Merge pull request #11661 from ClickHouse/return-not-nullable-from-count-distinct-2

Return non-Nullable results from COUNT(DISTINCT), more complete.

programs/odbc-bridge/CMakeLists.txt

@@ -14,6 +14,7 @@ set (CLICKHOUSE_ODBC_BRIDGE_SOURCES
 set (CLICKHOUSE_ODBC_BRIDGE_LINK
     PRIVATE
         clickhouse_parsers
+        clickhouse_aggregate_functions
         daemon
         dbms
         Poco::Data

src/AggregateFunctions/AggregateFunctionArray.cpp

@@ -36,7 +36,10 @@ public:
     }
 
     AggregateFunctionPtr transformAggregateFunction(
-        const AggregateFunctionPtr & nested_function, const DataTypes & arguments, const Array &) const override
+        const AggregateFunctionPtr & nested_function,
+        const AggregateFunctionProperties &,
+        const DataTypes & arguments,
+        const Array &) const override
     {
         return std::make_shared<AggregateFunctionArray>(nested_function, arguments);
     }

src/AggregateFunctions/AggregateFunctionCount.cpp

@@ -7,6 +7,12 @@
 namespace DB
 {
 
+AggregateFunctionPtr AggregateFunctionCount::getOwnNullAdapter(
+    const AggregateFunctionPtr &, const DataTypes & types, const Array & params) const
+{
+    return std::make_shared<AggregateFunctionCountNotNullUnary>(types[0], params);
+}
+
 namespace
 {
 
@@ -22,7 +28,7 @@ AggregateFunctionPtr createAggregateFunctionCount(const std::string & name, cons
 
 void registerAggregateFunctionCount(AggregateFunctionFactory & factory)
 {
-    factory.registerFunction("count", createAggregateFunctionCount, AggregateFunctionFactory::CaseInsensitive);
+    factory.registerFunction("count", {createAggregateFunctionCount, {true}}, AggregateFunctionFactory::CaseInsensitive);
 }
 
 }

src/AggregateFunctions/AggregateFunctionCount.h

@@ -68,16 +68,14 @@ public:
         data(place).count = new_count;
     }
 
-    /// The function returns non-Nullable type even when wrapped with Null combinator.
-    bool returnDefaultWhenOnlyNull() const override
-    {
-        return true;
-    }
+    AggregateFunctionPtr getOwnNullAdapter(
+        const AggregateFunctionPtr &, const DataTypes & types, const Array & params) const override;
 };
 
 
 /// Simply count number of not-NULL values.
-class AggregateFunctionCountNotNullUnary final : public IAggregateFunctionDataHelper<AggregateFunctionCountData, AggregateFunctionCountNotNullUnary>
+class AggregateFunctionCountNotNullUnary final
+    : public IAggregateFunctionDataHelper<AggregateFunctionCountData, AggregateFunctionCountNotNullUnary>
 {
 public:
     AggregateFunctionCountNotNullUnary(const DataTypePtr & argument, const Array & params)

src/AggregateFunctions/AggregateFunctionFactory.cpp

@@ -29,18 +29,18 @@ namespace ErrorCodes
 }
 
 
-void AggregateFunctionFactory::registerFunction(const String & name, Creator creator, CaseSensitiveness case_sensitiveness)
+void AggregateFunctionFactory::registerFunction(const String & name, Value creator_with_properties, CaseSensitiveness case_sensitiveness)
 {
-    if (creator == nullptr)
+    if (creator_with_properties.creator == nullptr)
         throw Exception("AggregateFunctionFactory: the aggregate function " + name + " has been provided "
             " a null constructor", ErrorCodes::LOGICAL_ERROR);
 
-    if (!aggregate_functions.emplace(name, creator).second)
+    if (!aggregate_functions.emplace(name, creator_with_properties).second)
         throw Exception("AggregateFunctionFactory: the aggregate function name '" + name + "' is not unique",
             ErrorCodes::LOGICAL_ERROR);
 
     if (case_sensitiveness == CaseInsensitive
-        && !case_insensitive_aggregate_functions.emplace(Poco::toLower(name), creator).second)
+        && !case_insensitive_aggregate_functions.emplace(Poco::toLower(name), creator_with_properties).second)
         throw Exception("AggregateFunctionFactory: the case insensitive aggregate function name '" + name + "' is not unique",
             ErrorCodes::LOGICAL_ERROR);
 }
@@ -59,6 +59,7 @@ AggregateFunctionPtr AggregateFunctionFactory::get(
     const String & name,
     const DataTypes & argument_types,
     const Array & parameters,
+    AggregateFunctionProperties & out_properties,
     int recursion_level) const
 {
     auto type_without_low_cardinality = convertLowCardinalityTypesToNested(argument_types);
@@ -76,18 +77,15 @@ AggregateFunctionPtr AggregateFunctionFactory::get(
         DataTypes nested_types = combinator->transformArguments(type_without_low_cardinality);
         Array nested_parameters = combinator->transformParameters(parameters);
 
-        AggregateFunctionPtr nested_function;
+        bool has_null_arguments = std::any_of(type_without_low_cardinality.begin(), type_without_low_cardinality.end(),
+            [](const auto & type) { return type->onlyNull(); });
 
-        /// A little hack - if we have NULL arguments, don't even create nested function.
-        /// Combinator will check if nested_function was created.
-        if (name == "count" || std::none_of(type_without_low_cardinality.begin(), type_without_low_cardinality.end(),
-            [](const auto & type) { return type->onlyNull(); }))
-            nested_function = getImpl(name, nested_types, nested_parameters, recursion_level);
-
-        return combinator->transformAggregateFunction(nested_function, type_without_low_cardinality, parameters);
+        AggregateFunctionPtr nested_function = getImpl(
+            name, nested_types, nested_parameters, out_properties, has_null_arguments, recursion_level);
+        return combinator->transformAggregateFunction(nested_function, out_properties, type_without_low_cardinality, parameters);
     }
 
