From ab2d39407c9eee80f311bba8a817e5446a0dce77 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Sascha=20K=C3=BChl?= <skuehl1972@gmail.com>
Date: Wed, 31 Dec 2025 11:56:12 +0100
Subject: [PATCH] schema progress (does not compile)

---
 .../matador/object/foreign_node_completer.hpp |  83 +---
 .../internal/observer_list_copy_creator.hpp   |  57 +++
 .../object/internal/observer_list_creator.hpp |  69 ++++
 .../object/internal/shadow_repository.hpp     |   5 +
 include/matador/object/object_generator.hpp   |  12 +-
 include/matador/object/object_info.hpp        |  44 +-
 include/matador/object/observer.hpp           |  10 +-
 include/matador/object/relation_completer.hpp | 111 ++---
 include/matador/object/relation_endpoint.hpp  |   2 +-
 include/matador/object/repository.hpp         |  48 ++-
 include/matador/object/repository_node.hpp    |  45 +-
 include/matador/orm/session_query_builder.hpp | 199 +++++----
 include/matador/query/builder.hpp             |  20 +-
 include/matador/query/column.hpp              |  11 +-
 include/matador/query/constraint.hpp          |   3 +
 .../criteria/abstract_column_criteria.hpp     |   6 +-
 .../query/criteria/between_criteria.hpp       |   6 +-
 .../query/criteria/binary_criteria.hpp        |  12 +-
 .../query/criteria/collection_criteria.hpp    |  10 +-
 .../query/criteria/criteria_operators.hpp     |  54 +--
 .../matador/query/criteria/like_criteria.hpp  |   6 +-
 include/matador/query/generator.hpp           |  17 -
 .../query_insert_intermediate.hpp             |   9 +-
 include/matador/query/query.hpp               |   5 +-
 include/matador/query/query_compiler.hpp      |   6 +-
 include/matador/query/query_utils.hpp         |   1 -
 include/matador/query/schema.hpp              |  82 ++--
 include/matador/query/table.hpp               |  30 +-
 include/matador/sql/query_macro.hpp           |   9 +-
 source/core/CMakeLists.txt                    |   2 +
 source/core/object/attribute.cpp              |   4 +-
 .../object/internal/shadow_repository.cpp     |  18 +-
 source/core/object/object_generator.cpp       |   2 +-
 source/core/object/repository.cpp             |  23 +-
 source/core/object/repository_node.cpp        |   6 -
 source/orm/orm/session.cpp                    |   2 +-
 source/orm/orm/session_query_builder.cpp      |  19 +-
 source/orm/query/builder.cpp                  |  37 +-
 source/orm/query/column.cpp                   |  69 +++-
 source/orm/query/constraint.cpp               |  17 +
 .../criteria/abstract_column_criteria.cpp     |   4 +-
 .../orm/query/criteria/between_criteria.cpp   |   8 +-
 source/orm/query/criteria/binary_criteria.cpp |  14 +-
 .../query/criteria/collection_criteria.cpp    |  13 +-
 source/orm/query/criteria/like_criteria.cpp   |   5 +-
 source/orm/query/generator.cpp                |   5 -
 .../query_create_intermediate.cpp             |  30 +-
 source/orm/query/query_compiler.cpp           |  38 +-
 source/orm/query/query_utils.cpp              |  32 +-
 source/orm/query/schema.cpp                   | 391 ++++++++++--------
 source/orm/query/table.cpp                    |  90 +++-
 test/backends/QueryBasicTest.cpp              |  14 +-
 test/backends/QueryFixture.cpp                |   2 +
 test/backends/QueryFixture.hpp                |   6 +-
 test/backends/QueryRecordTest.cpp             | 138 ++++---
 test/backends/QueryStatementTests.cpp         |  50 +--
 test/backends/QueryTest.cpp                   |  15 +-
 test/backends/SchemaTest.cpp                  |  22 +-
 test/backends/StatementTest.cpp               |  11 +-
 test/backends/TypeTraitsTest.cpp              |   2 +-
 test/core/object/RepositoryTest.cpp           |  31 +-
 test/orm/orm/SessionQueryBuilderTest.cpp      | 119 ++++--
 test/orm/query/GeneratorTests.cpp             |  30 +-
 test/orm/query/QueryBuilderTest.cpp           |  30 +-
 test/orm/sql/ColumnGeneratorTest.cpp          |   6 +-
 65 files changed, 1355 insertions(+), 922 deletions(-)
 create mode 100644 include/matador/object/internal/observer_list_copy_creator.hpp
 create mode 100644 include/matador/object/internal/observer_list_creator.hpp

diff --git a/include/matador/object/foreign_node_completer.hpp b/include/matador/object/foreign_node_completer.hpp
index f771b69..01e8ff2 100644
--- a/include/matador/object/foreign_node_completer.hpp
+++ b/include/matador/object/foreign_node_completer.hpp
@@ -2,6 +2,7 @@
 #define FOREIGN_NODE_COMPLETER_HPP
 
 #include "matador/object/internal/shadow_repository.hpp"
+#include "matador/object/internal/observer_list_copy_creator.hpp"
 #include "matador/object/many_to_many_relation.hpp"
 #include "matador/object/repository_node.hpp"
 #include "matador/object/join_columns_collector.hpp"
@@ -35,9 +36,9 @@ private:
   using node_ptr = std::shared_ptr<repository_node>;
 
 public:
-  static void complete(const std::shared_ptr<repository_node> &node, Observers<NodeType>... observers) {
+  static void complete(const std::shared_ptr<repository_node> &node, const std::vector<std::unique_ptr<observer<NodeType>>> &observers) {
     internal::shadow_repository shadow(node->repo_);
-    foreign_node_completer completer(shadow, observers...);
+    foreign_node_completer completer(shadow, observers);
 
     completer.complete_node(node);
   }
@@ -77,11 +78,10 @@ public:
   static void on_has_many_to_many(const char * /*id*/, CollectionType &/*collection*/, const utils::foreign_attributes &/*attr*/) {}
 
 private:
-  explicit foreign_node_completer(internal::shadow_repository &shadow, Observers<NodeType>... observers)
+  explicit foreign_node_completer(internal::shadow_repository &shadow, const std::vector<std::unique_ptr<observer<NodeType>>> &observers)
   : repo_(shadow)
-  , log_(logger::create_logger("node_completer")) {
-    // observers_.emplace_back(observers...);
-  }
+  , log_(logger::create_logger("node_completer"))
+  , observers_(observers) {}
 
   void complete_node(const std::shared_ptr<repository_node> &node) {
     nodes_.push(node);
@@ -91,75 +91,22 @@ private:
     nodes_.pop();
   }
 
-  template<typename Type>
-  void attach_node(const std::string &name) {
-    if (repo_.contains(typeid(Type))) {
-      return;
-    }
-    const auto node = repository_node::make_node<Type>(repo_.repo(), name);
-    if (auto result = repo_.attach_node(node)) {
-      foreign_node_completer<Type>::complete(result.value());
-    }
-  }
-
   template<typename Type>
   void attach_node() {
     if (repo_.contains(typeid(Type))) {
       return;
     }
 
-    const auto node = repository_node::make_node<Type>(repo_.repo(), "", []{ return std::make_unique<Type>(); });
-    if (auto result = repo_.attach_node(node)) {
-      foreign_node_completer<Type>::complete(result.value());
-    }
-  }
+    auto observers = internal::observer_list_copy_creator<NodeType, Type, Observers...>::copy_create(observers_);
 
-  template<typename Type>
-  void attach_relation_node(const std::string &name, const std::string &join_column, const std::string &inverse_join_column) {
-    using relation_value_type = many_to_many_relation<Type, NodeType>;
-    using value_type = Type;
-
-    // Check if the object_ptr type is already inserted in the schema (by id)
-    auto result = repo_.find_node(typeid(value_type));
-    if (!result) {
-      // Todo: throw internal error or attach node
+    if (repo_.is_node_announced(typeid(Type))) {
       return;
     }
-
-    const auto foreign_node = result.value();
-    result = repo_.find_node(name);
-    if (result) {
-      return;
-    }
-    // Relation does not exist. Create it.
-    auto creator = [join_column, inverse_join_column] {
-      return std::make_unique<relation_value_type>(join_column, inverse_join_column);
-    };
-
-    auto node = repository_node::make_node<relation_value_type>(repo_.repo(), name, std::move(creator));
-    result = repo_.attach_node(node);
-    if (!result) {
-      // Todo: throw internal error
-      return;
-    }
-
-    foreign_node_completer<relation_value_type>::complete(result.value());
-
-    // auto& node = result.value();
-    const auto local_endpoint = std::make_shared<relation_endpoint>(name, relation_type::HasMany, node);
-    const auto join_endpoint = std::make_shared<relation_endpoint>(join_column, relation_type::BelongsTo, nodes_.top());
-    const auto inverse_join_endpoint = std::make_shared<relation_endpoint>(inverse_join_column, relation_type::BelongsTo, foreign_node);
-    const auto foreign_endpoint = std::make_shared<relation_endpoint>(name, relation_type::HasMany, node);
-    // register relation endpoint in local node
-    nodes_.top()->info_->register_relation_endpoint(typeid(value_type), local_endpoint);
-    // register relation endpoint in foreign node
-    foreign_node->info_->register_relation_endpoint(nodes_.top()->type_index(), foreign_endpoint);
-    // register endpoints in relation node
-    node->info_->register_relation_endpoint(nodes_.top()->type_index(), join_endpoint);
-    node->info_->register_relation_endpoint(typeid(value_type), inverse_join_endpoint);
-    // link endpoints
-    link_relation_endpoints(local_endpoint, join_endpoint);
-    link_relation_endpoints(foreign_endpoint, inverse_join_endpoint);
+    const auto node = repository_node::make_node<Type>(repo_.repo(), "", []{ return std::make_unique<Type>(); }, std::move(observers));
+    repo_.push_announce_node(typeid(Type), node);
+    // if (auto result = repo_.attach_node(node)) {
+      // foreign_node_completer<Type>::complete(result.value(), {});
+    // }
   }
 
 private:
@@ -178,7 +125,7 @@ private:
   internal::shadow_repository &repo_;
   logger::logger log_;
   join_columns_collector join_columns_collector_{};
-  // const std::vector<Observers<NodeType>...> observers_;
+  const std::vector<std::unique_ptr<observer<NodeType>>>& observers_;
 };
 
 
@@ -190,7 +137,7 @@ void foreign_node_completer<NodeType, Observers...>::on_belongs_to(const char *
 
 template<typename NodeType, template<typename> typename ...Observers>
 template<class ForeignPointerType>
-void foreign_node_completer<NodeType, Observers...>::on_has_one(const char *, ForeignPointerType &, const utils::foreign_attributes &) {
+void foreign_node_completer<NodeType, Observers...>::on_has_one(const char * /*id*/, ForeignPointerType &, const utils::foreign_attributes &) {
   attach_node<typename ForeignPointerType::value_type>();
 }
 
diff --git a/include/matador/object/internal/observer_list_copy_creator.hpp b/include/matador/object/internal/observer_list_copy_creator.hpp
new file mode 100644
index 0000000..1eaba10
--- /dev/null
+++ b/include/matador/object/internal/observer_list_copy_creator.hpp
@@ -0,0 +1,57 @@
+#ifndef MATADOR_OBSERVER_LIST_COPY_CREATOR_HPP
+#define MATADOR_OBSERVER_LIST_COPY_CREATOR_HPP
+
+#include "matador/object/observer.hpp"
+
+#include <memory>
+#include <vector>
+
+namespace matador::object::internal {
+template <typename SourceType, typename DestType, template <typename> class... ObserverType>
+class observer_list_copy_creator
+{
+public:
+  using source_observer_vector = std::vector<std::unique_ptr<observer<SourceType>>>;
+  using observer_vector = std::vector<std::unique_ptr<observer<DestType>>>;
+  using iterator = typename observer_vector::iterator;
+
+  static observer_vector copy_create(const source_observer_vector &source_observers) {
+    observer_list_copy_creator creator(source_observers);
+
+    return std::move(creator.observers_);
+  }
+
+private:
+  explicit observer_list_copy_creator(const source_observer_vector &source_observers)
+  : source_observers_(source_observers) {
+    if constexpr (sizeof...(ObserverType) != 0) {
+      copy_observer<ObserverType...>();
+    }
+  }
+
+  template <template <typename> class FirstObserverType>
+  void copy_observer() {
+    try_copy_observer<FirstObserverType>();
+  }
+
+  template <template <typename> class FirstObserverType, template <typename> class NextObserverType, template <typename> class... RestObserverType>
+  void copy_observer() {
+    try_copy_observer<FirstObserverType>();
+    copy_observer<NextObserverType, RestObserverType...>();
+  }
+
+  template <template <typename> class CurrentObserverType>
+  void try_copy_observer() {
+    for ( const auto &obs : source_observers_ ) {;
+      if (const auto *casted_observer = dynamic_cast<const CurrentObserverType<SourceType>*>(obs.get()); casted_observer != nullptr) {
+        observers_.emplace_back(std::make_unique<CurrentObserverType<DestType>>(*casted_observer));
+        break;
+      }
+    }
+  }
+private:
+  const source_observer_vector &source_observers_;
+  observer_vector observers_;
+};
+}
+#endif //MATADOR_OBSERVER_LIST_COPY_CREATOR_HPP
\ No newline at end of file
diff --git a/include/matador/object/internal/observer_list_creator.hpp b/include/matador/object/internal/observer_list_creator.hpp
new file mode 100644
index 0000000..f6cf302
--- /dev/null
+++ b/include/matador/object/internal/observer_list_creator.hpp
@@ -0,0 +1,69 @@
+#ifndef MATADOR_OBSERVER_LIST_CREATOR_HPP
+#define MATADOR_OBSERVER_LIST_CREATOR_HPP
+
+#include "matador/object/observer.hpp"
+
+#include <memory>
+#include <vector>
+
+namespace matador::object::internal {
+template <typename Type, template <typename> class... ObserverType>
+class observer_list_creator
+{
+public:
+  using observer_vector = std::vector<std::unique_ptr<observer<Type>>>;
+
+  static void create_missing(observer_vector &observers) {
+    observer_list_creator creator(observers);
+  }
+
+private:
+  explicit observer_list_creator(observer_vector &observers)
+  : observers_(observers) {
+    if constexpr (sizeof...(ObserverType) != 0) {
+      build_observer<ObserverType...>();
+    }
+  }
+
+  template <template <typename> class FirstObserverType>
+  void build_observer() {
+    try_copy_on_missing<FirstObserverType>();
+  }
+
+  template <template <typename> class FirstObserverType, template <typename> class NextObserverType, template <typename> class... RestObserverType>
+  void build_observer() {
+    try_copy_on_missing<FirstObserverType>();
+    build_observer<NextObserverType, RestObserverType...>();
+  }
+
+  template <template <typename> class CurrentObserverType>
+  void try_copy_on_missing() {
+    bool is_missing{true};
+    for ( const auto &obs : observers_ ) {;
+      if (dynamic_cast<const CurrentObserverType<Type>*>(obs.get())) {
+        is_missing = false;
+        break;
+      }
+    }
+
+    if (is_missing) {
+      append<CurrentObserverType<Type>>();
+    }
+  }
+
+  template <class CurrentObserverType>
+  void append(std::enable_if_t<std::is_default_constructible_v<CurrentObserverType> || std::is_trivially_default_constructible_v<CurrentObserverType>>* = nullptr) {
+    observers_.emplace_back(std::make_unique<CurrentObserverType>());
+  }
+
+  template <class CurrentObserverType>
+  void append(std::enable_if_t<!std::is_default_constructible_v<CurrentObserverType> && !std::is_trivially_default_constructible_v<CurrentObserverType>>* = nullptr) {
+    static_assert("no default constructor");
+  }
+
+private:
+  observer_vector &observers_;
+};
+
+}
+#endif //MATADOR_OBSERVER_LIST_CREATOR_HPP
\ No newline at end of file
diff --git a/include/matador/object/internal/shadow_repository.hpp b/include/matador/object/internal/shadow_repository.hpp
index 632a567..aaaa1a2 100644
--- a/include/matador/object/internal/shadow_repository.hpp
+++ b/include/matador/object/internal/shadow_repository.hpp
@@ -40,6 +40,11 @@ public:
   [[nodiscard]] std::shared_ptr<object> object_for_type(const std::type_index &ti) const;
   void remove_object_for_type(const std::type_index &ti) const;
 
+  [[nodiscard]] bool is_node_announced(const std::type_index &ti) const;
+  void push_announce_node(const std::type_index &ti, const node_ptr &node) const;
+  [[nodiscard]] node_ptr announce_node(const std::type_index &ti) const;
+  [[nodiscard]] node_ptr pop_announce_node(const std::type_index &ti) const;
+
 private:
   repository& repo_;
 };
diff --git a/include/matador/object/object_generator.hpp b/include/matador/object/object_generator.hpp
index 8b56130..a5847d0 100644
--- a/include/matador/object/object_generator.hpp
+++ b/include/matador/object/object_generator.hpp
@@ -51,17 +51,17 @@ private:
 
 class object_generator {
 private:
-    explicit object_generator(repository& repo, const std::shared_ptr<object> &object);
+    explicit object_generator(const repository& repo, const std::shared_ptr<object> &object);
 
 public:
     template < class Type >
-    static std::shared_ptr<object> generate(repository &repo, const std::string &name) {
+    static std::shared_ptr<object> generate(const repository &repo, const std::string &name) {
         return generate(std::make_unique<Type>(), repo, name);
     }
 
     template < class Type >
-    static std::shared_ptr<object> generate(std::unique_ptr<Type>&& t, repository &repo, const std::string &name) {
-        const internal::shadow_repository shadow_repo(repo);
+    static std::shared_ptr<object> generate(std::unique_ptr<Type>&& t, const repository &repo, const std::string &name) {
+        const internal::shadow_repository shadow_repo(const_cast<repository&>(repo));
         const std::type_index ti(typeid(Type));
         if (shadow_repo.has_object_for_type(ti)) {
             auto obj = shadow_repo.object_for_type(ti);
@@ -129,7 +129,7 @@ private:
 
     static std::shared_ptr<object> acquire_object(repository &repo, const std::type_index &ti, const std::string& name);
 private:
-    repository &repo_;
+    const repository &repo_;
     std::shared_ptr<object> object_;
 };
 
@@ -167,7 +167,7 @@ void object_generator::create_fk_constraint(const std::string& name) const {
 template<typename Type>
 std::shared_ptr<object> object_generator::fk_object() const {
     const auto ti = std::type_index(typeid(Type));
-    const internal::shadow_repository shadow_repo(repo_);
+    const internal::shadow_repository shadow_repo(const_cast<repository &>(repo_));
     if (const auto result = shadow_repo.basic_info(ti)) {
         return result->get().object();
     }
diff --git a/include/matador/object/object_info.hpp b/include/matador/object/object_info.hpp
index 03c4b63..25157c0 100644
--- a/include/matador/object/object_info.hpp
+++ b/include/matador/object/object_info.hpp
@@ -9,21 +9,21 @@
 namespace matador::object {
 class repository_node;
 
-template<typename Type>
-class observer_ptr {
-public:
-  explicit observer_ptr(std::unique_ptr<observer<Type>> &&observer)
-  : observer(std::move(observer)) {}
-
-  operator bool() const { return observer != nullptr; }
-
-  observer<Type> *get() const { return observer.get(); }
-  observer<Type> &operator*() const { return *observer; }
-  observer<Type> *operator->() const { return observer.get(); }
-
-private:
-  std::unique_ptr<observer<Type>> observer;
-};
+// template<typename Type>
+// class observer_ptr {
+// public:
+//   explicit observer_ptr(std::unique_ptr<observer<Type>> &&o)
+//   : observer_(std::move(o)) {}
+//
+//   operator bool() const { return observer_ != nullptr; }
+//
+//   observer<Type> *get() const { return observer_.get(); }
+//   observer<Type> &operator*() const { return *observer_; }
+//   observer<Type> *operator->() const { return observer_.get(); }
+//
+// private:
+//   std::unique_ptr<observer<Type>> observer_;
+// };
 template<typename Type>
 class object_info final : public basic_object_info {
 public:
@@ -31,10 +31,11 @@ public:
 
   object_info(const std::shared_ptr<repository_node>& node,
               std::shared_ptr<class object> &&obj,
+              std::vector<std::unique_ptr<observer<Type>>>&& observers,
               create_func&& creator)
   : basic_object_info(node, std::move(obj))
-  , creator_(std::move(creator)){
-  }
+  , creator_(std::move(creator))
+  , observers_(std::move(observers)){}
 
   explicit object_info(const std::shared_ptr<repository_node>& node)
   : basic_object_info(node, {}) {
@@ -55,13 +56,18 @@ public:
     }
   }
 
-  void register_observer(observer_ptr<Type> observer) {
+  void register_observer(std::unique_ptr<observer<Type>>&& observer) {
     observers_.push_back(std::move(observer));
   }
+
+  const std::vector<std::unique_ptr<observer<Type>>>& observers() const {
+    return observers_;
+  }
+
 private:
   Type prototype_;
   create_func creator_{[]{ return std::make_unique<Type>(); }};
-  std::vector<observer_ptr<Type>> observers_;
+  std::vector<std::unique_ptr<observer<Type>>> observers_;
 };
 
 template<typename Type>
diff --git a/include/matador/object/observer.hpp b/include/matador/object/observer.hpp
index 8dd934b..feb1695 100644
--- a/include/matador/object/observer.hpp
+++ b/include/matador/object/observer.hpp
@@ -63,7 +63,7 @@ public:
    * @param node The attached repository_node
    * @param prototype The prototype object of the attached node
    */
-  virtual void on_attach(repository_node &node, const Type &prototype) = 0;
+  virtual void on_attach(const repository_node &node, const Type &prototype) const = 0;
 
   /**
    * @brief Called on repository_node detached
@@ -74,7 +74,7 @@ public:
    * @param node The to be detached repository_node
    * @param prototype The prototype object of the detached node
    */
-  virtual void on_detach(repository_node &node, const Type &prototype) = 0;
+  virtual void on_detach(const repository_node &node, const Type &prototype) const = 0;
 
   /**
    * @brief Called on object insertion.
@@ -84,7 +84,7 @@ public:
    *
    * @param obj The proxy of the inserted object.
    */
-  virtual void on_insert(Type &obj) = 0;
+  virtual void on_insert(const Type &obj) = 0;
 
   /**
    * @brief Called on object update.
@@ -94,7 +94,7 @@ public:
    *
    * @param obj The proxy of the updated object.
    */
-  virtual void on_update(Type &obj) = 0;
+  virtual void on_update(const Type &obj) = 0;
 
