public void TestArrowSqlCommandExecutorWithEmptyInput()
{
var udfWrapper = new Sql.ArrowUdfWrapper <StringArray, StringArray>(
(strings) => (StringArray)ToArrowArray(
Enumerable.Range(0, strings.Length)
.Select(i => $"udf: {strings.GetString(i)}")
.ToArray()));
var command = new SqlCommand()
{
ArgOffsets = new[] { 0 },
NumChainedFunctions = 1,
WorkerFunction = new Sql.ArrowWorkerFunction(udfWrapper.Execute),
SerializerMode = CommandSerDe.SerializedMode.Row,
DeserializerMode = CommandSerDe.SerializedMode.Row
};
var commandPayload = new Worker.CommandPayload()
{
EvalType = UdfUtils.PythonEvalType.SQL_SCALAR_PANDAS_UDF,
Commands = new[] { command }
};
using (var inputStream = new MemoryStream())
using (var outputStream = new MemoryStream())
{
// Write test data to the input stream.
Schema schema = new Schema.Builder()
.Field(b => b.Name("arg1").DataType(StringType.Default))
.Build();
var arrowWriter = new ArrowStreamWriter(inputStream, schema);
// The .NET ArrowStreamWriter doesn't currently support writing just a
// schema with no batches - but Java does. We use Reflection to simulate
// the request Spark sends.
MethodInfo writeSchemaMethod = arrowWriter.GetType().GetMethod(
"WriteSchemaAsync",
BindingFlags.NonPublic | BindingFlags.Instance);
writeSchemaMethod.Invoke(
arrowWriter,
new object[] { schema, CancellationToken.None });
SerDe.Write(inputStream, 0);
inputStream.Seek(0, SeekOrigin.Begin);
CommandExecutorStat stat = new CommandExecutor().Execute(
inputStream,
outputStream,
0,
commandPayload);
// Validate that all the data on the stream is read.
Assert.Equal(inputStream.Length, inputStream.Position);
Assert.Equal(0, stat.NumEntriesProcessed);
// Validate the output stream.
outputStream.Seek(0, SeekOrigin.Begin);
int arrowLength = SerDe.ReadInt32(outputStream);
Assert.Equal((int)SpecialLengths.START_ARROW_STREAM, arrowLength);
var arrowReader = new ArrowStreamReader(outputStream);
RecordBatch outputBatch = arrowReader.ReadNextRecordBatch();
Assert.Equal(1, outputBatch.Schema.Fields.Count);
Assert.IsType <StringType>(outputBatch.Schema.GetFieldByIndex(0).DataType);
Assert.Equal(0, outputBatch.Length);
Assert.Single(outputBatch.Arrays);
var array = (StringArray)outputBatch.Arrays.ElementAt(0);
Assert.Equal(0, array.Length);
int end = SerDe.ReadInt32(outputStream);
Assert.Equal(0, end);
// Validate all the data on the stream is read.
Assert.Equal(outputStream.Length, outputStream.Position);
}
}