nastra commented on code in PR #14800: URL: https://github.com/apache/iceberg/pull/14800#discussion_r2792950037
########## arrow/src/main/java/org/apache/iceberg/arrow/vectorized/parquet/VectorizedDeltaByteArrayValuesReader.java: ########## @@ -0,0 +1,185 @@ +/* + * 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.BaseFixedWidthVector; +import org.apache.arrow.vector.BaseVariableWidthVector; +import org.apache.arrow.vector.FieldVector; +import org.apache.arrow.vector.FixedWidthVector; +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 the encoding type DELTA_BYTE_ARRAY. 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 final VectorizedDeltaEncodedValuesReader prefixLengthReader; + private final VectorizedDeltaLengthByteArrayValuesReader suffixReader; + + private int[] prefixLengths; + private Binary previous; + private int currentIndex; + + public VectorizedDeltaByteArrayValuesReader() { + prefixLengthReader = new VectorizedDeltaEncodedValuesReader(); + suffixReader = new VectorizedDeltaLengthByteArrayValuesReader(); + } + + @Override + public void initFromPage(int valueCount, ByteBufferInputStream in) throws IOException { + prefixLengthReader.initFromPage(valueCount, in); + // actual number of elements in the page may be less than the passed valueCount here due to + // nulls + prefixLengths = prefixLengthReader.readIntegers(prefixLengthReader.getTotalValueCount(), 0); + suffixReader.initFromPage(valueCount, in); + previous = Binary.EMPTY; + currentIndex = 0; + } + + @Override + public Binary readBinary(int len) { + throw new UnsupportedOperationException(); + } + + @Override + public void readBinary(int total, FieldVector vec, int rowId, boolean setArrowValidityVector) { + if (vec instanceof BaseVariableWidthVector) { + BaseVariableWidthVector vector = (BaseVariableWidthVector) vec; + readValues(total, rowId, vector::setSafe); + } else if (vec instanceof FixedWidthVector) { + BaseFixedWidthVector vector = (BaseFixedWidthVector) vec; + readValues(total, rowId, (index, value) -> vector.setSafe(index, value, 0, value.length)); + } + } + + private void readValues(int total, int rowId, BinaryOutputWriter outputWriter) { + for (int i = 0; i < total; i++) { + int prefixLength = prefixLengths[currentIndex]; + Binary suffix = suffixReader.readBinaryForRow(rowId + i); + int length = prefixLength + suffix.length(); + + if (prefixLength != 0) { + byte[] out = new byte[length]; + System.arraycopy(previous.getBytesUnsafe(), 0, out, 0, prefixLength); + System.arraycopy(suffix.getBytesUnsafe(), 0, out, prefixLength, suffix.length()); + outputWriter.write(rowId + i, out); + previous = Binary.fromConstantByteArray(out); + } else { + outputWriter.write(rowId + i, suffix.getBytesUnsafe()); + previous = suffix; + } + + currentIndex++; + } + } + + /** DELTA_BYTE_ARRAY only supports BINARY */ + @Override + public boolean readBoolean() { + throw new UnsupportedOperationException("readBoolean is not supported"); + } + + /** DELTA_BYTE_ARRAY only supports BINARY */ + @Override + public byte readByte() { + throw new UnsupportedOperationException("readByte is not supported"); + } + + /** DELTA_BYTE_ARRAY only supports BINARY */ + @Override + public short readShort() { + throw new UnsupportedOperationException("readShort is not supported"); + } + + /** DELTA_BYTE_ARRAY only supports BINARY */ + @Override + public int readInteger() { + throw new UnsupportedOperationException("readInteger is not supported"); + } + + /** DELTA_BYTE_ARRAY only supports BINARY */ + @Override + public long readLong() { + throw new UnsupportedOperationException("readLong is not supported"); + } + + /** DELTA_BYTE_ARRAY only supports BINARY */ + @Override + public float readFloat() { + throw new UnsupportedOperationException("readFloat is not supported"); + } + + /** DELTA_BYTE_ARRAY only supports BINARY */ + @Override + public double readDouble() { + throw new UnsupportedOperationException("readDouble is not supported"); + } + + /** DELTA_BYTE_ARRAY only supports BINARY */ + @Override + public void readIntegers(int total, FieldVector vec, int rowId) { + throw new UnsupportedOperationException("readIntegers is not supported"); + } + + /** DELTA_BYTE_ARRAY only supports BINARY */ + @Override + public void readLongs(int total, FieldVector vec, int rowId) { + throw new UnsupportedOperationException("readLongs is not supported"); + } + + /** DELTA_BYTE_ARRAY only supports BINARY */ + @Override + public void readFloats(int total, FieldVector vec, int rowId) { + throw new UnsupportedOperationException("readFloats is not supported"); + } + + /** DELTA_BYTE_ARRAY only supports BINARY */ + @Override + public void readDoubles(int total, FieldVector vec, int rowId) { + throw new UnsupportedOperationException("readDoubles is not supported"); + } + + /** The Iceberg reader currently does not do skipping */ + @Override + public void skip() { + throw new UnsupportedOperationException("skip is not supported"); + } + + /** A functional interface to write binary values into a FieldVector */ + @FunctionalInterface + interface BinaryOutputWriter { Review Comment: ```suggestion private interface BinaryOutputWriter { ``` -- This is an automated message from the Apache Git Service. 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