   /**
    * @brief Called on object deletion.
@@ -104,7 +104,7 @@ public:
    *
    * @param obj The proxy of the deleted object.
    */
-  virtual void on_delete(Type &obj) = 0;
+  virtual void on_delete(const Type &obj) = 0;
 };
 
 namespace internal {
diff --git a/include/matador/object/relation_completer.hpp b/include/matador/object/relation_completer.hpp
index 571c519..3dae179 100644
--- a/include/matador/object/relation_completer.hpp
+++ b/include/matador/object/relation_completer.hpp
@@ -92,7 +92,7 @@ private:
  *      no has_many or belongs_to
  *      invalid relation -> error
  */
-template<typename Type>
+template<typename Type, template<typename> typename... Observers>
 class relation_completer final {
 private:
     using node_ptr = std::shared_ptr<repository_node>;
@@ -100,9 +100,9 @@ private:
 public:
   using endpoint_ptr = std::shared_ptr<relation_endpoint>;
 
-  static void complete(const std::shared_ptr<repository_node> &node) {
+  static void complete(const std::shared_ptr<repository_node> &node, const std::vector<std::unique_ptr<observer<Type>>> &observers) {
     internal::shadow_repository shadow(node->repo_);
-    relation_completer completer(shadow);
+    relation_completer completer(shadow, observers);
 
     completer.complete_node_relations(node);
   }
@@ -131,10 +131,10 @@ public:
   void on_has_many_to_many(const char *id, CollectionType &collection, const utils::foreign_attributes &attr);
 
 private:
-  explicit relation_completer(internal::shadow_repository &shadow)
-    : schema_(shadow)
-    , log_(logger::create_logger("relation_completer")) {
-  }
+  explicit relation_completer(internal::shadow_repository &shadow, const std::vector<std::unique_ptr<observer<Type>>>& observers)
+  : schema_(shadow)
+  , log_(logger::create_logger("relation_completer"))
+  , observers_(observers) {}
 
   void complete_node_relations(const std::shared_ptr<repository_node> &node) {
       nodes_.push(node);
@@ -152,16 +152,19 @@ private:
   static void link_relation_endpoints(const endpoint_ptr &endpoint,
                                       const endpoint_ptr &other_endpoint);
 
+  node_ptr find_node(const std::type_index &ti) const;
+
 private:
   std::stack<node_ptr> nodes_;
   internal::shadow_repository &schema_;
   logger::logger log_;
   join_columns_collector join_columns_collector_{};
+  const std::vector<std::unique_ptr<observer<Type>>>& observers_;
 };
 
-template<typename Type>
+template<typename Type, template<typename> typename... Observers>
 template<class CollectionType>
-void relation_completer<Type>::on_has_many(const char *id, CollectionType &,
+void relation_completer<Type, Observers...>::on_has_many(const char *id, CollectionType &,
                                            const char *join_column,
                                            const utils::foreign_attributes &,
                                            std::enable_if_t<is_object_ptr<typename CollectionType::value_type>::value> * /*unused*/) {
@@ -170,12 +173,11 @@ void relation_completer<Type>::on_has_many(const char *id, CollectionType &,
   using relation_value_type = many_to_many_relation<Type, value_type>;
 
   // Check if the object_ptr type is already inserted in the schema (by id)
-  auto result = schema_.find_node(typeid(value_type));
-  if (!result) {
+  auto foreign_node = find_node(typeid(value_type));
+  if (!foreign_node) {
     // Todo: throw internal error or attach node
     return;
   }
-  const auto foreign_node = result.value();
   // has foreign node corresponding join column (join_column)
 
   if (const auto it = foreign_node->info_->find_relation_endpoint(typeid(Type)); it != foreign_node->info().endpoint_end()) {
@@ -198,8 +200,8 @@ void relation_completer<Type>::on_has_many(const char *id, CollectionType &,
     log_.debug("node '%s' has has many foreign keys '%s' mapped by '%s'", nodes_.top()->name().c_str(), id, join_column);
     auto node = repository_node::make_node<relation_value_type>(schema_.repo(), id, [join_column] {
       return std::make_unique<relation_value_type>("id", join_column);
-    });
-    result = schema_.attach_node(node);
+    }, {});
+    const auto result = schema_.attach_node(node);
     if (!result) {
       // Todo: throw internal error
       return;
@@ -215,9 +217,9 @@ void relation_completer<Type>::on_has_many(const char *id, CollectionType &,
   }
 }
 
-template<typename Type>
+template<typename Type, template<typename> typename... Observers>
 template<class CollectionType>
-void relation_completer<Type>::on_has_many(const char *id, CollectionType &, const char *join_column,
+void relation_completer<Type, Observers...>::on_has_many(const char *id, CollectionType &, const char *join_column,
                                            const utils::foreign_attributes &,
                                            std::enable_if_t<!is_object_ptr<typename CollectionType::value_type>::value>
                                            * /*unused*/) {
@@ -226,7 +228,7 @@ void relation_completer<Type>::on_has_many(const char *id, CollectionType &, con
 
   auto node = repository_node::make_node<relation_value_type>(schema_.repo(), id, [join_column] {
     return std::make_unique<relation_value_type>(join_column, "value");
-  });
+  }, {});
   const auto result = schema_.attach_node(node);
   if (!result) {
     // Todo: throw internal exception
@@ -241,9 +243,9 @@ void relation_completer<Type>::on_has_many(const char *id, CollectionType &, con
   link_relation_endpoints(local_endpoint, foreign_endpoint);
 }
 
-template<typename Type>
+template<typename Type, template<typename> typename... Observers>
 template<class CollectionType>
-void relation_completer<Type>::on_has_many_to_many(const char *id,
+void relation_completer<Type, Observers...>::on_has_many_to_many(const char *id,
                                                    CollectionType &/*collection*/,
                                                    const char *join_column,
                                                    const char *inverse_join_column,
@@ -256,9 +258,9 @@ void relation_completer<Type>::on_has_many_to_many(const char *id,
   }
 }
 
-template<typename Type>
+template<typename Type, template<typename> typename... Observers>
 template<class CollectionType>
-void relation_completer<Type>::on_has_many_to_many(const char *id,
+void relation_completer<Type, Observers...>::on_has_many_to_many(const char *id,
                                                    CollectionType &collection,
                                                    const utils::foreign_attributes &attr) {
   const auto join_columns = join_columns_collector_.collect<typename CollectionType::value_type::value_type>();
@@ -270,46 +272,43 @@ void relation_completer<Type>::on_has_many_to_many(const char *id,
     attr);
 }
 
-template<typename Type>
+template<typename Type, template<typename> typename... Observers>
 template<class ForeignPointerType>
-void relation_completer<Type>::on_has_one(const char *id,
+void relation_completer<Type, Observers...>::on_has_one(const char *id,
                                           ForeignPointerType &/*obj*/,
                                           const utils::foreign_attributes &/*attr*/) {
   using value_type = typename ForeignPointerType::value_type;
-  const auto ti = std::type_index(typeid(value_type));
-  const auto result = schema_.find_node(ti);
-  if (!result) {
-    // Node was not found
-    // Todo: Throw internal error
+  auto foreign_node = find_node(typeid(value_type));
+  if (!foreign_node) {
+    // Todo: throw internal error or attach node
     return;
   }
 
   auto local_it = nodes_.top()->info().find_relation_endpoint(typeid(value_type));
   if (local_it == nodes_.top()->info().endpoint_end()) {
-    const auto local_endpoint = std::make_shared<relation_endpoint>(id, relation_type::HasOne, result.value());
+    const auto local_endpoint = std::make_shared<relation_endpoint>(id, relation_type::HasOne, foreign_node);
     local_it = nodes_.top()->info_->register_relation_endpoint(typeid(value_type), local_endpoint);
   }
-  if (const auto foreign_it = result.value()->info().find_relation_endpoint(typeid(Type)); foreign_it != result.value()->info().endpoint_end()) {
+  if (const auto foreign_it = foreign_node->info().find_relation_endpoint(typeid(Type)); foreign_it != foreign_node->info().endpoint_end()) {
     link_relation_endpoints(local_it->second, foreign_it->second);
   }
 
 }
 
-template<typename Type>
+template<typename Type, template<typename> typename... Observers>
 template<class ForeignPointerType>
-void relation_completer<Type>::on_belongs_to(const char *id,
+void relation_completer<Type, Observers...>::on_belongs_to(const char *id,
                                              ForeignPointerType & /*obj*/,
                                              const utils::foreign_attributes & /*attr*/) {
   using value_type = typename ForeignPointerType::value_type;
   const auto ti = std::type_index(typeid(value_type));
-  auto result = schema_.find_node(ti);
-  if (!result) {
-    // Type was not found
-    // Todo: Throw internal error
+  auto foreign_node = find_node(typeid(value_type));
+  if (!foreign_node) {
+    // Todo: throw internal error or attach node
     return;
   }
+
   // Type was found
-  const auto &foreign_node = result.value();
   // Check foreign node and relation endpoint
   if (const auto it = foreign_node->info_->find_relation_endpoint(nodes_.top()->type_index()); it != foreign_node->info().endpoint_end()) {
     // Found corresponding relation endpoint in the foreign node
@@ -341,21 +340,20 @@ void relation_completer<Type>::on_belongs_to(const char *id,
   }
 }
 
-template<typename Type>
+template<typename Type, template<typename> typename... Observers>
 template<typename NodeType>
-void relation_completer<Type>::attach_relation_node(const std::string &name, const std::string &join_column, const std::string &inverse_join_column) {
+void relation_completer<Type, Observers...>::attach_relation_node(const std::string &name, const std::string &join_column, const std::string &inverse_join_column) {
   using relation_value_type = many_to_many_relation<NodeType, Type>;
   using value_type = NodeType;
 
   // Check if the object_ptr type is already inserted in the schema (by id)
-  auto result = schema_.find_node(typeid(value_type));
-  if (!result) {
+  auto foreign_node = find_node(typeid(value_type));
+  if (!foreign_node) {
     // Todo: throw internal error or attach node
     return;
   }
 
-  const auto foreign_node = result.value();
-  result = schema_.find_node(name);
+  auto result = schema_.find_node(name);
   if (result) {
     return;
   }
@@ -364,14 +362,16 @@ void relation_completer<Type>::attach_relation_node(const std::string &name, con
     return std::make_unique<relation_value_type>(join_column, inverse_join_column);
   };
 
-  auto node = repository_node::make_node<relation_value_type>(schema_.repo(), name, std::move(creator));
+  auto observers = internal::observer_list_copy_creator<Type, relation_value_type, Observers...>::copy_create(observers_);
+
+  auto node = repository_node::make_node<relation_value_type>(schema_.repo(), name, std::move(creator), std::move(observers));
   result = schema_.attach_node(node);
   if (!result) {
     // Todo: throw internal error
     return;
   }
 
-  foreign_node_completer<relation_value_type>::complete(result.value());
+  foreign_node_completer<relation_value_type>::complete(result.value(), {});
 
   const auto local_endpoint = std::make_shared<relation_endpoint>(name, relation_type::HasMany, node);
   const auto join_endpoint = std::make_shared<relation_endpoint>(join_column, relation_type::BelongsTo, nodes_.top());
@@ -389,18 +389,31 @@ void relation_completer<Type>::attach_relation_node(const std::string &name, con
   link_relation_endpoints(foreign_endpoint, inverse_join_endpoint);
 }
 
-template<typename Type>
-void relation_completer<Type>::register_relation_endpoints(const endpoint_ptr &endpoint,
+template<typename Type, template<typename> typename... Observers>
+void relation_completer<Type, Observers...>::register_relation_endpoints(const endpoint_ptr &endpoint,
                                                            const endpoint_ptr &other_endpoint) {
   endpoint->node_->info_->register_relation_endpoint(other_endpoint->node_->type_index(), endpoint);
   other_endpoint->node_->info_->register_relation_endpoint(endpoint->node_->type_index(), other_endpoint);
   link_relation_endpoints(endpoint, other_endpoint);
 }
 
-template<typename Type>
-void relation_completer<Type>::link_relation_endpoints(const endpoint_ptr &endpoint, const endpoint_ptr &other_endpoint) {
+template<typename Type, template<typename> typename... Observers>
+void relation_completer<Type, Observers...>::link_relation_endpoints(const endpoint_ptr &endpoint, const endpoint_ptr &other_endpoint) {
   endpoint->link_foreign_endpoint(other_endpoint);
   other_endpoint->link_foreign_endpoint(endpoint);
 }
+
+template<typename Type, template <typename> class ... Observers>
+typename relation_completer<Type, Observers...>::node_ptr relation_completer<Type, Observers...>::find_node(const std::type_index &ti) const {
+  node_ptr foreign_node;
+  if (auto result = schema_.find_node(ti); result) {
+    return result.value();
+  }
+
+  if (!schema_.is_node_announced(ti)) {
+    return {};
+  }
+  return  schema_.announce_node(ti);
+}
 }
 #endif //RELATION_COMPLETER_HPP
diff --git a/include/matador/object/relation_endpoint.hpp b/include/matador/object/relation_endpoint.hpp
index f7c2264..328a11f 100644
--- a/include/matador/object/relation_endpoint.hpp
+++ b/include/matador/object/relation_endpoint.hpp
@@ -41,7 +41,7 @@ public:
   void link_foreign_endpoint(const std::shared_ptr<relation_endpoint>& endpoint);
 
 private:
-  template<typename Type>
+  template<typename Type, template<typename> typename... Observers>
   friend class relation_completer;
   template<typename Type, template<typename> typename ...Observers>
   friend class foreign_node_completer;
diff --git a/include/matador/object/repository.hpp b/include/matador/object/repository.hpp
index cdef623..1fcb028 100644
--- a/include/matador/object/repository.hpp
+++ b/include/matador/object/repository.hpp
@@ -38,44 +38,55 @@ public:
    */
   explicit repository(std::string name = "");
 
-  template<typename Type, typename... Observers>
-  [[nodiscard]] utils::result<void, utils::error> attach(const std::string &name, Observers&&... observers) {
-    return attach_type<Type, Observers...>(name, std::string{}, std::forward<Observers>(observers)...);
+  template<typename Type, template<typename> typename... Observers>
+  [[nodiscard]] utils::result<void, utils::error> attach(const std::string &name, Observers<Type>&&... observers) {
+    return attach_type<Type, Observers...>(name, std::string{}, std::forward<Observers<Type>>(observers)...);
   }
 
-  template<typename Type, typename SuperType, typename... Observers>
-  [[nodiscard]] utils::result<void, utils::error> attach(const std::string &name, Observers&&... observers) {
+  template<typename Type, typename SuperType, template<typename> typename... Observers>
+  [[nodiscard]] utils::result<void, utils::error> attach(const std::string &name, Observers<Type>&&... observers) {
     const auto ti = std::type_index(typeid(SuperType));
     auto result = find_node(ti);
     if (!result) {
       return utils::failure(make_error(error_code::NodeNotFound, "Parent node '" + std::string(ti.name()) + "' not found"));
     }
 
-    return attach_type<Type, Observers...>(name, (*result)->name(), std::forward<Observers>(observers)...);
+    return attach_type<Type, Observers...>(name, (*result)->name(), std::forward<Observers<Type>>(observers)...);
   }
 
-  template<typename Type, typename... Observers>
-  [[nodiscard]] utils::result<void, utils::error> attach(const std::string &name, const std::string &parent, Observers&&... observers) {
-    return attach_type<Type, Observers...>(name, parent, std::forward<Observers>(observers)...);
+  template<typename Type, template<typename> typename... Observers>
+  [[nodiscard]] utils::result<void, utils::error> attach(const std::string &name, const std::string &parent, Observers<Type>&&... observers) {
+    return attach_type<Type, Observers...>(name, parent, std::forward<Observers<Type>>(observers)...);
   }
-  template<typename Type, typename... Observers>
-  [[nodiscard]] utils::result<void, utils::error> attach_type(const std::string &name, const std::string &parent, Observers&&... observers) {
+  template<typename Type, template<typename> typename... Observers>
+  [[nodiscard]] utils::result<void, utils::error> attach_type(const std::string &name, const std::string &parent, Observers<Type>&&... observers) {
     if (const auto it = nodes_by_type_.find(typeid(Type)); it == nodes_by_type_.end() ) {
+      std::vector<std::unique_ptr<observer<Type>>> obs;
+      obs.reserve(sizeof...(Observers));
+      (obs.push_back(std::unique_ptr<observer<Type>>(new Observers<Type>(std::forward<Observers<Type>>(observers)))), ...);
       // if the type was not found
-      auto node = repository_node::make_node<Type>(*this, name, []{ return std::make_unique<Type>(); }, std::forward<Observers>(observers)...);
+      std::shared_ptr<repository_node> node;
+      if (is_node_announced(typeid(Type))) {
+        node = pop_announce_node(typeid(Type));
+        node->update_name(name);
+      } else {
+        node = repository_node::make_node<Type>(*this, name, []{ return std::make_unique<Type>(); }, std::move(obs));
+      }
       if (auto result = attach_node(node, parent); !result) {
           return utils::failure(result.err());
       }
 
-      foreign_node_completer<Type>::complete(node);
-      relation_completer<Type>::complete(node);
+      const auto info = node->template info<Type>();
+      foreign_node_completer<Type, Observers...>::complete(node, info.get().observers());
+      relation_completer<Type, Observers...>::complete(node, info.get().observers());
     } else if (!has_node(name)) {
       it->second->update_name(name);
       nodes_by_name_[name] = it->second;
       if (const auto i = nodes_by_name_.find(""); i != nodes_by_name_.end()) {
           nodes_by_name_.erase(i);
       }
-      relation_completer<Type>::complete(it->second);
+      const auto info = it->second->info<Type>();
+      relation_completer<Type, Observers...>::complete(it->second, info.get().observers());
       log_.info("attach: update node name to '%s' (type: %s)", it->second->name().c_str(), it->second->type_index().name());
     } else {
       return utils::failure(make_error(error_code::NodeAlreadyExists, "Node '" + name + "' already exists"));
@@ -195,6 +206,11 @@ private:
   [[nodiscard]] std::shared_ptr<object> object_for_type(const std::type_index &ti) const;
   void remove_object_for_type(const std::type_index &ti);
 
+  [[nodiscard]] bool is_node_announced(const std::type_index &ti) const;
+  void push_announce_node(const std::type_index &ti, const node_ptr &node);
+  [[nodiscard]] node_ptr announce_node(const std::type_index &ti);
+  [[nodiscard]] node_ptr pop_announce_node(const std::type_index &ti);
+
 private:
   friend class internal::shadow_repository;
   friend class repository_node;
@@ -209,9 +225,11 @@ private:
   t_type_index_node_map nodes_by_type_;
   logger::logger log_;
 
+  std::unordered_map<std::type_index, std::shared_ptr<repository_node>> announced_node_;
   std::unordered_map<std::type_index, attribute*> missing_references_;
   std::unordered_map<std::string, std::type_index> expected_relation_nodes_;
   std::unordered_map<std::type_index, std::shared_ptr<object>> object_by_type_;
+
 };
 }
 
diff --git a/include/matador/object/repository_node.hpp b/include/matador/object/repository_node.hpp
index 6002888..0d1f266 100644
--- a/include/matador/object/repository_node.hpp
+++ b/include/matador/object/repository_node.hpp
@@ -3,6 +3,7 @@
 
 #include "matador/object/object_generator.hpp"
 #include "matador/object/object_info.hpp"
+#include "matador/object/internal/observer_list_creator.hpp"
 
 #include "matador/utils/error.hpp"
 #include "matador/utils/result.hpp"
@@ -20,22 +21,11 @@ public:
   template< typename Type>
   using creator_func = std::function<std::unique_ptr<Type>()>;
 
-  template < typename Type, typename... Observers >
-  static std::shared_ptr<repository_node> make_node(repository& repo, const std::string& name, creator_func<Type> creator, Observers&&... observers) {
-    const std::type_index ti(typeid(Type));
-    auto node = std::shared_ptr<repository_node>(new repository_node(repo, name, ti));
-
-    auto obj = object_generator::generate<Type>(creator(), repo, name);
-    auto info = std::make_unique<object_info<Type>>(
-      node,
-      std::move(obj),
-      std::forward<creator_func<Type>>(creator)
-    );
-    (info->register_observer(observer_ptr<Type>(std::unique_ptr<Observers>(new Observers(std::forward<Observers>(observers))))), ...);
-    node->info_ = std::move(info);
-
-    return node;
-  }
+  template < typename Type, template<typename> typename... Observers >
+  static std::shared_ptr<repository_node> make_node(repository& repo,
+                                                    const std::string& name,
+                                                    creator_func<Type> creator,
+                                                    std::vector<std::unique_ptr<observer<Type>>>&& observers);
 
   static std::shared_ptr<repository_node> make_null_node(repository& repo);
 
@@ -74,11 +64,9 @@ private:
 
   void unlink();
 
-  static utils::result<node_ptr, utils::error> make_and_attach_node(repository& repo, const std::string& name, const std::type_index& ti);
-
 private:
   friend class repository;
-  template<typename Type>
+  template<typename Type, template<typename> typename... Observers>
   friend class relation_completer;
   template < typename NodeType, template<typename> typename ...Observers >
   friend class foreign_node_completer;
@@ -98,5 +86,24 @@ private:
   size_t depth_{0};
 };
 
+template<typename Type, template <typename> class ... Observers>
+std::shared_ptr<repository_node> repository_node::make_node(repository &repo, const std::string &name,
+  creator_func<Type> creator, std::vector<std::unique_ptr<observer<Type>>> &&observers) {
+  const std::type_index ti(typeid(Type));
+  auto node = std::shared_ptr<repository_node>(new repository_node(repo, name, ti));
+
+  internal::observer_list_creator<Type, Observers...>::create_missing(observers);
+
+  auto obj = object_generator::generate<Type>(creator(), repo, name);
+  auto info = std::make_unique<object_info<Type>>(
+    node,
+    std::move(obj),
+    std::move(observers),
+    std::forward<creator_func<Type>>(creator)
+  );
+  node->info_ = std::move(info);
+
+  return node;
+}
 }
 #endif //SCHEMA_NODE_HPP
diff --git a/include/matador/orm/session_query_builder.hpp b/include/matador/orm/session_query_builder.hpp
index 7ff2ccd..d3b8bb7 100644
--- a/include/matador/orm/session_query_builder.hpp
+++ b/include/matador/orm/session_query_builder.hpp
@@ -24,7 +24,7 @@
 namespace matador::orm {
 
 struct entity_query_data {
-  std::shared_ptr<query::table> root_table;
+  const query::table* root_table{nullptr};
   std::string pk_column_name{};
   std::vector<query::column> columns{};
   std::unordered_map<std::string, sql::statement> lazy_loading_statements{};
@@ -34,7 +34,7 @@ struct entity_query_data {
 
 class criteria_transformer final : public query::criteria_visitor {
 public:
-    criteria_transformer(const query::schema &repo, const std::unordered_map<std::string, std::shared_ptr<query::table>>& tables_by_name);
+    criteria_transformer(const query::schema &repo, const std::unordered_map<std::string, query::table>& tables_by_name);
     void visit( const query::between_criteria& node ) override;
     void visit( const query::binary_criteria& node ) override;
     void visit( const query::binary_column_criteria& node ) override;
@@ -49,7 +49,7 @@ private:
 
 private:
     const query::schema &repo_;
-    const std::unordered_map<std::string, std::shared_ptr<query::table>>& tables_by_name_;
+    const std::unordered_map<std::string, query::table>& tables_by_name_;
 };
 
 class session_query_builder final {
@@ -60,15 +60,16 @@ public:
 
   template<class EntityType>
   utils::result<entity_query_data, query_build_error> build(query::criteria_ptr clause = {}) {
-    const auto info = schema_.repo().info<EntityType>();
-    if (!info) {
+    const auto it = schema_.find(typeid(EntityType));
+    if (it == schema_.end()) {
       return utils::failure(query_build_error::UnknownType);
     }
-    table_info_stack_.push({info.value(), std::make_shared<query::table>(info.value().get().name(), build_alias('t', ++table_index))});
-    entity_query_data_ = { table_info_stack_.top().table };
-    processed_tables_.insert({info->get().name(), entity_query_data_.root_table});
+    table_info_stack_.push({it->second.node().info(), it->second.table().as(build_alias('t', ++table_index))});
+    entity_query_data_ = { &table_info_stack_.top().table };
+    processed_tables_.insert({it->second.name(), *entity_query_data_.root_table});
     try {
-      access::process(*this, info->get().prototype());
+      EntityType obj;
+      access::process(*this, obj);
 
       if (clause) {
         criteria_transformer transformer{schema_, processed_tables_};
@@ -101,45 +102,77 @@ public:
   }
 
   template<class Pointer>
-  void on_belongs_to(const char *id, Pointer &obj, const utils::foreign_attributes &attr)
-  {
+  void on_belongs_to(const char *id, Pointer &obj, const utils::foreign_attributes &attr) {
     on_foreign_object(id, obj, attr);
   }
 
   template<class Pointer>
-  void on_has_one(const char *id, Pointer &obj, const utils::foreign_attributes &attr)
-  {
+  void on_has_one(const char *id, Pointer &obj, const utils::foreign_attributes &attr) {
     on_foreign_object(id, obj, attr);
   }
 
