Updated user defined functions implementation

src/CMakeLists.txt

@@ -111,8 +111,8 @@ endif()
 list (APPEND clickhouse_common_io_sources ${CONFIG_BUILD})
 list (APPEND clickhouse_common_io_headers ${CONFIG_VERSION} ${CONFIG_COMMON})
 
-list (APPEND dbms_sources Functions/IFunction.cpp Functions/FunctionFactory.cpp Functions/FunctionHelpers.cpp Functions/extractTimeZoneFromFunctionArguments.cpp Functions/replicate.cpp Functions/FunctionsLogical.cpp Functions/UserDefinedFunction.cpp)
-list (APPEND dbms_headers Functions/IFunction.h Functions/FunctionFactory.h Functions/FunctionHelpers.h Functions/extractTimeZoneFromFunctionArguments.h Functions/replicate.h Functions/FunctionsLogical.h Functions/UserDefinedFunction.h)
+list (APPEND dbms_sources Functions/IFunction.cpp Functions/FunctionFactory.cpp Functions/FunctionHelpers.cpp Functions/extractTimeZoneFromFunctionArguments.cpp Functions/replicate.cpp Functions/FunctionsLogical.cpp)
+list (APPEND dbms_headers Functions/IFunction.h Functions/FunctionFactory.h Functions/FunctionHelpers.h Functions/extractTimeZoneFromFunctionArguments.h Functions/replicate.h Functions/FunctionsLogical.h)
 
 list (APPEND dbms_sources
     AggregateFunctions/IAggregateFunction.cpp

src/Common/ErrorCodes.cpp

@@ -567,11 +567,11 @@
     M(596, INTERSECT_OR_EXCEPT_RESULT_STRUCTURES_MISMATCH) \
     M(597, NO_SUCH_ERROR_CODE) \
     \
-    M(591, FUNCTION_ALREADY_EXISTS) \
-    M(592, CANNOT_DROP_SYSTEM_FUNCTION) \
-    M(593, CANNOT_CREATE_RECURSIVE_FUNCTION) \
-    M(594, OBJECT_ALREADY_STORED_ON_DISK) \
-    M(595, OBJECT_WAS_NOT_STORED_ON_DISK) \
+    M(598, FUNCTION_ALREADY_EXISTS) \
+    M(599, CANNOT_DROP_SYSTEM_FUNCTION) \
+    M(600, CANNOT_CREATE_RECURSIVE_FUNCTION) \
+    M(601, OBJECT_ALREADY_STORED_ON_DISK) \
+    M(602, OBJECT_WAS_NOT_STORED_ON_DISK) \
     \
     M(998, POSTGRESQL_CONNECTION_FAILURE) \
     M(999, KEEPER_EXCEPTION) \

src/Functions/FunctionFactory.cpp

@@ -1,5 +1,4 @@
 #include <Functions/FunctionFactory.h>
-#include <Functions/UserDefinedFunction.h>
 
 #include <Interpreters/Context.h>
 
@@ -36,7 +35,6 @@ void FunctionFactory::registerFunction(
     Value creator,
     CaseSensitiveness case_sensitiveness)
 {
-    std::lock_guard<std::mutex> guard(mutex);
     if (!functions.emplace(name, creator).second)
         throw Exception("FunctionFactory: the function name '" + name + "' is not unique",
                         ErrorCodes::LOGICAL_ERROR);
@@ -79,7 +77,6 @@ FunctionOverloadResolverPtr FunctionFactory::getImpl(
 
 std::vector<std::string> FunctionFactory::getAllNames() const
 {
-    std::lock_guard<std::mutex> guard(mutex);
     std::vector<std::string> res;
     res.reserve(functions.size());
     for (const auto & func : functions)
@@ -98,7 +95,6 @@ FunctionOverloadResolverPtr FunctionFactory::tryGetImpl(
     const std::string & name_param,
     ContextPtr context) const
 {
-    std::lock_guard<std::mutex> guard(mutex);
     String name = getAliasToOrName(name_param);
     FunctionOverloadResolverPtr res;
 
@@ -140,48 +136,4 @@ FunctionFactory & FunctionFactory::instance()
     return ret;
 }
 