-    auto res = getImpl(name, type_without_low_cardinality, parameters, recursion_level);
+    auto res = getImpl(name, type_without_low_cardinality, parameters, out_properties, false, recursion_level);
     if (!res)
         throw Exception("Logical error: AggregateFunctionFactory returned nullptr", ErrorCodes::LOGICAL_ERROR);
     return res;
@@ -98,19 +96,35 @@ AggregateFunctionPtr AggregateFunctionFactory::getImpl(
     const String & name_param,
     const DataTypes & argument_types,
     const Array & parameters,
+    AggregateFunctionProperties & out_properties,
+    bool has_null_arguments,
     int recursion_level) const
 {
     String name = getAliasToOrName(name_param);
+    Value found;
+
     /// Find by exact match.
     if (auto it = aggregate_functions.find(name); it != aggregate_functions.end())
-        return it->second(name, argument_types, parameters);
-
+    {
+        found = it->second;
+    }
     /// Find by case-insensitive name.
     /// Combinators cannot apply for case insensitive (SQL-style) aggregate function names. Only for native names.
-    if (recursion_level == 0)
+    else if (recursion_level == 0)
     {
-        if (auto it = case_insensitive_aggregate_functions.find(Poco::toLower(name)); it != case_insensitive_aggregate_functions.end())
-            return it->second(name, argument_types, parameters);
+        if (auto jt = case_insensitive_aggregate_functions.find(Poco::toLower(name)); jt != case_insensitive_aggregate_functions.end())
+            found = jt->second;
+    }
+
+    if (found.creator)
+    {
+        out_properties = found.properties;
+
+        /// The case when aggregate function should return NULL on NULL arguments. This case is handled in "get" method.
+        if (!out_properties.returns_default_when_only_null && has_null_arguments)
+            return nullptr;
+
+        return found.creator(name, argument_types, parameters);
     }
 
     /// Combinators of aggregate functions.
@@ -126,9 +140,8 @@ AggregateFunctionPtr AggregateFunctionFactory::getImpl(
         DataTypes nested_types = combinator->transformArguments(argument_types);
         Array nested_parameters = combinator->transformParameters(parameters);
 
-        AggregateFunctionPtr nested_function = get(nested_name, nested_types, nested_parameters, recursion_level + 1);
-
-        return combinator->transformAggregateFunction(nested_function, argument_types, parameters);
+        AggregateFunctionPtr nested_function = get(nested_name, nested_types, nested_parameters, out_properties, recursion_level + 1);
+        return combinator->transformAggregateFunction(nested_function, out_properties, argument_types, parameters);
     }
 
     auto hints = this->getHints(name);
@@ -140,10 +153,11 @@ AggregateFunctionPtr AggregateFunctionFactory::getImpl(
 }
 
 
-AggregateFunctionPtr AggregateFunctionFactory::tryGet(const String & name, const DataTypes & argument_types, const Array & parameters) const
+AggregateFunctionPtr AggregateFunctionFactory::tryGet(
+    const String & name, const DataTypes & argument_types, const Array & parameters, AggregateFunctionProperties & out_properties) const
 {
     return isAggregateFunctionName(name)
-        ? get(name, argument_types, parameters)
+        ? get(name, argument_types, parameters, out_properties)
         : nullptr;
 }
 

src/AggregateFunctions/AggregateFunctionFactory.h

@@ -26,34 +26,50 @@ using DataTypes = std::vector<DataTypePtr>;
  */
 using AggregateFunctionCreator = std::function<AggregateFunctionPtr(const String &, const DataTypes &, const Array &)>;
 
+struct AggregateFunctionWithProperties
+{
+    AggregateFunctionCreator creator;
+    AggregateFunctionProperties properties;
+
+    AggregateFunctionWithProperties() = default;
+    AggregateFunctionWithProperties(const AggregateFunctionWithProperties &) = default;
+
+    template <typename Creator, std::enable_if_t<!std::is_same_v<Creator, AggregateFunctionWithProperties>> * = nullptr>
+    AggregateFunctionWithProperties(Creator creator_, AggregateFunctionProperties properties_ = {})
+        : creator(std::forward<Creator>(creator_)), properties(std::move(properties_))
+    {
+    }
+};
+
 
 /** Creates an aggregate function by name.
   */
-class AggregateFunctionFactory final : private boost::noncopyable, public IFactoryWithAliases<AggregateFunctionCreator>
+class AggregateFunctionFactory final : private boost::noncopyable, public IFactoryWithAliases<AggregateFunctionWithProperties>
 {
 public:
-
     static AggregateFunctionFactory & instance();
 
     /// Register a function by its name.
     /// No locking, you must register all functions before usage of get.
     void registerFunction(
         const String & name,
-        Creator creator,
+        Value creator,
         CaseSensitiveness case_sensitiveness = CaseSensitive);
 
     /// Throws an exception if not found.
     AggregateFunctionPtr get(
         const String & name,
         const DataTypes & argument_types,
-        const Array & parameters = {},
+        const Array & parameters,
+        AggregateFunctionProperties & out_properties,
         int recursion_level = 0) const;
 
     /// Returns nullptr if not found.
     AggregateFunctionPtr tryGet(
         const String & name,
         const DataTypes & argument_types,
-        const Array & parameters = {}) const;
+        const Array & parameters,
+        AggregateFunctionProperties & out_properties) const;
 
     bool isAggregateFunctionName(const String & name, int recursion_level = 0) const;
 
