org.apache.lucene.facet.search
Class StandardFacetsAccumulator

java.lang.Object
  org.apache.lucene.facet.search.FacetsAccumulator
      org.apache.lucene.facet.search.StandardFacetsAccumulator

Direct Known Subclasses:

AdaptiveFacetsAccumulator, SamplingAccumulator

public class StandardFacetsAccumulator
extends FacetsAccumulator

Standard implementation for FacetsAccumulator, utilizing partitions to save on memory.

Why partitions? Because if there are say 100M categories out of which only top K are required, we must first compute value for all 100M categories (going over all documents) and only then could we select top K. This is made easier on memory by working in partitions of distinct categories: Once a values for a partition are found, we take the top K for that partition and work on the next partition, them merge the top K of both, and so forth, thereby computing top K with RAM needs for the size of a single partition rather than for the size of all the 100M categories.

Decision on partitions size is done at indexing time, and the facet information for each partition is maintained separately.

Implementation detail: Since facets information of each partition is maintained in a separate "category list", we can be more efficient at search time, because only the facet info for a single partition need to be read while processing that partition.

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

Field Summary

protected FloatArrayAllocator	floatArrayAllocator
protected IntArrayAllocator	intArrayAllocator
protected boolean	isUsingComplements
protected int	maxPartitions
protected int	partitionSize

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

DEFAULT_COMPLEMENT_THRESHOLD, DISABLE_COMPLEMENT, FORCE_COMPLEMENT, indexReader, searchParams, taxonomyReader

Constructor Summary

StandardFacetsAccumulator(FacetSearchParams searchParams, IndexReader indexReader, TaxonomyReader taxonomyReader)

StandardFacetsAccumulator(FacetSearchParams searchParams, IndexReader indexReader, TaxonomyReader taxonomyReader, IntArrayAllocator intArrayAllocator, FloatArrayAllocator floatArrayAllocator)

Method Summary

List<FacetResult>	accumulate(ScoredDocIDs docids) Accumulate facets over given documents, according to facet requests in effect.
protected ScoredDocIDs	actualDocsToAccumulate(ScoredDocIDs docids) Set the actual set of documents over which accumulation should take place.
protected HashMap<CategoryListIterator,Aggregator>	getCategoryListMap(FacetArrays facetArrays, int partition) Create an Aggregator and a CategoryListIterator for each and every FacetRequest.
protected double	getTotalCountsFactor() Expert: factor by which counts should be multiplied when initializing the count arrays from total counts.
protected boolean	shouldComplement(ScoredDocIDs docids) Check if it is worth to use complements

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

getComplementThreshold, isAllowLabeling, mayComplement, setAllowLabeling, setComplementThreshold

Methods inherited from class java.lang.Object

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

Field Detail

intArrayAllocator

protected final IntArrayAllocator intArrayAllocator

floatArrayAllocator

protected final FloatArrayAllocator floatArrayAllocator

partitionSize

protected int partitionSize

maxPartitions

protected int maxPartitions

isUsingComplements

protected boolean isUsingComplements

Constructor Detail

StandardFacetsAccumulator

public StandardFacetsAccumulator(FacetSearchParams searchParams,
                                 IndexReader indexReader,
                                 TaxonomyReader taxonomyReader,
                                 IntArrayAllocator intArrayAllocator,
                                 FloatArrayAllocator floatArrayAllocator)

StandardFacetsAccumulator

public StandardFacetsAccumulator(FacetSearchParams searchParams,
                                 IndexReader indexReader,
                                 TaxonomyReader taxonomyReader)

Method Detail

accumulate

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

Description copied from class: FacetsAccumulator

Accumulate facets over given documents, according to facet requests in effect.

Specified by:

accumulate in class FacetsAccumulator

Parameters:

docids - documents (and their scores) for which facets are Accumulated.

Returns:

Accumulated facets.

Throws:

IOException - on error.

actualDocsToAccumulate

protected ScoredDocIDs actualDocsToAccumulate(ScoredDocIDs docids)
                                       throws IOException

Set the actual set of documents over which accumulation should take place.

Allows to override the set of documents to accumulate for. Invoked just before actual accumulating starts. From this point that set of documents remains unmodified. Default implementation just returns the input unchanged.

Parameters:

docids - candidate documents to accumulate for

Returns:

actual documents to accumulate for

Throws:

IOException

shouldComplement

protected boolean shouldComplement(ScoredDocIDs docids)

Check if it is worth to use complements

getTotalCountsFactor

protected double getTotalCountsFactor()

Expert: factor by which counts should be multiplied when initializing the count arrays from total counts. Default implementation for this returns 1, which is a no op.

Returns:

a factor by which total counts should be multiplied

getCategoryListMap

protected HashMap<CategoryListIterator,Aggregator> getCategoryListMap(FacetArrays facetArrays,
                                                                      int partition)
                                                               throws IOException

Create an Aggregator and a CategoryListIterator for each and every FacetRequest. Generating a map, matching each categoryListIterator to its matching aggregator.

If two CategoryListIterators are served by the same aggregator, a single aggregator is returned for both. NOTE: If a given category list iterator is needed with two different aggregators (e.g counting and association) - an exception is thrown as this functionality is not supported at this time.

Throws:

IOException