTransform<? super PBegin,OutputT> t)
Likeapply(String, PTransform)
but defaulting to the name of thePTransform
.
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apply
public <OutputT extends POutput> OutputT apply(java.lang.String name, PTransform<? super PBegin,OutputT> t)
Applies the givenPTransform
to thisPBegin
, usingname
to identify this specific application of the transform.This name is used in various places, including the monitoring UI, logging, and to stably identify this application node in the job graph.
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getPipeline
public Pipeline getPipeline()
Description copied from interface:PInput
- Specified by:
getPipeline
in interfacePInput
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expand
public java.util.Map<TupleTag<?>,PValue> expand()
Description copied from interface:PInput
Expands thisPInput
into a list of its component outputPValues
.- A
PValue
expands to itself. - A tuple or list of
PValues
(such asPCollectionTuple
orPCollectionList
) expands to its componentPValue PValues
.
Not intended to be invoked directly by user code.
- A
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