@@ -62,19 +78,21 @@ private:
         const String & name,
         const DataTypes & argument_types,
         const Array & parameters,
+        AggregateFunctionProperties & out_properties,
+        bool has_null_arguments,
         int recursion_level) const;
 
 private:
-    using AggregateFunctions = std::unordered_map<String, Creator>;
+    using AggregateFunctions = std::unordered_map<String, Value>;
 
     AggregateFunctions aggregate_functions;
 
     /// Case insensitive aggregate functions will be additionally added here with lowercased name.
     AggregateFunctions case_insensitive_aggregate_functions;
 
-    const AggregateFunctions & getCreatorMap() const override { return aggregate_functions; }
+    const AggregateFunctions & getMap() const override { return aggregate_functions; }
 
-    const AggregateFunctions & getCaseInsensitiveCreatorMap() const override { return case_insensitive_aggregate_functions; }
+    const AggregateFunctions & getCaseInsensitiveMap() const override { return case_insensitive_aggregate_functions; }
 
     String getFactoryName() const override { return "AggregateFunctionFactory"; }
 

src/AggregateFunctions/AggregateFunctionForEach.cpp

@@ -33,7 +33,10 @@ public:
     }
 
     AggregateFunctionPtr transformAggregateFunction(
-        const AggregateFunctionPtr & nested_function, const DataTypes & arguments, const Array &) const override
+        const AggregateFunctionPtr & nested_function,
+        const AggregateFunctionProperties &,
+        const DataTypes & arguments,
+        const Array &) const override
     {
         return std::make_shared<AggregateFunctionForEach>(nested_function, arguments);
     }

src/AggregateFunctions/AggregateFunctionIf.cpp

@@ -31,7 +31,10 @@ public:
     }
 
     AggregateFunctionPtr transformAggregateFunction(
-        const AggregateFunctionPtr & nested_function, const DataTypes & arguments, const Array &) const override
+        const AggregateFunctionPtr & nested_function,
+        const AggregateFunctionProperties &,
+        const DataTypes & arguments,
+        const Array &) const override
     {
         return std::make_shared<AggregateFunctionIf>(nested_function, arguments);
     }

src/AggregateFunctions/AggregateFunctionMerge.cpp

@@ -34,7 +34,10 @@ public:
     }
 
     AggregateFunctionPtr transformAggregateFunction(
-        const AggregateFunctionPtr & nested_function, const DataTypes & arguments, const Array &) const override
+        const AggregateFunctionPtr & nested_function,
+        const AggregateFunctionProperties &,
+        const DataTypes & arguments,
+        const Array &) const override
     {
         const DataTypePtr & argument = arguments[0];
 

src/AggregateFunctions/AggregateFunctionNothing.h

@@ -25,7 +25,7 @@ public:
 
     DataTypePtr getReturnType() const override
     {
-        return std::make_shared<DataTypeNullable>(std::make_shared<DataTypeNothing>());
+        return argument_types.front();
     }
 
     void create(AggregateDataPtr) const override

src/AggregateFunctions/AggregateFunctionNull.cpp

@@ -31,13 +31,11 @@ public:
     }
 
     AggregateFunctionPtr transformAggregateFunction(
-        const AggregateFunctionPtr & nested_function, const DataTypes & arguments, const Array & params) const override
+        const AggregateFunctionPtr & nested_function,
+        const AggregateFunctionProperties & properties,
+        const DataTypes & arguments,
+        const Array & params) const override
     {
-        /// 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 (nested_function && nested_function->getName() == "count")
-            return std::make_shared<AggregateFunctionCountNotNullUnary>(arguments[0], params);
-
         bool has_nullable_types = false;
         bool has_null_types = false;
         for (const auto & arg_type : arguments)
@@ -58,15 +56,23 @@ public:
                 ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT);
 
         if (has_null_types)
-            return std::make_shared<AggregateFunctionNothing>(arguments, params);
+        {
+            /// Currently the only functions that returns not-NULL on all NULL arguments are count and uniq, and they returns UInt64.
+            if (properties.returns_default_when_only_null)
+                return std::make_shared<AggregateFunctionNothing>(DataTypes{
+                    std::make_shared<DataTypeUInt64>()}, params);
+            else
+                return std::make_shared<AggregateFunctionNothing>(DataTypes{
+                    std::make_shared<DataTypeNullable>(std::make_shared<DataTypeNothing>())}, params);
+        }
 
         assert(nested_function);
 
         if (auto adapter = nested_function->getOwnNullAdapter(nested_function, arguments, params))
             return adapter;
 
-        bool return_type_is_nullable = !nested_function->returnDefaultWhenOnlyNull() && nested_function->getReturnType()->canBeInsideNullable();
-        bool serialize_flag = return_type_is_nullable || nested_function->returnDefaultWhenOnlyNull();
+        bool return_type_is_nullable = !properties.returns_default_when_only_null && nested_function->getReturnType()->canBeInsideNullable();
+        bool serialize_flag = return_type_is_nullable || properties.returns_default_when_only_null;
 
         if (arguments.size() == 1)
         {

src/AggregateFunctions/AggregateFunctionOrFill.cpp

@@ -21,6 +21,7 @@ public:
 
     AggregateFunctionPtr transformAggregateFunction(
         const AggregateFunctionPtr & nested_function,
+        const AggregateFunctionProperties &,
         const DataTypes & arguments,
         const Array & params) const override
     {

src/AggregateFunctions/AggregateFunctionResample.cpp

@@ -43,6 +43,7 @@ public:
 
