Google Cloud Dataflow SDK for Java, version 1.9.1
com.google.cloud.dataflow.sdk.values
Class PBegin
- java.lang.Object
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- com.google.cloud.dataflow.sdk.values.PBegin
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- All Implemented Interfaces:
- PInput
public class PBegin extends Object implements PInput
PBegin
is the "input" to a rootPTransform
, such asRead
orCreate
.Typically created by calling
Pipeline.begin()
on a Pipeline.
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Constructor Summary
Constructors Modifier Constructor and Description protected
PBegin(Pipeline pipeline)
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Method Summary
All Methods Static Methods Instance Methods Concrete Methods Modifier and Type Method and Description <OutputT extends POutput>
OutputTapply(PTransform<? super PBegin,OutputT> t)
Likeapply(String, PTransform)
but defaulting to the name of thePTransform
.<OutputT extends POutput>
OutputTapply(String name, PTransform<? super PBegin,OutputT> t)
Applies the givenPTransform
to this inputPBegin
, usingname
to identify this specific application of the transform.Collection<? extends PValue>
expand()
void
finishSpecifying()
After building, finalizes thisPInput
to make it ready for being used as an input to aPTransform
.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(String name, PTransform<? super PBegin,OutputT> t)
Applies the givenPTransform
to this inputPBegin
, 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 Collection<? extends 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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finishSpecifying
public void finishSpecifying()
Description copied from interface:PInput
After building, finalizes thisPInput
to make it ready for being used as an input to aPTransform
.Automatically invoked whenever
apply()
is invoked on thisPInput
, so users do not normally call this explicitly.- Specified by:
finishSpecifying
in interfacePInput
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