ClickHouse/dbms/include/DB/DataStreams/AddingConstColumnBlockInputStream.h

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#pragma once
#include <Poco/SharedPtr.h>
#include <DB/DataStreams/IProfilingBlockInputStream.h>
#include <DB/Columns/ColumnConst.h>
#include <DB/Core/ColumnWithNameAndType.h>
namespace DB
{
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/** Добавляет в блок материализованный const column с заданным значением.
*/
template <typename ColumnType>
class AddingConstColumnBlockInputStream : public IProfilingBlockInputStream
{
public:
AddingConstColumnBlockInputStream(
BlockInputStreamPtr input_,
DataTypePtr data_type_,
ColumnType value_,
String column_name_)
: data_type(data_type_), value(value_), column_name(column_name_)
{
children.push_back(input_);
}
String getName() const override { return "AddingConstColumnBlockInputStream"; }
String getID() const override
{
std::stringstream res;
res << "AddingConstColumn(" << children.back()->getID() << ")";
return res.str();
}
protected:
Block readImpl() override
{
Block res = children.back()->read();
if (!res)
return res;
ColumnPtr column_ptr = ColumnConst<ColumnType>(res.rows(), value, data_type).convertToFullColumn();
ColumnWithNameAndType column(column_ptr, data_type, column_name);
res.insert(column);
return res;
}
private:
DataTypePtr data_type;
ColumnType value;
String column_name;
};
}