internal ParquetRowGroupWriter(Schema schema,
Stream stream,
ThriftStream thriftStream,
ThriftFooter footer,
CompressionMethod compressionMethod,
ParquetOptions formatOptions)
{
_schema = schema ?? throw new ArgumentNullException(nameof(schema));
_stream = stream ?? throw new ArgumentNullException(nameof(stream));
_thriftStream = thriftStream ?? throw new ArgumentNullException(nameof(thriftStream));
_footer = footer ?? throw new ArgumentNullException(nameof(footer));
_compressionMethod = compressionMethod;
_formatOptions = formatOptions;
_thriftRowGroup = _footer.AddRowGroup();
_rgStartPos = _stream.Position;
_thriftRowGroup.Columns = new List <Thrift.ColumnChunk>();
_thschema = _footer.GetWriteableSchema();
}
/// <summary>
/// Write out dataset to the output stream
/// </summary>
/// <param name="dataSet">Dataset to write</param>
/// <param name="compression">Compression method</param>
/// <param name="append">When true, appends to the file, otherwise creates a new file.</param>
public void Write(DataSet dataSet, CompressionMethod compression = CompressionMethod.Gzip, bool append = false)
{
PrepareFile(dataSet, append);
_footer.CustomMetadata = dataSet.Metadata.Custom;
int offset = 0;
int count;
List <Thrift.SchemaElement> writeableSchema = _footer.GetWriteableSchema().ToList();
do
{
count = Math.Min(_writerOptions.RowGroupsSize, dataSet.Count - offset);
Thrift.RowGroup rg = _footer.AddRowGroup();
long rgStartPos = Stream.Position;
rg.Columns = new List <Thrift.ColumnChunk>();
foreach (Thrift.SchemaElement tse in writeableSchema)
{
List <string> path = _footer.GetPath(tse);
string flatPath = string.Join(Schema.PathSeparator, path);
var cw = new ColumnarWriter(Stream, ThriftStream, _footer, tse, path, compression, _formatOptions, _writerOptions);
IList values = dataSet.GetColumn(flatPath, offset, count);
Thrift.ColumnChunk chunk = cw.Write(offset, count, values);
rg.Columns.Add(chunk);
}
//row group's size is a sum of _uncompressed_ sizes of all columns in it, including the headers
//luckily ColumnChunk already contains sizes of page+header in it's meta
rg.Total_byte_size = rg.Columns.Sum(c => c.Meta_data.Total_compressed_size);
rg.Num_rows = count;
offset += _writerOptions.RowGroupsSize;
}while (offset < dataSet.Count);
_dataWritten = true;
}