jduo commented on issue #38250:
URL: https://github.com/apache/arrow/issues/38250#issuecomment-1765507285
I've attached a test case that shows this problem.
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* http://www.apache.org/licenses/LICENSE-2.0
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package org.apache.arrow.dataset.file;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.IOException;
import java.nio.channels.Channels;
import java.nio.channels.SeekableByteChannel;
import java.nio.channels.WritableByteChannel;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;
import org.apache.arrow.dataset.TestDataset;
import org.apache.arrow.memory.BufferAllocator;
import org.apache.arrow.vector.VectorSchemaRoot;
import org.apache.arrow.vector.complex.MapVector;
import org.apache.arrow.vector.complex.impl.UnionMapWriter;
import org.apache.arrow.vector.ipc.ArrowStreamReader;
import org.apache.arrow.vector.ipc.ArrowStreamWriter;
import org.apache.arrow.vector.types.pojo.ArrowType;
import org.apache.arrow.vector.types.pojo.Field;
import org.apache.arrow.vector.types.pojo.FieldType;
import org.apache.arrow.vector.types.pojo.Schema;
import org.apache.arrow.vector.util.ByteArrayReadableSeekableByteChannel;
import org.junit.ClassRule;
import org.junit.Test;
import org.junit.rules.TemporaryFolder;
public class TestDatasetWriterMap extends TestDataset {
@ClassRule
public static final TemporaryFolder TMP = new TemporaryFolder();
private VectorSchemaRoot generateAllTypesVector(BufferAllocator allocator)
{
// Notes:
// - Float16 is not supported by Java.
// - IntervalMonthDayNano is not supported by Parquet.
// - Map (GH-38250) and SparseUnion are resulting in serialization
errors when writing with the Dataset API.
// "Unhandled type for Arrow to Parquet schema conversion" errors:
IntervalDay, IntervalYear, DenseUnion
List<Field> fields = List.of(
new Field("map", FieldType.nullable(new ArrowType.Map(/*keyssorted*/
false)),
Collections.singletonList(new Field("items",
FieldType.notNullable(ArrowType.Struct.INSTANCE),
Arrays.asList(Field.notNullable("keys", new
ArrowType.Int(32, true)),
Field.nullable("values", new ArrowType.Int(32, true))))))
);
VectorSchemaRoot root = VectorSchemaRoot.create(new Schema(fields),
allocator);
root.allocateNew();
root.setRowCount(2);
MapVector mapVector = ((MapVector) root.getVector("map"));
UnionMapWriter mapWriter = mapVector.getWriter();
for (int i = 0; i < 2; i++) {
mapWriter.startMap();
for (int j = 0; j < i + 1; j++) {
mapWriter.startEntry();
mapWriter.key().integer().writeInt(j);
mapWriter.value().integer().writeInt(j);
mapWriter.endEntry();
}
mapWriter.endMap();
}
return root;
}
private byte[] serializeFile(VectorSchemaRoot root) {
try (
ByteArrayOutputStream out = new ByteArrayOutputStream();
WritableByteChannel channel = Channels.newChannel(out);
ArrowStreamWriter writer = new ArrowStreamWriter(root, null, channel)
) {
writer.start();
writer.writeBatch();
writer.end();
return out.toByteArray();
} catch (IOException e) {
throw new IllegalArgumentException("Failed to serialize arrow file",
e);
}
}
@Test
public void testAllTypesParquet() throws Exception {
try (VectorSchemaRoot root = generateAllTypesVector(rootAllocator())) {
byte[] featherData = serializeFile(root);
try (SeekableByteChannel channel = new
ByteArrayReadableSeekableByteChannel(featherData)) {
try (ArrowStreamReader reader = new ArrowStreamReader(channel,
rootAllocator())) {
TMP.create();
final File writtenFolder = TMP.newFolder();
final String writtenParquet = writtenFolder.toURI().toString();
DatasetFileWriter.write(rootAllocator(), reader,
FileFormat.PARQUET,
writtenParquet);
}
}
}
}
}
`
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