yabola commented on code in PR #1042: URL: https://github.com/apache/parquet-mr/pull/1042#discussion_r1141357582
########## parquet-column/src/main/java/org/apache/parquet/column/values/bloomfilter/DynamicBlockBloomFilter.java: ########## @@ -0,0 +1,317 @@ +/* + * 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.parquet.column.values.bloomfilter; + +import static org.apache.parquet.column.values.bloomfilter.BlockSplitBloomFilter.LOWER_BOUND_BYTES; +import static org.apache.parquet.column.values.bloomfilter.BlockSplitBloomFilter.UPPER_BOUND_BYTES; + +import java.io.IOException; +import java.io.OutputStream; +import java.util.Arrays; +import java.util.Objects; +import java.util.TreeSet; + +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; + +import org.apache.parquet.Preconditions; +import org.apache.parquet.column.ColumnDescriptor; +import org.apache.parquet.io.api.Binary; + +/** + * `DynamicBlockBloomFilter` contains multiple `BlockSplitBloomFilter` as candidates and inserts values in + * the candidates at the same time. + * The purpose of this is to finally generate a bloom filter with the optimal bit size according to the number + * of real data distinct values. Use the largest bloom filter as an approximate deduplication counter, and then + * remove bad bloom filter candidate during data insertion. + */ +public class DynamicBlockBloomFilter implements BloomFilter { + + private static final Logger LOG = LoggerFactory.getLogger(DynamicBlockBloomFilter.class); + + // multiple candidates, inserting data at the same time. If the deduplication value is greater than the + // expected NDV of candidate, it will be removed and finally choose the smallest candidate to write out. + private final TreeSet<BloomFilterCandidate> candidates = new TreeSet<>(); + + // the largest among candidates and used as an approximate deduplication counter + private BloomFilterCandidate maxCandidate; + + // the accumulator of the number of distinct values that have been inserted so far + private int distinctValueCounter = 0; + + // indicates that the bloom filter candidate has been written out and new data should be no longer allowed to be inserted + private boolean finalized = false; + + private int maximumBytes = UPPER_BOUND_BYTES; + private int minimumBytes = LOWER_BOUND_BYTES; + // the hash strategy used in this bloom filter. + private final HashStrategy hashStrategy; + // the column to build bloom filter + private ColumnDescriptor column; + + public DynamicBlockBloomFilter(int numBytes, int candidatesNum, double fpp, ColumnDescriptor column) { + this(numBytes, LOWER_BOUND_BYTES, UPPER_BOUND_BYTES, HashStrategy.XXH64, fpp, candidatesNum, column); + } + + public DynamicBlockBloomFilter(int numBytes, int maximumBytes, int candidatesNum, double fpp, ColumnDescriptor column) { + this(numBytes, LOWER_BOUND_BYTES, maximumBytes, HashStrategy.XXH64, fpp, candidatesNum, column); + } + + public DynamicBlockBloomFilter(int numBytes, int minimumBytes, int maximumBytes, HashStrategy hashStrategy, + double fpp, int candidatesNum, ColumnDescriptor column) { + if (minimumBytes > maximumBytes) { + throw new IllegalArgumentException("the minimum bytes should be less or equal than maximum bytes"); + } + + if (minimumBytes > LOWER_BOUND_BYTES && minimumBytes < UPPER_BOUND_BYTES) { + this.minimumBytes = minimumBytes; + } + + if (maximumBytes > LOWER_BOUND_BYTES && maximumBytes < UPPER_BOUND_BYTES) { + this.maximumBytes = maximumBytes; + } + this.column = column; + switch (hashStrategy) { + case XXH64: + this.hashStrategy = hashStrategy; + break; + default: + throw new RuntimeException("Unsupported hash strategy"); + } + initCandidates(numBytes, candidatesNum, fpp); + } + + /** + * Given the maximum acceptable bytes size of bloom filter, generate candidates according + * to the max expected distinct values. The size of the candidate bytes needs to be a + * square number of 2. Therefore, set the candidate size according to `maxBytes` of `1/2`, `1/4`, `1/8`, etc. + * + * @param maxBytes the maximum acceptable bit size + * @param candidatesNum the number of candidates + * @param fpp the false positive probability + */ + private void initCandidates(int maxBytes, int candidatesNum, double fpp) { Review Comment: In the original implementation, `Integer.highestOneBit(numBytes)` got the largest power of two less than `numBytes`. And I think `<< 1` here makes result larger to achieve the effect of receiving NVD values. But it could be a bug when NVD is present and I fix it in https://github.com/apache/parquet-mr/pull/1043 -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. 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