+  template<typename T>
+  struct NoopDeleter {
+    void operator()(const T*) const {}
+  };
+
   template<class ContainerType>
   void on_has_many(const char * /*id*/, ContainerType &, const char *join_column, const utils::foreign_attributes &attr) {
-    if (attr.fetch() == utils::fetch_type::Eager) {
-      const auto result = schema_.repo().basic_info(typeid(typename ContainerType::value_type::value_type));
-      if (!result) {
-        throw query_builder_exception{query_build_error::UnknownType};
-      }
-
-      const auto &info = result.value().get();
-      auto next = processed_tables_.find(info.name());
-      if (next != processed_tables_.end()) {
-        return;
-      }
-      table_info_stack_.push({*result, std::make_shared<query::table>(info.name(), build_alias('t', ++table_index))});
-      next = processed_tables_.insert({info.name(), table_info_stack_.top().table}).first;
-      typename ContainerType::value_type::value_type obj;
-      access::process(*this , obj);
-      table_info_stack_.pop();
-
-      if (!info.has_primary_key()) {
-        throw query_builder_exception{query_build_error::MissingPrimaryKey};
-      }
-
-      append_join(
-        query::column{table_info_stack_.top().table.get(), table_info_stack_.top().info.get().primary_key_attribute()->name()},
-        query::column{next->second.get(), join_column}
-      );
+    if (attr.fetch() != utils::fetch_type::Eager) {
+      return;
     }
+
+    const auto it = schema_.find(typeid(typename ContainerType::value_type::value_type));
+    if (it == schema_.end()) {
+      throw query_builder_exception{query_build_error::UnknownType};
+    }
+
+    auto next = processed_tables_.find(it->second.name());
+    if (next != processed_tables_.end()) {
+      // node already processed
+      return;
+    }
+
+    table_info_stack_.push({it->second.node().info(), it->second.table().as(build_alias('t', ++table_index))});
+    next = processed_tables_.insert({it->second.name(), table_info_stack_.top().table}).first;
+    typename ContainerType::value_type::value_type obj;
+    access::process(*this , obj);
+    table_info_stack_.pop();
+
+    if (!it->second.node().info().has_primary_key()) {
+      throw query_builder_exception{query_build_error::MissingPrimaryKey};
+    }
+
+    append_join(
+      query::column{&table_info_stack_.top().table, table_info_stack_.top().info.primary_key_attribute()->name()},
+      query::column{&next->second, join_column}
+    );
+
+
+      // const auto result = schema_.repo().basic_info(typeid(typename ContainerType::value_type::value_type));
+      // if (!result) {
+      //   throw query_builder_exception{query_build_error::UnknownType};
+      // }
+      //
+      // const auto &info = result.value().get();
+      // auto next = processed_tables_.find(info.name());
+      // if (next != processed_tables_.end()) {
+      //   return;
+      // }
+      // table_info_stack_.push({*result, std::make_shared<query::table>(info.name(), build_alias('t', ++table_index))});
+      // next = processed_tables_.insert({info.name(), table_info_stack_.top().table}).first;
+      // typename ContainerType::value_type::value_type obj;
+      // access::process(*this , obj);
+      // table_info_stack_.pop();
+      //
+      // if (!info.has_primary_key()) {
+      //   throw query_builder_exception{query_build_error::MissingPrimaryKey};
+      // }
+      //
+      // append_join(
+      //   query::column{table_info_stack_.top().table.get(), table_info_stack_.top().info.get().primary_key_attribute()->name()},
+      //   query::column{next->second.get(), join_column}
+      // );
   }
 
   template<class ContainerType>
@@ -147,38 +180,42 @@ public:
     if (attr.fetch() != utils::fetch_type::Eager) {
       return;
     }
-    const auto result = schema_.repo().basic_info(typeid(typename ContainerType::value_type::value_type));
-    if (!result) {
+    const auto result = schema_.find(typeid(typename ContainerType::value_type::value_type));
+    if (result == schema_.end()) {
       throw query_builder_exception{query_build_error::UnknownType};
     }
 
-    const auto &info = result.value().get();
-    auto next = processed_tables_.find(info.name());
+    auto next = processed_tables_.find(result->second.name());
     if (next != processed_tables_.end()) {
+      // attribute was already processed
       return;
     }
+
     auto relation = processed_tables_.find(id);
     if (relation == processed_tables_.end()) {
-      relation = processed_tables_.insert({id, std::make_shared<query::table>(id, build_alias('t', ++table_index))}).first;
+      const auto it = schema_.find(id);
+      if (it == schema_.end()) {
+        throw query_builder_exception{query_build_error::UnknownType};
+      }
+      relation = processed_tables_.emplace(id, it->second.table().as(build_alias('t', ++table_index))).first;
     }
-
-    table_info_stack_.push({*result, std::make_shared<query::table>(info.name(), build_alias('t', ++table_index))});
-    next = processed_tables_.insert({info.name(), table_info_stack_.top().table}).first;
+    table_info_stack_.push({result->second.node().info(), result->second.table().as(build_alias('t', ++table_index))});
+    next = processed_tables_.insert({result->second.name(), table_info_stack_.top().table}).first;
     typename ContainerType::value_type::value_type obj;
     access::process(*this , obj);
     table_info_stack_.pop();
 
-    if (!info.has_primary_key()) {
+    if (!result->second.node().info().has_primary_key()) {
       throw query_builder_exception{query_build_error::MissingPrimaryKey};
     }
 
     append_join(
-      query::column{table_info_stack_.top().table.get(), table_info_stack_.top().info.get().primary_key_attribute()->name()},
-      query::column{relation->second.get(), join_column}
+      query::column{&table_info_stack_.top().table, table_info_stack_.top().info.primary_key_attribute()->name()},
+      query::column{&relation->second, join_column}
     );
     append_join(
-      query::column{relation->second.get(), inverse_join_column},
-      query::column{next->second.get(), info.primary_key_attribute()->name()}
+      query::column{&relation->second, inverse_join_column},
+      query::column{&next->second, result->second.node().info().primary_key_attribute()->name()}
     );
   }
 
@@ -187,40 +224,45 @@ public:
     if (attr.fetch() != utils::fetch_type::Eager) {
       return;
     }
-    const auto result = schema_.repo().basic_info(typeid(typename ContainerType::value_type::value_type));
-    if (!result) {
+    const auto result = schema_.find(typeid(typename ContainerType::value_type::value_type));
+    if (result == schema_.end()) {
       throw query_builder_exception{query_build_error::UnknownType};
     }
 
-    const auto &info = result.value().get();
-    auto next = processed_tables_.find(info.name());
+    auto next = processed_tables_.find(result->second.name());
     if (next != processed_tables_.end()) {
+      // attribute was already processed
       return;
     }
 
     auto relation = processed_tables_.find(id);
     if (relation == processed_tables_.end()) {
-      relation = processed_tables_.insert({id, std::make_shared<query::table>(id, build_alias('t', ++table_index))}).first;
+      const auto it = schema_.find(id);
+      if (it == schema_.end()) {
+        throw query_builder_exception{query_build_error::UnknownType};
+      }
+      const auto t = it->second.table().as(build_alias('t', ++table_index));
+      relation = processed_tables_.insert({id, t}).first;
     }
-    table_info_stack_.push({*result, std::make_shared<query::table>(info.name(), build_alias('t', ++table_index))});
-    next = processed_tables_.insert({info.name(), table_info_stack_.top().table}).first;
+    table_info_stack_.push({result->second.node().info(), result->second.table().as(build_alias('t', ++table_index))});
+    next = processed_tables_.insert({result->second.name(), table_info_stack_.top().table}).first;
     typename ContainerType::value_type::value_type obj;
     access::process(*this , obj);
     table_info_stack_.pop();
 
-    if (!info.has_primary_key()) {
+    if (!result->second.node().info().has_primary_key()) {
       throw query_builder_exception{query_build_error::MissingPrimaryKey};
     }
 
     const auto join_columns = join_columns_collector_.collect<typename ContainerType::value_type::value_type>();
 
     append_join(
-      query::column{table_info_stack_.top().table.get(), table_info_stack_.top().info.get().primary_key_attribute()->name()},
-      query::column{relation->second.get(), join_columns.inverse_join_column}
+      query::column{&table_info_stack_.top().table, table_info_stack_.top().info.primary_key_attribute()->name()},
+      query::column{&relation->second, join_columns.inverse_join_column}
     );
     append_join(
-      query::column{relation->second.get(), join_columns.join_column},
-      query::column{next->second.get(), info.primary_key_attribute()->name()}
+      query::column{&relation->second, join_columns.join_column},
+      query::column{&next->second, result->second.node().info().primary_key_attribute()->name()}
     );
   }
 
@@ -234,12 +276,14 @@ private:
 
 private:
   struct table_info {
-    std::reference_wrapper<const object::basic_object_info> info;
-    std::shared_ptr<query::table> table;
+    const object::basic_object_info &info;
+    query::table table;
+    // std::reference_wrapper<const object::basic_object_info> info;
+    // std::shared_ptr<query::table> table;
   };
 
   std::stack<table_info> table_info_stack_{};
-  std::unordered_map<std::string, std::shared_ptr<query::table>> processed_tables_{};
+  std::unordered_map<std::string, query::table> processed_tables_{};
   const query::schema &schema_;
   entity_query_data entity_query_data_{};
   unsigned int column_index{0};
@@ -250,30 +294,31 @@ private:
 
 template<class Pointer>
 void session_query_builder::on_foreign_object(const char *id, Pointer &, const utils::foreign_attributes &attr) {
-  const auto info = schema_.repo().info<typename Pointer::value_type>();
-  if (!info) {
+  const auto it = schema_.find(typeid(typename Pointer::value_type));
+  if (it == schema_.end()) {
     throw query_builder_exception{query_build_error::UnknownType};
   }
-  if (!info->get().has_primary_key()) {
+  if (!it->second.node().info().has_primary_key()) {
     throw query_builder_exception{query_build_error::MissingPrimaryKey};
   }
 
-  const auto foreign_table = std::make_shared<query::table>(info->get().name(), build_alias('t', ++table_index));
+  const auto& info = it->second.node().info();
+  auto foreign_table = it->second.table().as(build_alias('t', ++table_index));
   if (attr.fetch() == utils::fetch_type::Eager) {
 
-    auto next = processed_tables_.find(info->get().name());
+    auto next = processed_tables_.find(info.name());
     if (next != processed_tables_.end()) {
       return;
     }
-    table_info_stack_.push({info.value(), foreign_table});
-    next = processed_tables_.insert({info->get().name(), table_info_stack_.top().table}).first;
+    table_info_stack_.push({info, std::move(foreign_table)});
+    next = processed_tables_.insert({info.name(), table_info_stack_.top().table}).first;
     typename Pointer::value_type obj;
     access::process(*this, obj);
     table_info_stack_.pop();
 
     append_join(
-      query::column{table_info_stack_.top().table.get(), id},
-      query::column{next->second.get(), info->get().primary_key_attribute()->name()}
+      query::column{&table_info_stack_.top().table, id},
+      query::column{&next->second, info.primary_key_attribute()->name()}
     );
   } else {
     push(id);
@@ -281,8 +326,8 @@ void session_query_builder::on_foreign_object(const char *id, Pointer &, const u
     using namespace matador::query;
     // create select query
     auto result = matador::query::query::select(generator::columns<typename Pointer::value_type>(schema_, generator::column_generator_options::ForceLazy))
-      .from(*foreign_table)
-      .where(column(foreign_table.get(), info->get().primary_key_attribute()->name(), "") == _)
+      .from(foreign_table)
+      .where(column(&foreign_table, info.primary_key_attribute()->name(), "") == _)
       .prepare(executor_);
     if (!result) {
       throw query_builder_exception(query_build_error::QueryError, result.release_error());
diff --git a/include/matador/query/builder.hpp b/include/matador/query/builder.hpp
index c89d4f1..9906f6e 100644
--- a/include/matador/query/builder.hpp
+++ b/include/matador/query/builder.hpp
@@ -68,25 +68,25 @@ public:
   operator column() const; // NOLINT(*-explicit-constructor)
 
   column_builder& not_null();
+  column_builder& primary_key();
+  column_builder& unique();
 
 private:
   std::string column_name_;
   utils::basic_type type_{};
-  utils::constraints constraints_{};
+  utils::constraints constraints_{utils::constraints::NotNull};
+  size_t size_{0};
 };
 
 class table_builder {
 public:
   explicit table_builder(std::string name);
 
-  table_builder& as(std::string table_alias);
-
   // ReSharper disable once CppNonExplicitConversionOperator
   operator table() const; // NOLINT(*-explicit-constructor)
 
 private:
     std::string table_name;
-    std::string alias;
 };
 
 class constraint_builder {
@@ -100,16 +100,16 @@ public:
   operator class constraint() const; // NOLINT(*-explicit-constructor)
 
 private:
-  std::string constraint_name;
-  std::string pk_column_name;
-  std::string fk_column_name;
-  std::string table_name;
-  std::string column_name;
+  std::string constraint_name_;
+  std::string column_name_;
+  std::string ref_table_name_;
+  std::string ref_column_name_;
+  utils::constraints type_{};
 };
 
 constraint_builder constraint(std::string name);
 // table_builder table(std::string name);
-// column_builder column(std::string name, utils::basic_type type, size_t size = 0);
+column_builder column(std::string name, utils::basic_type type, size_t size = 0);
 
 }
 #endif //MATADOR_BUILDER_HPP
\ No newline at end of file
diff --git a/include/matador/query/column.hpp b/include/matador/query/column.hpp
index 6148156..4901199 100644
--- a/include/matador/query/column.hpp
+++ b/include/matador/query/column.hpp
@@ -8,6 +8,7 @@
 
 #include <memory>
 #include <string>
+#include <variant>
 
 namespace matador::query {
 
@@ -23,6 +24,9 @@ public:
   column(const class table* tab, std::string name);
   column(const class table* tab, std::string name, std::string alias);
   column(const class table* tab, std::string name, utils::basic_type type, const utils::field_attributes& attributes);
+  column(const class table*, std::string name, std::string alias, utils::basic_type type, const utils::field_attributes& attributes);
+  column& operator=(const column& other);
+  column(const column& other);
 
   [[nodiscard]] bool equals(const column &x) const;
 
@@ -39,18 +43,15 @@ public:
   [[nodiscard]] bool has_alias() const;
 
   [[nodiscard]] const class table* table() const;
-  void table(const query::table* t);
+  void table(const query::table* tab);
 
   // ReSharper disable once CppNonExplicitConversionOperator
   operator const std::string&() const; // NOLINT(*-explicit-constructor)
 
-private:
-  static query::table* default_table();
-
 private:
   friend class table;
 
-  const query::table* table_{nullptr};
+  const class table* table_{nullptr};
   std::string name_;
   std::string alias_;
   utils::basic_type type_{utils::basic_type::Unknown};
diff --git a/include/matador/query/constraint.hpp b/include/matador/query/constraint.hpp
index bb03e8b..b4a6c8a 100644
--- a/include/matador/query/constraint.hpp
+++ b/include/matador/query/constraint.hpp
@@ -13,7 +13,9 @@ public:
   constraint() = default;
   constraint(std::string column_name, std::string table_name, utils::constraints type);
   constraint(std::string column_name, std::string table_name, utils::constraints type, std::string referenced_table, std::string referenced_column);
+  constraint(std::string name, std::string column_name, std::string table_name, utils::constraints type, std::string referenced_table, std::string referenced_column);
 
+  [[nodiscard]] std::string name() const;
   [[nodiscard]] std::string column_name() const;
   [[nodiscard]] std::string table_name() const;
   [[nodiscard]] const utils::constraints& type() const;
@@ -24,6 +26,7 @@ public:
   [[nodiscard]] const std::string& referenced_column() const;
 
 private:
+  std::string name_;
   std::string column_name_;
   std::string table_name_;
   utils::constraints type_{};
diff --git a/include/matador/query/criteria/abstract_column_criteria.hpp b/include/matador/query/criteria/abstract_column_criteria.hpp
index 5f1b205..e34be18 100644
--- a/include/matador/query/criteria/abstract_column_criteria.hpp
+++ b/include/matador/query/criteria/abstract_column_criteria.hpp
@@ -10,12 +10,12 @@ namespace matador::query {
 class abstract_column_criteria : public abstract_criteria {
 public:
     abstract_column_criteria() = delete;
-    explicit abstract_column_criteria(column col);
+    explicit abstract_column_criteria(const class column& col);
 
-    [[nodiscard]] const column& col() const;
+    [[nodiscard]] const class column& col() const;
 
 protected:
-    column column_;
+    class column column_;
 };
 
 }
diff --git a/include/matador/query/criteria/between_criteria.hpp b/include/matador/query/criteria/between_criteria.hpp
index 4ce863a..46c17a1 100644
--- a/include/matador/query/criteria/between_criteria.hpp
+++ b/include/matador/query/criteria/between_criteria.hpp
@@ -4,15 +4,13 @@
 #include "matador/query/criteria/abstract_column_criteria.hpp"
 #include "matador/query/criteria/criteria_utils.hpp"
 
-#include "matador/utils/value.hpp"
-
 namespace matador::query {
 
 class between_criteria final : public abstract_column_criteria {
 public:
     between_criteria() = delete;
-    between_criteria(column col, int64_t min, int64_t max);
-    between_criteria(column col, utils::placeholder min, utils::placeholder max);
+    between_criteria(const class column& col, int64_t min, int64_t max);
+    between_criteria(const class column& col, utils::placeholder min, utils::placeholder max);
 
     void accept(criteria_visitor& visitor) const override;
 
diff --git a/include/matador/query/criteria/binary_criteria.hpp b/include/matador/query/criteria/binary_criteria.hpp
index c8bf1a4..91ebe17 100644
--- a/include/matador/query/criteria/binary_criteria.hpp
+++ b/include/matador/query/criteria/binary_criteria.hpp
@@ -19,7 +19,7 @@ enum class binary_operator {
 class binary_criteria final : public abstract_column_criteria {
 public:
     binary_criteria() = delete;
-    binary_criteria(column col, binary_operator operand, criteria_value value);
+    binary_criteria(const class column& col, binary_operator operand, criteria_value value);
 
     void accept( criteria_visitor& visitor ) const override;
 
@@ -34,18 +34,18 @@ private:
 class binary_column_criteria final : public abstract_criteria {
 public:
     binary_column_criteria() = delete;
-    binary_column_criteria(column left_column, binary_operator operand, column right_column);
+    binary_column_criteria(const class column& left_column, binary_operator operand, const class column& right_column);
 
     void accept(criteria_visitor& visitor) const override;
 
-    [[nodiscard]] const column& left_column() const;
+    [[nodiscard]] const class column& left_column() const;
     [[nodiscard]] binary_operator operand() const;
-    [[nodiscard]] const column& right_column() const;
+    [[nodiscard]] const class column& right_column() const;
 
 private:
-    column left_column_;
+    class column left_column_;
     binary_operator operator_{};
-    column right_column_;
+    class column right_column_;
 };
 }
 #endif //CRITERIA_BINARY_CRITERIA_NODE_HPP
\ No newline at end of file
diff --git a/include/matador/query/criteria/collection_criteria.hpp b/include/matador/query/criteria/collection_criteria.hpp
index 15c321b..c112a4e 100644
--- a/include/matador/query/criteria/collection_criteria.hpp
+++ b/include/matador/query/criteria/collection_criteria.hpp
@@ -4,10 +4,12 @@
 #include "matador/query/criteria/abstract_column_criteria.hpp"
 #include "matador/query/criteria/criteria_utils.hpp"
 
-#include "matador/query/column.hpp"
+#include "matador/query/table.hpp"
 #include "matador/sql/query_context.hpp"
 
 namespace matador::query {
+class column;
+
 enum class collection_operator {
   In,
   Out
@@ -36,8 +38,8 @@ public:
      * @param operand_ Operator to use
      * @param values List of values
      */
-    collection_criteria(column col, collection_operator operand_, std::vector<criteria_value> values);
-    collection_criteria(column col, collection_operator operand_, std::initializer_list<criteria_value> values);
+    collection_criteria(const class column& col, collection_operator operand_, std::vector<criteria_value> values);
+    collection_criteria(const class column& col, collection_operator operand_, std::initializer_list<criteria_value> values);
 
     void accept(criteria_visitor& visitor) const override;
 
