[HUDI-2756] Fix flink parquet writer decimal type conversion (#3988)

hudi-client/hudi-flink-client/src/main/java/org/apache/hudi/io/storage/row/parquet/ParquetSchemaConverter.java

@@ -564,7 +564,7 @@ public class ParquetSchemaConverter {
         int scale = ((DecimalType) type).getScale();
         int numBytes = computeMinBytesForDecimalPrecision(precision);
         return Types.primitive(
-            PrimitiveType.PrimitiveTypeName.BINARY, repetition)
+            PrimitiveType.PrimitiveTypeName.FIXED_LEN_BYTE_ARRAY, repetition)
             .precision(precision)
             .scale(scale)
             .length(numBytes)

hudi-flink/src/main/java/org/apache/hudi/table/format/cow/FixedLenBytesColumnReader.java

@@ -0,0 +1,85 @@
+/*
+ * 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.hudi.table.format.cow;
+
+import org.apache.flink.table.data.vector.writable.WritableBytesVector;
+import org.apache.flink.table.data.vector.writable.WritableColumnVector;
+import org.apache.flink.table.data.vector.writable.WritableIntVector;
+
+import org.apache.parquet.column.ColumnDescriptor;
+import org.apache.parquet.column.page.PageReader;
+import org.apache.parquet.io.api.Binary;
+import org.apache.parquet.schema.PrimitiveType;
+
+import java.io.IOException;
+import java.nio.ByteBuffer;
+
+/**
+ * Fixed length bytes {@code ColumnReader}, just for decimal.
+ *
+ * <p>Note: Reference Flink release 1.13.2
+ * {@code org.apache.flink.formats.parquet.vector.reader.FixedLenBytesColumnReader}
+ * to always write as legacy decimal format.
+ */
+public class FixedLenBytesColumnReader<V extends WritableColumnVector>
+    extends AbstractColumnReader<V> {
+
+  public FixedLenBytesColumnReader(
+      ColumnDescriptor descriptor, PageReader pageReader, int precision) throws IOException {
+    super(descriptor, pageReader);
+    checkTypeName(PrimitiveType.PrimitiveTypeName.FIXED_LEN_BYTE_ARRAY);
+  }
+
+  @Override
+  protected void readBatch(int rowId, int num, V column) {
+    int bytesLen = descriptor.getPrimitiveType().getTypeLength();
+    WritableBytesVector bytesVector = (WritableBytesVector) column;
+    for (int i = 0; i < num; i++) {
+      if (runLenDecoder.readInteger() == maxDefLevel) {
+        byte[] bytes = readDataBinary(bytesLen).getBytes();
+        bytesVector.appendBytes(rowId + i, bytes, 0, bytes.length);
+      } else {
+        bytesVector.setNullAt(rowId + i);
+      }
+    }
+  }
+
+  @Override
+  protected void readBatchFromDictionaryIds(
+      int rowId, int num, V column, WritableIntVector dictionaryIds) {
+    WritableBytesVector bytesVector = (WritableBytesVector) column;
+    for (int i = rowId; i < rowId + num; ++i) {
+      if (!bytesVector.isNullAt(i)) {
+        byte[] v = dictionary.decodeToBinary(dictionaryIds.getInt(i)).getBytes();
+        bytesVector.appendBytes(i, v, 0, v.length);
+      }
+    }
+  }
+
+  private Binary readDataBinary(int len) {
+    ByteBuffer buffer = readDataBuffer(len);
+    if (buffer.hasArray()) {
+      return Binary.fromConstantByteArray(
+          buffer.array(), buffer.arrayOffset() + buffer.position(), len);
+    } else {
+      byte[] bytes = new byte[len];
+      buffer.get(bytes);
+      return Binary.fromConstantByteArray(bytes);
+    }
+  }
+}

hudi-flink/src/main/java/org/apache/hudi/table/format/cow/ParquetSplitReaderUtil.java

@@ -24,7 +24,6 @@ import org.apache.flink.formats.parquet.vector.reader.ByteColumnReader;
 import org.apache.flink.formats.parquet.vector.reader.BytesColumnReader;
 import org.apache.flink.formats.parquet.vector.reader.ColumnReader;
 import org.apache.flink.formats.parquet.vector.reader.DoubleColumnReader;
-import org.apache.flink.formats.parquet.vector.reader.FixedLenBytesColumnReader;
 import org.apache.flink.formats.parquet.vector.reader.FloatColumnReader;
 import org.apache.flink.formats.parquet.vector.reader.IntColumnReader;
 import org.apache.flink.formats.parquet.vector.reader.LongColumnReader;
@@ -366,7 +365,7 @@ public class ParquetSplitReaderUtil {
             "TIME_MICROS original type is not ");
         return new HeapTimestampVector(batchSize);
       case DECIMAL:
-        checkArgument(typeName == PrimitiveType.PrimitiveTypeName.BINARY
+        checkArgument(typeName == PrimitiveType.PrimitiveTypeName.FIXED_LEN_BYTE_ARRAY
                 && primitiveType.getOriginalType() == OriginalType.DECIMAL,
             "Unexpected type: %s", typeName);
         return new HeapBytesVector(batchSize);