# Uses of Package
org.apache.lucene.search.grouping

- Classes in org.apache.lucene.search.grouping used by org.apache.lucene.search.grouping
  Class and Description
  AllGroupHeadsCollector This collector specializes in collecting the most relevant document (group head) for each group that matches the query.
  AllGroupHeadsCollector.GroupHead Represents a group head.
  CollectedSearchGroup Expert: representation of a group in `FirstPassGroupingCollector`, tracking the top doc and `FieldComparator` slot.
  DistinctValuesCollector.GroupCount Returned by `DistinctValuesCollector.getGroups()`, representing the value and set of distinct values for the group.
  GroupDocs Represents one group in the results.
  GroupFacetCollector Base class for computing grouped facets.
  GroupFacetCollector.FacetEntry Represents a facet entry with a value and a count.
  GroupFacetCollector.GroupedFacetResult The grouped facet result.
  GroupFacetCollector.SegmentResult Contains the local grouped segment counts for a particular segment.
  GroupingSearch Convenience class to perform grouping in a non distributed environment.
  GroupReducer Concrete implementations of this class define what to collect for individual groups during the second-pass of a grouping search.
  GroupSelector Defines a group, for use by grouping collectors A GroupSelector acts as an iterator over documents.
  GroupSelector.State What to do with the current value
  SearchGroup Represents a group that is found during the first pass search.
  SecondPassGroupingCollector SecondPassGroupingCollector runs over an already collected set of groups, further applying a `GroupReducer` to each group
  TermGroupFacetCollector An implementation of `GroupFacetCollector` that computes grouped facets based on the indexed terms from DocValues.
  TopGroups Represents result returned by a grouping search.
  TopGroups.ScoreMergeMode How the GroupDocs score (if any) should be merged.

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