/// <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);
var stats = new DataSetStats(dataSet);
int offset = 0;
int count;
do
{
count = Math.Min(_writerOptions.RowGroupsSize, dataSet.Count - offset);
Thrift.RowGroup rg = _meta.AddRowGroup();
long rgStartPos = _output.Position;
rg.Columns = dataSet.Schema.Elements
.Select(c =>
Write(c, dataSet.GetColumn(c.Name, offset, count), compression, stats.GetColumnStats(c)))
.ToList();
//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;
}
/// <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);
int offset = 0;
int count;
do
{
count = Math.Min(_writerOptions.RowGroupsSize, dataSet.Count - offset);
Thrift.RowGroup rg = _meta.AddRowGroup();
long rgStartPos = Stream.Position;
rg.Columns = new List <Thrift.ColumnChunk>();
foreach (SchemaElement se in dataSet.Schema.Flatten())
{
var cw = new ColumnWriter(Stream, ThriftStream, _meta, se, compression, _formatOptions, _writerOptions);
IList values = dataSet.GetColumn(se, 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;
}