com.bigdata.bop.controller

Class AbstractSubqueryOp

java.lang.Object

com.bigdata.bop.CoreBaseBOp

com.bigdata.bop.BOpBase

com.bigdata.bop.PipelineOp

com.bigdata.bop.controller.AbstractSubqueryOp

All Implemented Interfaces:

BOp, IPropertySet, Serializable, Cloneable

Direct Known Subclasses:

Steps, Union

public abstract class AbstractSubqueryOp
extends PipelineOp

Executes each of the operands as a subquery. The operands are evaluated in the order given and with the annotated parallelism. Each subquery is run as a separate query but is linked to the parent query in the operator is being evaluated. The subqueries receive bindings from the pipeline and may be executed independently. By default, the subqueries are run with unlimited parallelism. Since the #of subqueries is generally small (2), this means that the subqueries run in parallel.

Note: This operator must execute on the query controller.

If you want to route intermediate results from other computations into subqueries, then consider a Tee pattern instead.

For example:

 SLICE[1](
   UNION[2]([...],{subqueries=[a,b,c]})
   )
 

Will run the subqueries a, b, and c in parallel. Each subquery will be run once for each source IBindingSet.

Version:

$Id$

Author:

Bryan Thompson

See Also:

Serialized Form

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static interface	AbstractSubqueryOp.Annotations

Field Summary

Fields inherited from class com.bigdata.bop.CoreBaseBOp

DEFAULT_INITIAL_CAPACITY

Fields inherited from interface com.bigdata.bop.BOp

NOANNS, NOARGS

Constructor Summary

Constructors

Constructor and Description
AbstractSubqueryOp(AbstractSubqueryOp op) Deep copy constructor.
AbstractSubqueryOp(BOp[] args, Map<String,Object> annotations) Shallow copy constructor.

Method Summary

Methods

Modifier and Type	Method and Description
FutureTask<Void>	eval(BOpContext<IBindingSet> context) Return a FutureTask which computes the operator against the evaluation context.
int	getMaxParallelSubqueries()

Methods inherited from class com.bigdata.bop.PipelineOp

assertAtOnceJavaHeapOp, assertMaxParallelOne, getChunkCapacity, getChunkOfChunksCapacity, getChunkTimeout, getMaxMemory, getMaxParallel, isAtOnceEvaluation, isBlockedEvaluation, isLastPassRequested, isPipelinedEvaluation, isReorderSolutions, isSharedState, newStats

Methods inherited from class com.bigdata.bop.BOpBase

__replaceArg, _clearProperty, _set, _setProperty, annotations, annotationsCopy, annotationsEqual, annotationsRef, argIterator, args, argsCopy, arity, clearAnnotations, clearProperty, deepCopy, deepCopy, get, getProperty, setArg, setProperty, setUnboundProperty, toArray, toArray

Methods inherited from class com.bigdata.bop.CoreBaseBOp

annotationsEqual, annotationsToString, annotationsToString, annotationValueToString, checkArgs, clone, equals, getEvaluationContext, getId, getProperty, getRequiredProperty, hashCode, indent, isController, mutation, shortenName, toShortString, toString, toString

Methods inherited from class java.lang.Object

finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

AbstractSubqueryOp

public AbstractSubqueryOp(AbstractSubqueryOp op)

Deep copy constructor.

AbstractSubqueryOp

public AbstractSubqueryOp(BOp[] args,
                  Map<String,Object> annotations)

Shallow copy constructor.

Parameters:

args -

annotations -

Method Detail

getMaxParallelSubqueries

public int getMaxParallelSubqueries()

See Also:

AbstractSubqueryOp.Annotations.MAX_PARALLEL_SUBQUERIES

eval

public FutureTask<Void> eval(BOpContext<IBindingSet> context)

Description copied from class: PipelineOp

Return a FutureTask which computes the operator against the evaluation context. The caller is responsible for executing the FutureTask (this gives them the ability to hook the completion of the computation).

Specified by:

eval in class PipelineOp

Parameters:

context - The evaluation context.

Returns:

The FutureTask which will compute the operator's evaluation.