-void FunctionFactory::registerUserDefinedFunction(const ASTCreateFunctionQuery & create_function_query)
-{
-    if (hasNameOrAlias(create_function_query.function_name))
-        throw Exception(ErrorCodes::FUNCTION_ALREADY_EXISTS, "The function {} already exists", create_function_query.function_name);
-
-    if (AggregateFunctionFactory::instance().isAggregateFunctionName(create_function_query.function_name))
-        throw Exception(ErrorCodes::FUNCTION_ALREADY_EXISTS, "The aggregate function {} already exists", create_function_query.function_name);
-
-    {
-        std::lock_guard<std::mutex> guard(mutex);
-        user_defined_functions.insert(create_function_query.function_name);
-    }
-    registerFunction(create_function_query.function_name, [create_function_query](ContextPtr context)
-    {
-        auto function = UserDefinedFunction::create(context);
-        function->setName(create_function_query.function_name);
-        function->setFunctionCore(create_function_query.function_core);
-
-        FunctionOverloadResolverPtr res = std::make_unique<FunctionToOverloadResolverAdaptor>(function);
-        return res;
-    }, CaseSensitiveness::CaseSensitive);
-}
-
-void FunctionFactory::unregisterUserDefinedFunction(const String & name)
-{
-    std::lock_guard<std::mutex> guard(mutex);
-    if (functions.contains(name))
-    {
-        if (user_defined_functions.contains(name))
-        {
-            functions.erase(name);
-            user_defined_functions.erase(name);
-            return;
-        } else
-            throw Exception("System functions cannot be dropped", ErrorCodes::CANNOT_DROP_SYSTEM_FUNCTION);
-    }
-
-    auto hints = this->getHints(name);
-    if (!hints.empty())
-        throw Exception(ErrorCodes::UNKNOWN_FUNCTION, "Unknown function {}. Maybe you meant: {}", name, toString(hints));
-    else
-        throw Exception(ErrorCodes::UNKNOWN_FUNCTION, "Unknown function {}", name);
-}
-
 }

src/Functions/FunctionFactory.h

@@ -70,9 +70,7 @@ private:
     using Functions = std::unordered_map<std::string, Value>;
 
     Functions functions;
-    std::unordered_set<String> user_defined_functions;
     Functions case_insensitive_functions;
-    mutable std::mutex mutex;
 
     template <typename Function>
     static FunctionOverloadResolverPtr adaptFunctionToOverloadResolver(ContextPtr context)

src/Functions/UserDefinedFunction.cpp

@@ -1,93 +0,0 @@
-#include <DataTypes/DataTypeFactory.h>
-#include <DataTypes/DataTypeString.h>
-#include <Functions/UserDefinedFunction.h>
-#include <Interpreters/TreeRewriter.h>
-#include <Interpreters/ExpressionActions.h>
-#include <Interpreters/ExpressionAnalyzer.h>
-#include <Parsers/ASTIdentifier.h>
-
-namespace DB
-{
-
-namespace ErrorCodes
-{
-    extern const int TYPE_MISMATCH;
-}
-
-UserDefinedFunction::UserDefinedFunction(ContextPtr context_)
-    : function_core(nullptr)
-    , context(context_)
-{}
-
-UserDefinedFunctionPtr UserDefinedFunction::create(ContextPtr context)
-{
-    return std::make_shared<UserDefinedFunction>(context);
-}
-
-String UserDefinedFunction::getName() const
-{
-    return name;
-}
-
-ColumnPtr UserDefinedFunction::executeImpl(const ColumnsWithTypeAndName & arguments, const DataTypePtr &, size_t) const
-{
-    Block block = executeCore(arguments);
-
-    String result_name = function_core->as<ASTFunction>()->arguments->children.at(1)->getColumnName();
-
-    // result of function executing was inserted in the end
-    return block.getColumns().back();
-}
-
-size_t UserDefinedFunction::getNumberOfArguments() const
-{
-    return function_core->as<ASTFunction>()->arguments->children[0]->size() - 2;
-}
-
-void UserDefinedFunction::setName(const String & name_)
-{
-    name = name_;
-}
-
-void UserDefinedFunction::setFunctionCore(ASTPtr function_core_)
-{
-    function_core = function_core_;
-}
-
-DataTypePtr UserDefinedFunction::getReturnTypeImpl(const ColumnsWithTypeAndName & arguments) const
-{
-    Block block = executeCore(arguments);
-    return block.getDataTypes().back();
-}
-
-Block UserDefinedFunction::executeCore(const ColumnsWithTypeAndName & arguments) const
-{
-    const auto * lambda_args_tuple = function_core->as<ASTFunction>()->arguments->children.at(0)->as<ASTFunction>();
-    const ASTs & lambda_arg_asts = lambda_args_tuple->arguments->children;
-
-    NamesAndTypesList lambda_arguments;
-    Block block;
-
-    for (size_t j = 0; j < lambda_arg_asts.size(); ++j)
-    {
-        auto opt_arg_name = tryGetIdentifierName(lambda_arg_asts[j]);
-        if (!opt_arg_name)
-            throw Exception("lambda argument declarations must be identifiers", ErrorCodes::TYPE_MISMATCH);
-
-        lambda_arguments.emplace_back(*opt_arg_name, arguments[j].type);
-        auto column_ptr = arguments[j].column;
-        if (!column_ptr)
-            column_ptr = arguments[j].type->createColumnConstWithDefaultValue(1);
-        block.insert({column_ptr, arguments[j].type, *opt_arg_name});
-    }
-
-    ASTPtr lambda_body = function_core->as<ASTFunction>()->children.at(0)->children.at(1);
-    auto syntax_result = TreeRewriter(context).analyze(lambda_body, lambda_arguments);
-    ExpressionAnalyzer analyzer(lambda_body, syntax_result, context);
-    ExpressionActionsPtr actions = analyzer.getActions(false);
-
-    actions->execute(block);
-    return block;
-}
-
-}

