diff --git a/include/matador/sql/internal/query_result_impl.hpp b/include/matador/sql/internal/query_result_impl.hpp
index c746e56..a7e5252 100644
--- a/include/matador/sql/internal/query_result_impl.hpp
+++ b/include/matador/sql/internal/query_result_impl.hpp
@@ -161,13 +161,13 @@ template <class CollectionType>
 void query_result_impl::on_has_many(const char *id, CollectionType &cont, const char *join_column, const utils::foreign_attributes &attr, std::enable_if_t<!object::is_object_ptr<typename CollectionType::value_type>::value> *) {
   using value_type = typename CollectionType::value_type;
   auto object_resolver = resolver_->object_resolver<value_type>();
-  auto resolver = resolver_->collection_resolver<typename CollectionType::value_type>(result_type_, join_column);
+  auto resolver = resolver_->collection_resolver<value_type>(result_type_, join_column);
 
   if (attr.fetch() == utils::fetch_type::Lazy) {
-    cont.reset(std::make_shared<object::collection_proxy<typename CollectionType::value_type>>(resolver, current_pk_));
+    cont.reset(std::make_shared<object::collection_proxy<value_type>>(resolver, current_pk_));
   } else {
-    if (initialized_collections_.insert({result_type_, typeid(typename CollectionType::value_type), std::string{join_column}}).second) {
-      cont.reset(std::make_shared<object::collection_proxy<typename CollectionType::value_type>>(resolver, std::vector<typename CollectionType::value_type>()));
+    if (initialized_collections_.insert({result_type_, typeid(value_type), std::string{join_column}}).second) {
+      cont.reset(std::make_shared<object::collection_proxy<value_type>>(resolver, std::vector<value_type>()));
     }
 
     // read a single value
diff --git a/include/matador/utils/types.hpp b/include/matador/utils/types.hpp
index 49fd018..7e7fab7 100644
--- a/include/matador/utils/types.hpp
+++ b/include/matador/utils/types.hpp
@@ -46,6 +46,23 @@ struct time_type_t {
   uint32_t microsecond{};
 };
 
+namespace detail {
+template <typename T, typename Variant>
+struct is_in_variant;
+
+template <typename T, typename... Alts>
+struct is_in_variant<T, std::variant<Alts...>>
+  : std::bool_constant<(std::is_same_v<T, Alts> || ...)> {
+};
+}
+
+template<typename T>
+struct is_database_primitive : detail::is_in_variant<std::remove_cv_t<std::remove_reference_t<T>>, database_type> {
+};
+
+template <typename T>
+inline constexpr bool is_database_primitive_v = is_database_primitive<T>::value;
+
 void initialize_by_basic_type(basic_type type, database_type &val);
 
 
diff --git a/source/core/logger/log_manager.cpp b/source/core/logger/log_manager.cpp
index 4e747b5..4ca78bd 100644
--- a/source/core/logger/log_manager.cpp
+++ b/source/core/logger/log_manager.cpp
@@ -36,6 +36,7 @@ void log_manager::clear_all_sinks(const std::string &domain_name) {
 void log_manager::clear() {
   std::lock_guard lock(mutex_);
   log_domain_map_.clear();
+  default_log_domain_->clear();
 }
 
 void log_manager::max_default_log_level(const log_level max_level) {
diff --git a/test/core/CMakeLists.txt b/test/core/CMakeLists.txt
index 6fc35b7..602b50d 100644
--- a/test/core/CMakeLists.txt
+++ b/test/core/CMakeLists.txt
@@ -19,6 +19,7 @@ add_executable(CoreTests
   utils/StringTest.cpp
   utils/ThreadPoolTest.cpp
   utils/VersionTest.cpp
+  utils/IsDatabasePrimitiveTest.cpp
 )
 
 target_link_libraries(CoreTests matador-core Catch2::Catch2WithMain)
diff --git a/test/core/object/RepositoryTest.cpp b/test/core/object/RepositoryTest.cpp
index 5d38897..97c78fd 100644
--- a/test/core/object/RepositoryTest.cpp
+++ b/test/core/object/RepositoryTest.cpp
@@ -15,15 +15,12 @@ struct person {
   virtual ~person() = default;
 
   template<typename Operator>
-  void process(Operator &/*op*/) {
-  }
+  static void process(Operator &/*op*/) {}
 };
 
