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

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#pragma once
#include <Poco/SharedPtr.h>
#include <DB/Interpreters/Expression.h>
#include <DB/DataStreams/IProfilingBlockInputStream.h>
#include <DB/Columns/ColumnConst.h>
namespace DB
{
/** Добавляет в блок недостающие столбцы со значениями по-умолчанию.
* Эти столбцы - материалированные (не константы).
*/
class AddingDefaultBlockInputStream : public IProfilingBlockInputStream
{
public:
AddingDefaultBlockInputStream(
BlockInputStreamPtr input_,
NamesAndTypesListPtr required_columns_)
: input(input_), required_columns(required_columns_)
{
children.push_back(input);
}
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String getName() const { return "AddingDefaultBlockInputStream"; }
BlockInputStreamPtr clone() { return new AddingDefaultBlockInputStream(input, required_columns); }
protected:
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Block readImpl()
{
Block res = input->read();
if (!res)
return res;
for (NamesAndTypesList::const_iterator it = required_columns->begin(); it != required_columns->end(); ++it)
{
if (!res.has(it->first))
{
ColumnWithNameAndType col;
col.name = it->first;
col.type = it->second;
col.column = dynamic_cast<IColumnConst &>(*it->second->createConstColumn(
res.rows(), it->second->getDefault())).convertToFullColumn();
res.insert(col);
}
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}
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return res;
}
private:
BlockInputStreamPtr input;
NamesAndTypesListPtr required_columns;
};
}