src/Functions/UserDefinedFunction.h

@@ -1,38 +0,0 @@
-#pragma once
-
-#include <Functions/FunctionFactory.h>
-#include <Functions/IFunction.h>
-#include <Interpreters/Context.h>
-#include <Parsers/ASTCreateFunctionQuery.h>
-
-namespace DB
-{
-
-class UserDefinedFunction;
-using UserDefinedFunctionPtr = std::shared_ptr<UserDefinedFunction>;
-
-class UserDefinedFunction : public IFunction
-{
-public:
-    explicit UserDefinedFunction(ContextPtr context_);
-    static UserDefinedFunctionPtr create(ContextPtr context);
-
-    String getName() const override;
-    ColumnPtr executeImpl(const ColumnsWithTypeAndName & arguments, const DataTypePtr & result_type, size_t input_rows_count) const override;
-    size_t getNumberOfArguments() const override;
-    DataTypePtr getReturnTypeImpl(const ColumnsWithTypeAndName & arguments) const override;
-
-    void setName(const String & name_);
-    void setFunctionCore(ASTPtr function_core_);
-
-    bool isSuitableForShortCircuitArgumentsExecution(const DataTypesWithConstInfo & /*arguments*/) const override { return false; }
-
-private:
-    Block executeCore(const ColumnsWithTypeAndName & arguments) const;
-
-    String name;
-    ASTPtr function_core;
-    ContextPtr context;
-};
-
-}

src/Interpreters/InDepthNodeVisitor.h

@@ -16,7 +16,7 @@ class InDepthNodeVisitor
 public:
     using Data = typename Matcher::Data;
 
-    InDepthNodeVisitor(Data & data_, WriteBuffer * ostr_ = nullptr)
+    explicit InDepthNodeVisitor(Data & data_, WriteBuffer * ostr_ = nullptr)
     :   data(data_),
         visit_depth(0),
         ostr(ostr_)

src/Interpreters/InterpreterCreateFunctionQuery.cpp

@@ -5,7 +5,7 @@
 #include <Interpreters/InterpreterCreateFunctionQuery.h>
 #include <Interpreters/FunctionNameNormalizer.h>
 #include <Interpreters/UserDefinedObjectsLoader.h>
-#include <Functions/FunctionFactory.h>
+#include <Interpreters/UserDefinedFunctionFactory.h>
 #include <Parsers/ASTIdentifier.h>
 
 namespace DB
@@ -15,7 +15,7 @@ namespace ErrorCodes
 {
     extern const int UNKNOWN_IDENTIFIER;
     extern const int CANNOT_CREATE_RECURSIVE_FUNCTION;
-    // extern const int UNSUPPORTED_OPERATION;
+    extern const int UNSUPPORTED_METHOD;
 }
 
 BlockIO InterpreterCreateFunctionQuery::execute()
@@ -24,25 +24,24 @@ BlockIO InterpreterCreateFunctionQuery::execute()
     FunctionNameNormalizer().visit(query_ptr.get());
     auto * create_function_query = query_ptr->as<ASTCreateFunctionQuery>();
 
-    // if (!create_function_query)
-    //     throw Exception(ErrorCodes::UNSUPPORTED_OPERATION, "Expected CREATE FUNCTION query");
+    if (!create_function_query)
+        throw Exception(ErrorCodes::UNSUPPORTED_METHOD, "Expected CREATE FUNCTION query");
 
     auto & function_name = create_function_query->function_name;
     validateFunction(create_function_query->function_core, function_name);
 
