Class PhysicalOpParallelMultiLeftJoin

java.lang.Object

se.liu.ida.hefquin.engine.queryplan.physical.impl.PhysicalOpParallelMultiLeftJoin

All Implemented Interfaces:

QueryPlanOperator, PhysicalOperator, UnaryPhysicalOp

public class PhysicalOpParallelMultiLeftJoin
extends Object
implements UnaryPhysicalOp

A physical operator that implements a left-outer join for multiple optional parts; as a unary operator, the operator has a single input, which provides the solutions of the non-optional part. The idea of the algorithm associated with this operator is to perform bind joins for all the optional parts in parallel and then merge the results. TODO: describe the algorithm in more detail. The actual algorithm of this operator is implemented in the ExecOpParallelMultiwayLeftJoin class.

Field Summary

Fields

Modifier and Type	Field	Description
protected final boolean	mayReduce
protected final List<LogicalOpRequest<?,?>>	optionalParts

Constructor Summary

Constructors

Constructor	Description
PhysicalOpParallelMultiLeftJoin(List<LogicalOpRequest<?,?>> optionalParts, boolean mayReduce)

Method Summary

Modifier and Type	Method	Description
static List<LogicalOpRequest<?,?>>	checkApplicability(PhysicalPlan[] children)	Checks whether a LogicalOpMultiwayLeftJoin with the given list of physical plans can be implemented by the parallel multi-left-join (as captured by this physical operator).
UnaryExecutableOp	createExecOp(boolean collectExceptions, QueryPlanningInfo qpInfo, ExpectedVariables... inputVars)	Creates and returns the executable operator to be used for this physical operator.
boolean	equals(Object o)
ExpectedVariables	getExpectedVariables(ExpectedVariables... inputVars)	Returns the variables that can be expected in the solution mappings produced by this operator in the case that the input(s) to this operator contain solutions mappings with the given set(s) of variables.
int	hashCode()
String	toString()
void	visit(PhysicalPlanVisitor visitor)

Methods inherited from class java.lang.Object

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

Field Details

optionalParts

protected final List<LogicalOpRequest<?,?>> optionalParts

mayReduce

protected final boolean mayReduce

Constructor Details

PhysicalOpParallelMultiLeftJoin

public PhysicalOpParallelMultiLeftJoin(List<LogicalOpRequest<?,?>> optionalParts,
 boolean mayReduce)

Method Details

checkApplicability

public static List<LogicalOpRequest<?,?>> checkApplicability(PhysicalPlan[] children)

Checks whether a LogicalOpMultiwayLeftJoin with the given list of physical plans can be implemented by the parallel multi-left-join (as captured by this physical operator). If yes, this method returns the optional parts of that multi-left-join. If not, this method returns null.

getExpectedVariables

public ExpectedVariables getExpectedVariables(ExpectedVariables... inputVars)

Description copied from interface: QueryPlanOperator

Returns the variables that can be expected in the solution mappings produced by this operator in the case that the input(s) to this operator contain solutions mappings with the given set(s) of variables. The number of ExpectedVariables objects passed to this method must be in line with the degree of this operator (e.g., for a unary operator, exactly one such object must be passed).

Specified by:

getExpectedVariables in interface QueryPlanOperator

createExecOp

public UnaryExecutableOp createExecOp(boolean collectExceptions,
 QueryPlanningInfo qpInfo,
 ExpectedVariables... inputVars)

Description copied from interface: PhysicalOperator

Creates and returns the executable operator to be used for this physical operator. The implementation of this method has to create a new ExecutableOperator object each time it is called. The given QueryPlanningInfo object is passed to the created executable operator (to be available via the ExecutableOperator.getQueryPlanningInfo() method) and should be taken from the physical plan whose root operator is this physical operator. The given collectExceptions flag is passed to the executable operator and determines whether that operator collects its exceptions (see ExecutableOperator.getExceptionsCaughtDuringExecution()) or throws them immediately. The number of ExpectedVariables objects passed as arguments to this method must be in line with the degree of this operator (e.g., for a unary operator, exactly one such object must be passed).

Specified by:

createExecOp in interface PhysicalOperator

Specified by:

createExecOp in interface UnaryPhysicalOp

visit

public void visit(PhysicalPlanVisitor visitor)

Specified by:

visit in interface PhysicalOperator

equals

public boolean equals(Object o)

Overrides:

equals in class Object

hashCode

public int hashCode()

Overrides:

hashCode in class Object

toString

public String toString()

Overrides:

toString in class Object