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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 java.io.IOException;
import java.util.Collection;
import java.util.Collections;
import java.util.Map;
import org.apache.lucene.queries.function.ValueSource;
import org.apache.lucene.search.CachingCollector;
import org.apache.lucene.search.Collector;
import org.apache.lucene.search.IndexSearcher;
import org.apache.lucene.search.MultiCollector;
import org.apache.lucene.search.Query;
import org.apache.lucene.search.ScoreMode;
import org.apache.lucene.search.Sort;
import org.apache.lucene.search.SortField;
import org.apache.lucene.search.Weight;
import org.apache.lucene.util.Bits;
import org.apache.lucene.util.BytesRef;
import org.apache.lucene.util.mutable.MutableValue;
/**
* Convenience class to perform grouping in a non distributed environment.
*
* @lucene.experimental
*/
public class GroupingSearch {
private final GroupSelector grouper;
private final Query groupEndDocs;
private Sort groupSort = Sort.RELEVANCE;
private Sort sortWithinGroup = Sort.RELEVANCE;
private int groupDocsOffset;
private int groupDocsLimit = 1;
private boolean includeMaxScore = true;
private Double maxCacheRAMMB;
private Integer maxDocsToCache;
private boolean cacheScores;
private boolean allGroups;
private boolean allGroupHeads;
private Collection matchingGroups;
private Bits matchingGroupHeads;
/**
* Constructs a GroupingSearch instance that groups documents by index terms using
* DocValues. The group field can only have one token per document. This means that the field must
* not be analysed.
*
* @param groupField The name of the field to group by.
*/
public GroupingSearch(String groupField) {
this(new TermGroupSelector(groupField), null);
}
/**
* Constructs a GroupingSearch instance that groups documents using a {@link
* GroupSelector}
*
* @param groupSelector a {@link GroupSelector} that defines groups for this GroupingSearch
*/
public GroupingSearch(GroupSelector groupSelector) {
this(groupSelector, null);
}
/**
* Constructs a GroupingSearch instance that groups documents by function using a
* {@link ValueSource} instance.
*
* @param groupFunction The function to group by specified as {@link ValueSource}
* @param valueSourceContext The context of the specified groupFunction
*/
public GroupingSearch(ValueSource groupFunction, Map valueSourceContext) {
this(new ValueSourceGroupSelector(groupFunction, valueSourceContext), null);
}
/**
* Constructor for grouping documents by doc block. This constructor can only be used when
* documents belonging in a group are indexed in one block.
*
* @param groupEndDocs The query that marks the last document in all doc blocks
*/
public GroupingSearch(Query groupEndDocs) {
this(null, groupEndDocs);
}
private GroupingSearch(GroupSelector grouper, Query groupEndDocs) {
this.grouper = grouper;
this.groupEndDocs = groupEndDocs;
}
/**
* Executes a grouped search. Both the first pass and second pass are executed on the specified
* searcher.
*
* @param searcher The {@link org.apache.lucene.search.IndexSearcher} instance to execute the
* grouped search on.
* @param query The query to execute with the grouping
* @param groupOffset The group offset
* @param groupLimit The number of groups to return from the specified group offset
* @return the grouped result as a {@link TopGroups} instance
* @throws IOException If any I/O related errors occur
*/
@SuppressWarnings("unchecked")
public TopGroups search(
IndexSearcher searcher, Query query, int groupOffset, int groupLimit) throws IOException {
if (grouper != null) {
return groupByFieldOrFunction(searcher, query, groupOffset, groupLimit);
} else if (groupEndDocs != null) {
return (TopGroups) groupByDocBlock(searcher, query, groupOffset, groupLimit);
} else {
throw new IllegalStateException(
"Either groupField, groupFunction or groupEndDocs must be set."); // This can't happen...
}
}
@SuppressWarnings({"unchecked", "rawtypes"})
protected TopGroups groupByFieldOrFunction(
IndexSearcher searcher, Query query, int groupOffset, int groupLimit) throws IOException {
int topN = groupOffset + groupLimit;
final FirstPassGroupingCollector firstPassCollector =
new FirstPassGroupingCollector(grouper, groupSort, topN);
final AllGroupsCollector allGroupsCollector =
allGroups ? new AllGroupsCollector(grouper) : null;
final AllGroupHeadsCollector allGroupHeadsCollector =
allGroupHeads ? AllGroupHeadsCollector.newCollector(grouper, sortWithinGroup) : null;
final Collector firstRound =
MultiCollector.wrap(firstPassCollector, allGroupsCollector, allGroupHeadsCollector);
CachingCollector cachedCollector = null;
if (maxCacheRAMMB != null || maxDocsToCache != null) {
if (maxCacheRAMMB != null) {
cachedCollector = CachingCollector.create(firstRound, cacheScores, maxCacheRAMMB);
} else {
cachedCollector = CachingCollector.create(firstRound, cacheScores, maxDocsToCache);
}
searcher.search(query, cachedCollector);
} else {
searcher.search(query, firstRound);
}
matchingGroups = allGroups ? allGroupsCollector.getGroups() : Collections.emptyList();
matchingGroupHeads =
allGroupHeads
? allGroupHeadsCollector.retrieveGroupHeads(searcher.getIndexReader().maxDoc())
: new Bits.MatchNoBits(searcher.getIndexReader().maxDoc());
Collection topSearchGroups = firstPassCollector.getTopGroups(groupOffset);
if (topSearchGroups == null) {
return new TopGroups(new SortField[0], new SortField[0], 0, 0, new GroupDocs[0], Float.NaN);
}
int topNInsideGroup = groupDocsOffset + groupDocsLimit;
TopGroupsCollector secondPassCollector =
new TopGroupsCollector(
grouper, topSearchGroups, groupSort, sortWithinGroup, topNInsideGroup, includeMaxScore);
if (cachedCollector != null && cachedCollector.isCached()) {
cachedCollector.replay(secondPassCollector);
} else {
searcher.search(query, secondPassCollector);
}
if (allGroups) {
return new TopGroups(
secondPassCollector.getTopGroups(groupDocsOffset), matchingGroups.size());
} else {
return secondPassCollector.getTopGroups(groupDocsOffset);
}
}
protected TopGroups groupByDocBlock(
IndexSearcher searcher, Query query, int groupOffset, int groupLimit) throws IOException {
int topN = groupOffset + groupLimit;
final Query endDocsQuery = searcher.rewrite(this.groupEndDocs);
final Weight groupEndDocs =
searcher.createWeight(endDocsQuery, ScoreMode.COMPLETE_NO_SCORES, 1);
BlockGroupingCollector c =
new BlockGroupingCollector(
groupSort,
topN,
groupSort.needsScores() || sortWithinGroup.needsScores(),
groupEndDocs);
searcher.search(query, c);
int topNInsideGroup = groupDocsOffset + groupDocsLimit;
return c.getTopGroups(sortWithinGroup, groupOffset, groupDocsOffset, topNInsideGroup);
}
/**
* Enables caching for the second pass search. The cache will not grow over a specified limit in
* MB. The cache is filled during the first pass searched and then replayed during the second pass
* searched. If the cache grows beyond the specified limit, then the cache is purged and not used
* in the second pass search.
