org.apache.lucene.search.grouping.TopGroups Maven / Gradle / Ivy
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* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.lucene.search.grouping;
import org.apache.lucene.search.ScoreDoc;
import org.apache.lucene.search.Sort;
import org.apache.lucene.search.SortField;
import org.apache.lucene.search.TopDocs;
import org.apache.lucene.search.TopFieldDocs;
import org.apache.lucene.search.TotalHits;
import org.apache.lucene.search.TotalHits.Relation;
/** Represents result returned by a grouping search.
*
* @lucene.experimental */
public class TopGroups {
/** Number of documents matching the search */
public final int totalHitCount;
/** Number of documents grouped into the topN groups */
public final int totalGroupedHitCount;
/** The total number of unique groups. If null this value is not computed. */
public final Integer totalGroupCount;
/** Group results in groupSort order */
public final GroupDocs[] groups;
/** How groups are sorted against each other */
public final SortField[] groupSort;
/** How docs are sorted within each group */
public final SortField[] withinGroupSort;
/** Highest score across all hits, or
* Float.NaN if scores were not computed. */
public final float maxScore;
public TopGroups(SortField[] groupSort, SortField[] withinGroupSort, int totalHitCount, int totalGroupedHitCount, GroupDocs[] groups, float maxScore) {
this.groupSort = groupSort;
this.withinGroupSort = withinGroupSort;
this.totalHitCount = totalHitCount;
this.totalGroupedHitCount = totalGroupedHitCount;
this.groups = groups;
this.totalGroupCount = null;
this.maxScore = maxScore;
}
public TopGroups(TopGroups oldTopGroups, Integer totalGroupCount) {
this.groupSort = oldTopGroups.groupSort;
this.withinGroupSort = oldTopGroups.withinGroupSort;
this.totalHitCount = oldTopGroups.totalHitCount;
this.totalGroupedHitCount = oldTopGroups.totalGroupedHitCount;
this.groups = oldTopGroups.groups;
this.maxScore = oldTopGroups.maxScore;
this.totalGroupCount = totalGroupCount;
}
/** How the GroupDocs score (if any) should be merged. */
public enum ScoreMergeMode {
/** Set score to Float.NaN */
None,
/* Sum score across all shards for this group. */
Total,
/* Avg score across all shards for this group. */
Avg,
}
/**
* If either value is NaN then return the other value, otherwise
* return the greater of the two values by calling Math.max.
* @param a - one value
* @param b - another value
* @return ignoring any NaN return the greater of a and b
*/
private static float nonNANmax(float a, float b) {
if (Float.isNaN(a)) return b;
if (Float.isNaN(b)) return a;
return Math.max(a, b);
}
/** 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
*/
public static TopGroups merge(TopGroups[] shardGroups, Sort groupSort, Sort docSort, int docOffset, int docTopN, ScoreMergeMode scoreMergeMode) {
//System.out.println("TopGroups.merge");
if (shardGroups.length == 0) {
return null;
}
int totalHitCount = 0;
int totalGroupedHitCount = 0;
// Optionally merge the totalGroupCount.
Integer totalGroupCount = null;
final int numGroups = shardGroups[0].groups.length;
for(TopGroups shard : shardGroups) {
if (numGroups != shard.groups.length) {
throw new IllegalArgumentException("number of groups differs across shards; you must pass same top groups to all shards' second-pass collector");
}
totalHitCount += shard.totalHitCount;
totalGroupedHitCount += shard.totalGroupedHitCount;
if (shard.totalGroupCount != null) {
if (totalGroupCount == null) {
totalGroupCount = 0;
}
totalGroupCount += shard.totalGroupCount;
}
}
@SuppressWarnings({"unchecked","rawtypes"})
final GroupDocs[] mergedGroupDocs = new GroupDocs[numGroups];
final TopDocs[] shardTopDocs;
if (docSort.equals(Sort.RELEVANCE)) {
shardTopDocs = new TopDocs[shardGroups.length];
} else {
shardTopDocs = new TopFieldDocs[shardGroups.length];
}
float totalMaxScore = Float.NaN;
for(int groupIDX=0;groupIDX