diff --git a/CMakeLists.txt b/CMakeLists.txt
index 9a400b8..1eb24f6 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -30,15 +30,15 @@ endif ()
 
 set(SOURCES
     exceptions.cpp
-    table.cpp
+    storage.cpp
     database.cpp
 )
 
 set(HEADERS
   database.h
   exceptions.h
-  table.h
-  table.hpp
+  storage.h
+  storage.hpp
   cache.h
   cache.hpp
   serializer.h
diff --git a/cache.h b/cache.h
index 6f7042c..ba72f46 100644
--- a/cache.h
+++ b/cache.h
@@ -14,16 +14,18 @@
 // You should have received a copy of the GNU General Public License
 // along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
-#ifndef DATABASE_CACHE_H
-#define DATABASE_CACHE_H
+#ifndef LMDBDATABASE_CACHE_H
+#define LMDBDATABASE_CACHE_H
 
-#include "database.h"
-#include "table.h"
 #include <map>
 #include <set>
 
+#include "storage.h"
+
+namespace LMDBDataBase {
+
 template <class K, class V>
-class DataBase::Cache : public DataBase::Table<K, V> {
+class Cache : public Storage<K, V> {
     friend class DataBase;
     enum class Mode {       //it's a cache state when we:
         nothing,            //  - know nothing about records in database on disk
@@ -46,7 +48,7 @@ public:
     virtual V getRecord(const K& key) const override;
     virtual uint32_t count() const override;
 
-    using DataBase::Table<K, V>::drop;
+    using Storage<K, V>::drop;
     virtual int drop(MDB_txn * transaction) override;
     virtual std::map<K, V> readAll() const override;
     virtual void replaceAll(const std::map<K, V>& data) override;
@@ -59,6 +61,8 @@ protected:
     uint32_t* sizeDifference;
 };
 
+}
+
 #include "cache.hpp"
 
-#endif // DATABASE_CACHE_H
+#endif // LMDBDATABASE_CACHE_H
diff --git a/cache.hpp b/cache.hpp
index 811b161..1212f4e 100644
--- a/cache.hpp
+++ b/cache.hpp
@@ -14,15 +14,15 @@
 // You should have received a copy of the GNU General Public License
 // along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
-#ifndef DATABASE_CACHE_HPP
-#define DATABASE_CACHE_HPP
+#ifndef LMDBDATABASE_CACHE_HPP
+#define LMDBDATABASE_CACHE_HPP
 
 #include "cache.h"
 #include "exceptions.h"
 
 template<class K, class V>
-DataBase::Cache<K, V>::Cache(const std::string& p_name, DataBase* parent):
-    DataBase::Table<K, V>(p_name, parent),
+LMDBDataBase::Cache<K, V>::Cache(const std::string& p_name, DataBase* parent):
+    Storage<K, V>(p_name, parent),
     mode(new Mode),
     cache(new std::map<K, V>()),
     abscent(new std::set<K>()),
@@ -33,7 +33,7 @@ DataBase::Cache<K, V>::Cache(const std::string& p_name, DataBase* parent):
 }
 
 template<class K, class V>
-DataBase::Cache<K, V>::~Cache() {
+LMDBDataBase::Cache<K, V>::~Cache() {
     delete sizeDifference;
     delete mode;
     delete cache;
@@ -41,73 +41,62 @@ DataBase::Cache<K, V>::~Cache() {
 }
 
 template<class K, class V>
-void DataBase::Cache<K, V>::addRecord(const K& key, const V& value) {
-    if (!DataBase::Table<K, V>::db->opened) {
-        throw Closed("addRecord", DataBase::Table<K, V>::db->name, DataBase::Table<K, V>::name);
-    }
+void LMDBDataBase::Cache<K, V>::addRecord(const K& key, const V& value) {
+    StorageBase::ensureOpened(StorageBase::addRecordMethodName);
 
-    if (cache->count(key) > 0) {
-        throw Exist(DataBase::_Table::toString(key), DataBase::Table<K, V>::db->name, DataBase::Table<K, V>::name);
-    }
+    if (cache->count(key) > 0)
+        StorageBase::throwDuplicate(StorageBase::toString(key));
 
-    Table<K, V>::addRecord(key, value);
+    Storage<K, V>::addRecord(key, value);
     cache->insert(std::make_pair(key, value));
 
-    if (*mode != Mode::full) {
+    if (*mode != Mode::full)
         abscent->erase(key);
-    }
 }
 
 template<class K, class V>
-bool DataBase::Cache<K, V>::forceRecord(const K& key, const V& value) {
-    if (!DataBase::Table<K, V>::db->opened) {
-        throw Closed("forceRecord", DataBase::Table<K, V>::db->name, DataBase::Table<K, V>::name);
-    }
+bool LMDBDataBase::Cache<K, V>::forceRecord(const K& key, const V& value) {
+    StorageBase::ensureOpened(StorageBase::forceRecordMethodName);
 
