emkornfield commented on code in PR #3390: URL: https://github.com/apache/parquet-java/pull/3390#discussion_r2719799163
########## parquet-column/src/main/java/org/apache/parquet/column/values/alp/AlpValuesWriter.java: ########## @@ -0,0 +1,525 @@ +/* + * 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.alp; + +import static org.apache.parquet.column.values.alp.AlpConstants.*; + +import java.nio.ByteBuffer; +import java.nio.ByteOrder; +import org.apache.parquet.bytes.ByteBufferAllocator; +import org.apache.parquet.bytes.BytesInput; +import org.apache.parquet.bytes.CapacityByteArrayOutputStream; +import org.apache.parquet.column.Encoding; +import org.apache.parquet.column.values.ValuesWriter; + +/** + * ALP (Adaptive Lossless floating-Point) values writer. + * + * <p>ALP encoding converts floating-point values to integers using decimal scaling, + * then applies Frame of Reference (FOR) encoding and bit-packing. + * Values that cannot be losslessly converted are stored as exceptions. + * + * <p>Page Layout: + * <pre> + * ┌─────────┬────────────────┬────────────────┬─────────────┐ + * │ Header │ AlpInfo Array │ ForInfo Array │ Data Array │ + * │ 8 bytes │ 4B × N vectors │ 5B/9B × N │ Variable │ + * └─────────┴────────────────┴────────────────┴─────────────┘ + * </pre> + */ +public abstract class AlpValuesWriter extends ValuesWriter { + + protected final int initialCapacity; + protected final int pageSize; + protected final ByteBufferAllocator allocator; + protected CapacityByteArrayOutputStream outputStream; + + public AlpValuesWriter(int initialCapacity, int pageSize, ByteBufferAllocator allocator) { + this.initialCapacity = initialCapacity; + this.pageSize = pageSize; + this.allocator = allocator; + this.outputStream = new CapacityByteArrayOutputStream(initialCapacity, pageSize, allocator); + } + + @Override + public Encoding getEncoding() { + return Encoding.ALP; + } + + @Override + public void close() { + outputStream.close(); + } + + /** + * Float-specific ALP values writer. + */ + public static class FloatAlpValuesWriter extends AlpValuesWriter { + private float[] buffer; + private int count; + + public FloatAlpValuesWriter(int initialCapacity, int pageSize, ByteBufferAllocator allocator) { + super(initialCapacity, pageSize, allocator); + // Initial buffer size - will grow as needed + this.buffer = new float[Math.max(ALP_VECTOR_SIZE, initialCapacity / Float.BYTES)]; + this.count = 0; + } + + @Override + public void writeFloat(float v) { + if (count >= buffer.length) { Review Comment: I don't think we should be growing here to all floats. Once we reach vector-size we should be encoding the page. ########## parquet-column/src/main/java/org/apache/parquet/column/values/alp/AlpValuesWriter.java: ########## @@ -0,0 +1,525 @@ +/* + * 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.alp; + +import static org.apache.parquet.column.values.alp.AlpConstants.*; + +import java.nio.ByteBuffer; +import java.nio.ByteOrder; +import org.apache.parquet.bytes.ByteBufferAllocator; +import org.apache.parquet.bytes.BytesInput; +import org.apache.parquet.bytes.CapacityByteArrayOutputStream; +import org.apache.parquet.column.Encoding; +import org.apache.parquet.column.values.ValuesWriter; + +/** + * ALP (Adaptive Lossless floating-Point) values writer. + * + * <p>ALP encoding converts floating-point values to integers using decimal scaling, + * then applies Frame of Reference (FOR) encoding and bit-packing. + * Values that cannot be losslessly converted are stored as exceptions. + * + * <p>Page Layout: + * <pre> + * ┌─────────┬────────────────┬────────────────┬─────────────┐ + * │ Header │ AlpInfo Array │ ForInfo Array │ Data Array │ + * │ 8 bytes │ 4B × N vectors │ 5B/9B × N │ Variable │ + * └─────────┴────────────────┴────────────────┴─────────────┘ + * </pre> + */ +public abstract class AlpValuesWriter extends ValuesWriter { + + protected final int initialCapacity; + protected final int pageSize; + protected final ByteBufferAllocator allocator; + protected CapacityByteArrayOutputStream outputStream; + + public AlpValuesWriter(int initialCapacity, int pageSize, ByteBufferAllocator allocator) { + this.initialCapacity = initialCapacity; + this.pageSize = pageSize; + this.allocator = allocator; + this.outputStream = new CapacityByteArrayOutputStream(initialCapacity, pageSize, allocator); + } + + @Override + public Encoding getEncoding() { + return Encoding.ALP; + } + + @Override + public void close() { + outputStream.close(); + } + + /** + * Float-specific ALP values writer. + */ + public static class FloatAlpValuesWriter extends AlpValuesWriter { + private float[] buffer; + private int count; + + public FloatAlpValuesWriter(int initialCapacity, int pageSize, ByteBufferAllocator allocator) { + super(initialCapacity, pageSize, allocator); + // Initial buffer size - will grow as needed + this.buffer = new float[Math.max(ALP_VECTOR_SIZE, initialCapacity / Float.BYTES)]; + this.count = 0; + } + + @Override + public void writeFloat(float v) { + if (count >= buffer.length) { + // Grow buffer + float[] newBuffer = new float[buffer.length * 2]; + System.arraycopy(buffer, 0, newBuffer, 0, count); + buffer = newBuffer; + } + buffer[count++] = v; + } + + @Override + public long getBufferedSize() { + // Estimate: each float value contributes roughly 2-4 bytes after compression + // (actual size depends on data characteristics) + return count * 3L; // Conservative estimate + } + + @Override + public BytesInput getBytes() { + if (count == 0) { + return BytesInput.empty(); + } + + outputStream.reset(); + + // Calculate number of vectors + int numVectors = (count + ALP_VECTOR_SIZE - 1) / ALP_VECTOR_SIZE; + + // Prepare metadata arrays + int[] exponents = new int[numVectors]; + int[] factors = new int[numVectors]; + int[] numExceptions = new int[numVectors]; + int[] frameOfReference = new int[numVectors]; + int[] bitWidths = new int[numVectors]; + + // Prepare encoded data arrays + int[][] encodedValues = new int[numVectors][]; + short[][] exceptionPositions = new short[numVectors][]; + float[][] exceptionValues = new float[numVectors][]; + + // Process each vector + for (int v = 0; v < numVectors; v++) { + int vectorStart = v * ALP_VECTOR_SIZE; + int vectorEnd = Math.min(vectorStart + ALP_VECTOR_SIZE, count); + int vectorLen = vectorEnd - vectorStart; + + // Find best encoding parameters + AlpEncoderDecoder.EncodingParams params = Review Comment: Don't we want to cache encodings and use those first (and stop searching after a while)? -- This is an automated message from the Apache Git Service. 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