diff --git a/src/Functions/FunctionFactory.cpp b/src/Functions/FunctionFactory.cpp
index 35ac9ab647b..7f330d45c37 100644
--- a/src/Functions/FunctionFactory.cpp
+++ b/src/Functions/FunctionFactory.cpp
@@ -1,4 +1,5 @@
 #include <Functions/FunctionFactory.h>
+#include <Functions/UserDefinedFunction.h>
 
 #include <Interpreters/Context.h>
 
@@ -133,4 +134,19 @@ FunctionFactory & FunctionFactory::instance()
     return ret;
 }
 
+void FunctionFactory::registerUserDefinedFunction(
+        const ASTCreateFunctionQuery & create_function_query,
+        CaseSensitiveness case_sensitiveness)
+{
+    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);
+
+        FunctionOverloadResolverImplPtr res = std::make_unique<DefaultOverloadResolver>(function);
+        return res;
+    }, case_sensitiveness);
+}
+
 }
diff --git a/src/Functions/FunctionFactory.h b/src/Functions/FunctionFactory.h
index 96238a88420..176178f7593 100644
--- a/src/Functions/FunctionFactory.h
+++ b/src/Functions/FunctionFactory.h
@@ -1,8 +1,10 @@
 #pragma once
 
 #include <Functions/IFunctionAdaptors.h>
+#include <Functions/UserDefinedFunction.h>
 #include <Interpreters/Context_fwd.h>
 #include <Common/IFactoryWithAliases.h>
+#include <Parsers/ASTCreateFunctionQuery.h>
 
 #include <functional>
 #include <memory>
@@ -13,6 +15,8 @@
 namespace DB
 {
 
+class UserDefinedFunction;
+
 /** Creates function by name.
   * Function could use for initialization (take ownership of shared_ptr, for example)
   *  some dictionaries from Context.
@@ -38,6 +42,10 @@ public:
             registerFunction(name, &Function::create, case_sensitiveness);
     }
 
+    void registerUserDefinedFunction(
+            const ASTCreateFunctionQuery & create_function_query,
+            CaseSensitiveness case_sensitiveness = CaseSensitive);
+
     /// This function is used by YQL - internal Yandex product that depends on ClickHouse by source code.
     std::vector<std::string> getAllNames() const;
 