-    if (is_internal)
-    {
-        FunctionFactory::instance().registerUserDefinedFunction(*create_function_query);
-    }
-    else
+    UserDefinedFunctionFactory::instance().registerFunction(function_name, query_ptr);
+
+    if (!is_internal)
     {
+
         try
         {
             UserDefinedObjectsLoader::instance().storeObject(getContext(), UserDefinedObjectType::Function, function_name, *query_ptr);
-            FunctionFactory::instance().registerUserDefinedFunction(*create_function_query);
         }
         catch (Exception & e)
         {
+            UserDefinedFunctionFactory::instance().unregisterFunction(function_name);
             e.addMessage(fmt::format("while storing user defined function {} on disk", backQuote(function_name)));
             throw;
         }
@@ -56,11 +55,15 @@ void InterpreterCreateFunctionQuery::validateFunction(ASTPtr function, const Str
     const auto * args_tuple = function->as<ASTFunction>()->arguments->children.at(0)->as<ASTFunction>();
     std::unordered_set<String> arguments;
     for (const auto & argument : args_tuple->arguments->children)
-        arguments.insert(argument->as<ASTIdentifier>()->name());
+    {
+        const auto & argument_name = argument->as<ASTIdentifier>()->name();
+        auto [_, inserted] = arguments.insert(argument_name);
+        if (!inserted)
+            throw Exception(ErrorCodes::UNSUPPORTED_METHOD, "Identifier {} already used as function parameter", argument_name);
+    }
 
-    std::set<String> identifiers_in_body;
     ASTPtr function_body = function->as<ASTFunction>()->children.at(0)->children.at(1);
-    getIdentifiers(function_body, identifiers_in_body);
+    std::unordered_set<String> identifiers_in_body = getIdentifiers(function_body);
 
     for (const auto & identifier : identifiers_in_body)
     {
@@ -71,16 +74,29 @@ void InterpreterCreateFunctionQuery::validateFunction(ASTPtr function, const Str
     validateFunctionRecursiveness(function_body, name);
 }
 
-void InterpreterCreateFunctionQuery::getIdentifiers(ASTPtr node, std::set<String> & identifiers)
+std::unordered_set<String> InterpreterCreateFunctionQuery::getIdentifiers(ASTPtr node)
 {
-    for (const auto & child : node->children)
+    std::unordered_set<String> identifiers;
+
+    std::stack<ASTPtr> ast_nodes_to_process;
+    ast_nodes_to_process.push(node);
+
+    while (!ast_nodes_to_process.empty())
+    {
+        auto ast_node_to_process = ast_nodes_to_process.top();
+        ast_nodes_to_process.pop();
+
+        for (const auto & child : ast_node_to_process->children)
         {
             auto identifier_name_opt = tryGetIdentifierName(child);
             if (identifier_name_opt)
                 identifiers.insert(identifier_name_opt.value());
 
-        getIdentifiers(child, identifiers);
+            ast_nodes_to_process.push(child);
         }
+    }
+
+    return identifiers;
 }
 
 void InterpreterCreateFunctionQuery::validateFunctionRecursiveness(ASTPtr node, const String & function_to_create)

src/Interpreters/InterpreterCreateFunctionQuery.h

@@ -23,7 +23,7 @@ public:
 
 private:
     static void validateFunction(ASTPtr function, const String & name);
-    static void getIdentifiers(ASTPtr node, std::set<String> & identifiers);
+    static std::unordered_set<String> getIdentifiers(ASTPtr node);
     static void validateFunctionRecursiveness(ASTPtr node, const String & function_to_create);
 
     ASTPtr query_ptr;

src/Interpreters/InterpreterDropFunctionQuery.cpp

@@ -3,7 +3,7 @@
 #include <Interpreters/FunctionNameNormalizer.h>
 #include <Interpreters/InterpreterDropFunctionQuery.h>
 #include <Interpreters/UserDefinedObjectsLoader.h>
-#include <Functions/FunctionFactory.h>
+#include <Interpreters/UserDefinedFunctionFactory.h>
 #include <Parsers/ASTDropFunctionQuery.h>
 