-struct student final : person {
-};
+struct student final : person {};
 
-struct teacher final : person {
-};
+struct teacher final : person {};
 
 struct names {
   unsigned int id{};
diff --git a/test/core/utils/IsDatabasePrimitiveTest.cpp b/test/core/utils/IsDatabasePrimitiveTest.cpp
new file mode 100644
index 0000000..2c7c1e3
--- /dev/null
+++ b/test/core/utils/IsDatabasePrimitiveTest.cpp
@@ -0,0 +1,57 @@
+// tests/test_is_database_primitive.cpp
+#include <catch2/catch_test_macros.hpp>
+
+#include "matador/utils/types.hpp"
+
+#include <string>
+
+using namespace matador::utils;
+
+TEST_CASE("is_database_primitive: true for all database_type alternatives", "[type_traits]") {
+  STATIC_REQUIRE(is_database_primitive_v<uint8_t>);
+  STATIC_REQUIRE(is_database_primitive_v<uint16_t>);
+  STATIC_REQUIRE(is_database_primitive_v<uint32_t>);
+  STATIC_REQUIRE(is_database_primitive_v<uint64_t>);
+
+  STATIC_REQUIRE(is_database_primitive_v<int8_t>);
+  STATIC_REQUIRE(is_database_primitive_v<int16_t>);
+  STATIC_REQUIRE(is_database_primitive_v<int32_t>);
+  STATIC_REQUIRE(is_database_primitive_v<int64_t>);
+
+  STATIC_REQUIRE(is_database_primitive_v<float>);
+  STATIC_REQUIRE(is_database_primitive_v<double>);
+
+  STATIC_REQUIRE(is_database_primitive_v<bool>);
+
+  STATIC_REQUIRE(is_database_primitive_v<const char*>);
+  STATIC_REQUIRE(is_database_primitive_v<std::string>);
+
+  STATIC_REQUIRE(is_database_primitive_v<blob_type_t>);
+  STATIC_REQUIRE(is_database_primitive_v<timestamp_type_t>);
+  STATIC_REQUIRE(is_database_primitive_v<date_type_t>);
+  STATIC_REQUIRE(is_database_primitive_v<time_type_t>);
+
+  STATIC_REQUIRE(is_database_primitive_v<std::nullptr_t>);
+}
+
+TEST_CASE("is_database_primitive: strips cv/ref qualifiers", "[type_traits]") {
+  STATIC_REQUIRE(is_database_primitive_v<const std::string&>);
+  STATIC_REQUIRE(is_database_primitive_v<volatile uint32_t>);
+  STATIC_REQUIRE(is_database_primitive_v<const blob_type_t&&>);
+  STATIC_REQUIRE(is_database_primitive_v<const date_type_t&>);
+  STATIC_REQUIRE(is_database_primitive_v<const std::nullptr_t&>);
+}
+
+TEST_CASE("is_database_primitive: false for non-alternatives (even if convertible)", "[type_traits]") {
+  STATIC_REQUIRE_FALSE(is_database_primitive_v<char*>);            // not const char*
+  STATIC_REQUIRE_FALSE(is_database_primitive_v<char const[4]>);    // array type != const char*
+  STATIC_REQUIRE_FALSE(is_database_primitive_v<std::string_view>); // not in variant
+  STATIC_REQUIRE_FALSE(is_database_primitive_v<long double>);      // not in variant
+  STATIC_REQUIRE_FALSE(is_database_primitive_v<void*>);            // not in variant
+  STATIC_REQUIRE_FALSE(is_database_primitive_v<null_type_t>);      // your custom null wrapper isn't in variant
+}
+
+TEST_CASE("is_database_primitive: works via ::value too", "[type_traits]") {
+  STATIC_REQUIRE(is_database_primitive<int32_t>::value);
+  // STATIC_REQUIRE(is_database_primitive<unsigned>::value); // assuming unsigned != uint32_t on your platform
+}
\ No newline at end of file