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Implemented aggregate function 'count' with Nullable arguments to count number of not-NULL values [#CLICKHOUSE-2833].

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This commit is contained in:
Alexey Milovidov 2017-02-10 12:02:10 +03:00
parent 1ad4e2752e
commit 17e3a4ff1f
7 changed files with 181 additions and 18 deletions
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134
dbms/include/DB/AggregateFunctions/AggregateFunctionCount.h
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@ -3,8 +3,11 @@
#include <DB/IO/VarInt.h>
#include <DB/DataTypes/DataTypesNumberFixed.h>
#include <DB/DataTypes/DataTypeNullable.h>
#include <DB/AggregateFunctions/INullaryAggregateFunction.h>
#include <DB/AggregateFunctions/IUnaryAggregateFunction.h>
#include <DB/Columns/ColumnNullable.h>
namespace DB
@ -12,24 +15,26 @@ namespace DB
struct AggregateFunctionCountData
{
UInt64 count;
AggregateFunctionCountData() : count(0) {}
UInt64 count = 0;
};
/// Просто считает, сколько раз её вызвали
/// Simply count number of calls.
class AggregateFunctionCount final : public INullaryAggregateFunction<AggregateFunctionCountData, AggregateFunctionCount>
{
public:
String getName() const override { return "count"; }
void setArguments(const DataTypes & arguments) override
{
/// You may pass some arguments. All of them are ignored.
}
DataTypePtr getReturnType() const override
{
return std::make_shared<DataTypeUInt64>();
}
void addImpl(AggregateDataPtr place) const
{
++data(place).count;
@ -55,11 +60,128 @@ public:
static_cast<ColumnUInt64 &>(to).getData().push_back(data(place).count);
}
/// Для оптимизации
/// May be used for optimization.
void addDelta(AggregateDataPtr place, UInt64 x) const
{
data(place).count += x;
}
};
/// Simply count number of not-NULL values.
class AggregateFunctionCountNotNullUnary final : public IUnaryAggregateFunction<AggregateFunctionCountData, AggregateFunctionCountNotNullUnary>
{
public:
String getName() const override { return "count"; }
DataTypePtr getReturnType() const override
{
return std::make_shared<DataTypeUInt64>();
}
void addImpl(AggregateDataPtr place, const IColumn & column, size_t row_num, Arena * arena) const
{
data(place).count += !static_cast<const ColumnNullable &>(column).isNullAt(row_num);
}
void setArgument(const DataTypePtr & argument)
{
if (!argument->isNullable() && !argument->isNull())
throw Exception("Not Nullable argument passed to aggregate function count", ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT);
}
void merge(AggregateDataPtr place, ConstAggregateDataPtr rhs, Arena * arena) const override
{
data(place).count += data(rhs).count;
}
void serialize(ConstAggregateDataPtr place, WriteBuffer & buf) const override
{
writeVarUInt(data(place).count, buf);
}
void deserialize(AggregateDataPtr place, ReadBuffer & buf, Arena *) const override
{
readVarUInt(data(place).count, buf);
}
void insertResultInto(ConstAggregateDataPtr place, IColumn & to) const override
{
static_cast<ColumnUInt64 &>(to).getData().push_back(data(place).count);
}
};
/// Count number of calls with all arguments are not NULL.
class AggregateFunctionCountNotNullVariadic final : public IAggregateFunctionHelper<AggregateFunctionCountData>
{
public:
String getName() const override { return "count"; }
DataTypePtr getReturnType() const override
{
return std::make_shared<DataTypeUInt64>();
}
void setArguments(const DataTypes & arguments) override
{
number_of_arguments = arguments.size();
if (number_of_arguments == 1)
throw Exception("Logical error: single argument is passed to AggregateFunctionCountNotNullVariadic", ErrorCodes::LOGICAL_ERROR);
if (number_of_arguments > MAX_ARGS)
throw Exception("Maximum number of arguments for aggregate function with Nullable types is " + toString(MAX_ARGS),
ErrorCodes::NUMBER_OF_ARGUMENTS_DOESNT_MATCH);
for (size_t i = 0; i < number_of_arguments; ++i)
is_nullable[i] = arguments[i]->isNullable() || arguments[i]->isNull();
}
void add(AggregateDataPtr place, const IColumn ** columns, size_t row_num, Arena * arena) const override
{
for (size_t i = 0; i < number_of_arguments; ++i)
if (is_nullable[i] && static_cast<const ColumnNullable &>(*columns[i]).isNullAt(row_num))
return;
++data(place).count;
}
static void addFree(const IAggregateFunction * that, AggregateDataPtr place,
const IColumn ** columns, size_t row_num, Arena * arena)
{
return static_cast<const AggregateFunctionCountNotNullVariadic &>(*that).add(place, columns, row_num, arena);
}
AddFunc getAddressOfAddFunction() const override
{
return &addFree;
}
void merge(AggregateDataPtr place, ConstAggregateDataPtr rhs, Arena * arena) const override
{
data(place).count += data(rhs).count;
}
void serialize(ConstAggregateDataPtr place, WriteBuffer & buf) const override
{
writeVarUInt(data(place).count, buf);
}
void deserialize(AggregateDataPtr place, ReadBuffer & buf, Arena *) const override
{
readVarUInt(data(place).count, buf);
}
void insertResultInto(ConstAggregateDataPtr place, IColumn & to) const override
{
static_cast<ColumnUInt64 &>(to).getData().push_back(data(place).count);
}
private:
enum { MAX_ARGS = 8 };
size_t number_of_arguments = 0;
std::array<char, MAX_ARGS> is_nullable; /// Plain array is better than std::vector due to one indirection less.
};
}

