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

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#pragma once
#include <DB/AggregateFunctions/IAggregateFunction.h>
#include <DB/Columns/ColumnNullable.h>
#include <DB/DataTypes/DataTypeNullable.h>
namespace DB
{
namespace ErrorCodes
{
extern const int LOGICAL_ERROR;
}
/// This class implements a wrapper around an aggregate function. Despite its name,
/// this is an adapter. It is used to handle aggregate functions that are called with
/// at least one nullable argument. It implements the logic according to which any
/// row that contains at least one NULL is skipped.
class AggregateFunctionNull : public IAggregateFunction
{
public:
AggregateFunctionNull(AggregateFunctionPtr nested_function_)
: nested_function{nested_function_}
{
}
String getName() const override
{
return nested_function->getName();
}
void setArguments(const DataTypes & arguments) override
{
argument_count = arguments.size();
is_nullable.reserve(arguments.size());
for (const auto & arg : arguments)
{
bool res = arg->isNullable();
is_nullable.push_back(res);
}
DataTypes new_args;
new_args.reserve(arguments.size());
for (const auto & arg : arguments)
{
if (arg->isNullable())
{
const DataTypeNullable & nullable_type = static_cast<const DataTypeNullable &>(*arg);
const DataTypePtr & nested_type = nullable_type.getNestedType();
new_args.push_back(nested_type);
}
else
new_args.push_back(arg);
}
nested_function->setArguments(new_args);
}
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void setParameters(const Array & params) override
{
nested_function->setParameters(params);
}
DataTypePtr getReturnType() const override
{
return nested_function->getReturnType();
}
void create(AggregateDataPtr place) const override
{
nested_function->create(place);
}
void destroy(AggregateDataPtr place) const noexcept override
{
nested_function->destroy(place);
}
bool hasTrivialDestructor() const override
{
return nested_function->hasTrivialDestructor();
}
size_t sizeOfData() const override
{
return nested_function->sizeOfData();
}
size_t alignOfData() const override
{
return nested_function->alignOfData();
}
void add(AggregateDataPtr place, const IColumn ** columns, size_t row_num, Arena * arena) const override
{
/// This container stores the columns we really pass to the nested function.
const IColumn * passed_columns[argument_count];
for (size_t i = 0; i < argument_count; ++i)
{
if (is_nullable[i])
{
const ColumnNullable & nullable_col = static_cast<const ColumnNullable &>(*columns[i]);
if (nullable_col.isNullAt(row_num))
{
/// If at least one column has a null value in the current row,
/// we don't process this row.
return;
}
passed_columns[i] = nullable_col.getNestedColumn().get();
}
else
passed_columns[i] = columns[i];
}
nested_function->add(place, passed_columns, row_num, arena);
}
void merge(AggregateDataPtr place, ConstAggregateDataPtr rhs, Arena * arena) const override
{
nested_function->merge(place, rhs, arena);
}
void serialize(ConstAggregateDataPtr place, WriteBuffer & buf) const override
{
nested_function->serialize(place, buf);
}
void deserialize(AggregateDataPtr place, ReadBuffer & buf, Arena * arena) const override
{
nested_function->deserialize(place, buf, arena);
}
void insertResultInto(ConstAggregateDataPtr place, IColumn & to) const override
{
nested_function->insertResultInto(place, to);
}
static void addFree(const IAggregateFunction * that, AggregateDataPtr place,
const IColumn ** columns, size_t row_num, Arena * arena)
{
return static_cast<const AggregateFunctionNull &>(*that).add(place, columns, row_num, arena);
}
AddFunc getAddressOfAddFunction() const override
{
return &addFree;
}
private:
AggregateFunctionPtr nested_function;
std::vector<bool> is_nullable;
size_t argument_count = 0;
};
}