/*
* 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.codecs.bloom;
import org.apache.lucene.index.FieldInfo;
import org.apache.lucene.index.SegmentWriteState;
/**
* Default policy is to allocate a bitset with 10% saturation given a unique term per document.
* Bits are set via MurmurHash2 hashing function.
* @lucene.experimental
*/
public class DefaultBloomFilterFactory extends BloomFilterFactory {
@Override
public FuzzySet getSetForField(SegmentWriteState state,FieldInfo info) {
//Assume all of the docs have a unique term (e.g. a primary key) and we hope to maintain a set with 10% of bits set
return FuzzySet.createSetBasedOnQuality(state.segmentInfo.maxDoc(), 0.10f);
}
@Override
public boolean isSaturated(FuzzySet bloomFilter, FieldInfo fieldInfo) {
// Don't bother saving bitsets if >90% of bits are set - we don't want to
// throw any more memory at this problem.
return bloomFilter.getSaturation() > 0.9f;
}
}