diff --git a/src/dbzero/core/collections/vector/VLimitedMatrix.hpp b/src/dbzero/core/collections/vector/VLimitedMatrix.hpp
index f2b55823..df6db853 100644
--- a/src/dbzero/core/collections/vector/VLimitedMatrix.hpp
+++ b/src/dbzero/core/collections/vector/VLimitedMatrix.hpp
@@ -213,7 +213,7 @@ DB0_PACKED_END
         m_sparse_matrix.commit();
         super_t::commit();
     }
-
+    
     template <typename ItemT, unsigned int Dim2, typename PtrT>
     void VLimitedMatrix<ItemT, Dim2, PtrT>::push_back(const ItemT &value, std::uint32_t dim2_key)
     {
@@ -286,7 +286,7 @@ DB0_PACKED_END
                 << "Index (" << index.first << "," << index.second << ") not found" << THROWF_END;
         }
     }
-
+    
     template <typename ItemT, unsigned int Dim2, typename PtrT>
     void VLimitedMatrix<ItemT, Dim2, PtrT>::set(std::pair<std::uint32_t, std::uint32_t> index, const ItemT &value)
     {
diff --git a/src/dbzero/core/collections/vector/v_bdata_block.hpp b/src/dbzero/core/collections/vector/v_bdata_block.hpp
index 9a14e79e..cf7d5514 100644
--- a/src/dbzero/core/collections/vector/v_bdata_block.hpp
+++ b/src/dbzero/core/collections/vector/v_bdata_block.hpp
@@ -21,42 +21,38 @@ DB0_PACKED_BEGIN
     protected:
         using super_t = o_base<o_block_data<ItemT, b_class>, 0, false >;
         friend super_t;
-
-        o_block_data(std::uint32_t)
-        {            
+        
+        o_block_data(std::uint32_t page_size_hint) {
+            auto count = 0x1u << shift(page_size_hint);
+            // initialize with default values
+            std::uninitialized_fill(this->getData(), this->getData() + count, ItemT());            
         }
 
     public:
         using iterator = ItemT*;
         using const_iterator = const ItemT*;
         
-        ItemT *getData()
-        {
+        ItemT *getData() {
             return reinterpret_cast<ItemT *>(this);
         }
         
-        const ItemT *getData() const
-        {
+        const ItemT *getData() const {
             return reinterpret_cast<const ItemT *>(this);            
         }  
 
-        static std::size_t measure(std::uint32_t page_size_hint)
-        {
+        static std::size_t measure(std::uint32_t page_size_hint) {
             return sizeof(ItemT) << shift(page_size_hint);
         } 
 
-        template <class buf_t> static std::size_t safeSizeOf(buf_t buf)
-        {
+        template <class buf_t> static std::size_t safeSizeOf(buf_t buf) {
             throw std::runtime_error("o_block_data::safeSizeOf member not available");
         }
 
-        inline const ItemT &getItem(std::size_t index) const 
-        {            
+        inline const ItemT &getItem(std::size_t index) const {
             return getData()[index];
         }
 
-        ItemT &modifyItem(std::size_t index)
-        {            
+        ItemT &modifyItem(std::size_t index) {
             return getData()[index];
         }
 
@@ -84,20 +80,14 @@ DB0_PACKED_BEGIN
             }
             return result;
         }
-
-        /**
-         * Pull begin (first item) iterator for write
-         */
-        iterator begin() 
-        {
+        
+        // Pull begin (first item) iterator for write
+        iterator begin() {
             return getData();
         }
-
-        /**
-         * Pull begin (first item) iterator for read
-         */
-        const_iterator begin() const 
-        {
+        
+        // Pull begin (first item) iterator for read
+        const_iterator begin() const {
             return getData();
         }
     };
diff --git a/src/dbzero/core/crdt/CRDT_Allocator.cpp b/src/dbzero/core/crdt/CRDT_Allocator.cpp
index 2dc18ca2..f1e5d781 100644
--- a/src/dbzero/core/crdt/CRDT_Allocator.cpp
+++ b/src/dbzero/core/crdt/CRDT_Allocator.cpp
@@ -171,7 +171,7 @@ namespace db0
     std::uint32_t CRDT_Allocator::Alloc::getAllocSize(std::uint32_t address) const
     {
         // Get allocation size under a specific address or throw exception
-        if (!isAllocated(address)) {            
+        if (!isAllocated(address)) {
             THROWF(db0::BadAddressException) << "Invalid address: " << address << THROWF_END;
         }
         return m_stride;
diff --git a/src/dbzero/object_model/class/Class.hpp b/src/dbzero/object_model/class/Class.hpp
index 8e706eff..d0c1e3fb 100644
--- a/src/dbzero/object_model/class/Class.hpp
+++ b/src/dbzero/object_model/class/Class.hpp
@@ -42,8 +42,6 @@ namespace db0::object_model
 