diff --git a/src/Functions/UserDefinedFunction.cpp b/src/Functions/UserDefinedFunction.cpp
new file mode 100644
index 00000000000..b7b4ff8de3e
--- /dev/null
+++ b/src/Functions/UserDefinedFunction.cpp
@@ -0,0 +1,90 @@
+#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);
+        block.insert({arguments[j].column, 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;
+}
+
+}
diff --git a/src/Functions/UserDefinedFunction.h b/src/Functions/UserDefinedFunction.h
new file mode 100644
index 00000000000..2b519740204
--- /dev/null
+++ b/src/Functions/UserDefinedFunction.h
@@ -0,0 +1,37 @@
+#pragma once
+
+#include <Functions/FunctionFactory.h>
+#include <Functions/IFunctionImpl.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_);
+
+private:
+    Block executeCore(const ColumnsWithTypeAndName & arguments) const;
+
+private:
+    String name;
+    ASTPtr function_core;
+    ContextPtr context;
+};
+
+}
diff --git a/src/Functions/ya.make b/src/Functions/ya.make
index 2a541369ff4..fef9bae3685 100644
--- a/src/Functions/ya.make
+++ b/src/Functions/ya.make
@@ -104,6 +104,7 @@ SRCS(
     URL/registerFunctionsURL.cpp
     URL/tldLookup.generated.cpp
     URL/topLevelDomain.cpp
+    UserDefinedFunction.cpp
     abs.cpp
     acos.cpp
     acosh.cpp
diff --git a/src/Interpreters/InterpreterCreateFunctionQuery.cpp b/src/Interpreters/InterpreterCreateFunctionQuery.cpp
new file mode 100644
index 00000000000..4fa524534f3
--- /dev/null
+++ b/src/Interpreters/InterpreterCreateFunctionQuery.cpp
@@ -0,0 +1,18 @@
+#include <Interpreters/ExpressionActions.h>
+#include <Interpreters/ExpressionAnalyzer.h>
+#include <Interpreters/InterpreterCreateFunctionQuery.h>
+#include <Interpreters/FunctionNameNormalizer.h>
+#include <Functions/FunctionFactory.h>
+
+namespace DB
+{
+
+BlockIO InterpreterCreateFunctionQuery::execute()
+{
+    FunctionNameNormalizer().visit(query_ptr.get());
+    auto & create_function_query = query_ptr->as<ASTCreateFunctionQuery &>();
+    FunctionFactory::instance().registerUserDefinedFunction(create_function_query);
+    return {};
+}
+
+}
diff --git a/src/Interpreters/InterpreterCreateFunctionQuery.h b/src/Interpreters/InterpreterCreateFunctionQuery.h
new file mode 100644
index 00000000000..81347bcc711
--- /dev/null
+++ b/src/Interpreters/InterpreterCreateFunctionQuery.h
@@ -0,0 +1,22 @@
+#pragma once
+
+#include <Interpreters/IInterpreter.h>
+#include <Parsers/ASTCreateFunctionQuery.h>
+
+namespace DB
+{
+
+class ASTCreateFunctionQuery;
+
+class InterpreterCreateFunctionQuery : public IInterpreter, WithContext
+{
+public:
+    InterpreterCreateFunctionQuery(const ASTPtr & query_ptr_, ContextPtr context_) : WithContext(context_), query_ptr(query_ptr_) {}
+
+    BlockIO execute() override;
+
+private:
+    ASTPtr query_ptr;
+};
+
+}
diff --git a/src/Interpreters/InterpreterFactory.cpp b/src/Interpreters/InterpreterFactory.cpp
index 4af8b6ffa7d..54122292589 100644
--- a/src/Interpreters/InterpreterFactory.cpp
+++ b/src/Interpreters/InterpreterFactory.cpp
@@ -33,6 +33,7 @@
 #include <Interpreters/Context.h>
 #include <Interpreters/InterpreterAlterQuery.h>
 #include <Interpreters/InterpreterCheckQuery.h>
+#include <Interpreters/InterpreterCreateFunctionQuery.h>
 #include <Interpreters/InterpreterCreateQuery.h>
 #include <Interpreters/InterpreterCreateQuotaQuery.h>
 #include <Interpreters/InterpreterCreateRoleQuery.h>
@@ -264,6 +265,10 @@ std::unique_ptr<IInterpreter> InterpreterFactory::get(ASTPtr & query, ContextPtr