10
dbms/include/DB/AggregateFunctions/INullaryAggregateFunction.h
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@ -7,7 +7,7 @@
namespace DB
{
/** Интерфейс для ноль-арных агрегатных функций. Это, например, агрегатная функция count.
/** Interface for aggregate functions taking zero number of arguments. For example, this is 'count' aggregate function.
*/
template <typename T, typename Derived>
class INullaryAggregateFunction : public IAggregateFunctionHelper<T>
@ -17,15 +17,15 @@ private:
const Derived & getDerived() const { return static_cast<const Derived &>(*this); }
public:
/// Получить тип результата по типам аргументов. Если функция неприменима для данных аргументов - кинуть исключение.
void setArguments(const DataTypes & arguments) override final
/// By default, checks that number of arguments is zero. You could override if you would like to allow to have ignored arguments.
void setArguments(const DataTypes & arguments) override
{
if (arguments.size() != 0)
throw Exception("Passed " + toString(arguments.size()) + " arguments to nullary aggregate function " + this->getName(),
ErrorCodes::NUMBER_OF_ARGUMENTS_DOESNT_MATCH);
}
/// Добавить значение.
/// Accumulate a value.
void add(AggregateDataPtr place, const IColumn ** columns, size_t row_num, Arena *) const override final
{
getDerived().addImpl(place);
@ -38,7 +38,7 @@ public:
IAggregateFunction::AddFunc getAddressOfAddFunction() const override final { return &addFree; }
/** Реализуйте это в классе-наследнике:
/** Implement the following in descendant class:
* void addImpl(AggregateDataPtr place) const;
*/
};

2
dbms/include/DB/AggregateFunctions/IUnaryAggregateFunction.h
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@ -40,7 +40,7 @@ public:
IAggregateFunction::AddFunc getAddressOfAddFunction() const override { return &addFree; }
/** Implement the following in descendant class:
* void addImpl(AggregateDataPtr place, const IColumn & column, size_t row_num) const;
* void addImpl(AggregateDataPtr place, const IColumn & column, size_t row_num, Arena * arena) const;
* void setArgument(const DataTypePtr & argument);
*/
};

7
dbms/src/AggregateFunctions/AggregateFunctionCount.cpp
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@ -19,4 +19,11 @@ void registerAggregateFunctionCount(AggregateFunctionFactory & factory)
factory.registerFunction("count", createAggregateFunctionCount, AggregateFunctionFactory::CaseInsensitive);
}
AggregateFunctionPtr createAggregateFunctionCountNotNull(const DataTypes & argument_types)
{
if (argument_types.size() == 1)
return std::make_shared<AggregateFunctionCountNotNullUnary>();
return std::make_shared<AggregateFunctionCountNotNullVariadic>();
}
}