     AggregateFunctionPtr transformAggregateFunction(
         const AggregateFunctionPtr & nested_function,
+        const AggregateFunctionProperties &,
         const DataTypes & arguments,
         const Array & params) const override
     {

src/AggregateFunctions/AggregateFunctionState.cpp

@@ -24,7 +24,10 @@ public:
     }
 
     AggregateFunctionPtr transformAggregateFunction(
-        const AggregateFunctionPtr & nested_function, const DataTypes & arguments, const Array & params) const override
+        const AggregateFunctionPtr & nested_function,
+        const AggregateFunctionProperties &,
+        const DataTypes & arguments,
+        const Array & params) const override
     {
         return std::make_shared<AggregateFunctionState>(nested_function, arguments, params);
     }

src/AggregateFunctions/AggregateFunctionUniq.cpp

@@ -123,13 +123,13 @@ AggregateFunctionPtr createAggregateFunctionUniq(const std::string & name, const
 void registerAggregateFunctionsUniq(AggregateFunctionFactory & factory)
 {
     factory.registerFunction("uniq",
-        createAggregateFunctionUniq<AggregateFunctionUniqUniquesHashSetData, AggregateFunctionUniqUniquesHashSetDataForVariadic>);
+        {createAggregateFunctionUniq<AggregateFunctionUniqUniquesHashSetData, AggregateFunctionUniqUniquesHashSetDataForVariadic>, {true}});
 
     factory.registerFunction("uniqHLL12",
-        createAggregateFunctionUniq<false, AggregateFunctionUniqHLL12Data, AggregateFunctionUniqHLL12DataForVariadic>);
+        {createAggregateFunctionUniq<false, AggregateFunctionUniqHLL12Data, AggregateFunctionUniqHLL12DataForVariadic>, {true}});
 
     factory.registerFunction("uniqExact",
-        createAggregateFunctionUniq<true, AggregateFunctionUniqExactData, AggregateFunctionUniqExactData<String>>);
+        {createAggregateFunctionUniq<true, AggregateFunctionUniqExactData, AggregateFunctionUniqExactData<String>>, {true}});
 }
 
 }

src/AggregateFunctions/AggregateFunctionUniq.h

@@ -244,12 +244,6 @@ public:
     {
         assert_cast<ColumnUInt64 &>(to).getData().push_back(this->data(place).set.size());
     }
-
-    /// The function returns non-Nullable type even when wrapped with Null combinator.
-    bool returnDefaultWhenOnlyNull() const override
-    {
-        return true;
-    }
 };
 
 
@@ -304,12 +298,6 @@ public:
     {
         assert_cast<ColumnUInt64 &>(to).getData().push_back(this->data(place).set.size());
     }
-
-    /// The function returns non-Nullable type even when wrapped with Null combinator.
-    bool returnDefaultWhenOnlyNull() const override
-    {
-        return true;
-    }
 };
 
 }

src/AggregateFunctions/AggregateFunctionUniqUpTo.cpp

@@ -85,7 +85,7 @@ AggregateFunctionPtr createAggregateFunctionUniqUpTo(const std::string & name, c
 
 void registerAggregateFunctionUniqUpTo(AggregateFunctionFactory & factory)
 {
-    factory.registerFunction("uniqUpTo", createAggregateFunctionUniqUpTo);
+    factory.registerFunction("uniqUpTo", {createAggregateFunctionUniqUpTo, {true}});
 }
 
 }

src/AggregateFunctions/IAggregateFunction.h

@@ -166,17 +166,12 @@ public:
      *  nested_function is a smart pointer to this aggregate function itself.
      *  arguments and params are for nested_function.
      */
-    virtual AggregateFunctionPtr getOwnNullAdapter(const AggregateFunctionPtr & /*nested_function*/, const DataTypes & /*arguments*/, const Array & /*params*/) const
+    virtual AggregateFunctionPtr getOwnNullAdapter(
+        const AggregateFunctionPtr & /*nested_function*/, const DataTypes & /*arguments*/, const Array & /*params*/) const
     {
         return nullptr;
     }
 
-    /** When the function is wrapped with Null combinator,
-      * should we return Nullable type with NULL when no values were aggregated
-      * or we should return non-Nullable type with default value (example: count, countDistinct).
-      */
-    virtual bool returnDefaultWhenOnlyNull() const { return false; }
-
     const DataTypes & getArgumentTypes() const { return argument_types; }
     const Array & getParameters() const { return parameters; }
 
@@ -286,4 +281,15 @@ public:
 };
 
 
+/// Properties of aggregate function that are independent of argument types and parameters.
+struct AggregateFunctionProperties
+{
+    /** When the function is wrapped with Null combinator,
+      * should we return Nullable type with NULL when no values were aggregated
+      * or we should return non-Nullable type with default value (example: count, countDistinct).
+      */
+    bool returns_default_when_only_null = false;
+};
+
+
 }

src/AggregateFunctions/IAggregateFunctionCombinator.h

@@ -59,6 +59,7 @@ public:
       */
     virtual AggregateFunctionPtr transformAggregateFunction(
         const AggregateFunctionPtr & nested_function,
+        const AggregateFunctionProperties & properties,
         const DataTypes & arguments,
         const Array & params) const = 0;
 

src/CMakeLists.txt

@@ -381,6 +381,6 @@ if (ENABLE_TESTS AND USE_GTEST)
         -Wno-gnu-zero-variadic-macro-arguments
     )
 
