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

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#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>
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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_)
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{
}
void write(const Block & block) override
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{
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Block res = block;
/// Вычисляет явно указанные (в column_defaults) значения по-умолчанию.
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/** @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)
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/// @todo this line may be moved before `evaluateMissingDefaults` with passing {required_columns - explicitly-defaulted columns}
res.addDefaults(*required_columns);
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output->write(res);
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}
void flush() override { output->flush(); }
void writePrefix() override { output->writePrefix(); }
void writeSuffix() override { output->writeSuffix(); }
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private:
BlockOutputStreamPtr output;
NamesAndTypesListPtr required_columns;
const ColumnDefaults & column_defaults;
Context context;
bool only_explicit_column_defaults;
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};
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}