org.apache.lucene.facet.sampling

Class SamplingWrapper

java.lang.Object

org.apache.lucene.facet.search.FacetsAccumulator

org.apache.lucene.facet.search.StandardFacetsAccumulator

org.apache.lucene.facet.sampling.SamplingWrapper

public class SamplingWrapper
extends StandardFacetsAccumulator

Wrap any Facets Accumulator with sampling.

Note: Sampling accumulation (Accumulation over a sampled-set of the results), does not guarantee accurate values for FacetResult.getNumValidDescendants().

WARNING: This API is experimental and might change in incompatible ways in the next release.

Field Summary

Fields inherited from class org.apache.lucene.facet.search.StandardFacetsAccumulator

DEFAULT_COMPLEMENT_THRESHOLD, DISABLE_COMPLEMENT, FORCE_COMPLEMENT, isUsingComplements, maxPartitions, partitionSize

Fields inherited from class org.apache.lucene.facet.search.FacetsAccumulator

facetArrays, indexReader, searchParams, taxonomyReader

Constructor Summary

Constructors

Constructor and Description
SamplingWrapper(StandardFacetsAccumulator delegee, Sampler sampler)

Method Summary

Methods

Modifier and Type	Method and Description
List<FacetResult>	accumulate(ScoredDocIDs docids)
double	getComplementThreshold() Returns the complement threshold.
void	setComplementThreshold(double complementThreshold) Set the complement threshold.

Methods inherited from class org.apache.lucene.facet.search.StandardFacetsAccumulator

accumulate, actualDocsToAccumulate, createFacetResultsHandler, getCategoryListMap, getTotalCountsFactor, isUsingComplements, mayComplement, shouldComplement

Methods inherited from class org.apache.lucene.facet.search.FacetsAccumulator

create, emptyResult, getAggregator, getCategoryLists

Methods inherited from class java.lang.Object

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

Constructor Detail

SamplingWrapper

public SamplingWrapper(StandardFacetsAccumulator delegee,
               Sampler sampler)

Method Detail

accumulate

public List<FacetResult> accumulate(ScoredDocIDs docids)
                             throws IOException

Overrides:

accumulate in class StandardFacetsAccumulator

Throws:

IOException

getComplementThreshold

public double getComplementThreshold()

Description copied from class: StandardFacetsAccumulator

Returns the complement threshold.

Overrides:

getComplementThreshold in class StandardFacetsAccumulator

See Also:

StandardFacetsAccumulator.setComplementThreshold(double)

setComplementThreshold

public void setComplementThreshold(double complementThreshold)

Description copied from class: StandardFacetsAccumulator

Set the complement threshold. This threshold will dictate whether the complements optimization is applied. The optimization is to count for less documents. It is useful when the same FacetSearchParams are used for varying sets of documents. The first time complements is used the "total counts" are computed - counting for all the documents in the collection. Then, only the complementing set of documents is considered, and used to decrement from the overall counts, thereby walking through less documents, which is faster.

For the default settings see StandardFacetsAccumulator.DEFAULT_COMPLEMENT_THRESHOLD.

To forcing complements in all cases pass StandardFacetsAccumulator.FORCE_COMPLEMENT. This is mostly useful for testing purposes, as forcing complements when only tiny fraction of available documents match the query does not make sense and would incur performance degradations.

To disable complements pass StandardFacetsAccumulator.DISABLE_COMPLEMENT.

Overrides:

setComplementThreshold in class StandardFacetsAccumulator

Parameters:

complementThreshold - the complement threshold to set

See Also:

StandardFacetsAccumulator.getComplementThreshold()