-    target_link_libraries(unit_tests_dbms PRIVATE ${GTEST_BOTH_LIBRARIES} clickhouse_functions clickhouse_parsers dbms clickhouse_common_zookeeper string_utils)
+    target_link_libraries(unit_tests_dbms PRIVATE ${GTEST_BOTH_LIBRARIES} clickhouse_functions clickhouse_aggregate_functions clickhouse_parsers dbms clickhouse_common_zookeeper string_utils)
     add_check(unit_tests_dbms)
 endif ()

src/Client/tests/CMakeLists.txt

-add_executable(test-connect test_connect.cpp)
-target_link_libraries (test-connect PRIVATE dbms)

src/Client/tests/test_connect.cpp

-#include <sys/types.h>
-#include <sys/socket.h>
-#include <unistd.h>
-
-#include <iostream>
-#include <Poco/Net/StreamSocket.h>
-#include <Common/Exception.h>
-#include <IO/ReadHelpers.h>
-
-
-/** In a loop it connects to the server and immediately breaks the connection.
-  * Using the SO_LINGER option, we ensure that the connection is terminated by sending a RST packet (not FIN).
-  * This behavior causes a bug in the TCPServer implementation in the Poco library.
-  */
-int main(int argc, char ** argv)
-try
-{
-    for (size_t i = 0, num_iters = argc >= 2 ? DB::parse<size_t>(argv[1]) : 1; i < num_iters; ++i)
-    {
-        std::cerr << ".";
-
-        Poco::Net::SocketAddress address("localhost", 9000);
-
-        int fd = socket(PF_INET, SOCK_STREAM, IPPROTO_IP);
-
-        if (fd < 0)
-            DB::throwFromErrno("Cannot create socket", 0);
-
-        linger linger_value;
-        linger_value.l_onoff = 1;
-        linger_value.l_linger = 0;
-
-        if (0 != setsockopt(fd, SOL_SOCKET, SO_LINGER, &linger_value, sizeof(linger_value)))
-            DB::throwFromErrno("Cannot set linger", 0);
-
-        try
-        {
-            int res = connect(fd, address.addr(), address.length());
-
-            if (res != 0 && errno != EINPROGRESS && errno != EWOULDBLOCK)
-            {
-                close(fd);
-                DB::throwFromErrno("Cannot connect", 0);
-            }
-
-            close(fd);
-        }
-        catch (const Poco::Exception & e)
-        {
-            std::cerr << e.displayText() << "\n";
-        }
-    }
-
-    std::cerr << "\n";
-}
-catch (const Poco::Exception & e)
-{
-    std::cerr << e.displayText() << "\n";
-}

src/Common/IFactoryWithAliases.h

@@ -16,14 +16,14 @@ namespace ErrorCodes
 }
 
 /** If stored objects may have several names (aliases)
- * this interface may be helpful
- * template parameter is available as Creator
- */
-template <typename CreatorFunc>
-class IFactoryWithAliases : public IHints<2, IFactoryWithAliases<CreatorFunc>>
+  * this interface may be helpful
+  * template parameter is available as Value
+  */
+template <typename ValueType>
+class IFactoryWithAliases : public IHints<2, IFactoryWithAliases<ValueType>>
 {
 protected:
-    using Creator = CreatorFunc;
+    using Value = ValueType;
 
     String getAliasToOrName(const String & name) const
     {
@@ -43,13 +43,13 @@ public:
         CaseInsensitive
     };
 
-    /** Register additional name for creator
-     * real_name have to be already registered.
-     */
+    /** Register additional name for value
+      * real_name have to be already registered.
+      */
     void registerAlias(const String & alias_name, const String & real_name, CaseSensitiveness case_sensitiveness = CaseSensitive)
     {
-        const auto & creator_map = getCreatorMap();
-        const auto & case_insensitive_creator_map = getCaseInsensitiveCreatorMap();
+        const auto & creator_map = getMap();
+        const auto & case_insensitive_creator_map = getCaseInsensitiveMap();
         const String factory_name = getFactoryName();
 
         String real_dict_name;
@@ -80,7 +80,7 @@ public:
     {
         std::vector<String> result;
         auto getter = [](const auto & pair) { return pair.first; };
-        std::transform(getCreatorMap().begin(), getCreatorMap().end(), std::back_inserter(result), getter);
+        std::transform(getMap().begin(), getMap().end(), std::back_inserter(result), getter);
         std::transform(aliases.begin(), aliases.end(), std::back_inserter(result), getter);
         return result;
     }
@@ -88,7 +88,7 @@ public:
     bool isCaseInsensitive(const String & name) const
     {
         String name_lowercase = Poco::toLower(name);
-        return getCaseInsensitiveCreatorMap().count(name_lowercase) || case_insensitive_aliases.count(name_lowercase);
+        return getCaseInsensitiveMap().count(name_lowercase) || case_insensitive_aliases.count(name_lowercase);
     }
 
     const String & aliasTo(const String & name) const
@@ -109,11 +109,11 @@ public:
     virtual ~IFactoryWithAliases() override {}
 
 private:
-    using InnerMap = std::unordered_map<String, Creator>; // name -> creator
+    using InnerMap = std::unordered_map<String, Value>; // name -> creator
     using AliasMap = std::unordered_map<String, String>; // alias -> original type
 
-    virtual const InnerMap & getCreatorMap() const = 0;
-    virtual const InnerMap & getCaseInsensitiveCreatorMap() const = 0;
+    virtual const InnerMap & getMap() const = 0;
+    virtual const InnerMap & getCaseInsensitiveMap() const = 0;
     virtual String getFactoryName() const = 0;
 
     /// Alias map to data_types from previous two maps

src/DataStreams/tests/CMakeLists.txt

 set(SRCS)
 
 add_executable (finish_sorting_stream finish_sorting_stream.cpp ${SRCS})
-target_link_libraries (finish_sorting_stream PRIVATE dbms)
+target_link_libraries (finish_sorting_stream PRIVATE clickhouse_aggregate_functions dbms)

src/DataTypes/DataTypeAggregateFunction.cpp

@@ -392,7 +392,8 @@ static DataTypePtr create(const ASTPtr & arguments)
     if (function_name.empty())
         throw Exception("Logical error: empty name of aggregate function passed", ErrorCodes::LOGICAL_ERROR);
 
