/// <summary>
/// Test read, to be defined
/// </summary>
public DataSet Read()
{
_meta = ReadMetadata();
var ds = new DataSet(new Schema(_meta));
var cols = new List <IList>();
foreach (Thrift.RowGroup rg in _meta.Row_groups)
{
foreach (Thrift.ColumnChunk cc in rg.Columns)
{
var p = new PColumn(cc, ds.Schema, _input, _thrift, _options);
string columnName = string.Join(".", cc.Meta_data.Path_in_schema);
try
{
IList column = p.Read(columnName);
cols.Add(column);
}
catch (Exception ex)
{
throw new ParquetException($"fatal error reading column '{columnName}'", ex);
}
}
}
ds.AddColumnar(cols);
return(ds);
}
private void PrepareFile(bool append)
{
if (append)
{
if (!Stream.CanSeek)
{
throw new IOException("destination stream must be seekable for append operations.");
}
ValidateFile();
Thrift.FileMetaData fileMeta = ReadMetadata();
_footer = new ThriftFooter(fileMeta);
ValidateSchemasCompatible(_footer, _schema);
GoBeforeFooter();
}
else
{
if (_footer == null)
{
_footer = new ThriftFooter(_schema, 0 /* todo: don't forget to set the total row count at the end!!! */);
//file starts with magic
WriteMagic();
}
else
{
ValidateSchemasCompatible(_footer, _schema);
_footer.Add(0 /* todo: don't forget to set the total row count at the end!!! */);
}
}
}
void PrepareFile(DataSet ds, bool append)
{
if (append)
{
if (!Stream.CanSeek)
{
throw new IOException("destination stream must be seekable for append operations.");
}
ValidateFile();
Thrift.FileMetaData fileMeta = ReadMetadata();
_footer = new ThriftFooter(fileMeta);
ValidateSchemasCompatible(_footer, ds);
GoBeforeFooter();
}
else
{
if (_footer == null)
{
_footer = new ThriftFooter(ds.Schema, ds.RowCount);
//file starts with magic
WriteMagic();
}
else
{
ValidateSchemasCompatible(_footer, ds);
_footer.Add(ds.RowCount);
}
}
}
private void PrepareFile(DataSet ds, bool append)
{
if (append)
{
if (!_output.CanSeek)
{
throw new IOException("destination stream must be seekable for append operations.");
}
ValidateFile();
Thrift.FileMetaData fileMeta = ReadMetadata();
_meta.SetMeta(fileMeta);
Schema existingSchema = new FileMetadataParser(fileMeta).ParseSchema(_formatOptions);
if (!ds.Schema.Equals(existingSchema))
{
throw new ParquetException($"{nameof(DataSet)} schema does not match existing file schema");
}
GoBeforeFooter();
}
else
{
if (_existingSchema == null)
{
_existingSchema = ds.Schema;
//file starts with magic
WriteMagic();
_meta.AddSchema(ds);
}
else
{
if (!_existingSchema.Equals(ds.Schema))
{
throw new ParquetException($"expeted schema {_existingSchema} but found {ds.Schema}.");
}
}
}
}
/// <summary>
/// Creates an instance from input stream
/// </summary>
/// <param name="input">Input stream, must be readable and seekable</param>
/// <param name="parquetOptions">Optional reader options</param>
/// <param name="leaveStreamOpen">When true, leaves the stream passed in <paramref name="input"/> open after disposing the reader.</param>
/// <exception cref="ArgumentNullException">input</exception>
/// <exception cref="ArgumentException">stream must be readable and seekable - input</exception>
/// <exception cref="IOException">not a Parquet file (size too small)</exception>
public ParquetReader(Stream input, ParquetOptions parquetOptions = null, bool leaveStreamOpen = true) : this(input, leaveStreamOpen)
{
if (!input.CanRead || !input.CanSeek)
{
throw new ArgumentException("stream must be readable and seekable", nameof(input));
}
if (_input.Length <= 8)
{
throw new IOException("not a Parquet file (size too small)");
}
ValidateFile();
_parquetOptions = parquetOptions ?? new ParquetOptions();
//read metadata instantly, now
_meta = ReadMetadata();
_footer = new ThriftFooter(_meta);
ParquetEventSource.Current.OpenStream(input.Length, leaveStreamOpen, _meta.Row_groups.Count, _meta.Num_rows);
InitRowGroupReaders();
}
/// <summary>
/// Decodes raw bytes from <see cref="Thrift.Statistics"/> into a CLR value
/// </summary>
public static object DecodeSingleStatsValue(this Thrift.FileMetaData fileMeta, Thrift.ColumnChunk columnChunk, byte[] rawBytes)
{
if (rawBytes == null || rawBytes.Length == 0)
{
return(null);
}
var footer = new ThriftFooter(fileMeta);
Thrift.SchemaElement schema = footer.GetSchemaElement(columnChunk);
IDataTypeHandler handler = DataTypeFactory.Match(schema, new ParquetOptions {
TreatByteArrayAsString = true
});
using (var ms = new MemoryStream(rawBytes))
using (var reader = new BinaryReader(ms))