18
dbms/src/AggregateFunctions/AggregateFunctionFactory.cpp
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@ -54,6 +54,7 @@ AggregateFunctionPtr createAggregateFunctionState(AggregateFunctionPtr & nested)
AggregateFunctionPtr createAggregateFunctionMerge(AggregateFunctionPtr & nested);
AggregateFunctionPtr createAggregateFunctionNullUnary(AggregateFunctionPtr & nested);
AggregateFunctionPtr createAggregateFunctionNullVariadic(AggregateFunctionPtr & nested);
AggregateFunctionPtr createAggregateFunctionCountNotNull(const DataTypes & argument_types);
AggregateFunctionFactory::AggregateFunctionFactory()
@ -100,7 +101,7 @@ AggregateFunctionPtr AggregateFunctionFactory::get(const String & name, const Da
bool has_nullable_types = false;
for (const auto & arg_type : argument_types)
{
if (arg_type->isNullable())
if (arg_type->isNullable() || arg_type->isNull())
{
has_nullable_types = true;
break;
@ -109,8 +110,13 @@ AggregateFunctionPtr AggregateFunctionFactory::get(const String & name, const Da
if (has_nullable_types)
{
DataTypes new_argument_types;
new_argument_types.reserve(argument_types.size());
/// Special case for 'count' function. It could be called with Nullable arguments
/// - that means - count number of calls, when all arguments are not NULL.
if (Poco::toLower(name) == "count")
return createAggregateFunctionCountNotNull(argument_types);
DataTypes nested_argument_types;
nested_argument_types.reserve(argument_types.size());
for (const auto & arg_type : argument_types)
{
@ -118,13 +124,13 @@ AggregateFunctionPtr AggregateFunctionFactory::get(const String & name, const Da
{
const DataTypeNullable & actual_type = static_cast<const DataTypeNullable &>(*arg_type.get());
const DataTypePtr & nested_type = actual_type.getNestedType();
new_argument_types.push_back(nested_type);
nested_argument_types.push_back(nested_type);
}
else
new_argument_types.push_back(arg_type);
nested_argument_types.push_back(arg_type);
}
AggregateFunctionPtr function = getImpl(name, new_argument_types, recursion_level);
AggregateFunctionPtr function = getImpl(name, nested_argument_types, recursion_level);
if (argument_types.size() == 1)
return createAggregateFunctionNullUnary(function);

12
dbms/tests/queries/0_stateless/00425_count_nullable.reference Normal file
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@ -0,0 +1,12 @@
10
10
10
10
10
10
10
9
9
9
8
0

16
dbms/tests/queries/0_stateless/00425_count_nullable.sql Normal file
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@ -0,0 +1,16 @@
SELECT count() FROM (SELECT number AS x FROM system.numbers LIMIT 10);
SELECT count(x) FROM (SELECT number AS x FROM system.numbers LIMIT 10);
SELECT count(x, y) FROM (SELECT number AS x, number AS y FROM system.numbers LIMIT 10);
SELECT count(x) FROM (SELECT CAST(number AS Nullable(UInt64)) AS x FROM system.numbers LIMIT 10);
SELECT count(x, y) FROM (SELECT CAST(number AS Nullable(UInt64)) AS x, number AS y FROM system.numbers LIMIT 10);
SELECT count(x, y) FROM (SELECT number AS x, CAST(number AS Nullable(UInt64)) AS y FROM system.numbers LIMIT 10);
SELECT count(x, y) FROM (SELECT CAST(number AS Nullable(UInt64)) AS x, CAST(number AS Nullable(UInt64)) AS y FROM system.numbers LIMIT 10);
SELECT count(x) FROM (SELECT nullIf(number, 5) AS x FROM system.numbers LIMIT 10);
SELECT count(x, y) FROM (SELECT nullIf(number, 5) AS x, number AS y FROM system.numbers LIMIT 10);
SELECT count(x, y) FROM (SELECT number AS x, nullIf(number, 3) AS y FROM system.numbers LIMIT 10);
SELECT count(x, y) FROM (SELECT nullIf(number, 5) AS x, nullIf(number, 3) AS y FROM system.numbers LIMIT 10);
SELECT count(NULL);