-    function = AggregateFunctionFactory::instance().get(function_name, argument_types, params_row);
+    AggregateFunctionProperties properties;
+    function = AggregateFunctionFactory::instance().get(function_name, argument_types, params_row, properties);
     return std::make_shared<DataTypeAggregateFunction>(function, argument_types, params_row);
 }
 

src/DataTypes/DataTypeCustomSimpleAggregateFunction.cpp

@@ -110,7 +110,8 @@ static std::pair<DataTypePtr, DataTypeCustomDescPtr> create(const ASTPtr & argum
     if (function_name.empty())
         throw Exception("Logical error: empty name of aggregate function passed", ErrorCodes::LOGICAL_ERROR);
 
-    function = AggregateFunctionFactory::instance().get(function_name, argument_types, params_row);
+    AggregateFunctionProperties properties;
+    function = AggregateFunctionFactory::instance().get(function_name, argument_types, params_row, properties);
 
     // check function
     if (std::find(std::begin(supported_functions), std::end(supported_functions), function->getName()) == std::end(supported_functions))

src/DataTypes/DataTypeFactory.cpp

@@ -80,7 +80,7 @@ DataTypePtr DataTypeFactory::get(const String & family_name_param, const ASTPtr
 }
 
 
-void DataTypeFactory::registerDataType(const String & family_name, Creator creator, CaseSensitiveness case_sensitiveness)
+void DataTypeFactory::registerDataType(const String & family_name, Value creator, CaseSensitiveness case_sensitiveness)
 {
     if (creator == nullptr)
         throw Exception("DataTypeFactory: the data type family " + family_name + " has been provided "
@@ -136,7 +136,7 @@ void DataTypeFactory::registerSimpleDataTypeCustom(const String &name, SimpleCre
     }, case_sensitiveness);
 }
 
-const DataTypeFactory::Creator& DataTypeFactory::findCreatorByName(const String & family_name) const
+const DataTypeFactory::Value & DataTypeFactory::findCreatorByName(const String & family_name) const
 {
     {
         DataTypesDictionary::const_iterator it = data_types.find(family_name);

src/DataTypes/DataTypeFactory.h

@@ -23,7 +23,7 @@ class DataTypeFactory final : private boost::noncopyable, public IFactoryWithAli
 {
 private:
     using SimpleCreator = std::function<DataTypePtr()>;
-    using DataTypesDictionary = std::unordered_map<String, Creator>;
+    using DataTypesDictionary = std::unordered_map<String, Value>;
     using CreatorWithCustom = std::function<std::pair<DataTypePtr,DataTypeCustomDescPtr>(const ASTPtr & parameters)>;
     using SimpleCreatorWithCustom = std::function<std::pair<DataTypePtr,DataTypeCustomDescPtr>()>;
 
@@ -35,7 +35,7 @@ public:
     DataTypePtr get(const ASTPtr & ast) const;
 
     /// Register a type family by its name.
-    void registerDataType(const String & family_name, Creator creator, CaseSensitiveness case_sensitiveness = CaseSensitive);
+    void registerDataType(const String & family_name, Value creator, CaseSensitiveness case_sensitiveness = CaseSensitive);
 
     /// Register a simple data type, that have no parameters.
     void registerSimpleDataType(const String & name, SimpleCreator creator, CaseSensitiveness case_sensitiveness = CaseSensitive);
@@ -47,7 +47,7 @@ public:
     void registerSimpleDataTypeCustom(const String & name, SimpleCreatorWithCustom creator, CaseSensitiveness case_sensitiveness = CaseSensitive);
 
 private:
-    const Creator& findCreatorByName(const String & family_name) const;
+    const Value & findCreatorByName(const String & family_name) const;
 
 private:
     DataTypesDictionary data_types;
@@ -57,9 +57,9 @@ private:
 
     DataTypeFactory();
 
-    const DataTypesDictionary & getCreatorMap() const override { return data_types; }
+    const DataTypesDictionary & getMap() const override { return data_types; }
 
-    const DataTypesDictionary & getCaseInsensitiveCreatorMap() const override { return case_insensitive_data_types; }
+    const DataTypesDictionary & getCaseInsensitiveMap() const override { return case_insensitive_data_types; }
 
     String getFactoryName() const override { return "DataTypeFactory"; }
 };

src/Formats/tests/CMakeLists.txt

 set(SRCS )
 
 add_executable (tab_separated_streams tab_separated_streams.cpp ${SRCS})
-target_link_libraries (tab_separated_streams PRIVATE dbms)
+target_link_libraries (tab_separated_streams PRIVATE clickhouse_aggregate_functions dbms)

src/Functions/FunctionFactory.cpp

@@ -20,7 +20,7 @@ namespace ErrorCodes
 
 void FunctionFactory::registerFunction(const
     std::string & name,
-    Creator creator,
+    Value creator,
     CaseSensitiveness case_sensitiveness)
 {
     if (!functions.emplace(name, creator).second)

src/Functions/FunctionFactory.h

@@ -53,7 +53,7 @@ public:
     FunctionOverloadResolverImplPtr tryGetImpl(const std::string & name, const Context & context) const;
 
 private:
-    using Functions = std::unordered_map<std::string, Creator>;
+    using Functions = std::unordered_map<std::string, Value>;
 
     Functions functions;
     Functions case_insensitive_functions;
@@ -64,9 +64,9 @@ private:
         return std::make_unique<DefaultOverloadResolver>(Function::create(context));
     }
 
