Package org.apache.lucene.search.grouping

Class TopGroups<T>

java.lang.Object
org.apache.lucene.search.grouping.TopGroups<T>
public class TopGroups<T> extends Object
Represents result returned by a grouping search.
WARNING: This API is experimental and might change in incompatible ways in the next release.

  • Field Details

    • totalHitCount

      public final int totalHitCount
      Number of documents matching the search

    • totalGroupedHitCount

      public final int totalGroupedHitCount
      Number of documents grouped into the topN groups

    • totalGroupCount

      public final Integer totalGroupCount
      The total number of unique groups. If null this value is not computed.

    • groups

      public final GroupDocs<T>[] groups
      Group results in groupSort order

    • groupSort

      public final SortField[] groupSort
      How groups are sorted against each other

    • withinGroupSort

      public final SortField[] withinGroupSort
      How docs are sorted within each group

    • maxScore

      public final float maxScore
      Highest score across all hits, or Float.NaN if scores were not computed.

  • Constructor Details

    • TopGroups

      public TopGroups(SortField[] groupSort, SortField[] withinGroupSort, int totalHitCount, int totalGroupedHitCount, GroupDocs<T>[] groups, float maxScore)

    • TopGroups

      public TopGroups(TopGroups<T> oldTopGroups, Integer totalGroupCount)

  • Method Details

    • merge

      public static <T> TopGroups<T> merge(TopGroups<T>[] shardGroups, Sort groupSort, Sort docSort, int docOffset, int docTopN, TopGroups.ScoreMergeMode scoreMergeMode)
      Merges an array of TopGroups, for example obtained from the second-pass collector across multiple shards. Each TopGroups must have been sorted by the same groupSort and docSort, and the top groups passed to all second-pass collectors must be the same.

      NOTE: We can't always compute an exact totalGroupCount. Documents belonging to a group may occur on more than one shard and thus the merged totalGroupCount can be higher than the actual totalGroupCount. In this case the totalGroupCount represents a upper bound. If the documents of one group do only reside in one shard then the totalGroupCount is exact.

      NOTE: the topDocs in each GroupDocs is actually an instance of TopDocsAndShards

    • mergeBlockGroups

      public static <T> TopGroups<T> mergeBlockGroups(List<TopGroups<T>> shardGroups, Sort groupSort, int groupOffset, int topNGroups, Sort docSort)
      Merge TopGroups that are partitioned into blocks per shard. This method assumes that within each shard, the groups are sorted according to the groupSort.
      Parameters:
      shardGroups - list of TopGroups, one per shard.
      groupSort - The Sort used to sort the groups. The top sorted document within each group according to groupSort, determines how that group sorts against other groups. This must be non-null, ie, if you want to groupSort by relevance use Sort.RELEVANCE.
      groupOffset - Which group to start from.
      topNGroups - How many top groups to keep.
      docSort - The sort to use within each group
      Returns:
      TopGroups instance or null if there are no groups.