 {
 
-DB0_PACKED_BEGIN
-
     using namespace db0;
     using namespace db0::pools;
     using Fixture = db0::Fixture;
@@ -54,6 +52,8 @@ DB0_PACKED_BEGIN
 
     // fidelity + slot index
     using VFidelityVector = db0::v_bvector<std::pair<std::uint8_t, unsigned int> >;
+    
+DB0_PACKED_BEGIN
 
     struct DB0_PACKED_ATTR o_class: public db0::o_fixed<o_class>
     {        
@@ -83,6 +83,8 @@ DB0_PACKED_BEGIN
         );
     };
     
+DB0_PACKED_END
+
     // address <-> class_ref conversion functions
     // @param type_slot_addr_range the address of the types-specific slot
     std::uint32_t classRef(const Class &, std::pair<std::uint64_t, std::uint64_t> type_slot_addr_range);
@@ -327,6 +329,4 @@ DB0_PACKED_BEGIN
     
     std::optional<std::string> getNameVariant(const Class &, int variant_id);
     
-DB0_PACKED_END
-
 }
diff --git a/src/dbzero/object_model/class/Field.cpp b/src/dbzero/object_model/class/Field.cpp
index f8c04514..030bc1ac 100644
--- a/src/dbzero/object_model/class/Field.cpp
+++ b/src/dbzero/object_model/class/Field.cpp
@@ -3,7 +3,7 @@
 namespace db0::object_model
 
 {
-
+    
     o_field::o_field(RC_LimitedStringPool &string_pool, const char *name)
         : m_name(string_pool.addRef(name))
     {
diff --git a/src/dbzero/object_model/class/Field.hpp b/src/dbzero/object_model/class/Field.hpp
index 0df2b8a7..2ab8f87a 100644
--- a/src/dbzero/object_model/class/Field.hpp
+++ b/src/dbzero/object_model/class/Field.hpp
@@ -14,13 +14,13 @@
 namespace db0::object_model
 
 {
-
-DB0_PACKED_BEGIN
     
     class Class;
     using namespace db0;
     using namespace db0::pools;
     using ClassPtr = db0::db0_ptr<Class>;
+
+DB0_PACKED_BEGIN
     
     struct DB0_PACKED_ATTR o_field: public db0::o_fixed<o_field>
     {
@@ -29,10 +29,10 @@ DB0_PACKED_BEGIN
         o_field() = default;
         o_field(RC_LimitedStringPool &, const char *name);
     };
-    
+
+DB0_PACKED_END
+
     // NOTE: we use lofi_store<2> since it's the lowest supported type fidelity
     using VFieldMatrix = db0::VLimitedMatrix<o_field, lofi_store<2>::size()>;
-    
-DB0_PACKED_END
 
 }
diff --git a/src/dbzero/object_model/class/Schema.cpp b/src/dbzero/object_model/class/Schema.cpp
index 464951cf..3590083c 100644
--- a/src/dbzero/object_model/class/Schema.cpp
+++ b/src/dbzero/object_model/class/Schema.cpp
@@ -92,6 +92,18 @@ namespace db0::object_model
         return result;
     }
     
+    void o_schema::initTypeVector(Memspace &memspace, TypeVector &type_vector)
+    {
+        if (!type_vector) {
+            if (!m_type_vector_ptr) {
+                type_vector = TypeVector(memspace);
+                m_type_vector_ptr = db0::db0_ptr<TypeVector>(type_vector);
+            } else {
+                type_vector = m_type_vector_ptr(memspace);
+            }
+        }
+    }
+    
     void o_schema::update(Memspace &memspace,
         std::vector<std::tuple<FieldLoc, SchemaTypeId, int> >::const_iterator begin,
         std::vector<std::tuple<FieldLoc, SchemaTypeId, int> >::const_iterator end,
@@ -117,13 +129,7 @@ namespace db0::object_model
                     m_secondary_type = o_type_item();
                 }
             } else {
-                if (!type_vector) {
-                    if (m_type_vector_ptr) {
-                        type_vector = m_type_vector_ptr(memspace);
-                    } else {
-                        type_vector = TypeVector(memspace);
-                    }
-                }
+                initTypeVector(memspace, type_vector);
                 auto it = type_vector.find(o_type_item{std::get<1>(*begin), 0});
                 if (it == type_vector.end()) {
                     // add new type ID
@@ -160,7 +166,7 @@ namespace db0::object_model
         TypeVector type_vector;
         update(memspace, type_vector, collection_size);
     }
-
+    
     void o_schema::update(Memspace &memspace, TypeVector &type_vector, std::uint32_t collection_size)
     {
         // try swapping primary / secondary and extra types
@@ -183,9 +189,8 @@ namespace db0::object_model
             return;
         }
 
