1#pragma once
2
3#include <DataTypes/DataTypeAggregateFunction.h>
4#include <AggregateFunctions/IAggregateFunction.h>
5#include <Columns/ColumnAggregateFunction.h>
6#include <Common/typeid_cast.h>
7#include <Common/assert_cast.h>
8
9
10namespace DB
11{
12
13
14/** Not an aggregate function, but an adapter of aggregate functions,
15 * Aggregate functions with the `Merge` suffix accept `DataTypeAggregateFunction` as an argument
16 * (state of the aggregate function obtained earlier using the aggregate function with the `State` suffix)
17 * and combine them with aggregation.
18 */
19
20class AggregateFunctionMerge final : public IAggregateFunctionHelper<AggregateFunctionMerge>
21{
22private:
23 AggregateFunctionPtr nested_func;
24
25public:
26 AggregateFunctionMerge(const AggregateFunctionPtr & nested_, const DataTypePtr & argument)
27 : IAggregateFunctionHelper<AggregateFunctionMerge>({argument}, nested_->getParameters())
28 , nested_func(nested_)
29 {
30 const DataTypeAggregateFunction * data_type = typeid_cast<const DataTypeAggregateFunction *>(argument.get());
31
32 if (!data_type || data_type->getFunctionName() != nested_func->getName())
33 throw Exception("Illegal type " + argument->getName() + " of argument for aggregate function " + getName(),
34 ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT);
35 }
36
37 String getName() const override
38 {
39 return nested_func->getName() + "Merge";
40 }
41
42 DataTypePtr getReturnType() const override
43 {
44 return nested_func->getReturnType();
45 }
46
47 void create(AggregateDataPtr place) const override
48 {
49 nested_func->create(place);
50 }
51
52 void destroy(AggregateDataPtr place) const noexcept override
53 {
54 nested_func->destroy(place);
55 }
56
57 bool hasTrivialDestructor() const override
58 {
59 return nested_func->hasTrivialDestructor();
60 }
61
62 size_t sizeOfData() const override
63 {
64 return nested_func->sizeOfData();
65 }
66
67 size_t alignOfData() const override
68 {
69 return nested_func->alignOfData();
70 }
71
72 void add(AggregateDataPtr place, const IColumn ** columns, size_t row_num, Arena * arena) const override
73 {
74 nested_func->merge(place, assert_cast<const ColumnAggregateFunction &>(*columns[0]).getData()[row_num], arena);
75 }
76
77 void merge(AggregateDataPtr place, ConstAggregateDataPtr rhs, Arena * arena) const override
78 {
79 nested_func->merge(place, rhs, arena);
80 }
81
82 void serialize(ConstAggregateDataPtr place, WriteBuffer & buf) const override
83 {
84 nested_func->serialize(place, buf);
85 }
86
87 void deserialize(AggregateDataPtr place, ReadBuffer & buf, Arena * arena) const override
88 {
89 nested_func->deserialize(place, buf, arena);
90 }
91
92 void insertResultInto(ConstAggregateDataPtr place, IColumn & to) const override
93 {
94 nested_func->insertResultInto(place, to);
95 }
96
97 bool allocatesMemoryInArena() const override
98 {
99 return nested_func->allocatesMemoryInArena();
100 }
101};
102
103}
104