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#pragma once
#include <Core/Names.h>
#include <Formats/MarkInCompressedFile.h>
namespace DB
{
/** The Native format can contain a separately located index,
* which allows you to understand where what column is located,
* and skip unnecessary columns.
*/
/** The position of one piece of a single column. */
struct IndexOfOneColumnForNativeFormat
{
String name;
String type;
MarkInCompressedFile location;
};
/** The index for the data block. */
struct IndexOfBlockForNativeFormat
{
using Columns = std::vector<IndexOfOneColumnForNativeFormat>;
size_t num_columns;
size_t num_rows;
Columns columns;
/// Reads the index for the data block.
void read(ReadBuffer & istr);
/// Writes the index for the data block.
void write(WriteBuffer & ostr) const;
/// Returns the index only for the required columns.
IndexOfBlockForNativeFormat extractIndexForColumns(const NameSet & required_columns) const;
};
/** The whole index. */
struct IndexForNativeFormat
{
using Blocks = std::vector<IndexOfBlockForNativeFormat>;
Blocks blocks;
bool empty() const { return blocks.empty(); }
void clear() { blocks.clear(); }
/// Reads the index.
void read(ReadBuffer & istr);
/// Writes the index.
void write(WriteBuffer & ostr) const;
/// Returns the index only for the required columns.
IndexForNativeFormat extractIndexForColumns(const NameSet & required_columns) const;
};
}
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