org.aksw.limes.core.execution.planning.planner

Class HeliosPlanner

java.lang.Object

org.aksw.limes.core.execution.planning.planner.Planner

org.aksw.limes.core.execution.planning.planner.HeliosPlanner

All Implemented Interfaces:

IPlanner

public class HeliosPlanner
extends Planner

Implements the Helios planner class. It receives a link specification as input and generates an immutable NestedPlan.

Version:

1.0

Author:

Kleanthi Georgala (georgala@informatik.uni-leipzig.de)

Field Summary

Fields

Modifier and Type	Field and Description
IMapper.Language	lang Language of the source/target data.
ACache	source Source cache.
ACache	target Target cache.

Constructor Summary

Constructors

Constructor and Description
HeliosPlanner(ACache source, ACache target) Constructor of the Helios planner class.

Method Summary

Modifier and Type	Method and Description
double	getAtomicMappingSizes(String measure, double threshold) Computes atomic mapping sizes for a measure.
double	getAtomicRuntimeCosts(String measure, double threshold) Computes atomic costs for a metric expression.
NestedPlan	getBestConjunctivePlan(LinkSpecification spec, List<NestedPlan> plans, double selectivity) Computes the left-order best instructionList for a list of plans.
NestedPlan	getBestConjunctivePlan(LinkSpecification spec, NestedPlan left, List<NestedPlan> plans, double selectivity) Computes the best conjunctive instructionList for a instructionList against a list of plans by calling back the method.
NestedPlan	getBestConjunctivePlan(LinkSpecification spec, NestedPlan left, NestedPlan right, double selectivity) Find the least costly plan for a link specification with AND operator.
double	getFilterCosts(List<String> measures, int mappingSize) Computes costs for a filtering instruction.
boolean	isStatic() Returns the status of the planner.
LinkSpecification	normalize(LinkSpecification spec) Normalization of input link specification.
NestedPlan	plan(LinkSpecification spec) Generates a NestedPlan for a link specification.
NestedPlan	plan(LinkSpecification spec, ACache source, ACache target, AMapping sourceMapping, AMapping targetMapping) Generates a NestedPlan based on the optimality assumption used in databases.

Methods inherited from class java.lang.Object

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

Field Detail

source

public ACache source

Source cache.

target

public ACache target

Target cache.

lang

public IMapper.Language lang

Language of the source/target data.

Constructor Detail

HeliosPlanner

public HeliosPlanner(ACache source,
                     ACache target)

Constructor of the Helios planner class.

Parameters:

source - Source cache

target - Target get

Method Detail

getAtomicRuntimeCosts

public double getAtomicRuntimeCosts(String measure,
                                    double threshold)

Computes atomic costs for a metric expression. If the metric expression of is not supported by the framework, it throws an InvalidMeasureException exception.

Parameters:

measure - Measure of metric expression

threshold - Threshold of metric expression

Returns:

estimated runtime cost of the metric expression

getAtomicMappingSizes

public double getAtomicMappingSizes(String measure,
                                    double threshold)

Computes atomic mapping sizes for a measure. If the metric expression of is not supported by the framework, it throws an InvalidMeasureException exception.

Parameters:

measure - Measure of metric expression

threshold - Threshold of metric expression

Returns:

estimated size of returned mapping

getFilterCosts

public double getFilterCosts(List<String> measures,
                             int mappingSize)

Computes costs for a filtering instruction. If the metric expression of the filtering instruction is not supported by the framework, it throws an InvalidMeasureException exception.

Parameters:

measures - The set of expressions used to filter

mappingSize - Size of mapping

Returns:

estimated runtime cost of filteringInstruction(s)

plan

public NestedPlan plan(LinkSpecification spec)

Generates a NestedPlan for a link specification.

Parameters:

spec - Input link specification

Returns:

the corresponding NestedPlan of the input link specification

plan

public NestedPlan plan(LinkSpecification spec,
                       ACache source,
                       ACache target,
                       AMapping sourceMapping,
                       AMapping targetMapping)

Generates a NestedPlan based on the optimality assumption used in databases. If the input link specification has an AND operator, then the plan function will find the least costly plan from a set of alternatives (see getBestConjunctivePlan(org.aksw.limes.core.io.ls.LinkSpecification, java.util.List<org.aksw.limes.core.execution.planning.plan.NestedPlan>, double) }.

Parameters:

spec - Input link specification

source - Source cache

target - Target cache

sourceMapping - Size of source mapping

targetMapping - Size of target mapping

Returns:

a NestedPlan for the input link specification

getBestConjunctivePlan

public NestedPlan getBestConjunctivePlan(LinkSpecification spec,
                                         List<NestedPlan> plans,
                                         double selectivity)

Computes the left-order best instructionList for a list of plans. Only needed when AND has more than 2 children. Simply splits the task in computing the best instructionList for (leftmost, all others).

Parameters:

spec - Input link specification

plans - List of plans

selectivity - Selectivity of the instructionList (known beforehand)

Returns:

a NestedPlan of the input link specification

getBestConjunctivePlan

public NestedPlan getBestConjunctivePlan(LinkSpecification spec,
                                         NestedPlan left,
                                         List<NestedPlan> plans,
                                         double selectivity)

Computes the best conjunctive instructionList for a instructionList against a list of plans by calling back the method.

Parameters:

spec - Input link specification

left - Left instructionList

plans - List of other plans

selectivity - Overall selectivity

Returns:

a NestedPlan of the input link specification

getBestConjunctivePlan

public NestedPlan getBestConjunctivePlan(LinkSpecification spec,
                                         NestedPlan left,
                                         NestedPlan right,
                                         double selectivity)

Find the least costly plan for a link specification with AND operator. Computes all possible nested plans given the children plans: (1) Execute both children plans, perform intersection and filter the resulting mapping using the threshold of the link specification. (2) Execute the plan of the left child, use the right child measure expression as a filer and then filter the resulting mapping using the threshold of the link specification. (3) Execute the plan of the right child, use the left child measure expression as a filer and then filter the resulting mapping using the threshold of the link specification. The selection of the best alternative is based upon runtime estimations obtained for each of the atomic measure expressions included in the children specifications.

Parameters:

spec - The link specification

left - Left child nested plan

right - Right child nested plan

selectivity, - The overall selectivity

Returns:

the resulting nested plan for the input spec, that is least costly

isStatic

public boolean isStatic()

Returns the status of the planner.

Returns:

true

normalize

public LinkSpecification normalize(LinkSpecification spec)

Normalization of input link specification. In case of XOR operator, the output specification uses the extended form of XOR (i.e. XOR(cosine(x.name,y.name)|0.5, overlap(x.label,y.label)|0.6)> =0.8 will transformed into MINUS(OR(cosine(x.name,y.name)|0.5, overlap(x.label,y.label)|0.6)|0.8, AND(cosine(x.name,y.name)|0.5, overlap(x.label,y.label)|0.6)|0.8) )>=0.8

Parameters:

spec - The normalized link specification

Returns:

the normalized link specification