@@ -52,7 +54,7 @@ private:
 class collection_query_criteria final : public abstract_column_criteria {
 public:
     collection_query_criteria() = delete;
-    collection_query_criteria(column col, collection_operator operand_, sql::query_context ctx);
+    collection_query_criteria(const class column& col, collection_operator operand_, sql::query_context ctx);
 
     void accept(criteria_visitor& visitor) const override;
 
diff --git a/include/matador/query/criteria/criteria_operators.hpp b/include/matador/query/criteria/criteria_operators.hpp
index 4e7fd59..23c1957 100644
--- a/include/matador/query/criteria/criteria_operators.hpp
+++ b/include/matador/query/criteria/criteria_operators.hpp
@@ -14,48 +14,48 @@ namespace matador::query {
 class column;
 
 template<class Type>
-criteria_ptr operator==(const column &col, Type val) {
+criteria_ptr operator==(const class column &col, Type val) {
     return std::make_unique<binary_criteria>(col, binary_operator::EQUALS, utils::value(val));
 }
 
 template<class Type>
-criteria_ptr operator!=(const column &col, Type val) {
+criteria_ptr operator!=(const class column &col, Type val) {
     return std::make_unique<binary_criteria>(col, binary_operator::NOT_EQUALS, utils::value(val));
 }
 
 template<class Type>
-criteria_ptr operator>(const column &col, Type val) {
+criteria_ptr operator>(const class column &col, Type val) {
     return std::make_unique<binary_criteria>(col, binary_operator::GREATER_THAN, utils::value(val));
 }
 
 template<class Type>
-criteria_ptr operator>=(const column &col, Type val) {
+criteria_ptr operator>=(const class column &col, Type val) {
     return std::make_unique<binary_criteria>(col, binary_operator::GREATER_THAN_OR_EQUAL, utils::value(val));
 }
 
 template<class Type>
-criteria_ptr operator<(const column &col, Type val) {
+criteria_ptr operator<(const class column &col, Type val) {
     return std::make_unique<binary_criteria>(col, binary_operator::LESS_THAN, utils::value(val));
 }
 
 template<class Type>
-criteria_ptr operator<=(const column &col, Type val) {
+criteria_ptr operator<=(const class column &col, Type val) {
     return std::make_unique<binary_criteria>(col, binary_operator::LESS_THAN_OR_EQUAL, utils::value(val));
 }
 
-criteria_ptr operator==(const column &col_left, const column &col_right);
-criteria_ptr operator!=(const column &col_left, const column &col_right);
-criteria_ptr operator>(const column &col_left, const column &col_right);
-criteria_ptr operator>=(const column &col_left, const column &col_right);
-criteria_ptr operator<(const column &col_left, const column &col_right);
-criteria_ptr operator<=(const column &col_left, const column &col_right);
+criteria_ptr operator==(const class column &col_left, const class column &col_right);
+criteria_ptr operator!=(const class column &col_left, const class column &col_right);
+criteria_ptr operator>(const class column &col_left, const class column &col_right);
+criteria_ptr operator>=(const class column &col_left, const class column &col_right);
+criteria_ptr operator<(const class column &col_left, const class column &col_right);
+criteria_ptr operator<=(const class column &col_left, const class column &col_right);
 
-criteria_ptr operator==(const column &col, utils::placeholder p);
-criteria_ptr operator!=(const column &col, utils::placeholder p);
-criteria_ptr operator>(const column &col, utils::placeholder p);
-criteria_ptr operator>=(const column &col, utils::placeholder p);
-criteria_ptr operator<(const column &col, utils::placeholder p);
-criteria_ptr operator<=(const column &col, utils::placeholder p);
+criteria_ptr operator==(const class column &col, utils::placeholder p);
+criteria_ptr operator!=(const class column &col, utils::placeholder p);
+criteria_ptr operator>(const class column &col, utils::placeholder p);
+criteria_ptr operator>=(const class column &col, utils::placeholder p);
+criteria_ptr operator<(const class column &col, utils::placeholder p);
+criteria_ptr operator<=(const class column &col, utils::placeholder p);
 
 criteria_ptr operator&&(criteria_ptr left, criteria_ptr right);
 
@@ -64,7 +64,7 @@ criteria_ptr operator||(criteria_ptr left, criteria_ptr right);
 criteria_ptr operator!(criteria_ptr clause);
 
 template < class Type >
-criteria_ptr in(const column &col, std::initializer_list<Type> args) {
+criteria_ptr in(const class column &col, std::initializer_list<Type> args) {
     std::vector<criteria_value> values;
     for ( auto &&arg : args ) {
         values.emplace_back(utils::value{std::move(arg)});
@@ -73,12 +73,12 @@ criteria_ptr in(const column &col, std::initializer_list<Type> args) {
 }
 
 template <>
-criteria_ptr in(const column &col, std::initializer_list<utils::placeholder> args);
+criteria_ptr in(const class column &col, std::initializer_list<utils::placeholder> args);
 
-criteria_ptr in(const column &col, sql::query_context &&ctx);
+criteria_ptr in(const class column &col, sql::query_context &&ctx);
 
 template < class Type >
-criteria_ptr out(const column &col, std::initializer_list<Type> args) {
+criteria_ptr out(const class column &col, std::initializer_list<Type> args) {
     std::vector<criteria_value> values;
     for ( auto &&arg : args ) {
         values.emplace_back(utils::value{std::move(arg)});
@@ -87,14 +87,14 @@ criteria_ptr out(const column &col, std::initializer_list<Type> args) {
 }
 
 template <>
-criteria_ptr out(const column &col, std::initializer_list<utils::placeholder> args);
+criteria_ptr out(const class column &col, std::initializer_list<utils::placeholder> args);
 
-criteria_ptr out(const column &col, sql::query_context &&ctx);
+criteria_ptr out(const class column &col, sql::query_context &&ctx);
 
-criteria_ptr between(const column &col, int64_t min, int64_t max);
-criteria_ptr between(const column &col, utils::placeholder min, utils::placeholder max);
+criteria_ptr between(const class column &col, int64_t min, int64_t max);
+criteria_ptr between(const class column &col, utils::placeholder min, utils::placeholder max);
 
-criteria_ptr like(const column &col, const std::string &pattern);
+criteria_ptr like(const class column &col, const std::string &pattern);
 
 }
 #endif //CRITERIA_CRITERIA_OPERATORS_HPP
\ No newline at end of file
diff --git a/include/matador/query/criteria/like_criteria.hpp b/include/matador/query/criteria/like_criteria.hpp
index 32e5f6b..ed09560 100644
--- a/include/matador/query/criteria/like_criteria.hpp
+++ b/include/matador/query/criteria/like_criteria.hpp
@@ -3,13 +3,13 @@
 
 #include "matador/query/criteria/abstract_column_criteria.hpp"
 
-#include "matador/query/column.hpp"
-
 namespace matador::query {
+class column;
+
 class like_criteria final : public abstract_column_criteria {
 public:
   like_criteria() = delete;
-  like_criteria(column col, std::string pattern);
+  like_criteria(const class column& col, std::string pattern);
 
   void accept(criteria_visitor &visitor) const override;
 
diff --git a/include/matador/query/generator.hpp b/include/matador/query/generator.hpp
index 1a710c9..f2d2114 100644
--- a/include/matador/query/generator.hpp
+++ b/include/matador/query/generator.hpp
@@ -45,8 +45,6 @@ constexpr auto default_column_generator_options = column_generator_options::Forc
 
 class column_generator {
 public:
-  explicit column_generator(const std::string &table_name = "",
-                            column_generator_options options = default_column_generator_options);
   explicit column_generator(const schema &repo,
                             const std::string &table_name = "",
                             column_generator_options options = default_column_generator_options);
@@ -322,20 +320,5 @@ std::vector<column> columns(const Type &obj,
     return generator.generate(obj);
 }
 
-template<typename Type>
-std::vector<column> columns(const std::string &table_name = "",
-                            const column_generator_options options = default_column_generator_options) {
-    column_generator generator(table_name, options);
-    return generator.generate<Type>();
-}
-
-template<typename Type>
-std::vector<column> columns(const Type &obj,
-                            const std::string &table_name = "",
-                            const column_generator_options options = default_column_generator_options) {
-    column_generator generator(table_name, options);
-    return generator.generate(obj);
-}
-
 }
 #endif //MATADOR_GENERATOR_HPP
\ No newline at end of file
diff --git a/include/matador/query/intermediates/query_insert_intermediate.hpp b/include/matador/query/intermediates/query_insert_intermediate.hpp
index fbdf929..424552f 100644
--- a/include/matador/query/intermediates/query_insert_intermediate.hpp
+++ b/include/matador/query/intermediates/query_insert_intermediate.hpp
@@ -3,19 +3,18 @@
 
 #include "matador/query/intermediates/query_intermediate.hpp"
 #include "matador/query/intermediates/query_into_intermediate.hpp"
-
+#include "matador/query/schema.hpp"
 #include "matador/query/generator.hpp"
 
 namespace matador::query {
 
-class query_insert_intermediate : public query_intermediate
-{
+class query_insert_intermediate : public query_intermediate {
 public:
   query_insert_intermediate();
 
   template<class Type>
-  query_into_intermediate into(const table &tab, const object::repository &schema) {
-    return into(tab, generator::columns<Type>(schema));
+  query_into_intermediate into(const table &tab, const schema &scm) {
+    return into(tab, generator::columns<Type>(scm));
   }
   query_into_intermediate into(const table &tab, std::initializer_list<column> columns);
   query_into_intermediate into(const table &tab, std::vector<column> &&columns);
diff --git a/include/matador/query/query.hpp b/include/matador/query/query.hpp
index ddfcf0d..b079821 100644
--- a/include/matador/query/query.hpp
+++ b/include/matador/query/query.hpp
@@ -4,6 +4,7 @@
 #include "matador/query/query_intermediates.hpp"
 
 #include "matador/query/generator.hpp"
+#include "matador/query/schema.hpp"
 
 namespace matador::sql {
 class connection;
@@ -26,8 +27,8 @@ public:
   [[nodiscard]] static query_select_intermediate select(const std::vector<std::string> &column_names);
   [[nodiscard]] static query_select_intermediate select(std::vector<column> columns, std::initializer_list<column> additional_columns);
   template<class Type>
-  [[nodiscard]] static query_select_intermediate select(const object::repository &schema) {
-    return select(generator::columns<Type>(schema));
+  [[nodiscard]] static query_select_intermediate select(const schema &scm) {
+    return select(generator::columns<Type>(scm));
   }
   [[nodiscard]] static query_insert_intermediate insert();
   [[nodiscard]] static query_update_intermediate update(const table &table);
diff --git a/include/matador/query/query_compiler.hpp b/include/matador/query/query_compiler.hpp
index aa97f8b..7441071 100644
--- a/include/matador/query/query_compiler.hpp
+++ b/include/matador/query/query_compiler.hpp
@@ -77,9 +77,9 @@ protected:
   static std::string build_table_name(sql::dialect_token token, const sql::dialect &d, const table& t);
   static std::string determine_value(value_visitor &visitor, const std::variant<utils::placeholder, utils::database_type> &val);
 
-  std::string build_add_constraint_string(const class constraint& c);
-  std::string build_drop_constraint_string(const class constraint& c);
-  std::string build_constraint_name(const class constraint& c);
+  std::string build_add_constraint_string(const class constraint& c) const;
+  std::string build_drop_constraint_string(const class constraint& c) const;
+  static std::string build_constraint_name(const class constraint& c);
 
 protected:
   const query_data *data_{};
diff --git a/include/matador/query/query_utils.hpp b/include/matador/query/query_utils.hpp
index dabe82c..c6cb9da 100644
--- a/include/matador/query/query_utils.hpp
+++ b/include/matador/query/query_utils.hpp
@@ -13,7 +13,6 @@ namespace matador::query {
 class column;
 
 [[nodiscard]] std::string prepare_identifier(const sql::dialect& d, const column &col);
-[[nodiscard]] std::string prepare_identifier(const sql::dialect& d, const table &tab, const column &col);
 [[nodiscard]] std::string prepare_criteria(const sql::dialect& d, const column &col);
 }
 #endif //MATADOR_QUERY_UTILS_HPP
\ No newline at end of file
diff --git a/include/matador/query/schema.hpp b/include/matador/query/schema.hpp
index de184c8..a513ec0 100644
--- a/include/matador/query/schema.hpp
+++ b/include/matador/query/schema.hpp
@@ -10,6 +10,7 @@
 
 namespace matador::sql {
 class connection_pool;
+class connection;
 }
 
 namespace matador::query {
@@ -34,20 +35,42 @@ class schema_observer final : public object::observer<Type> {
 public:
   explicit schema_observer(schema& s)
   : schema_(s) {}
-  void on_attach(object::repository_node &node, const Type &prototype) override;
-  void on_detach(object::repository_node &node, const Type &prototype) override;
-  void on_insert(Type &obj) override;
-  void on_update(Type &obj) override;
-  void on_delete(Type &obj) override;
+  template<typename OtherType>
+  explicit schema_observer(const schema_observer<OtherType> &x)
+  : schema_(x.schema_)
+  {}
+  void on_attach(const object::repository_node &node, const Type &prototype) const override;
+  void on_detach(const object::repository_node &node, const Type &prototype) const override;
+  void on_insert(const Type &obj) override;
+  void on_update(const Type &obj) override;
+  void on_delete(const Type &obj) override;
 
 private:
+  template < class OtherType >
+  friend class schema_observer;
+
   schema& schema_;
 };
 
+class schema_node final {
+public:
+  schema_node(class table tab, const object::repository_node& node);
+
+  [[nodiscard]] const std::string& name() const;
+  [[nodiscard]] const class table& table() const;
+  [[nodiscard]] const object::repository_node& node() const;
+
+private:
+  class table table_;
+  const object::repository_node& node_;
+};
 class schema final {
 public:
-  explicit schema(sql::connection_pool &pool);
-  schema(sql::connection_pool &pool, const std::string &name);
+  using iterator = std::unordered_map<std::type_index, schema_node>::iterator;
+  using const_iterator = std::unordered_map<std::type_index, schema_node>::const_iterator;
+
+  schema() = default;
+  explicit schema(const std::string &name);
 
   template<typename Type, typename... Observers>
   [[nodiscard]] utils::result<void, utils::error> attach(const std::string &name, Observers&&... observers) {
@@ -64,21 +87,33 @@ public:
     return repo_.attach<Type, SuperType>(name, schema_observer<Type>{*this}, std::forward<Observers>(observers)...);
   }
 
-  [[nodiscard]] utils::result<void, utils::error> create() const;
-  [[nodiscard]] utils::result<void, utils::error> drop() const;
+  [[nodiscard]] utils::result<void, utils::error> create(const sql::connection &conn) const;
+  [[nodiscard]] utils::result<void, utils::error> drop(const sql::connection &conn) const;
 
   template<typename Type>
-  [[nodiscard]] utils::result<void, utils::error> drop_table();
-  [[nodiscard]] utils::result<void, utils::error> drop_table(const std::string &table_name) const;
+  [[nodiscard]] utils::result<void, utils::error> drop_table(const sql::connection &conn);
+  [[nodiscard]] utils::result<void, utils::error> drop_table(const std::string &table_name, const sql::connection &conn) const;
 
-  [[nodiscard]] utils::result<std::vector<object::attribute>, utils::error> describe_table(const std::string &table_name) const;
-  [[nodiscard]] utils::result<bool, utils::error> table_exists(const std::string &table_name) const;
+  [[nodiscard]] utils::result<std::vector<object::attribute>, utils::error> describe_table(const std::string &table_name, const sql::connection &conn) const;
+  [[nodiscard]] utils::result<bool, utils::error> table_exists(const std::string &table_name, const sql::connection &conn) const;
+
+  iterator begin();
+  iterator end();
+  const_iterator begin() const;
+  const_iterator end() const;
+
+  iterator find(const std::type_index& ti) { return schema_nodes_.find(ti); }
+  const_iterator find(const std::type_index& ti) const { return schema_nodes_.find(ti); }
+
+  iterator find(const std::string& name);
+  const_iterator find(const std::string& name) const;
 
   const object::repository &repo() const { return repo_; }
+  object::repository &repo() { return repo_; }
 
 private:
-  [[nodiscard]] sql::query_context build_add_constraint_context( const object::repository_node& node, const object::restriction& cons ) const;
-  [[nodiscard]] sql::query_context build_drop_constraint_context( const object::repository_node& node, const object::restriction& cons ) const;
+  [[nodiscard]] sql::query_context build_add_constraint_context(const object::repository_node& node, const object::restriction& cons, const sql::connection &conn) const;
+  [[nodiscard]] sql::query_context build_drop_constraint_context(const object::repository_node& node, const object::restriction& cons, const sql::connection &conn) const;
 
   void insert_table(const std::type_index& ti, const object::repository_node &node);
 
@@ -87,31 +122,30 @@ private:
   friend class schema_observer;
 
   object::repository repo_;
-  std::unordered_map<std::type_index, table> tables_;
-  sql::connection_pool &pool_;
+  std::unordered_map<std::type_index, schema_node> schema_nodes_;
 };
 
 template<typename Type>
-utils::result<void, utils::error> schema::drop_table() {
+utils::result<void, utils::error> schema::drop_table(const sql::connection &conn) {
   auto info = repo_.info<Type>();
   if (info) {
-    return drop_table(info->get().name());
+    return drop_table(info->get().name(), conn);
   }
 
   return utils::failure(info.err());
 }
 template <typename Type>
-void schema_observer<Type>::on_attach(object::repository_node &node, const Type &prototype) {
+void schema_observer<Type>::on_attach(const object::repository_node &node, const Type &/*prototype*/) const {
   schema_.insert_table(typeid(Type), node);
 }
 
 template <typename Type>
-void schema_observer<Type>::on_detach(object::repository_node &node, const Type &prototype) {}
+void schema_observer<Type>::on_detach(const object::repository_node &/*node*/, const Type &/*prototype*/) const {}
 template <typename Type>
-void schema_observer<Type>::on_insert(Type &obj) {}
+void schema_observer<Type>::on_insert(const Type &/*obj*/) {}
 template <typename Type>
-void schema_observer<Type>::on_update(Type &obj) {}
+void schema_observer<Type>::on_update(const Type &/*obj*/) {}
 template <typename Type>
-void schema_observer<Type>::on_delete(Type &obj) {}
+void schema_observer<Type>::on_delete(const Type &/*obj*/) {}
 }  // namespace matador::query
 #endif //MATADOR_SCHEMA_HPP
\ No newline at end of file
diff --git a/include/matador/query/table.hpp b/include/matador/query/table.hpp
index 269cf03..2528089 100644
--- a/include/matador/query/table.hpp
+++ b/include/matador/query/table.hpp
@@ -13,24 +13,36 @@ class table {
 public:
   table() = default;
   table(const char *name); // NOLINT(*-explicit-constructor)
-  table(std::string name); // NOLINT(*-explicit-constructor)
-  table(std::string name, std::string as);
-  table(std::string name, std::string as, const std::vector<column> &columns);
+  table(const std::string& name); // NOLINT(*-explicit-constructor)
+  table(const std::string& name, const std::vector<column>& columns);
+  table(const table& other);
+  table& operator=(const table& other);
+  table(table&& other) noexcept;
+  table& operator=(table&& other) noexcept;
+  ~table() = default;
 
-  table as(const std::string &a);
+  [[nodiscard]] table as(const std::string &alias) const;
 
   [[nodiscard]] bool operator==(const table &x) const;
 
-  [[nodiscard]] table as(const std::string &a) const;
+  [[nodiscard]] const std::string& table_name() const;
+  [[nodiscard]] const std::string& name() const;
+  [[nodiscard]] const std::vector<column>& columns() const;
 
   [[nodiscard]] bool has_alias() const;
 
-  [[nodiscard]] const std::string& name() const;
-  [[nodiscard]] const std::string& alias() const;
-  [[nodiscard]] const std::vector<column>& columns() const;
-
   // ReSharper disable once CppNonExplicitConversionOperator
   operator const std::vector<query::column>&() const; // NOLINT(*-explicit-constructor)
+
+  const class column* operator[](const std::string& column_name) const;
+  static const class column* column_by_name(const table &tab, const std::string& column_name);
+
+protected:
+  static const column& create_column(class table& tab, const std::string& name);
+
+private:
+  table(std::string  name, std::string  alias, const std::vector<column>& columns);
+
 private:
   friend class column;
 
diff --git a/include/matador/sql/query_macro.hpp b/include/matador/sql/query_macro.hpp
index ddebbb4..9f7b9b6 100644
--- a/include/matador/sql/query_macro.hpp
+++ b/include/matador/sql/query_macro.hpp
@@ -9,16 +9,17 @@
 #include <string>
 #include <ostream>
 
-#define FIELD(x) const matador::query::column x{*this, #x, ""};
+#define FIELD(x) const matador::query::column& x = create_column(*this, #x);
 
 #define QUERY_HELPER(C, V, ...) \
 namespace matador::query::meta {     \
 namespace internal {                      \
-struct C##_query : table {           \
-C##_query() : table(#C) {}                            \
+class C##_table : public table {           \
+public: \
+C##_table() : table(#C) {}                            \
 MAP(FIELD, __VA_ARGS__) \
 }; }                     \
-static const internal:: C##_query V;  \
+static const internal:: C##_table V;  \
 }
 
 #endif //QUERY_QUERY_HELPER_HPP
diff --git a/source/core/CMakeLists.txt b/source/core/CMakeLists.txt
index 34ff9bd..fe441d6 100644
--- a/source/core/CMakeLists.txt
+++ b/source/core/CMakeLists.txt
@@ -108,6 +108,8 @@ add_library(matador-core STATIC
   utils/uuid.cpp
   utils/value.cpp
   utils/version.cpp
+  ../../include/matador/object/internal/observer_list_creator.hpp
+  ../../include/matador/object/internal/observer_list_copy_creator.hpp
 )
 
 target_link_libraries(matador-core ${CMAKE_DL_LIBS})
diff --git a/source/core/object/attribute.cpp b/source/core/object/attribute.cpp
index f93e6d8..690d63b 100644
--- a/source/core/object/attribute.cpp
+++ b/source/core/object/attribute.cpp
@@ -16,8 +16,8 @@ attribute::attribute(std::string name,
 : name_(std::move(name))
 , type_(type)
 , options_(attr)
-, null_option_(null_opt)
-{}
+, null_option_(null_opt) {
+}
 
 const std::string &attribute::name() const {
   return name_;
diff --git a/source/core/object/internal/shadow_repository.cpp b/source/core/object/internal/shadow_repository.cpp
index b4124a5..b2dc557 100644
--- a/source/core/object/internal/shadow_repository.cpp
+++ b/source/core/object/internal/shadow_repository.cpp
@@ -4,7 +4,7 @@
 #include "matador/object/repository_node.hpp"
 
 namespace matador::object::internal {
-shadow_repository::shadow_repository( repository& s )
+shadow_repository::shadow_repository(repository& s)
 : repo_(s) {}
 
 repository& shadow_repository::repo() const {
@@ -62,4 +62,20 @@ std::shared_ptr<object> shadow_repository::object_for_type(const std::type_index
 void shadow_repository::remove_object_for_type(const std::type_index& ti) const {
   repo_.remove_object_for_type(ti);
 }
+
+bool shadow_repository::is_node_announced(const std::type_index &ti) const {
+  return repo_.is_node_announced(ti);
+}
+
+void shadow_repository::push_announce_node(const std::type_index &ti, const node_ptr &node) const {
+  repo_.push_announce_node(ti, node);
+}
+
+shadow_repository::node_ptr shadow_repository::announce_node(const std::type_index &ti) const {
+  return repo_.announce_node(ti);
+}
+
+shadow_repository::node_ptr shadow_repository::pop_announce_node(const std::type_index &ti) const {
+  return repo_.pop_announce_node(ti);
+}
 }
diff --git a/source/core/object/object_generator.cpp b/source/core/object/object_generator.cpp
index 884d081..9b8d28d 100644
--- a/source/core/object/object_generator.cpp
+++ b/source/core/object/object_generator.cpp
@@ -5,7 +5,7 @@
 #include <algorithm>
 
 namespace matador::object {
-object_generator::object_generator(repository& repo, const std::shared_ptr<object>& object)
+object_generator::object_generator(const repository& repo, const std::shared_ptr<object>& object)
 : repo_(repo)
 , object_(object) {}
 
diff --git a/source/core/object/repository.cpp b/source/core/object/repository.cpp
index f00b45d..626db88 100644
--- a/source/core/object/repository.cpp
+++ b/source/core/object/repository.cpp
@@ -104,8 +104,7 @@ void repository::dump( std::ostream& os, const node_ptr& node ) {
     }
 }
 
