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

Class ExecOpSymmetricHashJoin

java.lang.Object

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

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

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

All Implemented Interfaces:

StatsProvider, BinaryExecutableOp, ExecutableOperator

public class ExecOpSymmetricHashJoin
extends BinaryExecutableOpBase

Implementation of the symmetric hash join algorithm. This algorithm continuously builds two hash tables (one for each of the two inputs) and, at the same time, uses these hash tables to find join partners for solution mappings that arrive at the respective other input. More specifically, whenever a solution mappings appears at one of the inputs, it is added into the hash table for that input (using the value(s) that it has for the join variable(s) to decide where to place it in the hash table) and then the other hash table is probed for join partners (which must have arrived at the other input before the current solution mapping arrived at its input.

Field Summary

Fields

Modifier and Type	Field	Description
protected boolean	child1InputComplete
protected boolean	child2InputComplete
protected final SolutionMappingsIndex	indexForChild1
protected final SolutionMappingsIndex	indexForChild2
protected Stats	statsOfIndexForChild1
protected Stats	statsOfIndexForChild2

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

timeAtCurrentLeftProcStart, timeAtCurrentRightProcStart

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

collectExceptions

Constructor Summary

Constructors

Constructor	Description
ExecOpSymmetricHashJoin(ExpectedVariables inputVars1, ExpectedVariables inputVars2, boolean collectExceptions)

Method Summary

Modifier and Type	Method	Description
protected void	_processBlockFromChild1(IntermediateResultBlock input, IntermediateResultElementSink sink, ExecutionContext execCxt)	Implementations of this function need to process the given input block coming from the first operand and send the produced result elements (if any) to the given sink.
protected void	_processBlockFromChild2(IntermediateResultBlock input, IntermediateResultElementSink sink, ExecutionContext execCxt)	Implementations of this function need to process the given input block coming from the second operand and send the produced result elements (if any) to the given sink.
protected void	_wrapUpForChild1(IntermediateResultElementSink sink, ExecutionContext execCxt)	Implementations of this function need to finish up any processing related to the input coming from the first operand and send the remaining result elements (if any) to the given sink.
protected void	_wrapUpForChild2(IntermediateResultElementSink sink, ExecutionContext execCxt)	Implementations of this function need to finish up any processing related to the input coming from the second operand and send the remaining result elements (if any) to the given sink.
protected ExecutableOperatorStatsImpl	createStats()
int	preferredInputBlockSizeFromChild1()	Returns the preferred block size of input blocks that are passed to this executable operator from the first operand.
int	preferredInputBlockSizeFromChild2()	Returns the preferred block size of input blocks that are passed to this executable operator from the second operand.
boolean	requiresCompleteChild1InputFirst()	Returns true if this operator is implemented based on the assumption that the COMPLETE input from the first operand has been sent to it before input from the second operand is sent.
void	resetStats()
protected void	wrapUp()

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

getStats, processBlockFromChild1, processBlockFromChild2, wrapUpForChild1, wrapUpForChild2

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

getExceptionsCaughtDuringExecution, 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

Field Details

indexForChild1

protected final SolutionMappingsIndex indexForChild1

indexForChild2

protected final SolutionMappingsIndex indexForChild2

statsOfIndexForChild1

protected Stats statsOfIndexForChild1

statsOfIndexForChild2

protected Stats statsOfIndexForChild2

child1InputComplete

protected boolean child1InputComplete

child2InputComplete

protected boolean child2InputComplete

Constructor Details

ExecOpSymmetricHashJoin

public ExecOpSymmetricHashJoin(ExpectedVariables inputVars1,
 ExpectedVariables inputVars2,
 boolean collectExceptions)

Method Details

preferredInputBlockSizeFromChild1

public int preferredInputBlockSizeFromChild1()

Description copied from interface: BinaryExecutableOp

Returns the preferred block size of input blocks that are passed to this executable operator from the first operand. A query planner may use this number as an optimization hint but it does not have to use it.

preferredInputBlockSizeFromChild2

public int preferredInputBlockSizeFromChild2()

Description copied from interface: BinaryExecutableOp

Returns the preferred block size of input blocks that are passed to this executable operator from the second operand. A query planner may use this number as an optimization hint but it does not have to use it.

requiresCompleteChild1InputFirst

public boolean requiresCompleteChild1InputFirst()

Description copied from interface: BinaryExecutableOp

Returns true if this operator is implemented based on the assumption that the COMPLETE input from the first operand has been sent to it before input from the second operand is sent. An example of an operator that may return true here is a hash join (which first needs to add all result elements from the first operand into its hash table and, then, can start consuming the result elements from the second operand by probing into the hash table). In contrast, a symmetric hash join (which has two hash tables and can consume result elements from both inputs in any order) would return false. Operators that return true here may throw an IllegalStateException if their methods BinaryExecutableOp.processBlockFromChild2(IntermediateResultBlock, IntermediateResultElementSink, ExecutionContext) or BinaryExecutableOp.wrapUpForChild2(IntermediateResultElementSink, ExecutionContext) are called before BinaryExecutableOp.wrapUpForChild1(IntermediateResultElementSink, ExecutionContext) has been called.

_processBlockFromChild1

protected void _processBlockFromChild1(IntermediateResultBlock input,
 IntermediateResultElementSink sink,
 ExecutionContext execCxt)

Description copied from class: BinaryExecutableOpBase

Implementations of this function need to process the given input block coming from the first operand and send the produced result elements (if any) to the given sink. If an exception occurs while processing the input block, this exception needs to either be collected or be thrown, depending on whether BaseForExecOps.collectExceptions is set to true.

Specified by:

_processBlockFromChild1 in class BinaryExecutableOpBase

_wrapUpForChild1

protected void _wrapUpForChild1(IntermediateResultElementSink sink,
 ExecutionContext execCxt)

Description copied from class: BinaryExecutableOpBase

Implementations of this function need to finish up any processing related to the input coming from the first operand and send the remaining result elements (if any) to the given sink. If an exception occurs during this process, then this exception needs to either be collected or be thrown, depending on whether BaseForExecOps.collectExceptions is set to true.

Specified by:

_wrapUpForChild1 in class BinaryExecutableOpBase

_processBlockFromChild2

protected void _processBlockFromChild2(IntermediateResultBlock input,
 IntermediateResultElementSink sink,
 ExecutionContext execCxt)

Description copied from class: BinaryExecutableOpBase

Implementations of this function need to process the given input block coming from the second operand and send the produced result elements (if any) to the given sink. If an exception occurs while processing the input block, this exception needs to either be collected or be thrown, depending on whether BaseForExecOps.collectExceptions is set to true.

Specified by:

_processBlockFromChild2 in class BinaryExecutableOpBase

_wrapUpForChild2

protected void _wrapUpForChild2(IntermediateResultElementSink sink,
 ExecutionContext execCxt)

Description copied from class: BinaryExecutableOpBase

Implementations of this function need to finish up any processing related to the input coming from the second operand and send the remaining result elements (if any) to the given sink. If an exception occurs during this process, then this exception needs to either be collected or be thrown, depending on whether BaseForExecOps.collectExceptions is set to true.

Specified by:

_wrapUpForChild2 in class BinaryExecutableOpBase

wrapUp

protected void wrapUp()

resetStats

public void resetStats()

Specified by:

resetStats in interface StatsProvider

Overrides:

resetStats in class BinaryExecutableOpBase

createStats

protected ExecutableOperatorStatsImpl createStats()

Overrides:

createStats in class BinaryExecutableOpBase