package org.apache.lucene.search.grouping;
/*
* 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.
*/
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 java.io.IOException;
/** Represents result returned by a grouping search.
*
* @lucene.experimental */
public class TopGroups<GROUP_VALUE_TYPE> {
/** 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 <code>null</code> this value is not computed. */
public final Integer totalGroupCount;
/** Group results in groupSort order */
public final GroupDocs<GROUP_VALUE_TYPE>[] 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
* <code>Float.NaN</code> if scores were not computed. */
public final float maxScore;
public TopGroups(SortField[] groupSort, SortField[] withinGroupSort, int totalHitCount, int totalGroupedHitCount, GroupDocs<GROUP_VALUE_TYPE>[] 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<GROUP_VALUE_TYPE> 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,
};
/** 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.
*
* <b>NOTE</b>: 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.
*
* <b>NOTE</b>: the topDocs in each GroupDocs is actually
* an instance of TopDocsAndShards
*/
public static <T> TopGroups<T> merge(TopGroups<T>[] shardGroups, Sort groupSort, Sort docSort, int docOffset, int docTopN, ScoreMergeMode scoreMergeMode)
throws IOException {
//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<T> 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<T>[] mergedGroupDocs = new GroupDocs[numGroups];
final TopDocs[] shardTopDocs = new TopDocs[shardGroups.length];
float totalMaxScore = Float.MIN_VALUE;
for(int groupIDX=0;groupIDX<numGroups;groupIDX++) {
final T groupValue = shardGroups[0].groups[groupIDX].groupValue;
//System.out.println(" merge groupValue=" + groupValue + " sortValues=" + Arrays.toString(shardGroups[0].groups[groupIDX].groupSortValues));
float maxScore = Float.MIN_VALUE;
int totalHits = 0;
double scoreSum = 0.0;
for(int shardIDX=0;shardIDX<shardGroups.length;shardIDX++) {
//System.out.println(" shard=" + shardIDX);
final TopGroups<T> shard = shardGroups[shardIDX];
final GroupDocs<?> shardGroupDocs = shard.groups[groupIDX];
if (groupValue == null) {
if (shardGroupDocs.groupValue != null) {
throw new IllegalArgumentException("group values differ across shards; you must pass same top groups to all shards' second-pass collector");
}
} else if (!groupValue.equals(shardGroupDocs.groupValue)) {
throw new IllegalArgumentException("group values differ across shards; you must pass same top groups to all shards' second-pass collector");
}
/*
for(ScoreDoc sd : shardGroupDocs.scoreDocs) {
System.out.println(" doc=" + sd.doc);
}
*/
shardTopDocs[shardIDX] = new TopDocs(shardGroupDocs.totalHits,
shardGroupDocs.scoreDocs,
shardGroupDocs.maxScore);
maxScore = Math.max(maxScore, shardGroupDocs.maxScore);
totalHits += shardGroupDocs.totalHits;
scoreSum += shardGroupDocs.score;
}
final TopDocs mergedTopDocs = TopDocs.merge(docSort, docOffset + docTopN, shardTopDocs);
// Slice;
final ScoreDoc[] mergedScoreDocs;
if (docOffset == 0) {
mergedScoreDocs = mergedTopDocs.scoreDocs;
} else if (docOffset >= mergedTopDocs.scoreDocs.length) {
mergedScoreDocs = new ScoreDoc[0];
} else {
mergedScoreDocs = new ScoreDoc[mergedTopDocs.scoreDocs.length - docOffset];
System.arraycopy(mergedTopDocs.scoreDocs,
docOffset,
mergedScoreDocs,
0,
mergedTopDocs.scoreDocs.length - docOffset);
}
final float groupScore;
switch(scoreMergeMode) {
case None:
groupScore = Float.NaN;
break;
case Avg:
if (totalHits > 0) {
groupScore = (float) (scoreSum / totalHits);
} else {
groupScore = Float.NaN;
}
break;
case Total:
groupScore = (float) scoreSum;
break;
default:
throw new IllegalArgumentException("can't handle ScoreMergeMode " + scoreMergeMode);
}
//System.out.println("SHARDS=" + Arrays.toString(mergedTopDocs.shardIndex));
mergedGroupDocs[groupIDX] = new GroupDocs<T>(groupScore,
maxScore,
totalHits,
mergedScoreDocs,
groupValue,
shardGroups[0].groups[groupIDX].groupSortValues);
totalMaxScore = Math.max(totalMaxScore, maxScore);
}
if (totalGroupCount != null) {
TopGroups<T> result = new TopGroups<T>(groupSort.getSort(),
docSort == null ? null : docSort.getSort(),
totalHitCount,
totalGroupedHitCount,
mergedGroupDocs,
totalMaxScore);
return new TopGroups<T>(result, totalGroupCount);
} else {
return new TopGroups<T>(groupSort.getSort(),
docSort == null ? null : docSort.getSort(),
totalHitCount,
totalGroupedHitCount,
mergedGroupDocs,
totalMaxScore);
}
}
}