org.pentaho.aggdes.algorithm.impl

Interface Lattice

All Known Implementing Classes:

LatticeImpl, MonteCarloLatticeImpl

public interface Lattice

Data structure which contains the set of all possible aggregates, arranged so that you can navigate from any aggregate to its parents (aggregates having precisely one more attribute) and to its children (aggregates having precisely one fewer attribute).

The top of the lattice is the aggregate with no attributes and one row, that is, the grand total. The bottom of the lattice is the aggregate with all attributes, which is the same as the fully joined star schema with any duplicate rows removed.

Method Summary

Methods

Modifier and Type	Method and Description
AggregateImpl	chooseAggregate(double maxCost, double minCostBenefitRatio, Cost cost) Chooses the next un-materialized aggregate with the highest incremental benefit.
Lattice	copy() Returns a copy of this lattice.
Algorithm.CostBenefit	costBenefitOf(AggregateImpl aggregate) Returns an object representing the cost of the given aggregate, and benefit of adding it to the current lattice.
List<AggregateImpl>	getMaterializedAggregates()
void	materialize(AggregateImpl aggregate) Materializes an aggregate.

Method Detail

chooseAggregate

AggregateImpl chooseAggregate(double maxCost,
                            double minCostBenefitRatio,
                            Cost cost)

Chooses the next un-materialized aggregate with the highest incremental benefit.

Parameters:

maxCost -

minCostBenefitRatio -

cost - Output parameter, is populated with the benefit and the number of queries which will benefit by materializing the chosen aggregate

Returns:

Chosen aggregate

materialize

void materialize(AggregateImpl aggregate)

Materializes an aggregate.

Parameters:

aggregate - Aggregate

getMaterializedAggregates

List<AggregateImpl> getMaterializedAggregates()

costBenefitOf

Algorithm.CostBenefit costBenefitOf(AggregateImpl aggregate)

Returns an object representing the cost of the given aggregate, and benefit of adding it to the current lattice.

Parameters:

aggregate - Aggregate

Returns:

Incremental cost/benefit of the aggregate

copy

Lattice copy()

Returns a copy of this lattice.