{
object value = handler.Read(reader, schema, rawBytes.Length);
return(value);
}
}
/// <summary>
/// Creates an instance from input stream
/// </summary>
/// <param name="input">Input stream, must be readable and seekable</param>
/// <param name="parquetOptions">Optional reader options</param>
/// <param name="readerOptions">The reader options.</param>
/// <exception cref="ArgumentNullException">input</exception>
/// <exception cref="ArgumentException">stream must be readable and seekable - input</exception>
/// <exception cref="IOException">not a Parquet file (size too small)</exception>
public ParquetReader3(Stream input, ParquetOptions parquetOptions = null, ReaderOptions readerOptions = null) : base(input)
{
_input = input ?? throw new ArgumentNullException(nameof(input));
if (!input.CanRead || !input.CanSeek)
{
throw new ArgumentException("stream must be readable and seekable", nameof(input));
}
if (_input.Length <= 8)
{
throw new IOException("not a Parquet file (size too small)");
}
ValidateFile();
_parquetOptions = parquetOptions ?? new ParquetOptions();
_readerOptions = readerOptions ?? new ReaderOptions();
//read metadata instantly, now
_meta = ReadMetadata();
_footer = new ThriftFooter(_meta);
InitRowGroupReaders();
}
/// <summary>
/// Test read, to be defined
/// </summary>
public DataSet Read()
{
_readerOptions.Validate();
_meta = ReadMetadata();
var metaParser = new FileMetadataParser(_meta);
Schema schema = metaParser.ParseSchema(_formatOptions);
var pathToValues = new Dictionary <string, IList>();
long pos = 0;
long rowsRead = 0;
foreach (Thrift.RowGroup rg in _meta.Row_groups)
{
//check whether to skip RG completely
if ((_readerOptions.Count != -1 && rowsRead >= _readerOptions.Count) ||
(_readerOptions.Offset > pos + rg.Num_rows - 1))
{
pos += rg.Num_rows;
continue;
}
long offset = Math.Max(0, _readerOptions.Offset - pos);
long count = _readerOptions.Count == -1 ? rg.Num_rows : Math.Min(_readerOptions.Count - rowsRead, rg.Num_rows);
for (int icol = 0; icol < rg.Columns.Count; icol++)
{
Thrift.ColumnChunk cc = rg.Columns[icol];
SchemaElement se = schema[cc];
var p = new ColumnReader(cc, se, _input, ThriftStream, _formatOptions);
try
{
IList chunkValues = p.Read(offset, count);
if (!pathToValues.TryGetValue(se.Path, out IList allValues))
{
pathToValues[se.Path] = chunkValues;
}
else
{
allValues.AddRange(chunkValues);
}
if (icol == 0)
{
//todo: this may not work
rowsRead += chunkValues.Count;
}
}
catch (Exception ex)
{
throw new ParquetException($"fatal error reading column '{se}'", ex);
}
}
pos += rg.Num_rows;
}
return(new DataSet(schema, pathToValues, _meta.Num_rows, _meta.Created_by));
}
/// <summary>
/// Test read, to be defined
/// </summary>
public DataSet Read()
{
_readerOptions.Validate();
_meta = ReadMetadata();
var footer = new ThriftFooter(_meta);
var pathToValues = new Dictionary <string, IList>();
long pos = 0;
long rowsRead = 0;
foreach (Thrift.RowGroup rg in _meta.Row_groups)
{
//check whether to skip RG completely
if ((_readerOptions.Count != -1 && rowsRead >= _readerOptions.Count) ||
(_readerOptions.Offset > pos + rg.Num_rows - 1))
{
pos += rg.Num_rows;
continue;
}
long offset = Math.Max(0, _readerOptions.Offset - pos);
long count = _readerOptions.Count == -1 ? rg.Num_rows : Math.Min(_readerOptions.Count - rowsRead, rg.Num_rows);
for (int icol = 0; icol < rg.Columns.Count; icol++)
{
Thrift.ColumnChunk cc = rg.Columns[icol];
string path = cc.GetPath();
if (_fieldPredicates != null && !_fieldPredicates.Any(p => p.IsMatch(cc, path)))
{
continue;
}
var columnarReader = new ColumnarReader(_input, cc, footer, _formatOptions);
try
{
IList chunkValues = columnarReader.Read(offset, count);
if (!pathToValues.TryGetValue(path, out IList allValues))
{
pathToValues[path] = chunkValues;
}
else
{
foreach (object v in chunkValues)
{
allValues.Add(v);
}
}
if (icol == 0)
{
//todo: this may not work
rowsRead += chunkValues.Count;
}
}
catch (Exception ex)
{
throw new ParquetException($"fatal error reading column '{path}'", ex);
}
}
pos += rg.Num_rows;
}
Schema schema = footer.CreateModelSchema(_formatOptions);
schema = schema.Filter(_fieldPredicates);
var ds = new DataSet(schema, pathToValues, _meta.Num_rows, _meta.Created_by);
Dictionary <string, string> customMetadata = footer.CustomMetadata;
if (customMetadata != null)
{
ds.Metadata.Custom.AddRange(customMetadata);
}
ds.Thrift = _meta;
return(ds);
}