-        if (!type_vector) {
-            type_vector = m_type_vector_ptr(memspace);
-        }
+        initTypeVector(memspace, type_vector);
+        assert(type_vector);
         
         o_type_item max_item, second_max_item;
         for (auto &type_item : type_vector) {
@@ -440,14 +445,16 @@ namespace db0::object_model
         return *m_builder;
     }
     
-    void Schema::add(FieldID field_id, SchemaTypeId type_id) {
+    void Schema::add(FieldID field_id, SchemaTypeId type_id) 
+    {
         if (type_id == SchemaTypeId::UNDEFINED || type_id == SchemaTypeId::DELETED) {
             return;
         }
         getBuilder().collect(field_id, type_id, 1);
     }
     
-    void Schema::remove(FieldID field_id, SchemaTypeId type_id) {
+    void Schema::remove(FieldID field_id, SchemaTypeId type_id) 
+    {
         if (type_id == SchemaTypeId::UNDEFINED || type_id == SchemaTypeId::DELETED) {
             return;
         }
diff --git a/src/dbzero/object_model/class/Schema.hpp b/src/dbzero/object_model/class/Schema.hpp
index 9ac8d6a8..39064cef 100644
--- a/src/dbzero/object_model/class/Schema.hpp
+++ b/src/dbzero/object_model/class/Schema.hpp
@@ -135,8 +135,11 @@ DB0_PACKED_BEGIN
 
     private:
         void update(Memspace &, TypeVector &, std::uint32_t collection_size);
+        void initTypeVector(Memspace &, TypeVector &);
     };
     
+DB0_PACKED_END
+
     class Schema: protected db0::VLimitedMatrix<o_schema, lofi_store<2>::size()>
     {
     public:        
@@ -199,7 +202,5 @@ DB0_PACKED_BEGIN
         // Update to reflect the collection size change only
         void update(std::uint32_t collection_size);
     };
-    
-DB0_PACKED_END
 
 }
\ No newline at end of file
diff --git a/src/dbzero/object_model/enum/EnumValue.hpp b/src/dbzero/object_model/enum/EnumValue.hpp
index ec144b4f..01e5fbbb 100644
--- a/src/dbzero/object_model/enum/EnumValue.hpp
+++ b/src/dbzero/object_model/enum/EnumValue.hpp
@@ -10,8 +10,6 @@
 namespace db0::object_model
 
 {
-
-DB0_PACKED_BEGIN
     
     using LP_String = db0::LP_String;
     using ObjectSharedPtr = db0::object_model::LangConfig::ObjectSharedPtr;
@@ -29,6 +27,8 @@ DB0_PACKED_BEGIN
         std::uint64_t asULong() const;
     };
     
+DB0_PACKED_BEGIN
+
     class DB0_PACKED_ATTR o_enum_value_repr: public db0::o_base<o_enum_value_repr, 0, false>
     {
     protected:
@@ -54,6 +54,8 @@ DB0_PACKED_BEGIN
         }   
     };
     
+DB0_PACKED_END
+
     // EnumValue placeholder when EnumValue could not be created
     // e.g. due to read-only access
     struct EnumValueRepr
@@ -123,6 +125,8 @@ DB0_PACKED_BEGIN
         db0::swine_ptr<Fixture> getFixture() const;
     };
     
+DB0_PACKED_BEGIN
+
     class DB0_PACKED_ATTR o_enum_value: public db0::o_base<o_enum_value, 0, false>
     {
     protected:
diff --git a/tests/unit_tests/ObjectTests.cpp b/tests/unit_tests/ObjectTests.cpp
index 1a42539c..b33026e1 100644
--- a/tests/unit_tests/ObjectTests.cpp
+++ b/tests/unit_tests/ObjectTests.cpp
@@ -38,9 +38,9 @@ namespace tests
         data.m_types = std::vector<StorageClass> { StorageClass::INT64, StorageClass::POOLED_STRING };
         data.m_values = std::vector<Value> { Value(0), Value(0) };
 
-        ASSERT_EQ ( 47u, o_object::measure(0, {0, 0}, 0, data, 0) );
+        ASSERT_EQ ( 44u, o_object::measure(0, {0, 0}, 0, data, 0) );
     }
-
+    
     TEST_F( ObjectTest , testObjectInitializerCanBeFoundIfAdded )
     {
         Workspace workspace("", {}, {}, {}, {}, db0::object_model::initializer());