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

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#pragma once
#include <iomanip>
#include <Yandex/logger_useful.h>
#include <DB/Columns/ColumnAggregateFunction.h>
#include <DB/DataStreams/IProfilingBlockInputStream.h>
namespace DB
{
using Poco::SharedPtr;
/** Преобразует агрегатные функции (с промежуточным состоянием) в потоке блоков в конечные значения.
*/
class FinalizingAggregatedBlockInputStream : public IProfilingBlockInputStream
{
public:
FinalizingAggregatedBlockInputStream(BlockInputStreamPtr input_)
: log(&Logger::get("FinalizingAggregatedBlockInputStream"))
{
children.push_back(input_);
}
String getName() const { return "FinalizingAggregatedBlockInputStream"; }
String getID() const
{
std::stringstream res;
res << "FinalizingAggregated(" << children.back()->getID() << ")";
return res.str();
}
protected:
Block readImpl()
{
Block res = children.back()->read();
if (!res)
return res;
LOG_TRACE(log, "Finalizing aggregate functions");
Stopwatch watch;
size_t rows = res.rows();
size_t columns = res.columns();
for (size_t i = 0; i < columns; ++i)
{
ColumnWithNameAndType & column = res.getByPosition(i);
if (ColumnAggregateFunction * col = dynamic_cast<ColumnAggregateFunction *>(&*column.column))
{
ColumnAggregateFunction::Container_t & data = col->getData();
IAggregateFunction * func = col->getFunction();
column.type = func->getReturnType();
column.column = column.type->createColumn();
IColumn & finalized_column = *column.column;
finalized_column.reserve(rows);
for (size_t j = 0; j < rows; ++j)
func->insertResultInto(data[j], finalized_column);
}
}
double elapsed_seconds = watch.elapsedSeconds();
if (elapsed_seconds > 0.001)
{
LOG_TRACE(log, std::fixed << std::setprecision(3)
<< "Finalized aggregate functions. "
<< res.rows() << " rows, " << res.bytes() / 1048576.0 << " MiB"
<< " in " << elapsed_seconds << " sec."
<< " (" << res.rows() / elapsed_seconds << " rows/sec., " << res.bytes() / elapsed_seconds / 1048576.0 << " MiB/sec.)");
}
return res;
}
private:
Logger * log;
};
}