-    const Functions & getCreatorMap() const override { return functions; }
+    const Functions & getMap() const override { return functions; }
 
-    const Functions & getCaseInsensitiveCreatorMap() const override { return case_insensitive_functions; }
+    const Functions & getCaseInsensitiveMap() const override { return case_insensitive_functions; }
 
     String getFactoryName() const override { return "FunctionFactory"; }
 
@@ -74,7 +74,7 @@ private:
     /// No locking, you must register all functions before usage of get.
     void registerFunction(
             const std::string & name,
-            Creator creator,
+            Value creator,
             CaseSensitiveness case_sensitiveness = CaseSensitive);
 };
 

src/Functions/FunctionsBitmap.h

@@ -113,8 +113,9 @@ public:
         auto nested_type = array_type->getNestedType();
         DataTypes argument_types = {nested_type};
         Array params_row;
-        AggregateFunctionPtr bitmap_function
-            = AggregateFunctionFactory::instance().get(AggregateFunctionGroupBitmapData<UInt32>::name(), argument_types, params_row);
+        AggregateFunctionProperties properties;
+        AggregateFunctionPtr bitmap_function = AggregateFunctionFactory::instance().get(
+            AggregateFunctionGroupBitmapData<UInt32>::name(), argument_types, params_row, properties);
 
         return std::make_shared<DataTypeAggregateFunction>(bitmap_function, argument_types, params_row);
     }
@@ -156,8 +157,9 @@ private:
 
         // output data
         Array params_row;
-        AggregateFunctionPtr bitmap_function
-            = AggregateFunctionFactory::instance().get(AggregateFunctionGroupBitmapData<UInt32>::name(), argument_types, params_row);
+        AggregateFunctionProperties properties;
+        AggregateFunctionPtr bitmap_function = AggregateFunctionFactory::instance().get(
+            AggregateFunctionGroupBitmapData<UInt32>::name(), argument_types, params_row, properties);
         auto col_to = ColumnAggregateFunction::create(bitmap_function);
         col_to->reserve(offsets.size());
 

src/Functions/array/arrayReduce.cpp

@@ -97,7 +97,8 @@ DataTypePtr FunctionArrayReduce::getReturnTypeImpl(const ColumnsWithTypeAndName
         getAggregateFunctionNameAndParametersArray(aggregate_function_name_with_params,
                                                    aggregate_function_name, params_row, "function " + getName());
 
-        aggregate_function = AggregateFunctionFactory::instance().get(aggregate_function_name, argument_types, params_row);
+        AggregateFunctionProperties properties;
+        aggregate_function = AggregateFunctionFactory::instance().get(aggregate_function_name, argument_types, params_row, properties);
     }
 
     return aggregate_function->getReturnType();

src/Functions/array/arrayReduceInRanges.cpp

@@ -115,7 +115,8 @@ DataTypePtr FunctionArrayReduceInRanges::getReturnTypeImpl(const ColumnsWithType
         getAggregateFunctionNameAndParametersArray(aggregate_function_name_with_params,
                                                    aggregate_function_name, params_row, "function " + getName());
 
-        aggregate_function = AggregateFunctionFactory::instance().get(aggregate_function_name, argument_types, params_row);
+        AggregateFunctionProperties properties;
+        aggregate_function = AggregateFunctionFactory::instance().get(aggregate_function_name, argument_types, params_row, properties);
     }
 
     return std::make_shared<DataTypeArray>(aggregate_function->getReturnType());

src/Interpreters/ExpressionAnalyzer.cpp

@@ -420,8 +420,9 @@ bool ExpressionAnalyzer::makeAggregateDescriptions(ExpressionActionsPtr & action
             aggregate.argument_names[i] = name;
         }
 
+        AggregateFunctionProperties properties;
         aggregate.parameters = (node->parameters) ? getAggregateFunctionParametersArray(node->parameters) : Array();
-        aggregate.function = AggregateFunctionFactory::instance().get(node->name, types, aggregate.parameters);
+        aggregate.function = AggregateFunctionFactory::instance().get(node->name, types, aggregate.parameters, properties);
 
         aggregate_descriptions.push_back(aggregate);
     }

src/Interpreters/tests/CMakeLists.txt

@@ -34,11 +34,11 @@ target_include_directories (two_level_hash_map SYSTEM BEFORE PRIVATE ${SPARSEHAS
 target_link_libraries (two_level_hash_map PRIVATE dbms)
 
 add_executable (in_join_subqueries_preprocessor in_join_subqueries_preprocessor.cpp)
-target_link_libraries (in_join_subqueries_preprocessor PRIVATE dbms clickhouse_parsers)
+target_link_libraries (in_join_subqueries_preprocessor PRIVATE clickhouse_aggregate_functions dbms clickhouse_parsers)
 add_check(in_join_subqueries_preprocessor)
 
 add_executable (users users.cpp)
-target_link_libraries (users PRIVATE dbms clickhouse_common_config)
+target_link_libraries (users PRIVATE clickhouse_aggregate_functions dbms clickhouse_common_config)
 
 if (OS_LINUX)
     add_executable (internal_iotop internal_iotop.cpp)

src/Interpreters/tests/hash_map.cpp

@@ -103,9 +103,10 @@ int main(int argc, char ** argv)
     std::vector<Key> data(n);
     Value value;
 
