nastra commented on code in PR #15362: URL: https://github.com/apache/iceberg/pull/15362#discussion_r2828396815
########## arrow/src/main/java/org/apache/iceberg/arrow/vectorized/parquet/VectorizedDeltaByteArrayValuesReader.java: ########## @@ -0,0 +1,134 @@ +/* + * 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.iceberg.arrow.vectorized.parquet; + +import java.io.IOException; +import org.apache.arrow.vector.FieldVector; +import org.apache.parquet.bytes.ByteBufferInputStream; +import org.apache.parquet.column.values.ValuesReader; +import org.apache.parquet.io.api.Binary; + +/** + * A {@link VectorizedValuesReader} implementation for DELTA_BYTE_ARRAY encoding. This encoding + * stores delta-encoded prefix lengths followed by suffixes encoded as DELTA_LENGTH_BYTE_ARRAY. Each + * value is reconstructed by taking the prefix of the previous value and appending the suffix. This + * is adapted from Spark's VectorizedDeltaByteArrayReader. + * + * @see <a + * href="https://github.com/apache/parquet-format/blob/master/Encodings.md#delta-strings-delta_byte_array--7";> + * Parquet format encodings: DELTA_BYTE_ARRAY</a> + */ +public class VectorizedDeltaByteArrayValuesReader extends ValuesReader + implements VectorizedValuesReader { + + private int[] prefixLengths; + private VectorizedDeltaLengthByteArrayValuesReader suffixReader; + private Binary previous = Binary.EMPTY; + private int currentRow = 0; + + @Override + public void initFromPage(int valueCount, ByteBufferInputStream in) throws IOException { + VectorizedDeltaEncodedValuesReader prefixLengthReader = + new VectorizedDeltaEncodedValuesReader(); + prefixLengthReader.initFromPage(valueCount, in); + this.prefixLengths = prefixLengthReader.readIntegers(prefixLengthReader.totalValueCount(), 0); + this.suffixReader = new VectorizedDeltaLengthByteArrayValuesReader(); + this.suffixReader.initFromPage(valueCount, in); + } + + @Override + public int readInteger() { + return prefixLengths[currentRow] + suffixReader.lengthForCurrentRow(); + } + + @Override + public Binary readBinary(int len) { + Binary suffix = suffixReader.readBinary(len); + int prefixLength = prefixLengths[currentRow]; + this.currentRow++; + + if (prefixLength == 0) { + this.previous = suffix; + return suffix; + } + + byte[] prefixBytes = previous.getBytes(); + byte[] suffixBytes = suffix.getBytes(); + byte[] out = new byte[prefixLength + suffixBytes.length]; + System.arraycopy(prefixBytes, 0, out, 0, prefixLength); + System.arraycopy(suffixBytes, 0, out, prefixLength, suffixBytes.length); + this.previous = Binary.fromConstantByteArray(out); + return this.previous; + } + + @Override + public boolean readBoolean() { + throw new UnsupportedOperationException("readBoolean is not supported"); + } + + @Override + public byte readByte() { + throw new UnsupportedOperationException("readByte is not supported"); + } + + @Override + public short readShort() { + throw new UnsupportedOperationException("readShort is not supported"); + } + + @Override + public long readLong() { + throw new UnsupportedOperationException("readLong is not supported"); + } + + @Override + public float readFloat() { + throw new UnsupportedOperationException("readFloat is not supported"); + } + + @Override + public double readDouble() { + throw new UnsupportedOperationException("readDouble is not supported"); + } + + @Override + public void readIntegers(int total, FieldVector vec, int rowId) { + throw new UnsupportedOperationException("readIntegers is not supported"); + } + + @Override + public void readLongs(int total, FieldVector vec, int rowId) { + throw new UnsupportedOperationException("readLongs is not supported"); + } + + @Override + public void readFloats(int total, FieldVector vec, int rowId) { + throw new UnsupportedOperationException("readFloats is not supported"); + } Review Comment: these can all be removed once we throw the UOE in `VectorizedValuesReader` ```suggestion ``` -- This is an automated message from the Apache Git Service. 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