*
* @param maxCacheRAMMB The maximum amount in MB the cache is allowed to hold
* @param cacheScores Whether to cache the scores
* @return this
*/
public GroupingSearch setCachingInMB(double maxCacheRAMMB, boolean cacheScores) {
this.maxCacheRAMMB = maxCacheRAMMB;
this.maxDocsToCache = null;
this.cacheScores = cacheScores;
return this;
}
/**
* Enables caching for the second pass search. The cache will not contain more than the maximum
* specified documents. The cache is filled during the first pass searched and then replayed
* during the second pass searched. If the cache grows beyond the specified limit, then the cache
* is purged and not used in the second pass search.
*
* @param maxDocsToCache The maximum number of documents the cache is allowed to hold
* @param cacheScores Whether to cache the scores
* @return this
*/
public GroupingSearch setCaching(int maxDocsToCache, boolean cacheScores) {
this.maxDocsToCache = maxDocsToCache;
this.maxCacheRAMMB = null;
this.cacheScores = cacheScores;
return this;
}
/**
* Disables any enabled cache.
*
* @return this
*/
public GroupingSearch disableCaching() {
this.maxCacheRAMMB = null;
this.maxDocsToCache = null;
return this;
}
/**
* Specifies how groups are sorted. Defaults to {@link Sort#RELEVANCE}.
*
* @param groupSort The sort for the groups.
* @return this
*/
public GroupingSearch setGroupSort(Sort groupSort) {
this.groupSort = groupSort;
return this;
}
/**
* Specified how documents inside a group are sorted. Defaults to {@link Sort#RELEVANCE}.
*
* @param sortWithinGroup The sort for documents inside a group
* @return this
*/
public GroupingSearch setSortWithinGroup(Sort sortWithinGroup) {
this.sortWithinGroup = sortWithinGroup;
return this;
}
/**
* Specifies the offset for documents inside a group.
*
* @param groupDocsOffset The offset for documents inside a
* @return this
*/
public GroupingSearch setGroupDocsOffset(int groupDocsOffset) {
this.groupDocsOffset = groupDocsOffset;
return this;
}
/**
* Specifies the number of documents to return inside a group from the specified groupDocsOffset.
*
* @param groupDocsLimit The number of documents to return inside a group
* @return this
*/
public GroupingSearch setGroupDocsLimit(int groupDocsLimit) {
this.groupDocsLimit = groupDocsLimit;
return this;
}
/**
* Whether to include the score of the most relevant document per group.
*
* @param includeMaxScore Whether to include the score of the most relevant document per group
* @return this
*/
public GroupingSearch setIncludeMaxScore(boolean includeMaxScore) {
this.includeMaxScore = includeMaxScore;
return this;
}
/**
* Whether to also compute all groups matching the query. This can be used to determine the number
* of groups, which can be used for accurate pagination.
*
* When grouping by doc block the number of groups are automatically included in the {@link
* TopGroups} and this option doesn't have any influence.
*
* @param allGroups to also compute all groups matching the query
* @return this
*/
public GroupingSearch setAllGroups(boolean allGroups) {
this.allGroups = allGroups;
return this;
}
/**
* If {@link #setAllGroups(boolean)} was set to true then all matching groups are
* returned, otherwise an empty collection is returned.
*
* @param The group value type. This can be a {@link BytesRef} or a {@link MutableValue}
* instance. If grouping by doc block this the group value is always null.
* @return all matching groups are returned, or an empty collection
*/
@SuppressWarnings({"unchecked", "rawtypes"})
public Collection getAllMatchingGroups() {
return (Collection) matchingGroups;
}
/**
* Whether to compute all group heads (most relevant document per group) matching the query.
*
* This feature isn't enabled when grouping by doc block.
*
* @param allGroupHeads Whether to compute all group heads (most relevant document per group)
* matching the query
* @return this
*/
public GroupingSearch setAllGroupHeads(boolean allGroupHeads) {
this.allGroupHeads = allGroupHeads;
return this;
}
/**
* Returns the matching group heads if {@link #setAllGroupHeads(boolean)} was set to true or an
* empty bit set.
*
* @return The matching group heads if {@link #setAllGroupHeads(boolean)} was set to true or an
* empty bit set
*/
public Bits getAllGroupHeads() {
return matchingGroupHeads;
}
}