     {
         return std::make_unique<InterpreterExternalDDLQuery>(query, context);
     }
+    else if (query->as<ASTCreateFunctionQuery>())
+    {
+        return std::make_unique<InterpreterCreateFunctionQuery>(query, context);
+    }
     else
     {
         throw Exception("Unknown type of query: " + query->getID(), ErrorCodes::UNKNOWN_TYPE_OF_QUERY);
diff --git a/src/Interpreters/ya.make b/src/Interpreters/ya.make
index 105e1e11365..5c49c7e8946 100644
--- a/src/Interpreters/ya.make
+++ b/src/Interpreters/ya.make
@@ -54,7 +54,7 @@ SRCS(
     ExpressionAnalyzer.cpp
     ExternalDictionariesLoader.cpp
     ExternalLoader.cpp
-    ExternalLoaderDictionaryStorageConfigRepository.cpp
+    ExternalLoaderDatabaseConfigRepository.cpp
     ExternalLoaderTempConfigRepository.cpp
     ExternalLoaderXMLConfigRepository.cpp
     ExternalModelsLoader.cpp
@@ -70,6 +70,7 @@ SRCS(
     InternalTextLogsQueue.cpp
     InterpreterAlterQuery.cpp
     InterpreterCheckQuery.cpp
+    InterpreterCreateFunctionQuery.cpp
     InterpreterCreateQuery.cpp
     InterpreterCreateQuotaQuery.cpp
     InterpreterCreateRoleQuery.cpp
diff --git a/src/Parsers/ASTCreateFunctionQuery.cpp b/src/Parsers/ASTCreateFunctionQuery.cpp
new file mode 100644
index 00000000000..0b3991ddc44
--- /dev/null
+++ b/src/Parsers/ASTCreateFunctionQuery.cpp
@@ -0,0 +1,21 @@
+#include <Common/quoteString.h>
+#include <IO/Operators.h>
+#include <Parsers/ASTCreateFunctionQuery.h>
+
+namespace DB
+{
+
+ASTPtr ASTCreateFunctionQuery::clone() const
+{
+    return std::make_shared<ASTCreateFunctionQuery>(*this);
+}
+
+void ASTCreateFunctionQuery::formatImpl(const IAST::FormatSettings & settings, IAST::FormatState & state, IAST::FormatStateStacked frame) const
+{
+    settings.ostr << (settings.hilite ? hilite_keyword : "") << "CREATE FUNCTION " << (settings.hilite ? hilite_none : "");
+    settings.ostr << (settings.hilite ? hilite_identifier : "") << backQuoteIfNeed(function_name) << (settings.hilite ? hilite_none : "");
+    settings.ostr << (settings.hilite ? hilite_keyword : "") << " AS " << (settings.hilite ? hilite_none : "");
+    function_core->formatImpl(settings, state, frame);
+}
+
+}
diff --git a/src/Parsers/ASTCreateFunctionQuery.h b/src/Parsers/ASTCreateFunctionQuery.h
new file mode 100644
index 00000000000..3adddad8fbd
--- /dev/null
+++ b/src/Parsers/ASTCreateFunctionQuery.h
@@ -0,0 +1,22 @@
+#pragma once
+
+#include <Parsers/ASTExpressionList.h>
+#include <Parsers/ASTFunction.h>
+
+namespace DB
+{
+
+class ASTCreateFunctionQuery : public IAST
+{
+public:
+    String function_name;
+    ASTPtr function_core;
+
+    String getID(char) const override { return "CreateFunctionQuery"; }
+
+    ASTPtr clone() const override;
+
+    void formatImpl(const FormatSettings & s, FormatState & state, FormatStateStacked frame) const override;
+};
+
+}
diff --git a/src/Parsers/ParserCreateFunctionQuery.cpp b/src/Parsers/ParserCreateFunctionQuery.cpp
new file mode 100644
index 00000000000..1fcce6cbf45
--- /dev/null
+++ b/src/Parsers/ParserCreateFunctionQuery.cpp
@@ -0,0 +1,46 @@
+#include <Parsers/ASTCreateFunctionQuery.h>
+#include <Parsers/ASTExpressionList.h>
+#include <Parsers/ASTIdentifier.h>
+#include <Parsers/CommonParsers.h>
+#include <Parsers/ExpressionElementParsers.h>
+#include <Parsers/ExpressionListParsers.h>
+#include <Parsers/ParserCreateFunctionQuery.h>
+
+namespace DB
+{
