# Package org.apache.lucene.search.grouping.function

Support for grouping by `ValueSource`.

See: Description

- Class Summary
  Class | Description
  --- | ---
  FunctionAllGroupHeadsCollector | An implementation of `AbstractAllGroupHeadsCollector` for retrieving the most relevant groups when grouping by `ValueSource`.
  FunctionAllGroupsCollector | A collector that collects all groups that match the query.
  FunctionDistinctValuesCollector | Function based implementation of `AbstractDistinctValuesCollector`.
  FunctionDistinctValuesCollector.GroupCount | Holds distinct values for a single group.
  FunctionFirstPassGroupingCollector | Concrete implementation of `AbstractFirstPassGroupingCollector` that groups based on `ValueSource` instances.
  FunctionSecondPassGroupingCollector | Concrete implementation of `AbstractSecondPassGroupingCollector` that groups based on `ValueSource` instances.

## Package org.apache.lucene.search.grouping.function Description

Support for grouping by `ValueSource`.

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