Class ExecOpProject

java.lang.Object

se.liu.ida.hefquin.engine.queryplan.executable.impl.ops.BaseForExecOps

se.liu.ida.hefquin.engine.queryplan.executable.impl.ops.UnaryExecutableOpBase

se.liu.ida.hefquin.engine.queryplan.executable.impl.ops.UnaryExecutableOpBaseWithoutBlocking

se.liu.ida.hefquin.engine.queryplan.executable.impl.ops.ExecOpProject

All Implemented Interfaces:

StatsProvider, ExecutableOperator, UnaryExecutableOp

public class ExecOpProject
extends UnaryExecutableOpBaseWithoutBlocking

To be used for PROJECT clauses. This operator restricts each input solution mapping to a given set of variables by removing bindings for all other variables. For every input solution mapping, exactly one output solution mapping is produced.

Field Summary

Fields

Modifier and Type	Field	Description
protected final Set<org.apache.jena.sparql.core.Var>	variables

Fields inherited from class se.liu.ida.hefquin.engine.queryplan.executable.impl.ops.UnaryExecutableOpBaseWithoutBlocking

MAX_BATCH_SIZE

Fields inherited from class se.liu.ida.hefquin.engine.queryplan.executable.impl.ops.BaseForExecOps

collectExceptions, mayReduce, qpInfo

Constructor Summary

Constructors

Constructor	Description
ExecOpProject(Set<org.apache.jena.sparql.core.Var> variables, boolean mayReduce, boolean collectExceptions, QueryPlanningInfo qpInfo)

Method Summary

Modifier and Type	Method	Description
protected void	_concludeExecution(IntermediateResultElementSink sink, ExecutionContext execCxt)	Implementations of this function need to conclude the execution of this operator and send the remaining result elements (if any) to the given sink.
protected void	_process(Iterator<SolutionMapping> inputSolMaps, int maxBatchSize, IntermediateResultElementSink sink, ExecutionContext execCxt)	Processes input solution mappings of the given iterator by calling UnaryExecutableOpBase._process(SolutionMapping, IntermediateResultElementSink, ExecutionContext) for each of them, but consumes only as many input solution mappings as specified by the maxBatchSize argument (or less if the given iterator is exhausted earlier).
protected void	_process(SolutionMapping inputSolMap, IntermediateResultElementSink sink, ExecutionContext execCxt)	Implementations of this function need to process the given solution mapping as input and send the produced result elements (if any) to the given sink.
protected ExecutableOperatorStatsImpl	createStats()
void	resetStats()

Methods inherited from class se.liu.ida.hefquin.engine.queryplan.executable.impl.ops.UnaryExecutableOpBaseWithoutBlocking

_process

Methods inherited from class se.liu.ida.hefquin.engine.queryplan.executable.impl.ops.UnaryExecutableOpBase

concludeExecution, getStats, process, process

Methods inherited from class se.liu.ida.hefquin.engine.queryplan.executable.impl.ops.BaseForExecOps

getExceptionsCaughtDuringExecution, getQueryPlanningInfo, recordExceptionCaughtDuringExecution

Methods inherited from class java.lang.Object

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

Methods inherited from interface se.liu.ida.hefquin.engine.queryplan.executable.ExecutableOperator

getExceptionsCaughtDuringExecution, getQueryPlanningInfo

Field Details

variables

protected final Set<org.apache.jena.sparql.core.Var> variables

Constructor Details

ExecOpProject

public ExecOpProject(Set<org.apache.jena.sparql.core.Var> variables,
 boolean mayReduce,
 boolean collectExceptions,
 QueryPlanningInfo qpInfo)

Method Details

_process

protected void _process(SolutionMapping inputSolMap,
 IntermediateResultElementSink sink,
 ExecutionContext execCxt)
                 throws ExecOpExecutionException

Description copied from class: UnaryExecutableOpBase

Implementations of this function need to process the given solution mapping as input and send the produced result elements (if any) to the given sink. If an exception occurs while processing the solution mapping, then this exception needs to be thrown.

Specified by:

_process in class UnaryExecutableOpBase

Throws:

ExecOpExecutionException

_process

protected void _process(Iterator<SolutionMapping> inputSolMaps,
 int maxBatchSize,
 IntermediateResultElementSink sink,
 ExecutionContext execCxt)
                 throws ExecOpExecutionException

Description copied from class: UnaryExecutableOpBaseWithoutBlocking

Processes input solution mappings of the given iterator by calling UnaryExecutableOpBase._process(SolutionMapping, IntermediateResultElementSink, ExecutionContext) for each of them, but consumes only as many input solution mappings as specified by the maxBatchSize argument (or less if the given iterator is exhausted earlier). Subclasses may override this behavior to send a greater number of output solution mappings to the given sink at a time (which is useful to reduce the communication between threads in the push-based execution model). Yet, overriding implementations should not call the given iterator more often as specified by the maxBatchSize argument. If an exception occurs within the overriding implementation, then this exception needs to be thrown.

Overrides:

_process in class UnaryExecutableOpBaseWithoutBlocking

Throws:

ExecOpExecutionException

_concludeExecution

protected void _concludeExecution(IntermediateResultElementSink sink,
 ExecutionContext execCxt)

Description copied from class: UnaryExecutableOpBase

Implementations of this function need to conclude the execution of this operator and send the remaining result elements (if any) to the given sink. If an exception occurs during this process, then this exception needs to be thrown.

Specified by:

_concludeExecution in class UnaryExecutableOpBase

resetStats

public void resetStats()

Specified by:

resetStats in interface StatsProvider

Overrides:

resetStats in class UnaryExecutableOpBase

createStats

protected ExecutableOperatorStatsImpl createStats()

Overrides:

createStats in class UnaryExecutableOpBase