ClickHouse/dbms/include/DB/DataStreams/AddingDefaultBlockOutputStream.h
2015-09-11 18:11:41 +03:00

68 lines
2.1 KiB
C++
Raw Blame History

This file contains ambiguous Unicode characters

This file contains Unicode characters that might be confused with other characters. If you think that this is intentional, you can safely ignore this warning. Use the Escape button to reveal them.

#pragma once
#include <Poco/SharedPtr.h>
#include <DB/DataStreams/IBlockOutputStream.h>
#include <DB/Columns/ColumnConst.h>
#include <DB/Storages/ColumnDefault.h>
#include <DB/Interpreters/Context.h>
#include <DB/Interpreters/evaluateMissingDefaults.h>
namespace DB
{
/** Добавляет в блок недостающие столбцы со значениями по-умолчанию.
* Эти столбцы - материалированные (не константы).
*/
class AddingDefaultBlockOutputStream : public IBlockOutputStream
{
public:
AddingDefaultBlockOutputStream(
BlockOutputStreamPtr output_,
NamesAndTypesListPtr required_columns_,
const ColumnDefaults & column_defaults_,
const Context & context_,
bool only_explicit_column_defaults_)
: output(output_), required_columns(required_columns_),
column_defaults(column_defaults_), context(context_),
only_explicit_column_defaults(only_explicit_column_defaults_)
{
}
void write(const Block & block) override
{
Block res = block;
/// Вычисляет явно указанные (в column_defaults) значения по-умолчанию.
/** @todo if somehow block does not contain values for implicitly-defaulted columns that are prerequisites
* for explicitly-defaulted ones, exception will be thrown during evaluating such columns
* (implicitly-defaulted columns are evaluated on the line after following one. */
evaluateMissingDefaults(res, *required_columns, column_defaults, context);
/// Добавляет не указанные значения по-умолчанию.
if (!only_explicit_column_defaults)
/// @todo this line may be moved before `evaluateMissingDefaults` with passing {required_columns - explicitly-defaulted columns}
res.addDefaults(*required_columns);
output->write(res);
}
void flush() override { output->flush(); }
void writePrefix() override { output->writePrefix(); }
void writeSuffix() override { output->writeSuffix(); }
private:
BlockOutputStreamPtr output;
NamesAndTypesListPtr required_columns;
const ColumnDefaults & column_defaults;
Context context;
bool only_explicit_column_defaults;
};
}