1 | #include <Functions/IFunctionImpl.h> |
---|---|
2 | #include <Functions/FunctionFactory.h> |
3 | #include <Functions/FunctionHelpers.h> |
4 | #include <DataTypes/DataTypeAggregateFunction.h> |
5 | #include <Columns/ColumnAggregateFunction.h> |
6 | #include <Common/typeid_cast.h> |
7 | |
8 | |
9 | namespace DB |
10 | { |
11 | |
12 | namespace ErrorCodes |
13 | { |
14 | extern const int ILLEGAL_COLUMN; |
15 | extern const int ILLEGAL_TYPE_OF_ARGUMENT; |
16 | } |
17 | |
18 | |
19 | /** finalizeAggregation(agg_state) - get the result from the aggregation state. |
20 | * Takes state of aggregate function. Returns result of aggregation (finalized state). |
21 | */ |
22 | class FunctionFinalizeAggregation : public IFunction |
23 | { |
24 | public: |
25 | static constexpr auto name = "finalizeAggregation"; |
26 | static FunctionPtr create(const Context &) |
27 | { |
28 | return std::make_shared<FunctionFinalizeAggregation>(); |
29 | } |
30 | |
31 | String getName() const override |
32 | { |
33 | return name; |
34 | } |
35 | |
36 | bool isStateful() const override |
37 | { |
38 | return true; |
39 | } |
40 | |
41 | size_t getNumberOfArguments() const override |
42 | { |
43 | return 1; |
44 | } |
45 | |
46 | bool useDefaultImplementationForConstants() const override { return true; } |
47 | |
48 | DataTypePtr getReturnTypeImpl(const DataTypes & arguments) const override |
49 | { |
50 | const DataTypeAggregateFunction * type = checkAndGetDataType<DataTypeAggregateFunction>(arguments[0].get()); |
51 | if (!type) |
52 | throw Exception("Argument for function "+ getName() + " must have type AggregateFunction - state of aggregate function.", |
53 | ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT); |
54 | |
55 | return type->getReturnType(); |
56 | } |
57 | |
58 | void executeImpl(Block & block, const ColumnNumbers & arguments, size_t result, size_t /*input_rows_count*/) override |
59 | { |
60 | const ColumnAggregateFunction * column_with_states |
61 | = typeid_cast<const ColumnAggregateFunction *>(&*block.getByPosition(arguments.at(0)).column); |
62 | if (!column_with_states) |
63 | throw Exception("Illegal column "+ block.getByPosition(arguments.at(0)).column->getName() |
64 | + " of first argument of function " |
65 | + getName(), |
66 | ErrorCodes::ILLEGAL_COLUMN); |
67 | |
68 | block.getByPosition(result).column = column_with_states->convertToValues(); |
69 | } |
70 | }; |
71 | |
72 | |
73 | void registerFunctionFinalizeAggregation(FunctionFactory & factory) |
74 | { |
75 | factory.registerFunction<FunctionFinalizeAggregation>(); |
76 | } |
77 | |
78 | } |
79 |