org.apache.lucene.facet.search
Class StandardFacetsAccumulator

java.lang.Object
  extended by org.apache.lucene.facet.search.FacetsAccumulator
      extended by 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


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