com.bigdata.bop.join

Class NestedLoopJoinOp

java.lang.Object

com.bigdata.bop.CoreBaseBOp

com.bigdata.bop.BOpBase

com.bigdata.bop.PipelineOp

com.bigdata.bop.join.NestedLoopJoinOp

All Implemented Interfaces:

BOp, IPropertySet, Serializable, Cloneable

public class NestedLoopJoinOp
extends PipelineOp

This operator performs a nested loop join for solutions. Intermediate solutions read from the pipeline are joined against a scan of some other solution set. This operator is useful when the cardinality of the source solutions in the pipeline is low (typically one empty source solution which is exogenous to the query, but it is also cost efficient when there is a small set of source solutions to be tested for each solution drained from the named solution set). As the number of source solutions to be drained from the pipeline grows, it eventually becomes cheaper to build a hash index over the named solution set and perform a hash join with the source solutions.

Note: This operator MUST NOT reorder the solutions which are being scanned from the named solution set. The query planner relies on that behavior to optimize a SLICE from a pre-computed named solution set.

Version:

$Id: CopyOp.java 6010 2012-02-10 20:11:20Z thompsonbry $ TODO This join does not implement optional semantics. If a use case for a nested loop join with optional semantics is identified at some point, then we will have to add support for optional here (and in the test suite).

Author:

Bryan Thompson

See Also:

SPARQL Update , SPARQL UPDATE for SOLUTION SETS , Serialized Form

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static interface	NestedLoopJoinOp.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
NestedLoopJoinOp(BOp[] args, Map<String,Object> annotations) Shallow copy constructor.
NestedLoopJoinOp(BOp[] args, NV... annotations)
NestedLoopJoinOp(NestedLoopJoinOp op) Deep copy constructor.

Method Summary

Methods

Modifier and Type	Method and Description
protected IConstraint[]	constraints()
FutureTask<Void>	eval(BOpContext<IBindingSet> context) Return a FutureTask which computes the operator against the evaluation context.
protected IVariable<?>[]	getSelect()

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

NestedLoopJoinOp

public NestedLoopJoinOp(NestedLoopJoinOp op)

Deep copy constructor.

Parameters:

op -

NestedLoopJoinOp

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

Shallow copy constructor.

Parameters:

args -

annotations -

NestedLoopJoinOp

public NestedLoopJoinOp(BOp[] args,
                NV... annotations)

Method Detail

getSelect

protected IVariable<?>[] getSelect()

See Also:

JoinAnnotations.SELECT

constraints

protected IConstraint[] constraints()

See Also:

JoinAnnotations.CONSTRAINTS

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.