-utils::result<repository::node_ptr, utils::error> repository::attach_node(const std::shared_ptr<repository_node> &node,
-                                                                  const std::string &parent) {
+utils::result<repository::node_ptr, utils::error> repository::attach_node(const std::shared_ptr<repository_node> &node, const std::string &parent) {
   if (has_node(node)) {
     return utils::failure(make_error(error_code::NodeAlreadyExists, "Node '" + node->name() + "' already exists."));
   }
@@ -233,4 +232,24 @@ std::shared_ptr<object> repository::object_for_type(const std::type_index &ti) c
 void repository::remove_object_for_type(const std::type_index &ti) {
   object_by_type_.erase(ti);
 }
+
+bool repository::is_node_announced(const std::type_index &ti) const {
+  return announced_node_.count(ti) > 0;
+}
+
+void repository::push_announce_node(const std::type_index &ti, const node_ptr &node) {
+  announced_node_.insert({ti, node});
+}
+
+repository::node_ptr repository::announce_node(const std::type_index &ti) {
+  return announced_node_.find(ti)->second;
+}
+
+repository::node_ptr repository::pop_announce_node(const std::type_index &ti) {
+  const auto it = announced_node_.find(ti);
+  if (it != announced_node_.end()) {
+    announced_node_.erase(it);
+  }
+  return it->second;
+}
 } // namespace matador::object
diff --git a/source/core/object/repository_node.cpp b/source/core/object/repository_node.cpp
index bf12725..ab256f4 100644
--- a/source/core/object/repository_node.cpp
+++ b/source/core/object/repository_node.cpp
@@ -99,10 +99,4 @@ void repository_node::unlink() {
   next_sibling_.reset();
   previous_sibling_.reset();
 }
-
-utils::result<repository_node::node_ptr, utils::error> repository_node::make_and_attach_node(repository& repo, const std::string& name, const std::type_index& ti) {
-    const auto node = std::shared_ptr<repository_node>(new repository_node(repo, name, ti));
-
-    return repo.attach_node(node, "");
-}
 }
diff --git a/source/orm/orm/session.cpp b/source/orm/orm/session.cpp
index b85bdd7..3ebbcfe 100644
--- a/source/orm/orm/session.cpp
+++ b/source/orm/orm/session.cpp
@@ -227,7 +227,7 @@ query::fetchable_query session::build_select_query(entity_query_data &&data) {
       .from(*data.root_table)
       .join_left(data.joins)
       .where(std::move(data.where_clause))
-      .order_by({data.root_table.get(), data.pk_column_name})
+      .order_by({data.root_table, data.pk_column_name})
       .asc();
 }
 }
diff --git a/source/orm/orm/session_query_builder.cpp b/source/orm/orm/session_query_builder.cpp
index 45985fe..cb24acf 100644
--- a/source/orm/orm/session_query_builder.cpp
+++ b/source/orm/orm/session_query_builder.cpp
@@ -3,7 +3,7 @@
 #include <iostream>
 
 namespace matador::orm {
-criteria_transformer::criteria_transformer(const query::schema& repo, const std::unordered_map<std::string, std::shared_ptr<query::table>>& tables_by_name)
+criteria_transformer::criteria_transformer(const query::schema& repo, const std::unordered_map<std::string, query::table>& tables_by_name)
 : repo_(repo)
 , tables_by_name_(tables_by_name) {}
 
@@ -39,12 +39,15 @@ void criteria_transformer::visit( const query::not_criteria& node ) {
 }
 
 void criteria_transformer::update_criteria_column(const query::abstract_column_criteria& node) const {
-    const auto it = tables_by_name_.find(node.col().table()->name());
-    if (it == tables_by_name_.end()) {
-        return;
-    }
+  if (node.col().table() == nullptr) {
+    return;
+  }
+  const auto it = tables_by_name_.find(node.col().table()->name());
+  if (it == tables_by_name_.end()) {
+    return;
+  }
 
-    const_cast<query::column&>(node.col()).table(it->second.get());
+  const_cast<query::column&>(node.col()).table(&it->second);
 }
 
 void session_query_builder::on_revision(const char *id, uint64_t &/*rev*/) {
@@ -52,11 +55,11 @@ void session_query_builder::on_revision(const char *id, uint64_t &/*rev*/) {
 }
 
 void session_query_builder::push(const std::string &column_name) {
-  const auto it = processed_tables_.find(table_info_stack_.top().info.get().name());
+  const auto it = processed_tables_.find(table_info_stack_.top().info.name());
   if (it == processed_tables_.end()) {
     throw query_builder_exception{query_build_error::UnexpectedError};
   }
-  entity_query_data_.columns.emplace_back(it->second.get(), column_name, build_alias('c', ++column_index));
+  entity_query_data_.columns.emplace_back(&it->second, column_name, build_alias('c', ++column_index));
 }
 
 std::string session_query_builder::build_alias(const char prefix, const unsigned int count) {
diff --git a/source/orm/query/builder.cpp b/source/orm/query/builder.cpp
index 292d6cc..80e70e5 100644
--- a/source/orm/query/builder.cpp
+++ b/source/orm/query/builder.cpp
@@ -4,52 +4,61 @@ namespace matador::query {
 
 column_builder::column_builder(std::string column_name, const utils::basic_type type, const size_t size)
 : column_name_(std::move(column_name))
-, type_(type){}
+, type_(type)
+, size_(size) {}
 
 column_builder::operator class query::column() const {
-  return {column_name_};
+  return {nullptr, column_name_, type_, {size_, constraints_}};
 }
 
 column_builder& column_builder::not_null() {
+  constraints_ |= utils::constraints::NotNull;
+  return *this;
+}
 
-    return *this;
+column_builder & column_builder::primary_key() {
+  constraints_ |= utils::constraints::PrimaryKey;
+  return *this;
+}
+
+column_builder & column_builder::unique() {
+  constraints_ |= utils::constraints::Unique;
+  return *this;
 }
 
 table_builder::table_builder(std::string name)
 : table_name( std::move(name) ) {}
 
-table_builder& table_builder::as( std::string table_alias ) {
-  this->alias = std::move(table_alias);
-  return *this;
-}
 
 table_builder::operator class query::table() const {
-  return {table_name, alias, {}};
+  return {table_name, {}};
 }
 
 constraint_builder& constraint_builder::constraint( std::string name ) {
-  constraint_name = std::move(name);
+  constraint_name_ = std::move(name);
   return *this;
 }
 
 constraint_builder& constraint_builder::primary_key( std::string name ) {
-  pk_column_name = std::move(name);
+  column_name_ = std::move(name);
+  type_ = utils::constraints::PrimaryKey;
   return *this;
 }
 
 constraint_builder& constraint_builder::foreign_key( std::string name ) {
-  fk_column_name = std::move(name);
+  column_name_ = std::move(name);
+  type_ = utils::constraints::ForeignKey;
   return *this;
 }
 
 constraint_builder& constraint_builder::references( std::string table, std::string column ) {
-  this->table_name = std::move(table);
-  this->column_name = std::move(column);
+  this->ref_table_name_ = std::move(table);
+  this->ref_column_name_ = std::move(column);
   return *this;
 }
 
 constraint_builder::operator class constraint() const {
-  return {};
+  return {constraint_name_, column_name_, ref_table_name_, type_, ref_table_name_, ref_column_name_};
 }
 
 constraint_builder constraint( std::string name ) {
diff --git a/source/orm/query/column.cpp b/source/orm/query/column.cpp
index 10518bf..bae3f45 100644
--- a/source/orm/query/column.cpp
+++ b/source/orm/query/column.cpp
@@ -18,7 +18,7 @@ column operator ""_col(const char *name, const size_t len) {
     throw std::invalid_argument("Invalid column name: multiple dots found");
   }
 
-  return column{new table(str.substr(0, pos)), str.substr(pos + 1)};
+  return column{str.substr(pos + 1)};
 }
 
 column::column(const char *name)
@@ -26,27 +26,25 @@ column::column(const char *name)
 {}
 
 column::column(std::string name)
-: table_(default_table())
-, name_(std::move(name)) {}
+: name_(std::move(name)) {}
 column::column(std::string name, std::string alias)
-: table_(default_table())
-, name_(std::move(name))
+: name_(std::move(name))
 , alias_(std::move(alias)) {}
 
 column::column(const sql::sql_function_t func, std::string name)
-: table_(default_table())
-, name_(std::move(name))
+: name_(std::move(name))
 , function_(func) {}
 
 column::column(const class table* tab, std::string name)
 : table_(tab)
 , name_(std::move(name)) {}
 
-column::column(const class query::table* tab, std::string name, std::string alias)
+column::column(const class table* tab, std::string name, std::string alias)
 : table_(tab)
 , name_(std::move(name))
 , alias_(std::move(alias)) {}
-column::column(const class query::table* tab, std::string name,
+column::column(const class table* tab,
+               std::string name,
                const utils::basic_type type,
                const utils::field_attributes& attributes)
 : table_(tab)
@@ -54,16 +52,53 @@ column::column(const class query::table* tab, std::string name,
 , type_(type)
 , attributes_(attributes) {}
 
+column::column(const class table* tab,
+               std::string name,
+               std::string alias,
+               utils::basic_type type,
+               const utils::field_attributes &attributes)
+: table_(tab)
+, name_(std::move(name))
+, alias_(std::move(alias))
+, type_(type)
+, attributes_(attributes) {}
+
+column & column::operator=(const column &other) {
+  if (this == &other) {
+    return *this;
+  }
+  table_ = other.table_;
+  name_ = other.name_;
+  alias_ = other.alias_;
+  type_ = other.type_;
+  attributes_ = other.attributes_;
+  return *this;
+}
+
+column::column(const column &other)
+: table_(other.table_)
+, name_(other.name_)
+, alias_(other.alias_)
+, type_(other.type_)
+, attributes_(other.attributes_) {
+}
+
 bool column::equals(const column &x) const {
-  return *table_ == *x.table_ &&
-         name_ == x.name_ &&
-         alias_ == x.alias_ &&
-         function_ == x.function_;
+  if (table_ != nullptr && x.table_ != nullptr) {
+    return *table_ == *x.table_ &&
+           name_ == x.name_ &&
+           alias_ == x.alias_ &&
+           function_ == x.function_;
+  }
+
+  return name_ == x.name_ &&
+       alias_ == x.alias_ &&
+       function_ == x.function_;
 }
 
 column column::as(std::string a) {
   alias_ = std::move(a);
-  return *this;
+  return {table_, name_, alias_, type_, attributes_};
 }
 
 const std::string& column::name() const {
@@ -109,10 +144,4 @@ void column::table(const query::table* tab) {
 column::operator const std::string&() const {
   return name_;
 }
-
-query::table* column::default_table() {
-  static query::table default_table;
-
-  return &default_table;
-}
 }
diff --git a/source/orm/query/constraint.cpp b/source/orm/query/constraint.cpp
index 2bbf90e..33111f5 100644
--- a/source/orm/query/constraint.cpp
+++ b/source/orm/query/constraint.cpp
@@ -15,6 +15,23 @@ constraint::constraint(std::string column_name, std::string table_name, utils::c
 , referenced_table_(std::move(referenced_table))
 , referenced_column_(std::move(referenced_column)) {}
 
+constraint::constraint(std::string name,
+                       std::string column_name,
+                       std::string table_name,
+                       utils::constraints type,
+                       std::string referenced_table,
+                       std::string referenced_column)
+: name_(std::move(name))
+, column_name_(std::move(column_name))
+, table_name_(std::move(table_name))
+, type_(type)
+, referenced_table_(std::move(referenced_table))
+, referenced_column_(std::move(referenced_column)) {}
+
+std::string constraint::name() const {
+  return name_;
+}
+
 std::string constraint::column_name() const {
   return column_name_;
 }
diff --git a/source/orm/query/criteria/abstract_column_criteria.cpp b/source/orm/query/criteria/abstract_column_criteria.cpp
index fb27232..54aad33 100644
--- a/source/orm/query/criteria/abstract_column_criteria.cpp
+++ b/source/orm/query/criteria/abstract_column_criteria.cpp
@@ -1,8 +1,8 @@
 #include "matador/query/criteria/abstract_column_criteria.hpp"
 
 namespace matador::query {
-abstract_column_criteria::abstract_column_criteria(column col)
-: column_(std::move(col)) {}
+abstract_column_criteria::abstract_column_criteria(const class column& col)
+: column_(col) {}
 
 const column& abstract_column_criteria::col() const {
   return column_;
diff --git a/source/orm/query/criteria/between_criteria.cpp b/source/orm/query/criteria/between_criteria.cpp
index a200796..599a5c5 100644
--- a/source/orm/query/criteria/between_criteria.cpp
+++ b/source/orm/query/criteria/between_criteria.cpp
@@ -3,14 +3,14 @@
 #include "matador/query/criteria/criteria_visitor.hpp"
 
 namespace matador::query{
-between_criteria::between_criteria(column col, const int64_t min, const int64_t max)
-: abstract_column_criteria(std::move(col))
+between_criteria::between_criteria(const class column& col, const int64_t min, const int64_t max)
+: abstract_column_criteria(col)
 , min_(utils::value{min})
 , max_(utils::value{max})
 {}
 
-between_criteria::between_criteria(column col, utils::placeholder min, utils::placeholder max)
-: abstract_column_criteria(std::move(col))
+between_criteria::between_criteria(const class column& col, utils::placeholder min, utils::placeholder max)
+: abstract_column_criteria(col)
 , min_(min)
 , max_(max)
 {}
diff --git a/source/orm/query/criteria/binary_criteria.cpp b/source/orm/query/criteria/binary_criteria.cpp
index ec3b864..4204ea7 100644
--- a/source/orm/query/criteria/binary_criteria.cpp
+++ b/source/orm/query/criteria/binary_criteria.cpp
@@ -3,8 +3,8 @@
 #include "matador/query/criteria/criteria_visitor.hpp"
 
 namespace matador::query {
-binary_criteria::binary_criteria(column col, const binary_operator operand, criteria_value value)
-: abstract_column_criteria(std::move(col))
+binary_criteria::binary_criteria(const class column& col, const binary_operator operand, criteria_value value)
+: abstract_column_criteria(col)
 , operator_(operand)
 , value_(std::move(value))
 {}
@@ -21,16 +21,16 @@ const criteria_value& binary_criteria::value() const {
   return value_;
 }
 
-binary_column_criteria::binary_column_criteria(column left_column, binary_operator operand, column right_column)
-: left_column_(std::move(left_column))
+binary_column_criteria::binary_column_criteria(const class column& left_column, const binary_operator operand, const class column& right_column)
+: left_column_(left_column)
 , operator_(operand)
-, right_column_(std::move(right_column)){}
+, right_column_(right_column){}
 
 void binary_column_criteria::accept(criteria_visitor& visitor) const {
   visitor.visit(*this);
 }
 
-const column& binary_column_criteria::left_column() const {
+const class column& binary_column_criteria::left_column() const {
   return left_column_;
 }
 
@@ -38,7 +38,7 @@ binary_operator binary_column_criteria::operand() const {
   return operator_;
 }
 
-const column& binary_column_criteria::right_column() const {
+const class column& binary_column_criteria::right_column() const {
   return right_column_;
 }
 }
diff --git a/source/orm/query/criteria/collection_criteria.cpp b/source/orm/query/criteria/collection_criteria.cpp
index 9db0ee5..4ba08f7 100644
--- a/source/orm/query/criteria/collection_criteria.cpp
+++ b/source/orm/query/criteria/collection_criteria.cpp
@@ -1,16 +1,17 @@
 #include "matador/query/criteria/collection_criteria.hpp"
 
 #include "matador/query/criteria/criteria_visitor.hpp"
+#include "matador/query/column.hpp"
 
 namespace matador::query {
-collection_criteria::collection_criteria(column col, const collection_operator operand_, std::vector<criteria_value> values )
-: abstract_column_criteria(std::move(col))
+collection_criteria::collection_criteria(const class column& col, const collection_operator operand_, std::vector<criteria_value> values )
+: abstract_column_criteria(col)
 , operand_(operand_)
 , values_(std::move(values))
 {}
 
-collection_criteria::collection_criteria(column col, const collection_operator operand_, const std::initializer_list<criteria_value> values )
-: abstract_column_criteria(std::move(col))
+collection_criteria::collection_criteria(const class column& col, const collection_operator operand_, const std::initializer_list<criteria_value> values )
+: abstract_column_criteria(col)
 , operand_(operand_)
 , values_(values)
 {}
@@ -27,8 +28,8 @@ const std::vector<criteria_value>& collection_criteria::values() const {
   return values_;
 }
 
-collection_query_criteria::collection_query_criteria(column col, collection_operator operand_, sql::query_context ctx)
-: abstract_column_criteria(std::move(col))
+collection_query_criteria::collection_query_criteria(const class column& col, collection_operator operand_, sql::query_context ctx)
+: abstract_column_criteria(col)
 , operand_(operand_)
 , query_context_(std::move(ctx)){
 }
diff --git a/source/orm/query/criteria/like_criteria.cpp b/source/orm/query/criteria/like_criteria.cpp
index 28d67ed..12a535d 100644
--- a/source/orm/query/criteria/like_criteria.cpp
+++ b/source/orm/query/criteria/like_criteria.cpp
@@ -1,10 +1,11 @@
 #include "matador/query/criteria/like_criteria.hpp"
 
 #include "matador/query/criteria/criteria_visitor.hpp"
+#include "matador/query/column.hpp"
 
 namespace matador::query {
-like_criteria::like_criteria(column col, std::string pattern)
-: abstract_column_criteria(std::move(col))
+like_criteria::like_criteria(const class column& col, std::string pattern)
+: abstract_column_criteria(col)
 , pattern_(std::move(pattern)){}
 
 void like_criteria::accept(criteria_visitor &visitor) const {
diff --git a/source/orm/query/generator.cpp b/source/orm/query/generator.cpp
index c3452a2..6d717f5 100644
--- a/source/orm/query/generator.cpp
+++ b/source/orm/query/generator.cpp
@@ -1,11 +1,6 @@
 #include "matador/query/generator.hpp"
 
 namespace matador::query::generator {
-column_generator::column_generator(const std::string& table_name, const column_generator_options options)
-: options_(options) {
-  table_stack_.push(table_name.empty() ? std::make_shared<table>() : std::make_shared<table>(table_name));
-}
-
 column_generator::column_generator(const schema& repo, const std::string& table_name, const column_generator_options options)
 : repo_(std::cref(repo))
 , options_(options) {
diff --git a/source/orm/query/intermediates/query_create_intermediate.cpp b/source/orm/query/intermediates/query_create_intermediate.cpp
index 6b06287..94898f4 100644
--- a/source/orm/query/intermediates/query_create_intermediate.cpp
+++ b/source/orm/query/intermediates/query_create_intermediate.cpp
@@ -4,6 +4,8 @@
 
 #include "matador/query/constraint.hpp"
 
+#include "matador/object/object.hpp"
+
 #include <vector>
 
 namespace matador::query {
@@ -26,41 +28,55 @@ executable_query query_create_table_columns_intermediate::constraints(const std:
   return this->constraints(std::list(constraints));
 }
 
-executable_query query_create_table_columns_intermediate::constraints(std::initializer_list<constraint> constraints) {
-  return {context_};
+executable_query query_create_table_columns_intermediate::constraints(const std::initializer_list<constraint> constraints) {
+  return this->constraints(std::list(constraints));
 }
 
-executable_query query_create_table_columns_intermediate::constraints(const std::list<constraint>& restrictions){
+executable_query query_create_table_columns_intermediate::constraints(const std::list<constraint>& constraints){
+  context_->parts.push_back(std::make_unique<internal::query_create_table_constraints_part>(constraints));
   return {context_};
 }
 
 executable_query query_create_table_columns_intermediate::constraints(const std::list<object::restriction>& restrictions) {
   std::list<constraint> constraints;
-  for ( const auto& restr : restrictions ) {
-
+  for (const auto& restr : restrictions) {
+    if (restr.is_primary_key_constraint()) {
+      constraints.emplace_back(restr.column_name(), restr.owner()->name(), restr.attribute().attributes().options());
+    } else if (restr.is_foreign_key_constraint()) {
+      constraints.emplace_back(restr.column_name(), restr.owner()->name(), restr.attribute().attributes().options(), restr.ref_table_name(), restr.ref_column_name());
+    } else if (restr.is_unique_constraint()) {
+      constraints.emplace_back(restr.column_name(), restr.owner()->name(), restr.attribute().attributes().options());
+    }
   }
   context_->parts.push_back(std::make_unique<internal::query_create_table_constraints_part>(constraints));
   return {context_};
 }
 
-query_create_table_columns_intermediate query_create_table_intermediate::columns(std::initializer_list<object::attribute> attributes) {
+query_create_table_columns_intermediate query_create_table_intermediate::columns(const std::initializer_list<object::attribute> attributes) {
   return columns(std::list(attributes));
 }
 
 query_create_table_columns_intermediate query_create_table_intermediate::columns(const std::list<object::attribute>& attributes) {
   std::list<column> columns;
   for (const auto& attr : attributes) {
+    auto options = attr.attributes().options();
+    if (!attr.is_nullable()) {
+      options |= utils::constraints::NotNull;
+    }
 
+    columns.emplace_back(nullptr, attr.name(), attr.type(), utils::field_attributes{attr.attributes().size(), options});
   }
   context_->parts.push_back(std::make_unique<internal::query_create_table_columns_part>(columns));
   return {context_};
 }
 
 query_create_table_columns_intermediate query_create_table_intermediate::columns(std::initializer_list<column> columns) {
-  return {context_};
+  return this->columns(std::list(columns));
 }
 
 query_create_table_columns_intermediate query_create_table_intermediate::columns(const std::list<column>& columns) {
+  context_->parts.push_back(std::make_unique<internal::query_create_table_columns_part>(columns));
+
   return {context_};
 }
 }
diff --git a/source/orm/query/query_compiler.cpp b/source/orm/query/query_compiler.cpp
index 28b2783..0328e01 100644
--- a/source/orm/query/query_compiler.cpp
+++ b/source/orm/query/query_compiler.cpp
@@ -38,18 +38,21 @@ sql::query_context query_compiler::compile(const query_data &data,
 }
 
 std::string handle_column(sql::query_context &ctx, const sql::dialect *d, const query_data &data, const column &col) {
-    if (col.is_function()) {
-      ctx.prototype.emplace_back(col.has_alias() ? col.alias() : col.name());
-      ctx.prototype.back().change_type(utils::basic_type::Int32);
-    } else {
-        ctx.prototype.emplace_back(col.name());
-    }
+  if (col.is_function()) {
+    ctx.prototype.emplace_back(col.has_alias() ? col.alias() : col.name());
+    ctx.prototype.back().change_type(utils::basic_type::Int32);
+  } else {
+      ctx.prototype.emplace_back(col.name());
+  }
 