+bool ParserCreateFunctionQuery::parseImpl(IParser::Pos & pos, ASTPtr & node, Expected & expected)
+{
+    ParserKeyword s_create("CREATE");
+    ParserKeyword s_function("FUNCTION");
+    ParserIdentifier function_name_p;
+    ParserKeyword s_as("AS");
+    ParserLambdaExpression lambda_p;
+
+    ASTPtr function_name;
+    ASTPtr function_core;
+
+    if (!s_create.ignore(pos, expected))
+        return false;
+
+    if (!s_function.ignore(pos, expected))
+        return false;
+
+    if (!function_name_p.parse(pos, function_name, expected))
+        return false;
+
+    if (!s_as.ignore(pos, expected))
+        return false;
+
+    if (!lambda_p.parse(pos, function_core, expected))
+        return false;
+
+    auto create_function_query = std::make_shared<ASTCreateFunctionQuery>();
+    node = create_function_query;
+
+    create_function_query->function_name = function_name->as<ASTIdentifier &>().name();
+    create_function_query->function_core = function_core;
+
+    return true;
+}
+
+}
diff --git a/src/Parsers/ParserCreateFunctionQuery.h b/src/Parsers/ParserCreateFunctionQuery.h
new file mode 100644
index 00000000000..a48bbdeb563
--- /dev/null
+++ b/src/Parsers/ParserCreateFunctionQuery.h
@@ -0,0 +1,15 @@
+#pragma once
+
+#include "IParserBase.h"
+
+namespace DB
+{
+/// CREATE FUNCTION test AS x -> x || '1'
+class ParserCreateFunctionQuery : public IParserBase
+{
+protected:
+    const char * getName() const override { return "CREATE FUNCTION query"; }
+    bool parseImpl(Pos & pos, ASTPtr & node, Expected & expected) override;
+};
+
+}
diff --git a/src/Parsers/ParserQuery.cpp b/src/Parsers/ParserQuery.cpp
index 4550bdc8a75..274dc0201b3 100644
--- a/src/Parsers/ParserQuery.cpp
+++ b/src/Parsers/ParserQuery.cpp
@@ -1,4 +1,5 @@
 #include <Parsers/ParserAlterQuery.h>
+#include <Parsers/ParserCreateFunctionQuery.h>
 #include <Parsers/ParserCreateQuery.h>
 #include <Parsers/ParserCreateQuotaQuery.h>
 #include <Parsers/ParserCreateRoleQuery.h>
@@ -36,6 +37,7 @@ bool ParserQuery::parseImpl(Pos & pos, ASTPtr & node, Expected & expected)
     ParserCreateQuotaQuery create_quota_p;
     ParserCreateRowPolicyQuery create_row_policy_p;
     ParserCreateSettingsProfileQuery create_settings_profile_p;
+    ParserCreateFunctionQuery create_function_p;
     ParserDropAccessEntityQuery drop_access_entity_p;
     ParserGrantQuery grant_p;
     ParserSetRoleQuery set_role_p;
@@ -52,6 +54,7 @@ bool ParserQuery::parseImpl(Pos & pos, ASTPtr & node, Expected & expected)
         || create_quota_p.parse(pos, node, expected)
         || create_row_policy_p.parse(pos, node, expected)
         || create_settings_profile_p.parse(pos, node, expected)
+        || create_function_p.parse(pos, node, expected)
         || drop_access_entity_p.parse(pos, node, expected)
         || grant_p.parse(pos, node, expected)
         || external_ddl_p.parse(pos, node, expected);
diff --git a/src/Parsers/ya.make b/src/Parsers/ya.make
index 4bd31cb79de..3b9fcb33e0f 100644
--- a/src/Parsers/ya.make
+++ b/src/Parsers/ya.make
@@ -15,6 +15,7 @@ SRCS(
     ASTColumnsMatcher.cpp
     ASTColumnsTransformers.cpp
     ASTConstraintDeclaration.cpp
+    ASTCreateFunctionQuery.cpp
     ASTCreateQuery.cpp
     ASTCreateQuotaQuery.cpp
     ASTCreateRoleQuery.cpp
@@ -86,6 +87,7 @@ SRCS(
     ParserAlterQuery.cpp
     ParserCase.cpp
     ParserCheckQuery.cpp
+    ParserCreateFunctionQuery.cpp
     ParserCreateQuery.cpp
     ParserCreateQuotaQuery.cpp
     ParserCreateRoleQuery.cpp