com.pervasive.datarush.operators.partition

Class GatherHint

java.lang.Object

com.pervasive.datarush.operators.AbstractLogicalOperator

com.pervasive.datarush.operators.StreamingOperator

com.pervasive.datarush.operators.DeferredCompositeOperator

com.pervasive.datarush.operators.AbstractDeferredRecordOperator

com.pervasive.datarush.operators.partition.GatherHint

All Implemented Interfaces:

LogicalOperator, PipelineOperator<RecordPort>, RecordPipelineOperator

public final class GatherHint
extends AbstractDeferredRecordOperator

Forces parallel streams of data to be gathered into a single non-parallel stream. If requested, the output will also be sorted.

It is also possible to force data to be staged to disk, breaking physical streaming; consumers of the output will run in a physical graph executed after the physical graph executing this operator. Even if not forced, the transition from parallel to non-parallel may cause staging to occur.

Normally these actions happens automatically in a logical graph as required, but this operator provides a mechanism for explicit control.

By definition, this is a non-parallel operator.

Field Summary

Fields inherited from class com.pervasive.datarush.operators.AbstractDeferredRecordOperator

input, output

Constructor Summary

Constructors

Constructor and Description
GatherHint() Forces a gather of parallel streams of data.

Method Summary

Modifier and Type	Method and Description
protected void	compose(DeferredCompositionContext ctx) Compose the body of this operator.
protected void	computeMetadata(StreamingMetadataContext ctx) Implementations must adhere to all of the contracts specified by StreamingOperator.computeMetadata(com.pervasive.datarush.operators.StreamingMetadataContext).
DataOrdering	getDataOrdering() Gets the data ordering of the output.
boolean	isForceStaging() Indicates whether data will be forcibly staged to disk.
void	setDataOrdering(DataOrdering dataOrdering) Sets the data ordering of the output.
void	setForceStaging(boolean forceStaging) Sets whether data must be staged to disk.

Methods inherited from class com.pervasive.datarush.operators.AbstractDeferredRecordOperator

getInput, getOutput

Methods inherited from class com.pervasive.datarush.operators.DeferredCompositeOperator

computeOutputTypes

Methods inherited from class com.pervasive.datarush.operators.AbstractLogicalOperator

disableParallelism, getInputPorts, getOutputPorts, newInput, newInput, newOutput, newRecordInput, newRecordInput, newRecordOutput, notifyError

Methods inherited from class java.lang.Object

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

Methods inherited from interface com.pervasive.datarush.operators.LogicalOperator

disableParallelism, getInputPorts, getOutputPorts

Constructor Detail

GatherHint

public GatherHint()

Forces a gather of parallel streams of data. The resulting single stream will be unordered.

Method Detail

getDataOrdering

public DataOrdering getDataOrdering()

Gets the data ordering of the output.

Returns:

the requested data ordering

setDataOrdering

public void setDataOrdering(DataOrdering dataOrdering)

Sets the data ordering of the output. The output is guaranteed to be ordered in the specified manner.

Parameters:

dataOrdering - the requested data ordering

isForceStaging

public boolean isForceStaging()

Indicates whether data will be forcibly staged to disk.

Returns:

whether staging is required

setForceStaging

public void setForceStaging(boolean forceStaging)

Sets whether data must be staged to disk.

Parameters:

forceStaging - indicates whether the data must be staged

computeMetadata

protected void computeMetadata(StreamingMetadataContext ctx)

Description copied from class: DeferredCompositeOperator

Implementations must adhere to all of the contracts specified by StreamingOperator.computeMetadata(com.pervasive.datarush.operators.StreamingMetadataContext). In addition, DeferredCompositeOperators must declare required metadata so as to satisfy requirements of the operators that are added during DeferredCompositeOperator.compose(com.pervasive.datarush.operators.DeferredCompositionContext).

Specified by:

computeMetadata in class DeferredCompositeOperator

Parameters:

ctx - the context

compose

protected void compose(DeferredCompositionContext ctx)

Description copied from class: DeferredCompositeOperator

Compose the body of this operator. Implementations should do the following:

1. Instantiate and configure sub-operators, adding them to the provided context via the method OperatorComposable.add(O)
2. Create necessary connections via the method OperatorComposable.connect(P, P). This includes connections from the composite's input ports to sub-operators, connections between sub-operators, and connections from sub-operators output ports to the composite's output ports

Specified by:

compose in class DeferredCompositeOperator

Parameters:

ctx - the context