+
+  if (col.table() != nullptr) {
     if (const auto it = data.tables.find(col.table()->name()); it != data.tables.end()) {
-        return prepare_identifier(*d, it->second, {col.name(), col.alias()});
+      return prepare_identifier(*d,{&it->second, col.name(), col.alias()});
     }
+  }
 
-    return prepare_identifier(*d, col);
+  return prepare_identifier(*d, col);
 }
 
 void query_compiler::visit(internal::query_alter_part& part) {
@@ -125,7 +128,7 @@ void query_compiler::visit(internal::query_drop_key_constraint_part_by_name& par
   query_.sql += " " + dialect_->token_at(part.token()) + " " + part.name();
 }
 
-void query_compiler::visit(internal::query_drop_key_constraint_part_by_constraint& part) {
+void query_compiler::visit(internal::query_drop_key_constraint_part_by_constraint& /*part*/) {
 }
 
 void query_compiler::visit(internal::query_select_part &part) {
@@ -158,8 +161,7 @@ void query_compiler::visit(internal::query_from_part &part) {
   query_.sql += " " + build_table_name(part.token(), *dialect_, part.table());
 }
 
-void query_compiler::visit(internal::query_join_part &part)
-{
+void query_compiler::visit(internal::query_join_part &part) {
   query_.sql += " " + build_table_name(part.token(), *dialect_, part.table());
 }
 
@@ -403,9 +405,9 @@ std::string build_create_column(const column &col, const sql::dialect &d) {
 
 std::string build_constraint(const constraint& cons, const sql::dialect& d) {
     std::string result;
-    // if (!cons.name().empty()) {
-        // result.append(d.constraint()).append(" ").append(cons.name()).append(" ");
-    // }
+    if (!cons.name().empty()) {
+        result.append(d.constraint()).append(" ").append(cons.name()).append(" ");
+    }
     if (cons.is_primary_key_constraint()) {
         result
             .append(d.primary_key())
@@ -432,11 +434,11 @@ std::string build_constraint(const constraint& cons, const sql::dialect& d) {
 std::string query_compiler::build_table_name(const sql::dialect_token token, const sql::dialect &d, const table& t) {
   return d.token_at(token) + " " +
     (!d.default_schema_name().empty() ? d.prepare_identifier_string(d.default_schema_name()) + "." : "") +
-    d.prepare_identifier_string(t.name()) +
-    (t.alias().empty() ? "" : " " + d.prepare_identifier_string(t.alias()));
+    d.prepare_identifier_string(t.table_name()) +
+    (!t.has_alias() ? "" : " " + d.prepare_identifier_string(t.name()));
 }
 
-std::string query_compiler::build_add_constraint_string(const class constraint &c) {
+std::string query_compiler::build_add_constraint_string(const class constraint &c) const {
   std::string result = dialect_->add_constraint() + " " + build_constraint_name(c) + " ";
   if (c.is_primary_key_constraint()) {
     result.append(dialect_->primary_key()).append(" (").append(c.column_name()).append(")");
@@ -448,7 +450,7 @@ std::string query_compiler::build_add_constraint_string(const class constraint &
   return result;
 }
 
-std::string query_compiler::build_drop_constraint_string(const class constraint &c) {
+std::string query_compiler::build_drop_constraint_string(const class constraint &c) const {
   return dialect_->drop_constraint() + " " + build_constraint_name(c);
 }
 
diff --git a/source/orm/query/query_utils.cpp b/source/orm/query/query_utils.cpp
index a3e34a9..8836185 100644
--- a/source/orm/query/query_utils.cpp
+++ b/source/orm/query/query_utils.cpp
@@ -3,15 +3,11 @@
 #include "matador/query/table.hpp"
 
 namespace matador::query {
-std::string prepare_identifier( const sql::dialect& d, const column& col ) {
-  return prepare_identifier(d, *col.table(), col);
-}
-
-std::string prepare_identifier( const sql::dialect& d, const table& tab, const column& col ) {
+std::string prepare_identifier(const sql::dialect& d, const column& col) {
   std::string result;
   if (!col.is_function()) {
-    if (!tab.name().empty()) {
-      result = d.prepare_identifier_string(tab.has_alias() ? tab.alias() : tab.name()) + ".";
+    if (col.table()) {
+      result = d.prepare_identifier_string(col.table()->name()) + ".";
     }
     result += d.prepare_identifier_string(col.name());
   } else {
@@ -24,20 +20,16 @@ std::string prepare_identifier( const sql::dialect& d, const table& tab, const c
 }
 
 std::string prepare_criteria(const sql::dialect& d, const column& col) {
-    std::string result;
-    if (!col.is_function()) {
-        // if (!col.alias.empty()) {
-        //     result = col.alias;
-        // } else {
-        if (!col.table()->name().empty()) {
-            result = d.prepare_identifier_string(col.table()->has_alias() ? col.table()->alias() : col.table()->name()) + ".";
-        }
-        result += d.prepare_identifier_string(col.name());
-        // }
-    } else {
-        result = d.sql_function_at(col.function()) + "(" + col.name() + ")";
+  std::string result;
+  if (!col.is_function()) {
+    if (col.table()) {
+      result = d.prepare_identifier_string(col.table()->name()) + ".";
     }
+    result += d.prepare_identifier_string(col.name());
+  } else {
+    result = d.sql_function_at(col.function()) + "(" + col.name() + ")";
+  }
 
-    return result;
+  return result;
 }
 }
\ No newline at end of file
diff --git a/source/orm/query/schema.cpp b/source/orm/query/schema.cpp
index 7b657b9..faafa07 100644
--- a/source/orm/query/schema.cpp
+++ b/source/orm/query/schema.cpp
@@ -1,3 +1,5 @@
+#include <utility>
+
 #include "matador/query/schema.hpp"
 
 #include "matador/query/query.hpp"
@@ -7,208 +9,253 @@
 #include "matador/sql/backend_provider.hpp"
 #include "matador/sql/connection_pool.hpp"
 #include "matador/sql/dialect.hpp"
-#include "matador/sql/error_code.hpp"
 
 namespace matador::query {
-schema::schema(sql::connection_pool& pool)
-: repo_(sql::backend_provider::instance().connection_dialect(pool.info().type).default_schema_name())
-, pool_(pool) {
+schema_node::schema_node(class table tab, const object::repository_node& node)
+: table_(std::move(tab))
+, node_(std::move(node)) {
 }
 
-schema::schema(sql::connection_pool &pool, const std::string& name)
-: repo_(name)
-, pool_(pool) {}
-
-utils::result<void, utils::error> schema::create() const {
-    // Step 1: Build dependency graph
-    // std::unordered_map<std::string, std::vector<std::string> > dependency_graph;
-    // std::unordered_map<std::string, std::pair<int,object::repository::node_ptr>> in_degree;
-    //
-    // for (const auto &node: repo_) {
-    //     for (auto it = node->info().endpoint_begin(); it != node->info().endpoint_end(); ++it) {
-    //         dependency_graph[node->name()].push_back(it->second->node().name());
-    //
-    //         if (const auto dit = in_degree.find(it->second->node().name()); dit == in_degree.end()) {
-    //             in_degree[it->second->node().name()] = std::make_pair(1, it->second->node_ptr());
-    //         } else {
-    //             in_degree[it->second->node().name()].first++;
-    //         }
-    //     }
-    //
-    //     // Ensure the current node exists in the graph representation
-    //     if (in_degree.find(node->name()) == in_degree.end()) {
-    //         in_degree[node->name()] = std::make_pair(0, node);
-    //     }
-    // }
-    //
-    // for (const auto &it : dependency_graph) {
-    //     std::cout << "Dependency graph " << it.first << std::endl;
-    //     for (const auto &neighbor: it.second) {
-    //         std::cout << "  " << neighbor << std::endl;
-    //     }
-    //     std::cout << std::endl;
-    // }
-
-    std::vector<std::string> fk_sql_commands;
-    const auto c = pool_.acquire();
-
-    const auto q = query::query::create().schema( repo_.name() ).compile( *c );
-    std::cout << q.sql << std::endl;
-
-    // create plain tables without constraints
-    for (const auto &node: repo_) {
-        auto ctx = query::query::create()
-          .table(node->name())
-          .columns(node->info().attributes())
-          // .constraints(node->info().constraints())
-          .compile(*c);
-
-        std::cout << ctx.sql << std::endl;
-        if (auto result = c->execute(ctx.sql); !result) {
-            return utils::failure(result.err());
-        }
-    }
-
-    // create primary key constraints
-    for (const auto &node: repo_) {
-        for (const auto& cons : node->info().constraints()) {
-            if (!cons.is_primary_key_constraint()) {
-                continue;
-            }
-            auto ctx = build_add_constraint_context(*node, cons);
-
-            std::cout << ctx.sql << std::endl;
-            if (auto result = c->execute(ctx.sql); !result) {
-                return utils::failure(result.err());
-            }
-        }
-    }
-    // create table constraints
-    for (const auto &node: repo_) {
-        for (const auto& cons : node->info().constraints()) {
-            if (cons.is_primary_key_constraint()) {
-                continue;
-            }
-            auto ctx = build_add_constraint_context(*node, cons);
-
-            std::cout << ctx.sql << std::endl;
-            if (auto result = c->execute(ctx.sql); !result) {
-                return utils::failure(result.err());
-            }
-        }
-    }
-    return utils::ok<void>();
+const std::string & schema_node::name() const {
+  return table_.name();
 }
 
-utils::result<void, utils::error> schema::drop() const {
-    auto c = pool_.acquire();
-    // drop table primary key constraints
-    for (const auto &node: repo_) {
-        for (const auto& cons : node->info().constraints()) {
-            if (cons.is_primary_key_constraint()) {
-                continue;
-            }
-            auto ctx = query::query::alter()
-              .table(node->name())
-              .drop_constraint(cons)
-              .compile(*c);
-
-            std::cout << ctx.sql << std::endl;
-            if (auto result = c->execute(ctx.sql); !result) {
-                return utils::failure(result.err());
-            }
-        }
-    }
-
-    // drop table constraints
-    for (const auto &node: repo_) {
-        for (const auto& cons : node->info().constraints()) {
-            if (!cons.is_primary_key_constraint()) {
-                continue;
-            }
-            auto ctx = query::query::alter()
-              .table(node->name())
-              .drop_constraint(cons)
-              .compile(*c);
-
-            std::cout << ctx.sql << std::endl;
-            if (auto result = c->execute(ctx.sql); !result) {
-                return utils::failure(result.err());
-            }
-        }
-    }
-
-    // drop table
-    for (const auto &node: repo_) {
-        auto ctx = query::query::drop()
-          .table(node->name())
-          .compile(*c);
-
-        std::cout << ctx.sql << std::endl;
-        if (auto result = c->execute(ctx.sql); !result) {
-            return utils::failure(result.err());
-        }
-    }
-
-    return utils::ok<void>();
+const table &schema_node::table() const {
+  return table_;
 }
 
-utils::result<void, utils::error> schema::drop_table(const std::string& table_name) const {
-    const auto c = pool_.acquire();
-    auto result = query::query::drop()
-      .table(table_name)
-      .execute(*c);
-    if (result.is_error()) {
+const object::repository_node& schema_node::node() const {
+  return node_;
+}
+
+schema::schema(const std::string &name)
+: repo_(name) {
+}
+
+utils::result<void, utils::error> schema::create(const sql::connection &conn) const {
+  // Step 1: Build dependency graph
+  // std::unordered_map<std::string, std::vector<std::string> > dependency_graph;
+  // std::unordered_map<std::string, std::pair<int,object::repository::node_ptr>> in_degree;
+  //
+  // for (const auto &node: repo_) {
+  //     for (auto it = node->info().endpoint_begin(); it != node->info().endpoint_end(); ++it) {
+  //         dependency_graph[node->name()].push_back(it->second->node().name());
+  //
+  //         if (const auto dit = in_degree.find(it->second->node().name()); dit == in_degree.end()) {
+  //             in_degree[it->second->node().name()] = std::make_pair(1, it->second->node_ptr());
+  //         } else {
+  //             in_degree[it->second->node().name()].first++;
+  //         }
+  //     }
+  //
+  //     // Ensure the current node exists in the graph representation
+  //     if (in_degree.find(node->name()) == in_degree.end()) {
+  //         in_degree[node->name()] = std::make_pair(0, node);
+  //     }
+  // }
+  //
+  // for (const auto &it : dependency_graph) {
+  //     std::cout << "Dependency graph " << it.first << std::endl;
+  //     for (const auto &neighbor: it.second) {
+  //         std::cout << "  " << neighbor << std::endl;
+  //     }
+  //     std::cout << std::endl;
+  // }
+
+  std::vector<std::string> fk_sql_commands;
+
+  const auto q = query::query::create().schema(repo_.name()).compile(conn);
+  std::cout << q.sql << std::endl;
+
+  // create plain tables without constraints
+  for (const auto &node: repo_) {
+    auto ctx = query::query::create()
+        .table(node->name())
+        .columns(node->info().attributes())
+        // .constraints(node->info().constraints())
+        .compile(conn);
+
+    std::cout << ctx.sql << std::endl;
+    if (auto result = conn.execute(ctx.sql); !result) {
+      return utils::failure(result.err());
+    }
+  }
+
+  // create primary key constraints
+  for (const auto &node: repo_) {
+    for (const auto &cons: node->info().constraints()) {
+      if (!cons.is_primary_key_constraint()) {
+        continue;
+      }
+      auto ctx = build_add_constraint_context(*node, cons, conn);
+
+      std::cout << ctx.sql << std::endl;
+      if (auto result = conn.execute(ctx.sql); !result) {
         return utils::failure(result.err());
+      }
     }
+  }
+  // create table constraints
+  for (const auto &node: repo_) {
+    for (const auto &cons: node->info().constraints()) {
+      if (cons.is_primary_key_constraint()) {
+        continue;
+      }
+      auto ctx = build_add_constraint_context(*node, cons, conn);
 
-    return utils::ok<void>();
+      std::cout << ctx.sql << std::endl;
+      if (auto result = conn.execute(ctx.sql); !result) {
+        return utils::failure(result.err());
+      }
+    }
+  }
+  return utils::ok<void>();
 }
 
-utils::result<std::vector<object::attribute>, utils::error> schema::describe_table(const std::string& table_name) const {
-    const auto c = pool_.acquire();
-    if (!c.valid()) {
-        return utils::failure(utils::error(sql::error_code::FAILURE, "Failed to acquire connection."));
+utils::result<void, utils::error> schema::drop(const sql::connection &conn) const {
+  // drop table primary key constraints
+  for (const auto &node: repo_) {
+    for (const auto &cons: node->info().constraints()) {
+      if (cons.is_primary_key_constraint()) {
+        continue;
+      }
+      auto ctx = query::query::alter()
+          .table(node->name())
+          .drop_constraint(cons)
+          .compile(conn);
+
+      std::cout << ctx.sql << std::endl;
+      if (auto result = conn.execute(ctx.sql); !result) {
+        return utils::failure(result.err());
+      }
     }
-    return utils::ok(c->describe(table_name).release());
+  }
+
+  // drop table constraints
+  for (const auto &node: repo_) {
+    for (const auto &cons: node->info().constraints()) {
+      if (!cons.is_primary_key_constraint()) {
+        continue;
+      }
+      auto ctx = query::query::alter()
+          .table(node->name())
+          .drop_constraint(cons)
+          .compile(conn);
+
+      std::cout << ctx.sql << std::endl;
+      if (auto result = conn.execute(ctx.sql); !result) {
+        return utils::failure(result.err());
+      }
+    }
+  }
+
+  // drop table
+  for (const auto &node: repo_) {
+    auto ctx = query::query::drop()
+        .table(node->name())
+        .compile(conn);
+
+    std::cout << ctx.sql << std::endl;
+    if (auto result = conn.execute(ctx.sql); !result) {
+      return utils::failure(result.err());
+    }
+  }
+
+  return utils::ok<void>();
 }
 
-utils::result<bool, utils::error> schema::table_exists(const std::string& table_name) const {
-    const auto c = pool_.acquire();
-    if (!c.valid()) {
-        return utils::failure(utils::error(sql::error_code::FAILURE, "Failed to acquire connection."));
-    }
-    return c->exists(repo_.name(), table_name);
+utils::result<void, utils::error> schema::drop_table(const std::string &table_name, const sql::connection &conn) const {
+  auto result = query::query::drop()
+      .table(table_name)
+      .execute(conn);
+  if (result.is_error()) {
+    return utils::failure(result.err());
+  }
+
+  return utils::ok<void>();
 }
 
-sql::query_context schema::build_add_constraint_context( const object::repository_node& node, const object::restriction& cons ) const {
+utils::result<std::vector<object::attribute>, utils::error>
+schema::describe_table(const std::string &table_name, const sql::connection &conn) const {
+  // if (!conn.valid()) {
+    // return utils::failure(utils::error(sql::error_code::FAILURE, "Failed to acquire connection."));
+  // }
+  return utils::ok(conn.describe(table_name).release());
+}
+
+utils::result<bool, utils::error> schema::table_exists(const std::string &table_name, const sql::connection &conn) const {
+  // if (!c.valid()) {
+    // return utils::failure(utils::error(sql::error_code::FAILURE, "Failed to acquire connection."));
+  // }
+  return conn.exists(repo_.name(), table_name);
+}
+
+schema::iterator schema::begin() {
+  return schema_nodes_.begin();
+}
+
+schema::iterator schema::end() {
+  return schema_nodes_.end();
+}
+
+schema::const_iterator schema::begin() const {
+  return schema_nodes_.begin();
+}
+
+schema::const_iterator schema::end() const {
+  return schema_nodes_.end();
+}
+
+schema::iterator schema::find(const std::string &name) {
+  const auto result = repo_.basic_info(name);
+  if (!result) {
+    return schema_nodes_.end();
+  }
+
+  return schema_nodes_.find(result->get().type_index());
+}
+
+schema::const_iterator schema::find(const std::string &name) const {
+  const auto result = repo_.basic_info(name);
+  if (!result) {
+    return schema_nodes_.end();
+  }
+
+  return schema_nodes_.find(result->get().type_index());
+}
+
+sql::query_context schema::build_add_constraint_context(const object::repository_node &node,
+                                                        const object::restriction &cons,
+                                                        const sql::connection &conn) const {
   if (cons.is_foreign_key_constraint()) {
     return query::query::alter()
-      .table(node.name())
-      .add_constraint(cons)
-      .compile(*pool_.acquire());
+        .table(node.name())
+        .add_constraint(cons)
+        .compile(conn);
   }
   if (cons.is_primary_key_constraint()) {
-      return query::query::alter()
-      .table(node.name())
-      .add_constraint(cons)
-      .compile(*pool_.acquire());
+    return query::query::alter()
+        .table(node.name())
+        .add_constraint(cons)
+        .compile(conn);
   }
   return {};
 }
 
-sql::query_context schema::build_drop_constraint_context( const object::repository_node& node, const object::restriction& cons ) const {
+sql::query_context schema::build_drop_constraint_context(const object::repository_node &node,
+                                                         const object::restriction &cons,
+                                                         const sql::connection &conn) const {
   return query::query::alter()
-    .table(node.name())
-    .drop_constraint(cons)
-    .compile(*pool_.acquire());
+      .table(node.name())
+      .drop_constraint(cons)
+      .compile(conn);
 }
 
-void schema::insert_table(const std::type_index& ti, const object::repository_node& node) {
+void schema::insert_table(const std::type_index &ti, const object::repository_node &node) {
   std::vector<column> columns;
-  for (const auto &attr : node.info().attributes()) {
+  for (const auto &attr: node.info().attributes()) {
     columns.emplace_back(nullptr, attr.name(), attr.type(), attr.attributes());
   }
-  std::ignore = tables_.insert({ti, table(node.name(), "", columns)}).first;
+  std::ignore = schema_nodes_.insert({ti, schema_node{table(node.name(), columns), node}}).first;
 }
-}  // namespace matador::query
+} // namespace matador::query
diff --git a/source/orm/query/table.cpp b/source/orm/query/table.cpp
index 0747f1e..a822eb5 100644
--- a/source/orm/query/table.cpp
+++ b/source/orm/query/table.cpp
@@ -1,3 +1,5 @@
+#include <utility>
+
 #include "matador/query/table.hpp"
 
 namespace matador::query {
@@ -6,46 +8,63 @@ table::table(const char* name)
 : table(std::string(name))
 {}
 
-table::table(std::string name)
-: name_(std::move(name))
-{}
+table::table(const std::string& name)
+: table(name, name, {}) {}
 
-table::table(std::string name, std::string as)
-: name_(std::move(name))
-, alias_(std::move(as))
-{}
+table::table(const std::string& name, const std::vector<column> &columns)
+: table(name, name, columns) {
+}
 
-table::table( std::string name, std::string as, const std::vector<query::column>& columns )
+table::table(std::string  name, std::string  alias, const std::vector<column> &columns)
 : name_(std::move(name))
-, alias_(std::move(as))
+, alias_(std::move(alias))
 , columns_(columns) {
-  for (auto& col : columns_) {
-    col.table_ = this;
+  for (auto &col : columns_) {
+    col.table(this);
   }
 }
 
-bool table::operator==( const table& x ) const {
-  return name_ == x.name_;
+table::table(const table &other)
+: table(other.name_,  other.alias_, other.columns_) {
+  for (auto &col : columns_) {
+    col.table(this);
+  }
 }
 
-table table::as(const std::string &a) {
-  alias_ = a;
+table & table::operator=(const table &other) {
+  if (this == &other) {
+    return *this;
+  }
+  return *this = table(other);
+}
+
+table::table(table &&other) noexcept {
+  *this = std::move(other);
+}
+
+table & table::operator=(table &&other) noexcept {
+  name_ = std::move(other.name_);
+  alias_ = std::move(other.alias_);
+  columns_ = std::move(other.columns_);
+  for (auto &col : columns_) {
+    col.table(this);
+  }
   return *this;
 }
 
-table table::as(const std::string &a) const {
-  return { name_, a, columns_ };
+bool table::operator==(const table& x) const {
+  return name_ == x.name_ && alias_ == x.alias_;
 }
 
-bool table::has_alias() const {
-    return !alias_.empty();
+table table::as(const std::string &alias) const {
+  return { name_, alias, columns_ };
 }
 
-const std::string& table::name() const {
+const std::string & table::table_name() const {
   return name_;
 }
 
-const std::string& table::alias() const {
+const std::string& table::name() const {
   return alias_;
 }
 
@@ -53,10 +72,39 @@ const std::vector<column>& table::columns() const {
   return columns_;
 }
 
+bool table::has_alias() const {
+  return name_ != alias_;
+}
+
 table::operator const std::vector<query::column>&() const {
   return columns_;
 }
 
