xiangfu0 commented on code in PR #11993: URL: https://github.com/apache/pinot/pull/11993#discussion_r1406738352
########## pinot-segment-spi/src/main/java/org/apache/pinot/segment/spi/compression/DictCompressionType.java: ########## @@ -0,0 +1,23 @@ +/** + * 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.pinot.segment.spi.compression; + +public enum DictCompressionType { Review Comment: Do you foresee there will be single value dict compression type? If so, maybe we can use one bit or a few bits to represent some feature can has builtin method like `isMvDictionary()`. ########## pinot-spi/src/main/java/org/apache/pinot/spi/config/table/FieldConfig.java: ########## @@ -119,7 +119,19 @@ public enum IndexType { } public enum CompressionCodec { Review Comment: Shall we separate since raw and dictionary compression has no overlap? ########## pinot-segment-local/src/main/java/org/apache/pinot/segment/local/segment/index/loader/ForwardIndexHandler.java: ########## @@ -381,37 +368,64 @@ private boolean shouldDisableDictionary(String column, ColumnMetadata existingCo return true; } - private boolean shouldChangeCompressionType(String column, SegmentDirectory.Reader segmentReader) + private boolean shouldChangeRawCompressionType(String column, SegmentDirectory.Reader segmentReader) throws Exception { - ColumnMetadata existingColMetadata = _segmentDirectory.getSegmentMetadata().getColumnMetadataFor(column); - // The compression type for an existing segment can only be determined by reading the forward index header. + ColumnMetadata existingColMetadata = _segmentDirectory.getSegmentMetadata().getColumnMetadataFor(column); + ChunkCompressionType existingCompressionType; try (ForwardIndexReader<?> fwdIndexReader = ForwardIndexType.read(segmentReader, existingColMetadata)) { - ChunkCompressionType existingCompressionType = fwdIndexReader.getCompressionType(); + existingCompressionType = fwdIndexReader.getCompressionType(); Preconditions.checkState(existingCompressionType != null, "Existing compressionType cannot be null for raw forward index column=" + column); + } - // Get the new compression type. - ChunkCompressionType newCompressionType = _fieldIndexConfigs.get(column).getConfig(StandardIndexes.forward()) - .getChunkCompressionType(); + // Get the new compression type. + ChunkCompressionType newCompressionType = + _fieldIndexConfigs.get(column).getConfig(StandardIndexes.forward()).getChunkCompressionType(); - // Note that default compression type (PASS_THROUGH for metric and LZ4 for dimension) is not considered if the - // compressionType is not explicitly provided in tableConfig. This is to avoid incorrectly rewriting all the - // forward indexes during segmentReload when the default compressionType changes. - return newCompressionType != null && existingCompressionType != newCompressionType; + // Note that default compression type (PASS_THROUGH for metric and LZ4 for dimension) is not considered if the + // compressionType is not explicitly provided in tableConfig. This is to avoid incorrectly rewriting all the + // forward indexes during segmentReload when the default compressionType changes. + return newCompressionType != null && existingCompressionType != newCompressionType; + } + + private boolean shouldChangeDictCompressionType(String column, SegmentDirectory.Reader segmentReader) + throws Exception { + // The compression type for an existing segment can only be determined by reading the forward index header. + ColumnMetadata existingColMetadata = _segmentDirectory.getSegmentMetadata().getColumnMetadataFor(column); + DictCompressionType existingCompressionType; + try (ForwardIndexReader<?> fwdIndexReader = ForwardIndexType.read(segmentReader, existingColMetadata)) { + existingCompressionType = fwdIndexReader.getDictCompressionType(); } + + // Get the new compression type. + DictCompressionType newCompressionType = + _fieldIndexConfigs.get(column).getConfig(StandardIndexes.forward()).getDictCompressionType(); + // MV_ENTRY_DICT can only be applied to multi-value columns. + if (newCompressionType == DictCompressionType.MV_ENTRY_DICT && existingColMetadata.isSingleValue()) { Review Comment: This if check will be hard to maintain, shall we consider having a static method in `DictCompressionType` like `isMultiValueDictionary(DictCompressionType type)`? ########## pinot-segment-local/src/main/java/org/apache/pinot/segment/local/segment/index/readers/forward/FixedBitMVEntryDictForwardIndexReader.java: ########## @@ -0,0 +1,155 @@ +/** + * 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.pinot.segment.local.segment.index.readers.forward; + +import com.google.common.base.Preconditions; +import java.util.List; +import org.apache.pinot.segment.local.io.util.FixedBitIntReaderWriter; +import org.apache.pinot.segment.local.io.util.PinotDataBitSet; +import org.apache.pinot.segment.local.io.writer.impl.FixedBitMVEntryDictForwardIndexWriter; +import org.apache.pinot.segment.spi.compression.DictCompressionType; +import org.apache.pinot.segment.spi.index.reader.ForwardIndexReader; +import org.apache.pinot.segment.spi.index.reader.ForwardIndexReaderContext; +import org.apache.pinot.segment.spi.memory.PinotDataBuffer; +import org.apache.pinot.spi.data.FieldSpec.DataType; + + +/** + * Bit-compressed dictionary-encoded forward index reader for multi-value columns, where a second level dictionary + * encoding for multi-value entries (instead of individual values within the entry) are maintained within the forward + * index. + * See {@link FixedBitMVEntryDictForwardIndexWriter} for index layout. + */ +public final class FixedBitMVEntryDictForwardIndexReader implements ForwardIndexReader<ForwardIndexReaderContext> { + public static final int MAGIC_MARKER = FixedBitMVEntryDictForwardIndexWriter.MAGIC_MARKER; + public static final short VERSION = FixedBitMVEntryDictForwardIndexWriter.VERSION; + private static final int HEADER_SIZE = 24; Review Comment: This can also use FixedBitMVEntryDictForwardIndexWriter.HEADER_SIZE? ########## pinot-segment-local/src/test/java/org/apache/pinot/segment/local/segment/index/forward/FixedBitMVEntryDictForwardIndexTest.java: ########## @@ -0,0 +1,98 @@ +/** + * 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.pinot.segment.local.segment.index.forward; + +import java.io.File; +import java.io.IOException; +import java.util.Random; +import org.apache.commons.io.FileUtils; +import org.apache.pinot.segment.local.io.writer.impl.FixedBitMVEntryDictForwardIndexWriter; +import org.apache.pinot.segment.local.segment.index.readers.forward.FixedBitMVEntryDictForwardIndexReader; +import org.apache.pinot.segment.spi.V1Constants; +import org.apache.pinot.segment.spi.memory.PinotDataBuffer; +import org.testng.annotations.AfterClass; +import org.testng.annotations.BeforeClass; +import org.testng.annotations.Test; + +import static org.testng.Assert.assertEquals; + + +public class FixedBitMVEntryDictForwardIndexTest { Review Comment: Can you add a test for all null value or all empty array ? -- This is an automated message from the Apache Git Service. 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