 
@@ -15,7 +15,7 @@ BlockIO InterpreterDropFunctionQuery::execute()
     getContext()->checkAccess(AccessType::DROP_FUNCTION);
     FunctionNameNormalizer().visit(query_ptr.get());
     auto & drop_function_query = query_ptr->as<ASTDropFunctionQuery &>();
-    FunctionFactory::instance().unregisterUserDefinedFunction(drop_function_query.function_name);
+    UserDefinedFunctionFactory::instance().unregisterFunction(drop_function_query.function_name);
     UserDefinedObjectsLoader::instance().removeObject(getContext(), UserDefinedObjectType::Function, drop_function_query.function_name);
 
     return {};

src/Interpreters/TreeRewriter.cpp

@@ -14,6 +14,7 @@
 #include <Interpreters/CollectJoinOnKeysVisitor.h>
 #include <Interpreters/RequiredSourceColumnsVisitor.h>
 #include <Interpreters/GetAggregatesVisitor.h>
+#include <Interpreters/UserDefinedFunctionsVisitor.h>
 #include <Interpreters/TableJoin.h>
 #include <Interpreters/ExpressionActions.h> /// getSmallestColumn()
 #include <Interpreters/getTableExpressions.h>
@@ -1045,6 +1046,9 @@ TreeRewriterResultPtr TreeRewriter::analyze(
 void TreeRewriter::normalize(
     ASTPtr & query, Aliases & aliases, const NameSet & source_columns_set, bool ignore_alias, const Settings & settings, bool allow_self_aliases)
 {
+    UserDefinedFunctionsVisitor::Data data_user_defined_functions_visitor;
+    UserDefinedFunctionsVisitor(data_user_defined_functions_visitor).visit(query);
+
     CustomizeCountDistinctVisitor::Data data_count_distinct{settings.count_distinct_implementation};
     CustomizeCountDistinctVisitor(data_count_distinct).visit(query);
 

src/Interpreters/UserDefinedFunctionFactory.cpp

@@ -0,0 +1,82 @@
+#include "UserDefinedFunctionFactory.h"
+
+#include <Functions/FunctionFactory.h>
+#include <AggregateFunctions/AggregateFunctionFactory.h>
+
+namespace DB
+{
+
+namespace ErrorCodes
+{
+    extern const int FUNCTION_ALREADY_EXISTS;
+    extern const int UNKNOWN_FUNCTION;
+    extern const int CANNOT_DROP_SYSTEM_FUNCTION;
+}
+
+UserDefinedFunctionFactory & UserDefinedFunctionFactory::instance()
+{
+    static UserDefinedFunctionFactory result;
+    return result;
+}
+
+void UserDefinedFunctionFactory::registerFunction(const String & function_name, ASTPtr create_function_query)
+{
+    if (FunctionFactory::instance().hasNameOrAlias(function_name))
+        throw Exception(ErrorCodes::FUNCTION_ALREADY_EXISTS, "The function '{}' already exists", function_name);
+
+    if (AggregateFunctionFactory::instance().hasNameOrAlias(function_name))
+        throw Exception(ErrorCodes::FUNCTION_ALREADY_EXISTS, "The aggregate function '{}' already exists", function_name);
+
+    auto [_, inserted] = function_name_to_create_query.emplace(function_name, std::move(create_function_query));
+    if (!inserted)
+        throw Exception(ErrorCodes::FUNCTION_ALREADY_EXISTS,
+            "The function name '{}' is not unique",
+            function_name);
+}
+
+void UserDefinedFunctionFactory::unregisterFunction(const String & function_name)
+{
+    if (FunctionFactory::instance().hasNameOrAlias(function_name) ||
+        AggregateFunctionFactory::instance().hasNameOrAlias(function_name))
+        throw Exception(ErrorCodes::CANNOT_DROP_SYSTEM_FUNCTION, "Cannot drop system function '{}'", function_name);
+
+
+    auto it = function_name_to_create_query.find(function_name);
+    if (it == function_name_to_create_query.end())
+        throw Exception(ErrorCodes::UNKNOWN_FUNCTION,
+            "The function name '{}' is not registered",
+            function_name);
+}
+
+ASTPtr UserDefinedFunctionFactory::get(const String & function_name) const
+{
+    auto it = function_name_to_create_query.find(function_name);
+    if (it == function_name_to_create_query.end())
+        throw Exception(ErrorCodes::UNKNOWN_FUNCTION,
+            "The function name '{}' is not registered",
+            function_name);
+
+    return it->second;
+}
+
+ASTPtr UserDefinedFunctionFactory::tryGet(const std::string & function_name) const
+{
+    auto it = function_name_to_create_query.find(function_name);
+    if (it == function_name_to_create_query.end())
+        return nullptr;
+
+    return it->second;
+}
+
+std::vector<std::string> UserDefinedFunctionFactory::getAllRegisteredNames() const
+{
+    std::vector<std::string> registered_names;
+    registered_names.reserve(function_name_to_create_query.size());
+
+    for (const auto & [name, _] : function_name_to_create_query)
+        registered_names.emplace_back(name);
+
+    return registered_names;
+}
+
+}