+const class column* table::operator[](const std::string &column_name) const {
+  for (const auto &col : columns_) {
+    if (col.name() == column_name) {
+      return &col;
+    }
+  }
+  return nullptr;
+}
+
+const class column * table::column_by_name(const table &tab, const std::string &column_name) {
+  for (const auto &col : tab.columns_) {
+    if (col.name() == column_name) {
+      return &col;
+    }
+  }
+  return nullptr;
+}
+
+const column& table::create_column(class table &tab, const std::string &name) {
+  tab.columns_.emplace_back(name);
+  tab.columns_.back().table(&tab);
+  return tab.columns_.back();
+}
+
+
 table operator ""_tab(const char *name, size_t len) {
   return {{name, len}};
 }
diff --git a/test/backends/QueryBasicTest.cpp b/test/backends/QueryBasicTest.cpp
index b3bbcdc..adee50f 100644
--- a/test/backends/QueryBasicTest.cpp
+++ b/test/backends/QueryBasicTest.cpp
@@ -1,15 +1,13 @@
 #include "catch2/catch_test_macros.hpp"
 #include "catch2/matchers/catch_matchers_string.hpp"
 
-#include "matador/object/attribute.hpp"
-#include "matador/object/repository.hpp"
-
 #include "matador/sql/connection.hpp"
 #include "matador/sql/dialect.hpp"
 
 #include "matador/query/criteria.hpp"
 #include "matador/query/generator.hpp"
 #include "matador/query/query.hpp"
+#include "matador/query/schema.hpp"
 
 #include "matador/utils/basic_types.hpp"
 #include "matador/utils/string.hpp"
@@ -25,9 +23,9 @@ using namespace matador::sql;
 using namespace matador::object;
 using namespace matador::query;
 
-TEST_CASE_METHOD( QueryFixture, "Insert and select basic datatypes", "[query][datatypes]" ) {
+TEST_CASE_METHOD(QueryFixture, "Insert and select basic datatypes", "[query][datatypes]") {
   REQUIRE(repo.attach<types>("types"));
-  auto obj = object_generator::generate<types>(repo, "types");
+  auto obj = object_generator::generate<types>(repo.repo(), "types");
   auto res = query::create()
     .table(obj->name())
     .columns(obj->attributes())
@@ -290,7 +288,7 @@ TEST_CASE_METHOD(QueryFixture, "Test describe table", "[query][describe][table]"
   using namespace matador::sql;
 
   REQUIRE(repo.attach<types>("types"));
-  auto obj = object_generator::generate<types>(repo, "types");
+  auto obj = object_generator::generate<types>(repo.repo(), "types");
   auto res = query::create()
     .table(obj->name())
     .columns(obj->attributes())
@@ -368,7 +366,7 @@ TEST_CASE_METHOD(QueryFixture, "Test primary key", "[query][primary key]") {
   using namespace matador::sql;
 
   REQUIRE(repo.attach<pk>("pk"));
-  auto obj = object_generator::generate<pk>(repo, "pk");
+  auto obj = object_generator::generate<pk>(repo.repo(), "pk");
   auto res = query::create()
     .table(obj->name())
     .columns(obj->attributes())
@@ -400,7 +398,7 @@ TEST_CASE_METHOD(QueryFixture, "Test primary key prepared", "[query][primary key
   using namespace matador::sql;
 
   REQUIRE(repo.attach<pk>("pk"));
-  auto obj = object_generator::generate<pk>(repo, "pk");
+  auto obj = object_generator::generate<pk>(repo.repo(), "pk");
   auto res = query::create()
     .table(obj->name())
     .columns(obj->attributes())
diff --git a/test/backends/QueryFixture.cpp b/test/backends/QueryFixture.cpp
index 29c7f8e..39c37cd 100644
--- a/test/backends/QueryFixture.cpp
+++ b/test/backends/QueryFixture.cpp
@@ -4,6 +4,8 @@
 
 #include "matador/sql/dialect.hpp"
 
+#include "connection.hpp"
+
 #include "catch2/catch_test_macros.hpp"
 
 namespace matador::test {
diff --git a/test/backends/QueryFixture.hpp b/test/backends/QueryFixture.hpp
index b0c4c85..eebfc7f 100644
--- a/test/backends/QueryFixture.hpp
+++ b/test/backends/QueryFixture.hpp
@@ -1,12 +1,10 @@
 #ifndef MATADOR_QUERY_FIXTURE_HPP
 #define MATADOR_QUERY_FIXTURE_HPP
 
-#include "matador/object/repository.hpp"
+#include "matador/query/schema.hpp"
 
 #include "matador/sql/connection.hpp"
 
-#include "connection.hpp"
-
 #include <stack>
 
 namespace matador::test {
@@ -22,7 +20,7 @@ public:
 protected:
   sql::connection db;
   std::stack <std::string> tables_to_drop;
-  object::repository repo;
+  query::schema repo;
 
 private:
   void drop_table_if_exists(const std::string &table_name) const;
diff --git a/test/backends/QueryRecordTest.cpp b/test/backends/QueryRecordTest.cpp
index 178824f..09df1eb 100644
--- a/test/backends/QueryRecordTest.cpp
+++ b/test/backends/QueryRecordTest.cpp
@@ -2,6 +2,7 @@
 
 #include "matador/sql/connection.hpp"
 
+#include "matador/query/builder.hpp"
 #include "matador/query/criteria.hpp"
 #include "matador/query/query.hpp"
 #include "matador/query/column.hpp"
@@ -23,26 +24,31 @@ using namespace matador::utils;
 TEST_CASE_METHOD(QueryFixture, "Test all data types for record", "[query][record][data types]") {
   check_table_not_exists("types");
 
+  const table tab("types");
+
+  // auto r = query::create().table(tab).columns({
+    // column("id", basic_type::UInt32)
+  // });
   auto res = query::create()
-    .table("types")
+    .table(tab)
     .columns({
-        attribute("id", basic_type::UInt32),
-        attribute("val_char", basic_type::Int8),
-        attribute("val_short", basic_type::Int16),
-        attribute("val_int", basic_type::Int32),
-        attribute("val_long_long", basic_type::Int64),
-        attribute("val_uchar", basic_type::UInt8),
-        attribute("val_ushort", basic_type::UInt16),
-        attribute("val_uint", basic_type::UInt32),
-        attribute("val_ulong_long", basic_type::UInt64),
-        attribute("val_bool", basic_type::Boolean),
-        attribute("val_float", basic_type::Float),
-        attribute("val_double", basic_type::Double),
-        attribute("val_string", basic_type::Text),
-        attribute("val_varchar", basic_type::Varchar, 63),
-        // attribute("val_date", basic_type::type_date),
-        // attribute("val_time", basic_type::type_time),
-        attribute("val_blob", basic_type::Blob),
+        column("id", basic_type::UInt32),
+        column("val_char", basic_type::Int8),
+        column("val_short", basic_type::Int16),
+        column("val_int", basic_type::Int32),
+        column("val_long_long", basic_type::Int64),
+        column("val_uchar", basic_type::UInt8),
+        column("val_ushort", basic_type::UInt16),
+        column("val_uint", basic_type::UInt32),
+        column("val_ulong_long", basic_type::UInt64),
+        column("val_bool", basic_type::Boolean),
+        column("val_float", basic_type::Float),
+        column("val_double", basic_type::Double),
+        column("val_string", basic_type::Text),
+        column("val_varchar", basic_type::Varchar, 63),
+        // column("val_date", basic_type::type_date),
+        // column("val_time", basic_type::type_time),
+        column("val_blob", basic_type::Blob),
     })
     .constraints({
         constraint("PK_types").primary_key("id")
@@ -126,9 +132,9 @@ TEST_CASE_METHOD(QueryFixture, "Create and drop table statement", "[query][recor
   auto res = query::create()
     .table("person")
     .columns({
-        attribute("id", basic_type::UInt32),
-        attribute("name", basic_type::Varchar, 255),
-        attribute("age", basic_type::UInt16)
+        column("id", basic_type::UInt32),
+        column("name", basic_type::Varchar, 255),
+        column("age", basic_type::UInt16)
     })
     .constraints({
         constraint("PK_person").primary_key("id")
@@ -154,9 +160,9 @@ TEST_CASE_METHOD(QueryFixture, "Create and drop table statement with foreign key
   auto res = query::create()
   .table("airplane")
     .columns({
-        attribute("id", basic_type::UInt32),
-        attribute("brand", basic_type::Varchar, 255),
-        attribute("model", basic_type::Varchar, 255),
+        column("id", basic_type::UInt32),
+        column("brand", basic_type::Varchar, 255),
+        column("model", basic_type::Varchar, 255),
     })
     .constraints({
         constraint("PK_airplane").primary_key("id"),
@@ -171,9 +177,9 @@ TEST_CASE_METHOD(QueryFixture, "Create and drop table statement with foreign key
   res = query::create()
   .table("flight")
     .columns({
-        attribute("id", basic_type::UInt32),
-        attribute("airplane_id", basic_type::UInt32),
-        attribute("pilot_name", basic_type::Varchar, 255)
+        column("id", basic_type::UInt32),
+        column("airplane_id", basic_type::UInt32),
+        column("pilot_name", basic_type::Varchar, 255)
     })
     .constraints({
         constraint("PK_flight").primary_key("id"),
@@ -208,9 +214,9 @@ TEST_CASE_METHOD(QueryFixture, "Execute insert record statement", "[query][recor
   auto res = query::create()
     .table("person")
     .columns({
-        attribute("id", basic_type::UInt32),
-        attribute("name", basic_type::Varchar, 255),
-        attribute("age", basic_type::UInt16)
+        column("id", basic_type::UInt32),
+        column("name", basic_type::Varchar, 255),
+        column("age", basic_type::UInt16)
     })
     .constraints({
         constraint("PK_person").primary_key("id")
@@ -251,9 +257,9 @@ TEST_CASE_METHOD(QueryFixture, "Execute insert record statement with foreign key
   auto res = query::create()
     .table("airplane")
     .columns({
-        attribute("id", basic_type::UInt32),
-        attribute("brand", basic_type::Varchar, 255),
-        attribute("model", basic_type::Varchar, 255),
+        column("id", basic_type::UInt32),
+        column("brand", basic_type::Varchar, 255),
+        column("model", basic_type::Varchar, 255),
     })
     .constraints({
         constraint("PK_airplane").primary_key("id"),
@@ -266,9 +272,9 @@ TEST_CASE_METHOD(QueryFixture, "Execute insert record statement with foreign key
   res = query::create()
     .table("flight")
       .columns({
-          attribute("id", basic_type::UInt32),
-          attribute("airplane_id", basic_type::UInt32),
-          attribute("pilot_name", basic_type::Varchar, 255)
+          column("id", basic_type::UInt32),
+          column("airplane_id", basic_type::UInt32),
+          column("pilot_name", basic_type::Varchar, 255)
       })
       .constraints({
           constraint("PK_flight").primary_key("id"),
@@ -314,9 +320,9 @@ TEST_CASE_METHOD(QueryFixture, "Execute update record statement", "[query][recor
   auto res = query::create()
     .table("person")
     .columns({
-        attribute("id", basic_type::UInt32),
-        attribute("name", basic_type::Varchar, 255),
-        attribute("age", basic_type::UInt16)
+        column("id", basic_type::UInt32),
+        column("name", basic_type::Varchar, 255),
+        column("age", basic_type::UInt16)
     })
     .constraints({
         constraint("PK_person").primary_key("id")
@@ -367,9 +373,9 @@ TEST_CASE_METHOD(QueryFixture, "Execute select statement", "[query][record]")
   auto res = query::create()
     .table("person")
     .columns({
-        attribute("id", basic_type::UInt32),
-        attribute("name", basic_type::Varchar, 255),
-        attribute("age", basic_type::UInt16)
+        column("id", basic_type::UInt32),
+        column("name", basic_type::Varchar, 255),
+        column("age", basic_type::UInt16)
     })
     .constraints({
         constraint("PK_person").primary_key("id")
@@ -427,9 +433,9 @@ TEST_CASE_METHOD(QueryFixture, "Execute select statement with order by", "[query
   auto res = query::create()
     .table("person")
     .columns({
-        attribute("id", basic_type::UInt32),
-        attribute("name", basic_type::Varchar, 255),
-        attribute("age", basic_type::UInt16)
+        column("id", basic_type::UInt32),
+        column("name", basic_type::Varchar, 255),
+        column("age", basic_type::UInt16)
     })
     .constraints({
         constraint("PK_person").primary_key("id")
@@ -473,9 +479,9 @@ TEST_CASE_METHOD(QueryFixture, "Execute select statement with group by and order
   auto res = query::create()
     .table("person")
     .columns({
-        attribute("id", basic_type::UInt32),
-        attribute("name", basic_type::Varchar, 255),
-        attribute("age", basic_type::UInt16)
+        column("id", basic_type::UInt32),
+        column("name", basic_type::Varchar, 255),
+        column("age", basic_type::UInt16)
     })
     .constraints({
         constraint("PK_person").primary_key("id")
@@ -526,9 +532,9 @@ TEST_CASE_METHOD(QueryFixture, "Execute delete statement", "[query][record]") {
   auto res = query::create()
     .table("person")
     .columns({
-        attribute("id", basic_type::UInt32),
-        attribute("name", basic_type::Varchar, 255),
-        attribute("age", basic_type::UInt16)
+        column("id", basic_type::UInt32),
+        column("name", basic_type::Varchar, 255),
+        column("age", basic_type::UInt16)
     })
     .constraints({
         constraint("PK_person").primary_key("id")
@@ -576,8 +582,8 @@ TEST_CASE_METHOD(QueryFixture, "Test quoted identifier record", "[query][record]
   auto res = query::create()
     .table("quotes")
     .columns({
-        attribute("from", basic_type::Varchar, 255),
-        attribute("to", basic_type::Varchar, 255)
+        column("from", basic_type::Varchar, 255),
+        column("to", basic_type::Varchar, 255)
     })
     .execute(db);
   REQUIRE(res.is_ok());
@@ -637,9 +643,9 @@ TEST_CASE_METHOD(QueryFixture, "Test create record", "[query][record][create]")
   auto res = query::create()
     .table("person")
     .columns({
-        attribute("id", basic_type::UInt32),
-        attribute("name", basic_type::Varchar, 255),
-        attribute("age", basic_type::UInt16)
+        column("id", basic_type::UInt32),
+        column("name", basic_type::Varchar, 255),
+        column("age", basic_type::UInt16)
     })
     .constraints({
         constraint("PK_person").primary_key("id")
@@ -664,9 +670,9 @@ TEST_CASE_METHOD(QueryFixture, "Test insert record", "[query][record][insert]")
   auto res = query::create()
     .table("person")
     .columns({
-        attribute("id", basic_type::UInt32),
-        attribute("name", basic_type::Varchar, 255),
-        attribute("age", basic_type::UInt16)
+        column("id", basic_type::UInt32),
+        column("name", basic_type::Varchar, 255),
+        column("age", basic_type::UInt16)
     })
     .constraints({
         constraint("PK_person").primary_key("id")
@@ -701,9 +707,9 @@ TEST_CASE_METHOD(QueryFixture, "Test update record", "[query][record][update]")
   auto res = query::create()
     .table("person")
     .columns({
-        attribute("id", basic_type::UInt32),
-        attribute("name", basic_type::Varchar, 255),
-        attribute("age", basic_type::UInt16)
+        column("id", basic_type::UInt32),
+        column("name", basic_type::Varchar, 255),
+        column("age", basic_type::UInt16)
     })
     .constraints({
         constraint("PK_person").primary_key("id")
@@ -755,9 +761,9 @@ TEST_CASE_METHOD(QueryFixture, "Test prepared record statement", "[query][record
   auto stmt = query::create()
     .table("person")
     .columns({
-        attribute("id", basic_type::UInt32),
-        attribute("name", basic_type::Varchar, 255),
-        attribute("age", basic_type::UInt16)
+        column("id", basic_type::UInt32),
+        column("name", basic_type::Varchar, 255),
+        column("age", basic_type::UInt16)
     })
     .constraints({
         constraint("PK_person").primary_key("id")
@@ -785,7 +791,7 @@ TEST_CASE_METHOD(QueryFixture, "Test scalar result", "[query][record][scalar][re
   auto res = query::create()
     .table("person")
     .columns({
-        attribute("id", basic_type::UInt32)
+        column("id", basic_type::UInt32)
     })
     .constraints({
         constraint("PK_person").primary_key("id")
diff --git a/test/backends/QueryStatementTests.cpp b/test/backends/QueryStatementTests.cpp
index 1d1177c..ee9b845 100644
--- a/test/backends/QueryStatementTests.cpp
+++ b/test/backends/QueryStatementTests.cpp
@@ -20,7 +20,7 @@ using namespace matador::test;
 
 TEST_CASE_METHOD(QueryFixture, "Test create statement", "[query][statement][create]") {
   REQUIRE(repo.attach<matador::test::person>("person"));
-  const auto obj = object_generator::generate<person>(repo, "person");
+  const auto obj = object_generator::generate<person>(repo.repo(), "person");
   auto stmt = query::create()
     .table(obj->name())
     .columns(obj->attributes())
@@ -47,12 +47,12 @@ TEST_CASE_METHOD(QueryFixture, "Test insert statement", "[query][statement][inse
   using namespace matador::test;
 
   REQUIRE(repo.attach<person>("person"));
-    const auto obj = object_generator::generate<person>(repo, "person");
-    auto stmt = query::create()
-      .table(obj->name())
-      .columns(obj->attributes())
-      .constraints(obj->constraints())
-      .prepare(db);
+  const auto obj = object_generator::generate<person>(repo.repo(), "person");
+  auto stmt = query::create()
+    .table(obj->name())
+    .columns(obj->attributes())
+    .constraints(obj->constraints())
+    .prepare(db);
   REQUIRE(stmt);
 
   auto res = stmt->execute();
@@ -92,12 +92,12 @@ TEST_CASE_METHOD(QueryFixture, "Test update statement", "[query][statement][upda
   using namespace matador::utils;
 
   REQUIRE(repo.attach<matador::test::person>("person"));
-    const auto obj = object_generator::generate<person>(repo, "person");
-    auto stmt = query::create()
-      .table(obj->name())
-      .columns(obj->attributes())
-      .constraints(obj->constraints())
-      .prepare(db);
+  const auto obj = object_generator::generate<person>(repo.repo(), "person");
+  auto stmt = query::create()
+    .table(obj->name())
+    .columns(obj->attributes())
+    .constraints(obj->constraints())
+    .prepare(db);
   REQUIRE(stmt);
 
   auto res = stmt->execute();
@@ -161,12 +161,12 @@ TEST_CASE_METHOD(QueryFixture, "Test delete statement", "[query][statement][dele
   using namespace matador::test;
 
   REQUIRE(repo.attach<matador::test::person>("person"));
-    const auto obj = object_generator::generate<person>(repo, "person");
-    auto stmt = query::create()
-      .table(obj->name())
-      .columns(obj->attributes())
-      .constraints(obj->constraints())
-      .prepare(db);
+  const auto obj = object_generator::generate<person>(repo.repo(), "person");
+  auto stmt = query::create()
+    .table(obj->name())
+    .columns(obj->attributes())
+    .constraints(obj->constraints())
+    .prepare(db);
   REQUIRE(stmt);
 
   auto res = stmt->execute();
@@ -251,12 +251,12 @@ TEST_CASE_METHOD(QueryFixture, "Test reuse prepared statement", "[query][stateme
   using namespace matador::test;
 
   REQUIRE(repo.attach<matador::test::person>("person"));
-    const auto obj = object_generator::generate<person>(repo, "person");
-    auto stmt = query::create()
-      .table(obj->name())
-      .columns(obj->attributes())
-      .constraints(obj->constraints())
-      .prepare(db);
+  const auto obj = object_generator::generate<person>(repo.repo(), "person");
+  auto stmt = query::create()
+    .table(obj->name())
+    .columns(obj->attributes())
+    .constraints(obj->constraints())
+    .prepare(db);
   REQUIRE(stmt);
 
   auto res = stmt->execute();
diff --git a/test/backends/QueryTest.cpp b/test/backends/QueryTest.cpp
index adc8225..44c1796 100644
--- a/test/backends/QueryTest.cpp
+++ b/test/backends/QueryTest.cpp
@@ -1,7 +1,6 @@
 #include "catch2/catch_test_macros.hpp"
 
-#include "matador/object/attribute.hpp"
-
+#include "matador/query/builder.hpp"
 #include "matador/query/criteria.hpp"
 #include "matador/query/generator.hpp"
 #include "matador/query/query.hpp"
@@ -23,7 +22,7 @@ TEST_CASE_METHOD(QueryFixture, "Create table with foreign key relation", "[query
     .and_then( [this] { return repo.attach<flight>("flight");} );
   REQUIRE(result.is_ok());
 
-  auto obj = object_generator::generate<airplane>(repo, "airplane");
+  auto obj = object_generator::generate<airplane>(repo.repo(), "airplane");
   auto res = query::create()
     .table(obj->name())
     .columns(obj->attributes())
@@ -35,7 +34,7 @@ TEST_CASE_METHOD(QueryFixture, "Create table with foreign key relation", "[query
   check_table_exists("airplane");
   tables_to_drop.emplace("airplane");
 
-  obj = object_generator::generate<flight>(repo, "flight");
+  obj = object_generator::generate<flight>(repo.repo(), "flight");
   res = query::create()
     .table(obj->name())
     .columns(obj->attributes())
@@ -50,7 +49,7 @@ TEST_CASE_METHOD(QueryFixture, "Create table with foreign key relation", "[query
 
 TEST_CASE_METHOD(QueryFixture, "Execute select statement with where clause", "[query][where]") {
   REQUIRE(repo.attach<person>("person"));
-  const auto obj = object_generator::generate<person>(repo, "person");
+  const auto obj = object_generator::generate<person>(repo.repo(), "person");
   auto res = query::create()
     .table(obj->name())
     .columns(obj->attributes())
@@ -110,9 +109,9 @@ TEST_CASE_METHOD(QueryFixture, "Execute insert statement", "[query][insert]") {
   auto res = query::create()
     .table("person")
     .columns({
-        attribute("id", matador::utils::basic_type::UInt32),
-        attribute("name", matador::utils::basic_type::Varchar, 255),
-        attribute("color", matador::utils::basic_type::Varchar, 63)
+        column("id", matador::utils::basic_type::UInt32),
+        column("name", matador::utils::basic_type::Varchar, 255),
+        column("color", matador::utils::basic_type::Varchar, 63)
     })
     .constraints({
         constraint("PK_person").primary_key("id")
diff --git a/test/backends/SchemaTest.cpp b/test/backends/SchemaTest.cpp
index 9524479..10a3d86 100644
--- a/test/backends/SchemaTest.cpp
+++ b/test/backends/SchemaTest.cpp
@@ -15,46 +15,48 @@ using namespace matador::test;
 
