WriteFiles (Apache Beam 2.12.0)

java.lang.Object
- org.apache.beam.sdk.transforms.PTransform<PCollection<UserT>,WriteFilesResult<DestinationT>>
- - org.apache.beam.sdk.io.WriteFiles<UserT,DestinationT,OutputT>

All Implemented Interfaces:

java.io.Serializable, HasDisplayData
```
@Experimental(value=SOURCE_SINK)
public abstract class WriteFiles<UserT,DestinationT,OutputT>
extends PTransform<PCollection<UserT>,WriteFilesResult<DestinationT>>
```
A PTransform that writes to a FileBasedSink. A write begins with a sequential global initialization of a sink, followed by a parallel write, and ends with a sequential finalization of the write. The output of a write is PDone.
By default, every bundle in the input PCollection will be processed by a FileBasedSink.WriteOperation, so the number of output will vary based on runner behavior, though at least 1 output will always be produced. The exact parallelism of the write stage can be controlled using withNumShards(int), typically used to control how many files are produced or to globally limit the number of workers connecting to an external service. However, this option can often hurt performance: it adds an additional GroupByKey to the pipeline.
Example usage with runner-determined sharding:
```
 p.apply(WriteFiles.to(new MySink(...)));
```
Example usage with a fixed number of shards:
```
 p.apply(WriteFiles.to(new MySink(...)).withNumShards(3));
```
See Also:

Serialized Form

Field Summary

Fields
Modifier and Type Field and Description

static java.lang.Class<? extends WriteFiles> CONCRETE_CLASS
For internal use by runners.
- Fields inherited from class org.apache.beam.sdk.transforms.PTransform
  name

Fields
Modifier and Type	Field and Description
`static java.lang.Class<? extends WriteFiles>`	`CONCRETE_CLASS` For internal use by runners.

Constructor Summary

Constructors
Constructor and Description

WriteFiles()

Constructors
Constructor and Description
`WriteFiles()`

Method Summary

All Methods Static Methods Instance Methods Abstract Methods Concrete Methods
Modifier and Type	Method and Description
`WriteFilesResult<DestinationT>`	`expand(PCollection<UserT> input)` Override this method to specify how this `PTransform` should be expanded on the given `InputT`.
`java.util.Map<TupleTag<?>,PValue>`	`getAdditionalInputs()` Returns all `PValues` that are consumed as inputs to this `PTransform` that are independent of the expansion of the `InputT` within `PTransform.expand(PInput)`.
`abstract PTransform<PCollection<UserT>,PCollectionView<java.lang.Integer>>`	`getComputeNumShards()`
`abstract ValueProvider<java.lang.Integer>`	`getNumShardsProvider()`
`abstract FileBasedSink<UserT,DestinationT,OutputT>`	`getSink()`
`abstract boolean`	`getWindowedWrites()`
`void`	`populateDisplayData(DisplayData.Builder builder)` Register display data for the given transform or component.
`static <UserT,DestinationT,OutputT> WriteFiles<UserT,DestinationT,OutputT>`	`to(FileBasedSink<UserT,DestinationT,OutputT> sink)` Creates a `WriteFiles` transform that writes to the given `FileBasedSink`, letting the runner control how many different shards are produced.
`void`	`validate(PipelineOptions options)` Called before running the Pipeline to verify this transform is fully and correctly specified.
`WriteFiles<UserT,DestinationT,OutputT>`	`withMaxNumWritersPerBundle(int maxNumWritersPerBundle)` Set the maximum number of writers created in a bundle before spilling to shuffle.
`WriteFiles<UserT,DestinationT,OutputT>`	`withNoSpilling()` Returns a new `WriteFiles` that writes all data without spilling, simplifying the pipeline.
`WriteFiles<UserT,DestinationT,OutputT>`	`withNumShards(int numShards)` Returns a new `WriteFiles` that will write to the current `FileBasedSink` using the specified number of shards.
`WriteFiles<UserT,DestinationT,OutputT>`	`withNumShards(ValueProvider<java.lang.Integer> numShardsProvider)` Returns a new `WriteFiles` that will write to the current `FileBasedSink` using the `ValueProvider` specified number of shards.
`WriteFiles<UserT,DestinationT,OutputT>`	`withRunnerDeterminedSharding()` Returns a new `WriteFiles` that will write to the current `FileBasedSink` with runner-determined sharding.
`WriteFiles<UserT,DestinationT,OutputT>`	`withSharding(PTransform<PCollection<UserT>,PCollectionView<java.lang.Integer>> sharding)` Returns a new `WriteFiles` that will write to the current `FileBasedSink` using the specified `PTransform` to compute the number of shards.
`WriteFiles<UserT,DestinationT,OutputT>`	`withSideInputs(java.util.List<PCollectionView<?>> sideInputs)`
`WriteFiles<UserT,DestinationT,OutputT>`	`withWindowedWrites()` Returns a new `WriteFiles` that writes preserves windowing on it's input.