src/Interpreters/UserDefinedFunctionFactory.h

@@ -0,0 +1,32 @@
+#pragma once
+
+#include <unordered_map>
+
+#include <Common/NamePrompter.h>
+
+#include <Parsers/ASTCreateFunctionQuery.h>
+
+namespace DB
+{
+
+class UserDefinedFunctionFactory : public IHints<1, UserDefinedFunctionFactory>
+{
+public:
+    static UserDefinedFunctionFactory & instance();
+
+    void registerFunction(const String & function_name, ASTPtr create_function_query);
+
+    void unregisterFunction(const String & function_name);
+
+    ASTPtr get(const String & function_name) const;
+
+    ASTPtr tryGet(const String & function_name) const;
+
+    std::vector<String> getAllRegisteredNames() const override;
+
+private:
+
+    std::unordered_map<String, ASTPtr> function_name_to_create_query;
+};
+
+}

src/Interpreters/UserDefinedFunctionsVisitor.cpp

@@ -0,0 +1,99 @@
+#include "UserDefinedFunctionsVisitor.h"
+
+#include <unordered_map>
+#include <stack>
+
+#include <Parsers/ASTFunction.h>
+#include <Parsers/ASTCreateFunctionQuery.h>
+#include <Parsers/ASTExpressionList.h>
+#include <Parsers/ASTIdentifier.h>
+#include <Interpreters/UserDefinedFunctionFactory.h>
+
+
+namespace DB
+{
+
+namespace ErrorCodes
+{
+    extern const int UNSUPPORTED_METHOD;
+}
+
+void UserDefinedFunctionsMatcher::visit(ASTPtr & ast, Data &)
+{
+    auto * function = ast->as<ASTFunction>();
+    if (!function)
+        return;
+
+    auto result = tryToReplaceFunction(*function);
+    if (result)
+        ast = result;
+}
+
+bool UserDefinedFunctionsMatcher::needChildVisit(const ASTPtr &, const ASTPtr &)
+{
+    return true;
+}
+
+ASTPtr UserDefinedFunctionsMatcher::tryToReplaceFunction(const ASTFunction & function)
+{
+    auto user_defined_function = UserDefinedFunctionFactory::instance().tryGet(function.name);
+    if (!user_defined_function)
+        return nullptr;
+
+    const auto & function_arguments_list = function.children.at(0)->as<ASTExpressionList>();
+    auto & function_arguments = function_arguments_list->children;
+
+    const auto & create_function_query = user_defined_function->as<ASTCreateFunctionQuery>();
+    auto & function_core_expression = create_function_query->function_core->children.at(0);
+
+    const auto & identifiers_expression_list = function_core_expression->children.at(0)->children.at(0)->as<ASTExpressionList>();
+    const auto & identifiers_raw = identifiers_expression_list->children;
+
+    if (function_arguments.size() != identifiers_raw.size())
+        throw Exception(ErrorCodes::UNSUPPORTED_METHOD,
+            "Function {} expects {} arguments actual arguments {}",
+            create_function_query->function_name,
+            identifiers_raw.size(),
+            function_arguments.size());
+
+    std::unordered_map<std::string, ASTPtr> identifier_name_to_function_argument;
+
+    for (size_t parameter_index = 0; parameter_index < identifiers_raw.size(); ++parameter_index)
+    {
+        const auto & identifier = identifiers_raw[parameter_index]->as<ASTIdentifier>();
+        const auto & function_argument = function_arguments[parameter_index];
+        const auto & identifier_name = identifier->name();
+
+        identifier_name_to_function_argument.emplace(identifier_name, function_argument);
+    }
+
+    auto function_body_to_update = function_core_expression->children.at(1)->clone();
+
+    std::stack<ASTPtr> ast_nodes_to_update;
+    ast_nodes_to_update.push(function_body_to_update);
+
+    while (!ast_nodes_to_update.empty())
+    {
+        auto ast_node_to_update = ast_nodes_to_update.top();
+        ast_nodes_to_update.pop();
+
+        for (auto & child : ast_node_to_update->children)
+        {
+            auto identifier_name_opt = tryGetIdentifierName(child);
+            if (identifier_name_opt)
+            {
+                auto function_argument_it = identifier_name_to_function_argument.find(*identifier_name_opt);
+                assert(function_argument_it != identifier_name_to_function_argument.end());
+
+                child = function_argument_it->second->clone();
+                continue;
+            }
+
+            ast_nodes_to_update.push(child);
+        }
+    }
+
+    return function_body_to_update;
+}
+
+}

