Package org.apache.beam.sdk.transforms.windowing

@DefaultAnnotation(org.checkerframework.checker.nullness.qual.NonNull.class) package org.apache.beam.sdk.transforms.windowing

Defines the Window transform for dividing the elements in a PCollection into windows, and the Trigger for controlling when those elements are output.

Window logically divides up or groups the elements of a PCollection into finite windows according to a WindowFn. The output of Window contains the same elements as input, but they have been logically assigned to windows. The next GroupByKeys, including one within composite transforms, will group by the combination of keys and windows.

Windowing a PCollection allows chunks of it to be processed individually, before the entire PCollection is available. This is especially important for PCollections with unbounded size, since the full PCollection is never available at once.

For PCollections with a bounded size, by default, all data is implicitly in a single window, and this replicates conventional batch mode. However, windowing can still be a convenient way to express time-sliced algorithms over bounded PCollections.

As elements are assigned to a window, they are placed into a pane. When the trigger fires all of the elements in the current pane are output.

The DefaultTrigger will output a window when the system watermark passes the end of the window. See AfterWatermark for details on the watermark.

Related Packages

Package	Description
org.apache.beam.sdk.transforms	Defines PTransforms for transforming data in a pipeline.
org.apache.beam.sdk.transforms.display	Defines HasDisplayData for annotating components which provide display data used within UIs and diagnostic tools.
org.apache.beam.sdk.transforms.errorhandling	Provides utilities for handling errors in Pipelines.
org.apache.beam.sdk.transforms.join	Defines the CoGroupByKey transform for joining multiple PCollections.
org.apache.beam.sdk.transforms.resourcehints	Defines ResourceHints for configuring pipeline execution.
org.apache.beam.sdk.transforms.splittabledofn	Defines utilities related to splittable DoFn.

Class	Description
AfterAll	A composite Trigger that fires when all of its sub-triggers are ready.
AfterEach	A composite Trigger that executes its sub-triggers in order.
AfterFirst	A composite Trigger that fires once after at least one of its sub-triggers have fired.
AfterPane	A Trigger that fires at some point after a specified number of input elements have arrived.
AfterProcessingTime	A Trigger trigger that fires at a specified point in processing time, relative to when input first arrives.
AfterSynchronizedProcessingTime	FOR INTERNAL USE ONLY.
AfterWatermark	AfterWatermark triggers fire based on progress of the system watermark.
AfterWatermark.AfterWatermarkEarlyAndLate
AfterWatermark.FromEndOfWindow	A watermark trigger targeted relative to the end of the window.
BoundedWindow	A BoundedWindow represents window information assigned to data elements.
CalendarWindows	A collection of WindowFns that windows values into calendar-based windows such as spans of days, months, or years.
CalendarWindows.DaysWindows	A WindowFn that windows elements into periods measured by days.
CalendarWindows.MonthsWindows	A WindowFn that windows elements into periods measured by months.
CalendarWindows.YearsWindows	A WindowFn that windows elements into periods measured by years.
DefaultTrigger	A trigger that is equivalent to Repeatedly.forever(AfterWatermark.pastEndOfWindow()).
FixedWindows	A WindowFn that windows values into fixed-size timestamp-based windows.
GlobalWindow	The default window into which all data is placed (via GlobalWindows).
GlobalWindow.Coder	GlobalWindow.Coder for encoding and decoding GlobalWindows.
GlobalWindows	A WindowFn that assigns all data to the same window.
IncompatibleWindowException	Exception thrown by WindowFn.verifyCompatibility(WindowFn) if two compared WindowFns are not compatible, including the explanation of incompatibility.
IntervalWindow	An implementation of BoundedWindow that represents an interval from IntervalWindow.start (inclusive) to IntervalWindow.end (exclusive).
IntervalWindow.IntervalWindowCoder	Encodes an IntervalWindow as a pair of its upper bound and duration.
MergeOverlappingIntervalWindows	For internal use only; no backwards compatibility guarantees.
Never	A Trigger which never fires.
Never.NeverTrigger	The actual trigger class for Never triggers.
NonMergingWindowFn<T,W extends BoundedWindow>	Abstract base class for WindowFns that do not merge windows.
OrFinallyTrigger	A Trigger that executes according to its main trigger until its "finally" trigger fires.
PaneInfo	Provides information about the pane an element belongs to.
PaneInfo.PaneInfoCoder	A Coder for encoding PaneInfo instances.
PaneInfo.Timing	Enumerates the possibilities for the timing of this pane firing related to the input and output watermarks for its computation.
PartitioningWindowFn<T,W extends BoundedWindow>	A WindowFn that places each value into exactly one window based on its timestamp and never merges windows.
Repeatedly	A Trigger that fires according to its subtrigger forever.
ReshuffleTrigger<W extends BoundedWindow>	For internal use only; no backwards compatibility guarantees.
Sessions	A WindowFn that windows values into sessions separated by periods with no input for at least the duration specified by Sessions.getGapDuration().
SlidingWindows	A WindowFn that windows values into possibly overlapping fixed-size timestamp-based windows.
TimestampCombiner	Policies for combining timestamps that occur within a window.
TimestampTransform	For internal use only; no backwards-compatibility guarantees.
TimestampTransform.AlignTo	For internal use only; no backwards-compatibility guarantees.
TimestampTransform.Delay	For internal use only; no backwards-compatibility guarantees.
Trigger	Triggers control when the elements for a specific key and window are output.
Trigger.OnceTrigger	For internal use only; no backwards-compatibility guarantees.
Window<T>	Window logically divides up or groups the elements of a PCollection into finite windows according to a WindowFn.
Window.Assign<T>	A Primitive PTransform that assigns windows to elements based on a WindowFn.
Window.ClosingBehavior	Specifies the conditions under which a final pane will be created when a window is permanently closed.
Window.OnTimeBehavior	Specifies the conditions under which an on-time pane will be created when a window is closed.
WindowFn<T,W extends BoundedWindow>	The argument to the Window transform used to assign elements into windows and to determine how windows are merged.
WindowMappingFn<TargetWindowT extends BoundedWindow>	A function that takes the windows of elements in a main input and maps them to the appropriate window in a PCollectionView consumed as a side input.