Class PhysicalOpIndexNestedLoopsJoin

java.lang.Object

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

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

All Implemented Interfaces:

QueryPlanOperator, PhysicalOperator, PhysicalOperatorForLogicalOperator, UnaryPhysicalOp, UnaryPhysicalOpForLogicalOp

public class PhysicalOpIndexNestedLoopsJoin
extends BaseForPhysicalOpSingleInputJoin

A physical operator that implements a version of the index nested loops join algorithm where the federation member is used as an index to request join partners for the input solution mappings.

Semantics: This operator implements the logical operators gpAdd (see LogicalOpGPAdd) and gpOptAdd (see LogicalOpGPOptAdd). That is, for a given graph pattern, a federation member, and an input sequence of solution mappings (produced by the sub-plan under this operator), the operator produces the solutions resulting from the join (inner or left outer) between the input solutions and the solutions of evaluating the given graph pattern over the data of the federation member.

Algorithm description: The outer loop iterates over the sequence of input solution mappings. For each such solution mapping, join partners within the result of the given graph pattern over the data of the federation member are retrieved by using the federation member as a form of index. The inner loop then iterates over these join partners and merges them with the current input solution mapping from the outer loop. The retrieval of join partners is done by applying the current input solution mapping from the outer loop to the given graph pattern of the operator (i.e., substituting the join variables in the pattern by the values assigned in the current input solution mapping) and, then, performing a request with the graph pattern resulting from the substitution. Hence, this is like a bind join without batching.

The actual algorithm of this operator is implemented in the following three classes, where each of them is specific to a different type of federation member.

• ExecOpIndexNestedLoopsJoinTPF
• invalid reference

  ExecOpIndexNestedLoopsJoinBRTPF

• ExecOpIndexNestedLoopsJoinSPARQL

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	PhysicalOpIndexNestedLoopsJoin.Factory

Field Summary

Fields

Modifier and Type	Field	Description
protected static final PhysicalOpIndexNestedLoopsJoin.Factory	factory

Fields inherited from class se.liu.ida.hefquin.engine.queryplan.physical.impl.BaseForPhysicalOpSingleInputJoin

lop

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	PhysicalOpIndexNestedLoopsJoin(LogicalOpGPAdd lop)
protected	PhysicalOpIndexNestedLoopsJoin(LogicalOpGPOptAdd lop)

Method Summary

Modifier and Type	Method	Description
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)
static PhysicalOpFactory	getFactory()
int	hashCode()
String	toString()
void	visit(PhysicalPlanVisitor visitor)

Methods inherited from class se.liu.ida.hefquin.engine.queryplan.physical.impl.BaseForPhysicalOpSingleInputJoin

getLogicalOperator

Methods inherited from class java.lang.Object

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

Methods inherited from interface se.liu.ida.hefquin.engine.queryplan.physical.PhysicalOperatorForLogicalOperator

getExpectedVariables

Field Details

factory

protected static final PhysicalOpIndexNestedLoopsJoin.Factory factory

Constructor Details

PhysicalOpIndexNestedLoopsJoin

protected PhysicalOpIndexNestedLoopsJoin(LogicalOpGPAdd lop)

PhysicalOpIndexNestedLoopsJoin

protected PhysicalOpIndexNestedLoopsJoin(LogicalOpGPOptAdd lop)

Method Details

getFactory

public static PhysicalOpFactory getFactory()

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).

visit

public void visit(PhysicalPlanVisitor visitor)

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