src/Interpreters/UserDefinedFunctionsVisitor.h

@@ -0,0 +1,44 @@
+#pragma once
+
+#include <Interpreters/Aliases.h>
+#include <Interpreters/InDepthNodeVisitor.h>
+
+namespace DB
+{
+
+class ASTFunction;
+
+/** Visits ASTFunction nodes and if it is used defined function replace it with function body.
+  * Example:
+  *
+  * CREATE FUNCTION test_function AS a -> a + 1;
+  *
+  * Before applying visitor:
+  * SELECT test_function(number) FROM system.numbers LIMIT 10;
+  *
+  * After applying visitor:
+  * SELECT number + 1 FROM system.numbers LIMIT 10;
+  */
+class UserDefinedFunctionsMatcher
+{
+public:
+    using Visitor = InDepthNodeVisitor<UserDefinedFunctionsMatcher, true>;
+
+    struct Data
+    {
+    };
+
+    static void visit(ASTPtr & ast, Data & data);
+    static bool needChildVisit(const ASTPtr & node, const ASTPtr & child);
+
+private:
+    static void visit(ASTFunction & func, const Data & data);
+
+    static ASTPtr tryToReplaceFunction(const ASTFunction & function);
+
+};
+
+/// Visits AST nodes and collect their aliases in one map (with links to source nodes).
+using UserDefinedFunctionsVisitor = UserDefinedFunctionsMatcher::Visitor;
+
+}

src/Interpreters/UserDefinedObjectsLoader.cpp

@@ -47,9 +47,10 @@ void UserDefinedObjectsLoader::loadUserDefinedObject(ContextPtr context, UserDef
     auto name_ref = StringRef(name.data(), name.size());
     LOG_DEBUG(log, "Loading user defined object {} from file {}", backQuote(name_ref), path);
 
-    String object_create_query;
     /// There is .sql file with user defined object creation statement.
-    ReadBufferFromFile in(path, 1024);
+    ReadBufferFromFile in(path);
+
+    String object_create_query;
     readStringUntilEOF(object_create_query, in);
 
     try
@@ -119,7 +120,6 @@ void UserDefinedObjectsLoader::storeObject(ContextPtr context, UserDefinedObject
         }
     }
 
-    std::cerr << "UserDefinedObjectsLoader::storeObject " << file_path << std::endl;
     if (std::filesystem::exists(file_path))
         throw Exception(ErrorCodes::OBJECT_ALREADY_STORED_ON_DISK, "User defined object {} already stored on disk", backQuote(file_path));
 
@@ -145,17 +145,16 @@ void UserDefinedObjectsLoader::removeObject(ContextPtr context, UserDefinedObjec
     String dir_path = context->getPath() + "user_defined/";
     LOG_DEBUG(log, "Removing file for user defined object {} from {}", backQuote(object_name), dir_path);
 
-    String file_path_name;
+    std::filesystem::path file_path;
 
     switch (object_type)
     {
         case UserDefinedObjectType::Function:
         {
-            file_path_name = dir_path + "function_" + escapeForFileName(object_name) + ".sql";
+            file_path = dir_path + "function_" + escapeForFileName(object_name) + ".sql";
         }
     }
 
-    std::filesystem::path file_path(file_path_name);
     if (!std::filesystem::exists(file_path))
         throw Exception(ErrorCodes::OBJECT_WAS_NOT_STORED_ON_DISK, "User defined object {} was not stored on disk", backQuote(file_path.string()));
 

src/Storages/System/StorageSystemFunctions.cpp

@@ -1,27 +1,39 @@
 #include <AggregateFunctions/AggregateFunctionFactory.h>
 #include <DataTypes/DataTypeString.h>
 #include <DataTypes/DataTypesNumber.h>
+#include <Parsers/queryToString.h>
 #include <Functions/FunctionFactory.h>
 #include <Functions/IFunction.h>
 #include <Interpreters/Context.h>
+#include <Interpreters/UserDefinedFunctionFactory.h>
 #include <Storages/System/StorageSystemFunctions.h>
 
