SQLUserDefinedFunctions added DROP IF EXISTS support

src/Interpreters/InterpreterDropFunctionQuery.cpp

@@ -18,6 +18,11 @@ BlockIO InterpreterDropFunctionQuery::execute()
     FunctionNameNormalizer().visit(query_ptr.get());
     auto & drop_function_query = query_ptr->as<ASTDropFunctionQuery &>();
 
+    auto & user_defined_functions_factory = UserDefinedSQLFunctionFactory::instance();
+
+    if (drop_function_query.if_exists && !user_defined_functions_factory.has(drop_function_query.function_name))
+        return {};
+
     UserDefinedSQLFunctionFactory::instance().unregisterFunction(drop_function_query.function_name);
     UserDefinedSQLObjectsLoader::instance().removeObject(current_context, UserDefinedSQLObjectType::Function, drop_function_query.function_name);
 

src/Interpreters/UserDefinedSQLFunctionFactory.cpp

@@ -77,6 +77,11 @@ ASTPtr UserDefinedSQLFunctionFactory::tryGet(const std::string & function_name)
     return it->second;
 }
 
+bool UserDefinedSQLFunctionFactory::has(const String & function_name) const
+{
+    return tryGet(function_name) != nullptr;
+}
+
 std::vector<std::string> UserDefinedSQLFunctionFactory::getAllRegisteredNames() const
 {
     std::vector<std::string> registered_names;

src/Interpreters/UserDefinedSQLFunctionFactory.h

@@ -23,6 +23,8 @@ public:
 
     ASTPtr tryGet(const String & function_name) const;
 
+    bool has(const String & function_name) const;
+
     std::vector<String> getAllRegisteredNames() const override;
 
 private:

src/Parsers/ASTDropFunctionQuery.cpp

@@ -14,6 +14,8 @@ void ASTDropFunctionQuery::formatImpl(const IAST::FormatSettings & settings, IAS
 {
     settings.ostr << (settings.hilite ? hilite_keyword : "") << "DROP FUNCTION " << (settings.hilite ? hilite_none : "");
     settings.ostr << (settings.hilite ? hilite_identifier : "") << backQuoteIfNeed(function_name) << (settings.hilite ? hilite_none : "");
+    if (if_exists)
+        settings.ostr << "IF EXISTS";
 }
 
 }

src/Parsers/ASTDropFunctionQuery.h

@@ -10,6 +10,8 @@ class ASTDropFunctionQuery : public IAST
 public:
     String function_name;
 
+    bool if_exists = false;
+
     String getID(char) const override { return "DropFunctionQuery"; }
 
     ASTPtr clone() const override;

src/Parsers/ParserDropFunctionQuery.cpp

@@ -11,7 +11,10 @@ bool ParserDropFunctionQuery::parseImpl(IParser::Pos & pos, ASTPtr & node, Expec
 {
     ParserKeyword s_drop("DROP");
     ParserKeyword s_function("FUNCTION");
+    ParserKeyword s_if_exists("IF EXISTS");
+
     ParserIdentifier function_name_p;
+    bool if_exists = false;
 
     ASTPtr function_name;
 
@@ -21,10 +24,14 @@ bool ParserDropFunctionQuery::parseImpl(IParser::Pos & pos, ASTPtr & node, Expec
     if (!s_function.ignore(pos, expected))
         return false;
 
+    if (s_if_exists.ignore(pos, expected))
+        if_exists = true;
+
     if (!function_name_p.parse(pos, function_name, expected))
         return false;
 
     auto drop_function_query = std::make_shared<ASTDropFunctionQuery>();
+    drop_function_query->if_exists = if_exists;
     node = drop_function_query;
 
     drop_function_query->function_name = function_name->as<ASTIdentifier &>().name();

tests/queries/0_stateless/02101_sql_user_defined_functions_drop_if_exists.reference

@@ -0,0 +1 @@
+2

tests/queries/0_stateless/02101_sql_user_defined_functions_drop_if_exists.sql

@@ -0,0 +1,9 @@
+-- Tags: no-parallel
+
+CREATE FUNCTION 02101_test_function AS x -> x + 1;
+
+SELECT 02101_test_function(1);
+
+DROP FUNCTION 02101_test_function;
+DROP FUNCTION 02101_test_function; --{serverError 46}
+DROP FUNCTION IF EXISTS 02101_test_function;