ClickHouse/src/Processors/Formats/Impl/ArrowColumnToCHColumn.h
2022-03-25 12:05:40 +01:00

64 lines
1.8 KiB
C++

#pragma once
#include "config_formats.h"
#if USE_ARROW || USE_ORC || USE_PARQUET
#include <DataTypes/IDataType.h>
#include <Core/ColumnWithTypeAndName.h>
#include <Core/Block.h>
#include <arrow/table.h>
namespace DB
{
class Block;
class Chunk;
class ArrowColumnToCHColumn
{
public:
using NameToColumnPtr = std::unordered_map<std::string, std::shared_ptr<arrow::ChunkedArray>>;
ArrowColumnToCHColumn(
const Block & header_,
const std::string & format_name_,
bool import_nested_,
bool allow_missing_columns_,
bool case_insensitive_matching_ = false);
void arrowTableToCHChunk(Chunk & res, std::shared_ptr<arrow::Table> & table);
void arrowColumnsToCHChunk(Chunk & res, NameToColumnPtr & name_to_column_ptr);
/// Get missing columns that exists in header but not in arrow::Schema
std::vector<size_t> getMissingColumns(const arrow::Schema & schema) const;
/// Transform arrow schema to ClickHouse header. If hint_header is provided,
/// we will skip columns in schema that are not in hint_header.
static Block arrowSchemaToCHHeader(
const arrow::Schema & schema,
const std::string & format_name,
bool skip_columns_with_unsupported_types = false,
const Block * hint_header = nullptr,
bool ignore_case = false);
private:
const Block & header;
const std::string format_name;
bool import_nested;
/// If false, throw exception if some columns in header not exists in arrow table.
bool allow_missing_columns;
bool case_insensitive_matching;
/// Map {column name : dictionary column}.
/// To avoid converting dictionary from Arrow Dictionary
/// to LowCardinality every chunk we save it and reuse.
std::unordered_map<std::string, std::shared_ptr<ColumnWithTypeAndName>> dictionary_values;
};
}
#endif