Methods inherited from class org.apache.beam.sdk.transforms.PTransform
compose, compose, getDefaultOutputCoder, getDefaultOutputCoder, getDefaultOutputCoder, getKindString, getName, toString

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

- Field Detail
  - CONCRETE_CLASS
```
@Internal
public static final java.lang.Class<? extends WriteFiles> CONCRETE_CLASS
```
    For internal use by runners.
- Constructor Detail
  - WriteFiles
```
public WriteFiles()
```
- Method Detail
  - to
```
public static <UserT,DestinationT,OutputT> WriteFiles<UserT,DestinationT,OutputT> to(FileBasedSink<UserT,DestinationT,OutputT> sink)
```
    Creates a WriteFiles transform that writes to the given FileBasedSink, letting the runner control how many different shards are produced.
  - getSink
```
public abstract FileBasedSink<UserT,DestinationT,OutputT> getSink()
```
  - getComputeNumShards
```
@Nullable
public abstract PTransform<PCollection<UserT>,PCollectionView<java.lang.Integer>> getComputeNumShards()
```
  - getNumShardsProvider
```
@Nullable
public abstract ValueProvider<java.lang.Integer> getNumShardsProvider()
```
  - getWindowedWrites
```
public abstract boolean getWindowedWrites()
```
  - getAdditionalInputs
```
public java.util.Map<TupleTag<?>,PValue> getAdditionalInputs()
```
    Description copied from class: PTransform
    
    Returns all PValues that are consumed as inputs to this PTransform that are independent of the expansion of the InputT within PTransform.expand(PInput).
    For example, this can contain any side input consumed by this PTransform.
    
    Overrides:
    
    getAdditionalInputs in class PTransform<PCollection<UserT>,WriteFilesResult<DestinationT>>
  - withNumShards
```
public WriteFiles<UserT,DestinationT,OutputT> withNumShards(int numShards)
```
    Returns a new WriteFiles that will write to the current FileBasedSink using the specified number of shards.
    This option should be used sparingly as it can hurt performance. See WriteFiles for more information.
    A value less than or equal to 0 will be equivalent to the default behavior of runner-determined sharding.
  - withNumShards
```
public WriteFiles<UserT,DestinationT,OutputT> withNumShards(ValueProvider<java.lang.Integer> numShardsProvider)
```
    Returns a new WriteFiles that will write to the current FileBasedSink using the ValueProvider specified number of shards.
    This option should be used sparingly as it can hurt performance. See WriteFiles for more information.
  - withMaxNumWritersPerBundle
```
public WriteFiles<UserT,DestinationT,OutputT> withMaxNumWritersPerBundle(int maxNumWritersPerBundle)
```
    Set the maximum number of writers created in a bundle before spilling to shuffle.
  - withSideInputs
```
public WriteFiles<UserT,DestinationT,OutputT> withSideInputs(java.util.List<PCollectionView<?>> sideInputs)
```
  - withSharding
```
public WriteFiles<UserT,DestinationT,OutputT> withSharding(PTransform<PCollection<UserT>,PCollectionView<java.lang.Integer>> sharding)
```
    Returns a new WriteFiles that will write to the current FileBasedSink using the specified PTransform to compute the number of shards.
    This option should be used sparingly as it can hurt performance. See WriteFiles for more information.
  - withRunnerDeterminedSharding
```
public WriteFiles<UserT,DestinationT,OutputT> withRunnerDeterminedSharding()
```
    Returns a new WriteFiles that will write to the current FileBasedSink with runner-determined sharding.
  - withWindowedWrites
```
public WriteFiles<UserT,DestinationT,OutputT> withWindowedWrites()
```
    Returns a new WriteFiles that writes preserves windowing on it's input.
    If this option is not specified, windowing and triggering are replaced by GlobalWindows and DefaultTrigger.
    If there is no data for a window, no output shards will be generated for that window. If a window triggers multiple times, then more than a single output shard might be generated multiple times; it's up to the sink implementation to keep these output shards unique.
    This option can only be used if withNumShards(int) is also set to a positive value.
  - withNoSpilling
```
public WriteFiles<UserT,DestinationT,OutputT> withNoSpilling()
```
    Returns a new WriteFiles that writes all data without spilling, simplifying the pipeline. This option should not be used with withMaxNumWritersPerBundle(int) and it will eliminate this limit possibly causing many writers to be opened. Use with caution.
    This option only applies to writes withRunnerDeterminedSharding().
  - validate
```
public void validate(PipelineOptions options)
```
    Description copied from class: PTransform
    
    Called before running the Pipeline to verify this transform is fully and correctly specified.
    By default, does nothing.
    
    Overrides:
    
    validate in class PTransform<PCollection<UserT>,WriteFilesResult<DestinationT>>
  - expand
```
public WriteFilesResult<DestinationT> expand(PCollection<UserT> 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<PCollection<UserT>,WriteFilesResult<DestinationT>>
  - 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<PCollection<UserT>,WriteFilesResult<DestinationT>>
    
    Parameters:
    
    builder - The builder to populate with display data.
    
    See Also:
    
    HasDisplayData

Class WriteFiles<UserT,DestinationT,OutputT>

Field Summary

Fields inherited from class org.apache.beam.sdk.transforms.PTransform

Constructor Summary

Method Summary

Methods inherited from class org.apache.beam.sdk.transforms.PTransform

Methods inherited from class java.lang.Object

Field Detail

CONCRETE_CLASS

Constructor Detail

WriteFiles

Method Detail

to

getSink

getComputeNumShards

getNumShardsProvider

getWindowedWrites

getAdditionalInputs

withNumShards

withNumShards

withMaxNumWritersPerBundle

withSideInputs

withSharding

withRunnerDeterminedSharding

withWindowedWrites

withNoSpilling

validate

expand

populateDisplayData