mirror of
https://github.com/ClickHouse/ClickHouse.git
synced 2024-12-02 20:42:04 +00:00
112 lines
2.2 KiB
C++
112 lines
2.2 KiB
C++
#pragma once
|
|
|
|
#include <DB/IO/WriteHelpers.h>
|
|
#include <DB/IO/ReadHelpers.h>
|
|
|
|
#include <DB/AggregateFunctions/IUnaryAggregateFunction.h>
|
|
|
|
|
|
namespace DB
|
|
{
|
|
|
|
|
|
struct AggregateFunctionMinTraits
|
|
{
|
|
static bool better(const Field & lhs, const Field & rhs) { return lhs < rhs; }
|
|
static String name() { return "min"; }
|
|
};
|
|
|
|
struct AggregateFunctionMaxTraits
|
|
{
|
|
static bool better(const Field & lhs, const Field & rhs) { return lhs > rhs; }
|
|
static String name() { return "max"; }
|
|
};
|
|
|
|
|
|
struct AggregateFunctionsMinMaxData
|
|
{
|
|
Field value;
|
|
};
|
|
|
|
|
|
/// Берёт минимальное (или максимальное) значение. Если таких много - то первое попавшееся из них.
|
|
template <typename Traits>
|
|
class AggregateFunctionsMinMax : public IUnaryAggregateFunction<AggregateFunctionsMinMaxData>
|
|
{
|
|
private:
|
|
DataTypePtr type;
|
|
|
|
public:
|
|
String getName() const { return Traits::name(); }
|
|
String getTypeID() const { return Traits::name(); }
|
|
|
|
DataTypePtr getReturnType() const
|
|
{
|
|
return type;
|
|
}
|
|
|
|
void setArgument(const DataTypePtr & argument)
|
|
{
|
|
type = argument;
|
|
}
|
|
|
|
|
|
void addOne(AggregateDataPtr place, const Field & value_) const
|
|
{
|
|
Data & d = data(place);
|
|
|
|
if (!d.value.isNull())
|
|
{
|
|
if (Traits::better(value_, d.value))
|
|
d.value = value_;
|
|
}
|
|
else
|
|
d.value = value_;
|
|
}
|
|
|
|
void merge(AggregateDataPtr place, ConstAggregateDataPtr rhs) const
|
|
{
|
|
Data & d = data(place);
|
|
const Data & d_rhs = data(rhs);
|
|
|
|
if (!d.value.isNull())
|
|
{
|
|
if (Traits::better(d_rhs.value, d.value))
|
|
d.value = d_rhs.value;
|
|
}
|
|
else
|
|
d.value = d_rhs.value;
|
|
}
|
|
|
|
void serialize(ConstAggregateDataPtr place, WriteBuffer & buf) const
|
|
{
|
|
type->serializeBinary(data(place).value, buf);
|
|
}
|
|
|
|
void deserializeMerge(AggregateDataPtr place, ReadBuffer & buf) const
|
|
{
|
|
Data & d = data(place);
|
|
|
|
if (!d.value.isNull())
|
|
{
|
|
Field value_;
|
|
type->deserializeBinary(value_, buf);
|
|
if (Traits::better(value_, d.value))
|
|
d.value = value_;
|
|
}
|
|
else
|
|
type->deserializeBinary(d.value, buf);
|
|
}
|
|
|
|
Field getResult(ConstAggregateDataPtr place) const
|
|
{
|
|
return data(place).value;
|
|
}
|
|
};
|
|
|
|
|
|
typedef AggregateFunctionsMinMax<AggregateFunctionMinTraits> AggregateFunctionMin;
|
|
typedef AggregateFunctionsMinMax<AggregateFunctionMaxTraits> AggregateFunctionMax;
|
|
|
|
}
|