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82 lines
2.0 KiB
C++
82 lines
2.0 KiB
C++
#pragma once
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#include <DB/IO/WriteHelpers.h>
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#include <DB/IO/ReadHelpers.h>
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#include <DB/DataTypes/DataTypesNumberFixed.h>
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#include <DB/AggregateFunctions/IUnaryAggregateFunction.h>
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namespace DB
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{
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template <typename T>
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struct AggregateFunctionAvgData
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{
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T sum;
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UInt64 count;
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AggregateFunctionAvgData() : sum(0), count(0) {}
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};
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/// Считает арифметическое среднее значение чисел.
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template <typename T>
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class AggregateFunctionAvg final : public IUnaryAggregateFunction<AggregateFunctionAvgData<typename NearestFieldType<T>::Type>, AggregateFunctionAvg<T> >
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{
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public:
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String getName() const { return "avg"; }
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DataTypePtr getReturnType() const
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{
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return new DataTypeFloat64;
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}
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void setArgument(const DataTypePtr & argument)
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{
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if (!argument->isNumeric())
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throw Exception("Illegal type " + argument->getName() + " of argument for aggregate function " + getName(),
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ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT);
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}
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void addOne(AggregateDataPtr place, const IColumn & column, size_t row_num) const
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{
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this->data(place).sum += static_cast<const ColumnVector<T> &>(column).getData()[row_num];
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++this->data(place).count;
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}
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void merge(AggregateDataPtr place, ConstAggregateDataPtr rhs) const
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{
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this->data(place).sum += this->data(rhs).sum;
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this->data(place).count += this->data(rhs).count;
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}
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void serialize(ConstAggregateDataPtr place, WriteBuffer & buf) const
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{
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writeBinary(this->data(place).sum, buf);
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writeVarUInt(this->data(place).count, buf);
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}
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void deserializeMerge(AggregateDataPtr place, ReadBuffer & buf) const
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{
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typename NearestFieldType<T>::Type tmp_sum = 0;
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UInt64 tmp_count = 0;
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readBinary(tmp_sum, buf);
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readVarUInt(tmp_count, buf);
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this->data(place).sum += tmp_sum;
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this->data(place).count += tmp_count;
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}
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void insertResultInto(ConstAggregateDataPtr place, IColumn & to) const
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{
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static_cast<ColumnFloat64 &>(to).getData().push_back(
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static_cast<Float64>(this->data(place).sum) / this->data(place).count);
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}
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};
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}
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