ClickHouse/dbms/include/DB/AggregateFunctions/AggregateFunctionSum.h

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#pragma once
#include <DB/IO/WriteHelpers.h>
#include <DB/IO/ReadHelpers.h>
#include <DB/DataTypes/DataTypesNumberFixed.h>
#include <DB/AggregateFunctions/IUnaryAggregateFunction.h>
namespace DB
{
template <typename T> struct AggregateFunctionSumTraits;
template <> struct AggregateFunctionSumTraits<UInt64>
{
static DataTypePtr getReturnType() { return new DataTypeUInt64; }
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static void write(UInt64 x, WriteBuffer & buf) { writeVarUInt(x, buf); }
static void read(UInt64 & x, ReadBuffer & buf) { readVarUInt(x, buf); }
};
template <> struct AggregateFunctionSumTraits<Int64>
{
static DataTypePtr getReturnType() { return new DataTypeInt64; }
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static void write(Int64 x, WriteBuffer & buf) { writeVarInt(x, buf); }
static void read(Int64 & x, ReadBuffer & buf) { readVarInt(x, buf); }
};
template <> struct AggregateFunctionSumTraits<Float64>
{
static DataTypePtr getReturnType() { return new DataTypeFloat64; }
static void write(Float64 x, WriteBuffer & buf) { writeFloatBinary(x, buf); }
static void read(Float64 & x, ReadBuffer & buf) { readFloatBinary(x, buf); }
};
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template <typename T>
struct AggregateFunctionSumData
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{
T sum;
AggregateFunctionSumData() : sum(0) {}
};
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/// Считает сумму чисел. Параметром шаблона может быть UInt64, Int64 или Float64.
template <typename T>
class AggregateFunctionSum : public IUnaryAggregateFunction<AggregateFunctionSumData<T> >
{
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public:
String getName() const { return "sum"; }
String getTypeID() const { return "sum_" + TypeName<T>::get(); }
DataTypePtr getReturnType() const
{
return AggregateFunctionSumTraits<T>::getReturnType();
}
void setArgument(const DataTypePtr & argument)
{
if (!argument->isNumeric())
throw Exception("Illegal type " + argument->getName() + " of argument for aggregate function " + getName(),
ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT);
}
void addOne(AggregateDataPtr place, const Field & value) const
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{
this->data(place).sum += get<const T &>(value);
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}
void merge(AggregateDataPtr place, ConstAggregateDataPtr rhs) const
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{
this->data(place).sum += this->data(rhs).sum;
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}
void serialize(ConstAggregateDataPtr place, WriteBuffer & buf) const
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{
AggregateFunctionSumTraits<T>::write(this->data(place).sum, buf);
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}
void deserializeMerge(AggregateDataPtr place, ReadBuffer & buf) const
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{
T tmp;
AggregateFunctionSumTraits<T>::read(tmp, buf);
this->data(place).sum += tmp;
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}
Field getResult(ConstAggregateDataPtr place) const
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{
return this->data(place).sum;
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}
};
}