-    AggregateFunctionPtr func_count = factory.get("count", data_types_empty);
-    AggregateFunctionPtr func_avg = factory.get("avg", data_types_uint64);
-    AggregateFunctionPtr func_uniq = factory.get("uniq", data_types_uint64);
+    AggregateFunctionProperties properties;
+    AggregateFunctionPtr func_count = factory.get("count", data_types_empty, {}, properties);
+    AggregateFunctionPtr func_avg = factory.get("avg", data_types_uint64, {}, properties);
+    AggregateFunctionPtr func_uniq = factory.get("uniq", data_types_uint64, {}, properties);
 
     #define INIT \
     { \

src/Processors/Merges/Algorithms/SummingSortedAlgorithm.cpp

@@ -47,7 +47,8 @@ struct SummingSortedAlgorithm::AggregateDescription
 
     void init(const char * function_name, const DataTypes & argument_types)
     {
-        function = AggregateFunctionFactory::instance().get(function_name, argument_types);
+        AggregateFunctionProperties properties;
+        function = AggregateFunctionFactory::instance().get(function_name, argument_types, {}, properties);
         add_function = function->getAddressOfAddFunction();
         state.reset(function->sizeOfData(), function->alignOfData());
     }

src/Storages/MergeTree/registerStorageMergeTree.cpp

@@ -117,8 +117,9 @@ static void appendGraphitePattern(
                                                        aggregate_function_name, params_row, "GraphiteMergeTree storage initialization");
 
             /// TODO Not only Float64
-            pattern.function = AggregateFunctionFactory::instance().get(aggregate_function_name, {std::make_shared<DataTypeFloat64>()},
-                                                                        params_row);
+            AggregateFunctionProperties properties;
+            pattern.function = AggregateFunctionFactory::instance().get(
+                aggregate_function_name, {std::make_shared<DataTypeFloat64>()}, params_row, properties);
         }
         else if (startsWith(key, "retention"))
         {

src/TableFunctions/TableFunctionFactory.cpp

@@ -15,7 +15,7 @@ namespace ErrorCodes
 }
 
 
-void TableFunctionFactory::registerFunction(const std::string & name, Creator creator, CaseSensitiveness case_sensitiveness)
+void TableFunctionFactory::registerFunction(const std::string & name, Value creator, CaseSensitiveness case_sensitiveness)
 {
     if (!table_functions.emplace(name, creator).second)
         throw Exception("TableFunctionFactory: the table function name '" + name + "' is not unique",

src/TableFunctions/TableFunctionFactory.h

@@ -24,12 +24,11 @@ using TableFunctionCreator = std::function<TableFunctionPtr()>;
 class TableFunctionFactory final: private boost::noncopyable, public IFactoryWithAliases<TableFunctionCreator>
 {
 public:
-
     static TableFunctionFactory & instance();
 
     /// Register a function by its name.
     /// No locking, you must register all functions before usage of get.
-    void registerFunction(const std::string & name, Creator creator, CaseSensitiveness case_sensitiveness = CaseSensitive);
+    void registerFunction(const std::string & name, Value creator, CaseSensitiveness case_sensitiveness = CaseSensitive);
 
     template <typename Function>
     void registerFunction(CaseSensitiveness case_sensitiveness = CaseSensitive)
@@ -50,11 +49,11 @@ public:
     bool isTableFunctionName(const std::string & name) const;
 
 private:
-    using TableFunctions = std::unordered_map<std::string, Creator>;
+    using TableFunctions = std::unordered_map<std::string, Value>;
 
-    const TableFunctions & getCreatorMap() const override { return table_functions; }
+    const TableFunctions & getMap() const override { return table_functions; }
 
-    const TableFunctions & getCaseInsensitiveCreatorMap() const override { return case_insensitive_table_functions; }
+    const TableFunctions & getCaseInsensitiveMap() const override { return case_insensitive_table_functions; }
 
     String getFactoryName() const override { return "TableFunctionFactory"; }
 

tests/queries/0_stateless/01315_count_distinct_return_not_nullable.reference

@@ -4,6 +4,13 @@
 5
 5
 5
+---
 0
+0
+0
+---
+\N
+\N
+\N
 \N
 \N

tests/queries/0_stateless/01315_count_distinct_return_not_nullable.sql

@@ -6,7 +6,14 @@ SELECT uniq(number >= 5 ? number : NULL) FROM numbers(10);
 SELECT uniqExact(number >= 5 ? number : NULL) FROM numbers(10);
 SELECT count(DISTINCT number >= 5 ? number : NULL) FROM numbers(10);
 
+SELECT '---';
 SELECT count(NULL);
--- These two returns NULL for now, but we want to change them to return 0.
 SELECT uniq(NULL);
 SELECT count(DISTINCT NULL);
+
+SELECT '---';
+SELECT avg(NULL);
+SELECT sum(NULL);
+SELECT corr(NULL, NULL);
+SELECT corr(1, NULL);
+SELECT corr(NULL, 1);

utils/convert-month-partitioned-parts/CMakeLists.txt

 add_executable (convert-month-partitioned-parts main.cpp)
-target_link_libraries(convert-month-partitioned-parts PRIVATE dbms clickhouse_parsers boost::program_options)
+target_link_libraries(convert-month-partitioned-parts PRIVATE clickhouse_aggregate_functions dbms clickhouse_parsers boost::program_options)

utils/zookeeper-adjust-block-numbers-to-parts/CMakeLists.txt

 add_executable (zookeeper-adjust-block-numbers-to-parts main.cpp ${SRCS})
 target_compile_options(zookeeper-adjust-block-numbers-to-parts PRIVATE -Wno-format)
-target_link_libraries (zookeeper-adjust-block-numbers-to-parts PRIVATE dbms clickhouse_common_zookeeper boost::program_options)
+target_link_libraries (zookeeper-adjust-block-numbers-to-parts PRIVATE clickhouse_aggregate_functions dbms clickhouse_common_zookeeper boost::program_options)