 TEST_CASE_METHOD(SchemaFixture, "Test schema one-two-many", "[schema][one-to-many]") {
   using namespace matador::test;
-  query::schema repo(pool/*, "NoopSchema"*/);
+  query::schema repo;
 
   auto result = repo.attach<department>("departments")
     .and_then([&repo] { return repo.attach<employee>("employees"); });
   REQUIRE(result);
 
-  result = repo.create();
+  auto conn = pool.acquire();
+  result = repo.create(*conn);
   REQUIRE(result);
 
-  auto exists_result = repo.table_exists("departments");
+  auto exists_result = repo.table_exists("departments", *conn);
   REQUIRE(exists_result.is_ok());
   REQUIRE(exists_result.value());
 
-  result = repo.drop();
+  result = repo.drop(*conn);
   REQUIRE(result);
 
-  exists_result = repo.table_exists("departments");
+  exists_result = repo.table_exists("departments", *conn);
   REQUIRE(exists_result.is_ok());
   REQUIRE(!exists_result.value());
 }
 
 TEST_CASE_METHOD(SchemaFixture, "Test schema many-to-many", "[schema][many-to-many]") {
   using namespace matador::test;
-  query::schema repo(pool/*, "NoopSchema"*/);
+  query::schema repo;
 
   auto result = repo.attach<recipe>("recipes")
     .and_then([&repo] { return repo.attach<ingredient>("ingredients"); });
   REQUIRE(result);
 
-  result = repo.create();
+  auto conn = pool.acquire();
+  result = repo.create(*conn);
   REQUIRE(result);
 
-  auto exists_result = repo.table_exists("recipes");
+  auto exists_result = repo.table_exists("recipes", *conn);
   REQUIRE(exists_result.is_ok());
   REQUIRE(exists_result.value());
 
-  result = repo.drop();
+  result = repo.drop(*conn);
   REQUIRE(result);
 
-  exists_result = repo.table_exists("recipes");
+  exists_result = repo.table_exists("recipes", *conn);
   REQUIRE(exists_result.is_ok());
   REQUIRE(!exists_result.value());
 }
diff --git a/test/backends/StatementTest.cpp b/test/backends/StatementTest.cpp
index a296cfa..fa9aa34 100644
--- a/test/backends/StatementTest.cpp
+++ b/test/backends/StatementTest.cpp
@@ -23,18 +23,15 @@ using namespace matador::test;
 
 namespace matador::test::detail {
 template<class Type, typename... Args>
-[[maybe_unused]] object_ptr<Type> make_object_ptr(Args&&... args)
-{
+[[maybe_unused]] object_ptr<Type> make_object_ptr(Args&&... args) {
   return object_ptr(new Type(std::forward<Args>(args)...));
 }
 }
 
-class StatementTestFixture : public QueryFixture
-{
+class StatementTestFixture : public QueryFixture {
 public:
-  StatementTestFixture()
-  {
-    const auto obj = object_generator::generate<airplane>(repo, "airplane");
+  StatementTestFixture() {
+    const auto obj = object_generator::generate<airplane>(repo.repo(), "airplane");
     const auto res = query::create()
       .table(obj->name())
       .columns(obj->attributes())
diff --git a/test/backends/TypeTraitsTest.cpp b/test/backends/TypeTraitsTest.cpp
index 1a973e8..c910655 100644
--- a/test/backends/TypeTraitsTest.cpp
+++ b/test/backends/TypeTraitsTest.cpp
@@ -22,7 +22,7 @@ class TypeTraitsTestFixture : public QueryFixture
 public:
   TypeTraitsTestFixture() {
     REQUIRE(db.open());
-    const auto obj = matador::object::object_generator::generate<location>(repo, "location");
+    const auto obj = matador::object::object_generator::generate<location>(repo.repo(), "location");
     const auto res = query::create()
       .table(obj->name())
       .columns(obj->attributes())
diff --git a/test/core/object/RepositoryTest.cpp b/test/core/object/RepositoryTest.cpp
index 1275930..5d38897 100644
--- a/test/core/object/RepositoryTest.cpp
+++ b/test/core/object/RepositoryTest.cpp
@@ -75,16 +75,6 @@ TEST_CASE("Test next and previous of schema node", "[schema_node][next][previous
   REQUIRE(++it == repo.end());
 }
 
-TEST_CASE("Test automatic creating of a relation table with foreign key", "[schema][relation_table][foreign_key]") {
-  object::repository repo;
-
-  REQUIRE(repo.empty());
-
-  auto res = repo.attach<test::department>("department");
-  REQUIRE(res.is_ok());
-  REQUIRE(repo.size() == 2);
-}
-
 TEST_CASE("Test automatic creating of a relation table with values", "[schema][relation_table][values]") {
   object::repository repo;
 
@@ -175,22 +165,13 @@ TEST_CASE("Test many to many relation", "[relation][many-to-many]") {
 template<typename Type>
 class test_observer : public matador::object::observer<Type> {
 public:
-  void on_attach(object::repository_node& node, const Type& prototype) override {
-    int i  = 0;
-  }
-  void on_detach(object::repository_node& node, const Type& prototype) override {
-
-  }
-  void on_insert(Type& obj) override {
-
-  }
-  void on_update(Type& obj) override {
-
-  }
-  void on_delete(Type& obj) override {
-
-  }
+  void on_attach(const object::repository_node& /*node*/, const Type& /*prototype*/) const override {}
+  void on_detach(const object::repository_node& /*node*/, const Type& /*prototype*/) const override {}
+  void on_insert(const Type& /*obj*/) override {}
+  void on_update(const Type& /*obj*/) override {}
+  void on_delete(const Type& /*obj*/) override {}
 };
+
 TEST_CASE("Test repository observer", "[repository][observer]") {
   object::repository repo;
 
diff --git a/test/orm/orm/SessionQueryBuilderTest.cpp b/test/orm/orm/SessionQueryBuilderTest.cpp
index cf94563..1a7b099 100644
--- a/test/orm/orm/SessionQueryBuilderTest.cpp
+++ b/test/orm/orm/SessionQueryBuilderTest.cpp
@@ -12,6 +12,8 @@
 #include "matador/query/table.hpp"
 #include "matador/query/schema.hpp"
 
+#include "matador/utils/macro_map.hpp"
+
 #include "matador/orm/session_query_builder.hpp"
 
 #include "../backend/test_connection.hpp"
@@ -33,26 +35,63 @@ using namespace matador::utils;
 using namespace matador::sql;
 using namespace matador::test;
 
+// #define FIELD(FIELD_NAME) const matador::query::column& FIELD_NAME = create_column(*this, #FIELD_NAME);
+//
+// #define META_TABLE(TABLE_NAME, VARIABLE_NAME, ...) \
+// namespace matador::query::meta {     \
+// namespace internal {                      \
+// class TABLE_NAME##_table : public table {           \
+// public: \
+// TABLE_NAME##_table() : table(#TABLE_NAME) {}                            \
+// MAP(FIELD, __VA_ARGS__) \
+// }; }                     \
+// static const internal:: TABLE_NAME##_table VARIABLE_NAME;  \
+// }
+//
+// META_TABLE( books, BOOK, id, author_id, title, published_in )
+
+class book_table : public table {
+public:
+  book_table()
+  : table("books", {"id", "title", "author_id"})
+  , id(*column_by_name(*this, "id"))
+  , title(*column_by_name(*this, "id"))
+  , author_id(*column_by_name(*this, "author_id")) {
+  }
+
+  const column& id;
+  const column& title;
+  const column& author_id;
+};
+
+book_table BOOK;
+
+using namespace matador::test;
+
 TEST_CASE("Create sql query data for entity with eager has one", "[query][entity][builder]") {
   using namespace matador::test;
   backend_provider::instance().register_backend("noop", std::make_unique<orm::test_backend_service>());
   connection db("noop://noop.db");
   connection_pool pool("noop://noop.db", 4);
 
-  schema scm(pool);
+  schema scm;
   auto result = scm.attach<airplane>("airplanes")
     .and_then( [&scm] { return scm.attach<flight>("flights"); } );
   REQUIRE(result);
 
   session_query_builder eqb(scm, db);
 
-  auto data = eqb.build<flight>("flights.id"_col == _);
+  const auto it = scm.find(typeid(flight));
+  REQUIRE(it != scm.end());
+  const auto* col = it->second.table()["id"];
+  REQUIRE(col);
+  auto data = eqb.build<flight>(*col == _);
 
   REQUIRE(data.is_ok());
-  REQUIRE(data->root_table->name() == "flights");
+  REQUIRE(data->root_table->table_name() == "flights");
   REQUIRE(data->joins.size() == 1);
-  const auto flights = table("flights");
-  const auto airplanes = table("airplanes");
+  const auto flights = table("flights").as("t01");
+  const auto airplanes = table("airplanes").as("t02");
   const std::vector<column> expected_columns {
     { &flights, "id", "c01" },
     { &airplanes, "id", "c02" },
@@ -73,7 +112,7 @@ TEST_CASE("Create sql query data for entity with eager has one", "[query][entity
   size_t index{0};
   criteria_evaluator evaluator(db.dialect(), qc);
   for (const auto &[join_table, condition] : data->joins) {
-    REQUIRE(join_table->name() == expected_join_data[index].first);
+    REQUIRE(join_table->table_name() == expected_join_data[index].first);
     REQUIRE(evaluator.evaluate(*condition) == expected_join_data[index].second);
     ++index;
   }
@@ -89,20 +128,24 @@ TEST_CASE("Create sql query data for entity with eager belongs to", "[query][ent
   connection db("noop://noop.db");
   connection_pool pool("noop://noop.db", 4);
 
-  schema scm(pool);
+  schema scm;
   auto result = scm.attach<author>("authors")
     .and_then( [&scm] { return scm.attach<book>("books"); } );
   REQUIRE(result);
 
   session_query_builder eqb(scm, db);
 
-  auto data = eqb.build<book>("books.id"_col == _);
+  const auto it = scm.find(typeid(book));
+  REQUIRE(it != scm.end());
+  const auto* col = it->second.table()["id"];
+  REQUIRE(col);
+  auto data = eqb.build<book>(*col == _);
 
   REQUIRE(data.is_ok());
-  REQUIRE(data->root_table->name() == "books");
+  REQUIRE(data->root_table->table_name() == "books");
   REQUIRE(data->joins.size() == 1);
-  const auto books = table("books");
-  const auto authors = table("authors");
+  const auto books = table("books").as("t01");
+  const auto authors = table("authors").as("t02");
   const std::vector<column> expected_columns {
     { &books, "id", "c01" },
     { &books, "title", "c02" },
@@ -127,7 +170,7 @@ TEST_CASE("Create sql query data for entity with eager belongs to", "[query][ent
   size_t index{0};
   criteria_evaluator evaluator(db.dialect(), qc);
   for (const auto & [join_table, clause] : data->joins) {
-    REQUIRE(join_table->name() == expected_join_data[index].first);
+    REQUIRE(join_table->table_name() == expected_join_data[index].first);
     REQUIRE(evaluator.evaluate(*clause) == expected_join_data[index].second);
     ++index;
   }
@@ -154,7 +197,7 @@ TEST_CASE("Create sql query data for entity with eager has many belongs to", "[q
   connection db("noop://noop.db");
   connection_pool pool("noop://noop.db", 4);
 
-  schema scm(pool);
+  schema scm;
   auto result = scm.attach<product>("products")
     .and_then( [&scm] { return scm.attach<order_details>("order_details"); } )
     .and_then( [&scm] { return scm.attach<supplier>("suppliers"); } )
@@ -164,13 +207,17 @@ TEST_CASE("Create sql query data for entity with eager has many belongs to", "[q
 
   session_query_builder eqb(scm, db);
 
-  auto data = eqb.build<order>("orders.order_id"_col == _);
+  const auto it = scm.find(typeid(order));
+  REQUIRE(it != scm.end());
+  const auto* col = it->second.table()["order_id"];
+  REQUIRE(col);
+  auto data = eqb.build<order>(*col == _);
 
   REQUIRE(data.is_ok());
-  REQUIRE(data->root_table->name() == "orders");
+  REQUIRE(data->root_table->table_name() == "orders");
   REQUIRE(data->joins.size() == 1);
-  const auto orders = table("orders");
-  const auto order_details = table("order_details");
+  const auto orders = table("orders").as("t01");
+  const auto order_details = table("order_details").as("t02");
   const std::vector<column> expected_columns = {
     { &orders, "order_id", "c01" },
     { &orders, "order_date", "c02" },
@@ -201,7 +248,7 @@ TEST_CASE("Create sql query data for entity with eager has many belongs to", "[q
   size_t index{0};
   criteria_evaluator evaluator(db.dialect(), qc);
   for (const auto &jd : data->joins) {
-    REQUIRE(jd.join_table->name() == expected_join_data[index].first);
+    REQUIRE(jd.join_table->table_name() == expected_join_data[index].first);
     REQUIRE(evaluator.evaluate(*jd.condition) == expected_join_data[index].second);
     ++index;
   }
@@ -217,20 +264,24 @@ TEST_CASE("Create sql query data for entity with eager many to many", "[query][e
   connection db("noop://noop.db");
   connection_pool pool("noop://noop.db", 4);
 
-  schema scm(pool);
+  schema scm;
   auto result = scm.attach<recipe>("recipes")
     .and_then( [&scm] { return scm.attach<ingredient>("ingredients"); } );
   REQUIRE(result);
 
   session_query_builder eqb(scm, db);
 
-  auto data = eqb.build<ingredient>("ingredients.id"_col == _);
+  const auto it = scm.find(typeid(ingredient));
+  REQUIRE(it != scm.end());
+  const auto* col = it->second.table()["id"];
+  REQUIRE(col);
+  auto data = eqb.build<ingredient>(*col == _);
 
   REQUIRE(data.is_ok());
-  REQUIRE(data->root_table->name() == "ingredients");
+  REQUIRE(data->root_table->table_name() == "ingredients");
   REQUIRE(data->joins.size() == 2);
-  const auto ingredients = table("ingredients");
-  const auto recipes = table("recipes");
+  const auto ingredients = table("ingredients").as("t01");
+  const auto recipes = table("recipes").as("t03");
   const std::vector<column> expected_columns {
     { &ingredients, "id", "c01" },
     { &ingredients, "name", "c02" },
@@ -251,7 +302,7 @@ TEST_CASE("Create sql query data for entity with eager many to many", "[query][e
   size_t index{0};
   criteria_evaluator evaluator(db.dialect(), qc);
   for (const auto &jd : data->joins) {
-    REQUIRE(jd.join_table->name() == expected_join_data[index].first);
+    REQUIRE(jd.join_table->table_name() == expected_join_data[index].first);
     REQUIRE(evaluator.evaluate(*jd.condition) == expected_join_data[index].second);
     ++index;
   }
@@ -267,20 +318,24 @@ TEST_CASE("Create sql query data for entity with eager many to many (inverse par
   connection db("noop://noop.db");
   connection_pool pool("noop://noop.db", 4);
 
-  schema scm(pool);
+  schema scm;
   auto result = scm.attach<student>("students")
     .and_then( [&scm] { return scm.attach<course>("courses"); } );
   REQUIRE(result);
 
   session_query_builder eqb(scm, db);
 
-  auto data = eqb.build<course>("courses.id"_col == _);
+  const auto it = scm.find(typeid(course));
+  REQUIRE(it != scm.end());
+  const auto* col = it->second.table()["id"];
+  REQUIRE(col);
+  auto data = eqb.build<course>(*col == _);
 
   REQUIRE(data.is_ok());
-  REQUIRE(data->root_table->name() == "courses");
+  REQUIRE(data->root_table->table_name() == "courses");
   REQUIRE(data->joins.size() == 2);
-  const auto courses = table("courses");
-  const auto students = table("students");
+  const auto courses = table("courses").as("t01");
+  const auto students = table("students").as("t03");
   const std::vector<column> expected_columns {
     { &courses, "id", "c01" },
     { &courses, "title", "c02" },
@@ -301,7 +356,7 @@ TEST_CASE("Create sql query data for entity with eager many to many (inverse par
   size_t index{0};
   criteria_evaluator evaluator(db.dialect(), qc);
   for (const auto &jd : data->joins) {
-    REQUIRE(jd.join_table->name() == expected_join_data[index].first);
+    REQUIRE(jd.join_table->table_name() == expected_join_data[index].first);
     REQUIRE(evaluator.evaluate(*jd.condition) == expected_join_data[index].second);
     ++index;
   }
@@ -317,7 +372,7 @@ TEST_CASE("Test eager relationship", "[session][eager]") {
   connection db("noop://noop.db");
   connection_pool pool("noop://noop.db", 4);
 
-  schema scm(pool);
+  schema scm;
   auto result = scm.attach<department>("departments")
     .and_then( [&scm] { return scm.attach<employee>("employees"); } );
   REQUIRE(result);
@@ -331,7 +386,7 @@ TEST_CASE("Test eager relationship", "[session][eager]") {
   .from(*data->root_table)
   .join_left(data->joins)
   .where(std::move(data->where_clause))
-  .order_by(column{data->root_table.get(), data->pk_column_name})
+  .order_by(column{data->root_table, data->pk_column_name})
   .asc()
   .str(db);
 
diff --git a/test/orm/query/GeneratorTests.cpp b/test/orm/query/GeneratorTests.cpp
index ada6902..ec07d07 100644
--- a/test/orm/query/GeneratorTests.cpp
+++ b/test/orm/query/GeneratorTests.cpp
@@ -32,18 +32,18 @@ TEST_CASE("Test column value generator", "[generator][column_value]") {
   }
 }
 
-TEST_CASE("Test column generator", "[generator][column]") {
-    SECTION("Test column generator for simple table") {
-        const std::vector expected_columns {
-            column("id"),
-            column("brand"),
-            column("model"),
-        };
-        const auto result = generator::columns<airplane>();
-        REQUIRE(result.size() == expected_columns.size());
-        auto it = result.begin();
-        for (const auto& c : expected_columns) {
-            REQUIRE(c.equals( *it++));
-        }
-    }
-}
\ No newline at end of file
+// TEST_CASE("Test column generator", "[generator][column]") {
+//     SECTION("Test column generator for simple table") {
+//         const std::vector expected_columns {
+//             column("id"),
+//             column("brand"),
+//             column("model"),
+//         };
+//         const auto result = generator::columns<airplane>();
+//         REQUIRE(result.size() == expected_columns.size());
+//         auto it = result.begin();
+//         for (const auto& c : expected_columns) {
+//             REQUIRE(c.equals( *it++));
+//         }
+//     }
+// }
\ No newline at end of file
diff --git a/test/orm/query/QueryBuilderTest.cpp b/test/orm/query/QueryBuilderTest.cpp
index 7fc8996..ef5ea91 100644
--- a/test/orm/query/QueryBuilderTest.cpp
+++ b/test/orm/query/QueryBuilderTest.cpp
@@ -39,9 +39,9 @@ TEST_CASE_METHOD(QueryFixture, "Test create table sql statement string", "[query
   auto result = query::create()
     .table({"person"})
     .columns({
-        attribute("id", basic_type::UInt32),
-        attribute("name", basic_type::Varchar, 255),
-        attribute("age", basic_type::UInt16)
+        column("id", basic_type::UInt32),
+        column("name", basic_type::Varchar, 255),
+        column("age", basic_type::UInt16)
     })
     .constraints({
         constraint("PK_person").primary_key({"id"})
@@ -53,10 +53,10 @@ TEST_CASE_METHOD(QueryFixture, "Test create table sql statement string", "[query
   auto ctx = query::create()
     .table("person")
     .columns({
-        attribute("id", basic_type::UInt32),
-        attribute("name", basic_type::Varchar, {255, constraints::Unique}),
-        attribute("age", basic_type::UInt16),
-        attribute("address", basic_type::UInt32)
+        column("id", basic_type::UInt32),
+        column("name", basic_type::Varchar, 255).unique(),
+        column("age", basic_type::UInt16),
+        column("address", basic_type::UInt32)
     })
     .constraints({
         constraint("PK_person").primary_key({"id"}),
@@ -221,9 +221,9 @@ TEST_CASE_METHOD(QueryFixture, "Test create, insert and select a blob column", "
   auto result = query::create()
     .table("person")
     .columns({
-        attribute("id", basic_type::UInt32),
-        attribute("name", basic_type::Varchar, 255),
-        attribute("data", basic_type::Blob)
+        column("id", basic_type::UInt32),
+        column("name", basic_type::Varchar, 255),
+        column("data", basic_type::Blob)
     })
     .constraints({
         constraint("PK_person").primary_key({"id"})
@@ -247,10 +247,14 @@ TEST_CASE_METHOD(QueryFixture, "Test create, insert and select a blob column", "
 }
 
 TEST_CASE_METHOD(QueryFixture, "Test select statement with join_left", "[query][statement][join_left]") {
+  const auto ap = table("airplane").as("ap");
+  const auto f = table("flight").as("f");
+  const class matador::query::column col1 = {&f, "airplane_id"};
+  const class matador::query::column col2 = {&ap, "id"};
   const auto result = query::select({"f.id", "ap.brand", "f.pilot_name"})
-    .from({"flight", "f"})
-    .join_left({"airplane", "ap"})
-    .on("f.airplane_id"_col == "ap.id"_col)
+    .from(table{"flight"}.as("f"))
+    .join_left(table{"airplane"}.as("ap"))
+    .on(col1 == col2)
     .str(*db);
 
   REQUIRE(result == R"(SELECT "f"."id", "ap"."brand", "f"."pilot_name" FROM "flight" "f" LEFT JOIN "airplane" "ap" ON "f"."airplane_id" = "ap"."id")");
diff --git a/test/orm/sql/ColumnGeneratorTest.cpp b/test/orm/sql/ColumnGeneratorTest.cpp
index c56b137..b1fc63f 100644
--- a/test/orm/sql/ColumnGeneratorTest.cpp
+++ b/test/orm/sql/ColumnGeneratorTest.cpp
@@ -26,7 +26,7 @@ TEST_CASE("Generate columns from object", "[column][generator]") {
   backend_provider::instance().register_backend("noop", std::make_unique<orm::test_backend_service>());
   connection_pool pool("noop://noop.db", 4);
 
-  schema s(pool);
+  schema s;
   auto result = s.attach<product>("product");
   REQUIRE( result );
 
@@ -56,7 +56,7 @@ TEST_CASE("Generate columns for object with has many relation", "[column][genera
   backend_provider::instance().register_backend("noop", std::make_unique<orm::test_backend_service>());
   connection_pool pool("noop://noop.db", 4);
 
-  schema s(pool);
+  schema s;
   auto result = s.attach<supplier>("supplier")
     .and_then( [&s] { return s.attach<category>("categories"); } )
     .and_then( [&s] { return s.attach<order_details>("order_details"); } )
@@ -99,7 +99,7 @@ TEST_CASE("Generate columns for object with eager foreign key relation", "[colum
   backend_provider::instance().register_backend("noop", std::make_unique<orm::test_backend_service>());
   connection_pool pool("noop://noop.db", 4);
 
-  schema s(pool);
+  schema s;
   auto result = s.attach<book>("books")
     .and_then( [&s] { return s.attach<author>("authors"); } );
   REQUIRE(result);