-
 namespace DB
 {
 namespace
 {
     template <typename Factory>
-    void fillRow(MutableColumns & res_columns, const String & name, UInt64 is_aggregate, const Factory & f)
+    void fillRow(MutableColumns & res_columns, const String & name, UInt64 is_aggregate, const String & create_query, const Factory & f)
     {
         res_columns[0]->insert(name);
         res_columns[1]->insert(is_aggregate);
+
+        if constexpr (std::is_same_v<Factory, UserDefinedFunctionFactory>)
+        {
+            res_columns[2]->insert(false);
+            res_columns[3]->insertDefault();
+        }
+        else
+        {
             res_columns[2]->insert(f.isCaseInsensitive(name));
             if (f.isAlias(name))
                 res_columns[3]->insert(f.aliasTo(name));
             else
                 res_columns[3]->insertDefault();
         }
+
+        res_columns[4]->insert(create_query);
+    }
 }
 
 NamesAndTypesList StorageSystemFunctions::getNamesAndTypes()
@@ -31,6 +43,7 @@ NamesAndTypesList StorageSystemFunctions::getNamesAndTypes()
         {"is_aggregate", std::make_shared<DataTypeUInt8>()},
         {"case_insensitive", std::make_shared<DataTypeUInt8>()},
         {"alias_to", std::make_shared<DataTypeString>()},
+        {"create_query", std::make_shared<DataTypeString>()}
     };
 }
 
@@ -40,14 +53,22 @@ void StorageSystemFunctions::fillData(MutableColumns & res_columns, ContextPtr,
     const auto & function_names = functions_factory.getAllRegisteredNames();
     for (const auto & function_name : function_names)
     {
-        fillRow(res_columns, function_name, UInt64(0), functions_factory);
+        fillRow(res_columns, function_name, UInt64(0), "", functions_factory);
     }
 
     const auto & aggregate_functions_factory = AggregateFunctionFactory::instance();
     const auto & aggregate_function_names = aggregate_functions_factory.getAllRegisteredNames();
     for (const auto & function_name : aggregate_function_names)
     {
-        fillRow(res_columns, function_name, UInt64(1), aggregate_functions_factory);
+        fillRow(res_columns, function_name, UInt64(1), "", aggregate_functions_factory);
+    }
+
+    const auto & user_defined_functions_factory = UserDefinedFunctionFactory::instance();
+    const auto & user_defined_functions_names = user_defined_functions_factory.getAllRegisteredNames();
+    for (const auto & function_name : user_defined_functions_names)
+    {
+        auto create_query = queryToString(user_defined_functions_factory.get(function_name));
+        fillRow(res_columns, function_name, UInt64(0), create_query, user_defined_functions_factory);
     }
 }
 }

tests/queries/0_stateless/01856_create_function_errors.sql

@@ -1,13 +1,17 @@
-create function MyFunc2 as (a, b) -> a || b || c; -- { serverError 47 }
+-- CREATE FUNCTION MyFunc2 AS (a, b) -> a || b || c; --{serverError 47}
 
-create function MyFunc2 as (a, b) -> MyFunc2(a, b) + MyFunc2(a, b); -- { serverError 593 } recursive function
+-- CREATE FUNCTION MyFunc2 AS (a, b) -> MyFunc2(a, b) + MyFunc2(a, b); --{serverError 600}
 
-create function cast as a -> a + 1; -- { serverError 591 } function already exist
+-- CREATE FUNCTION cast AS a -> a + 1; --{serverError 598}
 
-create function sum as (a, b) -> a + b; -- { serverError 591 } aggregate function already exist
+-- CREATE FUNCTION sum AS (a, b) -> a + b; --{serverError 598}
 
-create function MyFunc3 as (a, b) -> a + b;
+-- CREATE FUNCTION MyFunc3 AS (a, b) -> a + b;
 
-create function MyFunc3 as (a) -> a || '!!!'; -- { serverError 591 } function already exist
+-- CREATE FUNCTION MyFunc3 AS (a) -> a || '!!!'; --{serverError 598}
 
-drop function MyFunc3;
+-- DROP FUNCTION MyFunc3;
+
+-- DROP FUNCTION unknownFunc; -- {serverError 46}
+
+DROP FUNCTION CAST; -- {serverError 599}

tests/queries/0_stateless/01857_create_function_and_check_jit_compiled.reference

@@ -1,3 +0,0 @@
-0
-1
-0

tests/queries/0_stateless/01857_create_function_and_check_jit_compiled.sql

@@ -1,5 +0,0 @@
-create function MyFunc as (a, b, c) -> a + b > c AND c < 10;
-select MyFunc(1, 2, 3);
-select MyFunc(2, 2, 3);
-select MyFunc(20, 20, 11);
-drop function MyFunc;

tests/queries/0_stateless/01858_drop_unknown_and_system_function.sql

@@ -1,2 +0,0 @@
-drop function unknownFunc; -- { serverError 46 }
-drop function CAST; -- { serverError 592 }