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#pragma once
#include <Formats/IndexForNativeFormat.h>
#include <Formats/MarkInCompressedFile.h>
#include <Common/PODArray.h>
#include <Core/Block.h>
namespace DB
{
class CompressedReadBufferFromFile;
/** Deserializes the stream of blocks from the native binary format (with names and column types).
* Designed for communication between servers.
*
* Can also be used to store data on disk.
* In this case, can use the index.
*/
class NativeReader
{
public:
/// If a non-zero server_revision is specified, additional block information may be expected and read.
NativeReader(ReadBuffer & istr_, UInt64 server_revision_);
/// For cases when data structure (header) is known in advance.
/// NOTE We may use header for data validation and/or type conversions. It is not implemented.
NativeReader(
ReadBuffer & istr_,
const Block & header_,
UInt64 server_revision_,
bool skip_unknown_columns_ = false,
bool null_as_default_ = false,
bool allow_types_conversion_ = false,
BlockMissingValues * block_missing_values_ = nullptr);
/// For cases when we have an index. It allows to skip columns. Only columns specified in the index will be read.
NativeReader(ReadBuffer & istr_, UInt64 server_revision_,
IndexForNativeFormat::Blocks::const_iterator index_block_it_,
IndexForNativeFormat::Blocks::const_iterator index_block_end_);
static void readData(const ISerialization & serialization, ColumnPtr & column, ReadBuffer & istr, size_t rows, double avg_value_size_hint);
Block getHeader() const;
void resetParser();
Block read();
private:
ReadBuffer & istr;
Block header;
UInt64 server_revision;
bool skip_unknown_columns = false;
bool null_as_default = false;
bool allow_types_conversion = false;
BlockMissingValues * block_missing_values = nullptr;
bool use_index = false;
IndexForNativeFormat::Blocks::const_iterator index_block_it;
IndexForNativeFormat::Blocks::const_iterator index_block_end;
IndexOfBlockForNativeFormat::Columns::const_iterator index_column_it;
/// If an index is specified, then `istr` must be CompressedReadBufferFromFile. Unused otherwise.
CompressedReadBufferFromFile * istr_concrete = nullptr;
PODArray<double> avg_value_size_hints;
void updateAvgValueSizeHints(const Block & block);
};
}
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