org.apache.solr.search.LuceneQueryOptimizer Maven / Gradle / Ivy
/**
* 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.solr.search;
/* Copyright (c) 2003 The Nutch Organization. All rights reserved. */
/* Use subject to the conditions in http://www.nutch.org/LICENSE.txt. */
import org.apache.lucene.search.*;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.io.IOException;
/** Utility which converts certain query clauses into {@link QueryFilter}s and
* caches these. Only required {@link TermQuery}s whose boost is zero and
* whose term occurs in at least a certain fraction of documents are converted
* to cached filters. This accelerates query constraints like language,
* document format, etc., which do not affect ranking but might otherwise slow
* search considerably. */
// Taken from Nutch and modified - YCS
class LuceneQueryOptimizer {
private LinkedHashMap cache; // an LRU cache of QueryFilter
private float threshold;
/** Construct an optimizer that caches and uses filters for required {@link
* TermQuery}s whose boost is zero.
* @param cacheSize the number of QueryFilters to cache
* @param threshold the fraction of documents which must contain term
*/
public LuceneQueryOptimizer(final int cacheSize, float threshold) {
this.cache = new LinkedHashMap(cacheSize, 0.75f, true) {
protected boolean removeEldestEntry(Map.Entry eldest) {
return size() > cacheSize; // limit size of cache
}
};
this.threshold = threshold;
}
public TopDocs optimize(BooleanQuery original,
Searcher searcher,
int numHits,
Query[] queryOut,
Filter[] filterOut
)
throws IOException {
BooleanQuery query = new BooleanQuery();
BooleanQuery filterQuery = null;
for (BooleanClause c : (List)original.clauses()) {
/***
System.out.println("required="+c.required);
System.out.println("boost="+c.query.getBoost());
System.out.println("isTermQuery="+(c.query instanceof TermQuery));
if (c.query instanceof TermQuery) {
System.out.println("term="+((TermQuery)c.query).getTerm());
System.out.println("docFreq="+searcher.docFreq(((TermQuery)c.query).getTerm()));
}
***/
Query q = c.getQuery();
if (c.isRequired() // required
&& q.getBoost() == 0.0f // boost is zero
&& q instanceof TermQuery // TermQuery
&& (searcher.docFreq(((TermQuery)q).getTerm())
/ (float)searcher.maxDoc()) >= threshold) { // check threshold
if (filterQuery == null)
filterQuery = new BooleanQuery();
filterQuery.add(q, BooleanClause.Occur.MUST); // filter it
//System.out.println("WooHoo... qualified to be hoisted to a filter!");
} else {
query.add(c); // query it
}
}
Filter filter = null;
if (filterQuery != null) {
synchronized (cache) { // check cache
filter = (Filter)cache.get(filterQuery);
}
if (filter == null) { // miss
filter = new CachingWrapperFilter(new QueryWrapperFilter(filterQuery)); // construct new entry
synchronized (cache) {
cache.put(filterQuery, filter); // cache it
}
}
}
// YCS: added code to pass out optimized query and filter
// so they can be used with Hits
if (queryOut != null && filterOut != null) {
queryOut[0] = query; filterOut[0] = filter;
return null;
} else {
return searcher.search(query, filter, numHits);
}
}
}