-    bool added = Table<K, V>::forceRecord(key, value);
+    bool added = Storage<K, V>::forceRecord(key, value);
     if (*mode == Mode::full) {
         (*cache)[key] = value;
     } else {
-        if (added) {
+        if (added)
             abscent->erase(key);
-        }
+
         std::pair<typename std::map<K, V>::iterator, bool> result = cache->insert(std::make_pair(key, value));
-        if (!result.second) {
+        if (!result.second)
             result.first->second = value;
-        } else if (!added) {        //this way database had value but cache didn't, so, need to decrease sizeDifference
+        else if (!added)    //this way database had value but cache didn't, so, need to decrease sizeDifference
             handleMode();
-        }
     }
 
     return added;
 }
 
 template<class K, class V>
-void DataBase::Cache<K, V>::changeRecord(const K& key, const V& value) {
-    if (!DataBase::Table<K, V>::db->opened) {
-        throw Closed("changeRecord", DataBase::Table<K, V>::db->name, DataBase::Table<K, V>::name);
-    }
+void LMDBDataBase::Cache<K, V>::changeRecord(const K& key, const V& value) {
+    StorageBase::ensureOpened(StorageBase::changeRecordMethodName);
 
     if (*mode == Mode::full) {
         typename std::map<K, V>::iterator itr = cache->find(key);
-        if (itr == cache->end()) {
-            throw NotFound(DataBase::_Table::toString(key), DataBase::Table<K, V>::db->name, DataBase::Table<K, V>::name);
-        }
-        Table<K, V>::changeRecord(key, value);
+        if (itr == cache->end())
+            StorageBase::throwNotFound(StorageBase::toString(key));
+
+        Storage<K, V>::changeRecord(key, value);
         itr->second = value;
     } else {
-        if (abscent->count(key) > 0) {
-            throw NotFound(DataBase::_Table::toString(key), DataBase::Table<K, V>::db->name, DataBase::Table<K, V>::name);
-        }
+        if (abscent->count(key) > 0)
+            StorageBase::throwNotFound(StorageBase::toString(key));
 
         try {
-            Table<K, V>::changeRecord(key, value);
+            Storage<K, V>::changeRecord(key, value);
             typename std::pair<typename std::map<K, V>::iterator, bool> res = cache->insert(std::make_pair(key, value));
-            if (!res.second) {
+            if (!res.second)
                 res.first->second = value;
-            } else {
+            else
                 handleMode();
-            }
         } catch (const NotFound& error) {
             abscent->insert(key);
             throw error;
@@ -116,70 +105,60 @@ void DataBase::Cache<K, V>::changeRecord(const K& key, const V& value) {
 }
 
 template<class K, class V>
-V DataBase::Cache<K, V>::getRecord(const K& key) const {
-    if (!DataBase::Table<K, V>::db->opened) {
-        throw Closed("getRecord", DataBase::Table<K, V>::db->name, DataBase::Table<K, V>::name);
-    }
+V LMDBDataBase::Cache<K, V>::getRecord(const K& key) const {
+    StorageBase::ensureOpened(StorageBase::getRecordMethodName);
 
     typename std::map<K, V>::const_iterator itr = cache->find(key);
-    if (itr != cache->end()) {
+    if (itr != cache->end())
         return itr->second;
-    }
 
-    if (*mode == Mode::full || abscent->count(key) != 0) {
-        throw NotFound(DataBase::_Table::toString(key), DataBase::Table<K, V>::db->name, DataBase::Table<K, V>::name);
-    }
+    if (*mode == Mode::full || abscent->count(key) != 0)
+        StorageBase::throwNotFound(StorageBase::toString(key));
 
     try {
-        V value = Table<K, V>::getRecord(key);
+        V value = Storage<K, V>::getRecord(key);
         cache->insert(std::make_pair(key, value));
         handleMode();
         return value;
     } catch (const NotFound& error) {
-        if (*mode != Mode::full) {
+        if (*mode != Mode::full)
             abscent->insert(key);
-        }
+
         throw error;
     }
 }
 
 template<class K, class V>
-bool DataBase::Cache<K, V>::checkRecord(const K& key) const {
-    if (!DataBase::Table<K, V>::db->opened) {
-        throw Closed("checkRecord", DataBase::Table<K, V>::db->name, DataBase::Table<K, V>::name);
-    }
+bool LMDBDataBase::Cache<K, V>::checkRecord(const K& key) const {
+    StorageBase::ensureOpened(StorageBase::checkRecordMethodName);
 
     typename std::map<K, V>::const_iterator itr = cache->find(key);
-    if (itr != cache->end()) {
+    if (itr != cache->end())
         return true;
-    }
 
-    if (*mode == Mode::full || abscent->count(key) != 0) {
+    if (*mode == Mode::full || abscent->count(key) != 0)
         return false;
-    }
 
     try {
-        V value = Table<K, V>::getRecord(key);
+        V value = Storage<K, V>::getRecord(key);
         cache->insert(std::make_pair(key, value));
         handleMode();
         return true;
     } catch (const NotFound& error) {
-        if (*mode != Mode::full) {
+        if (*mode != Mode::full)
             abscent->insert(key);
-        }
+
         return false;
     }
 }
 
 template<class K, class V>
-std::map<K, V> DataBase::Cache<K, V>::readAll() const {
-    if (!DataBase::Table<K, V>::db->opened) {
-        throw Closed("readAll", DataBase::Table<K, V>::db->name, DataBase::Table<K, V>::name);
-    }
+std::map<K, V> LMDBDataBase::Cache<K, V>::readAll() const {
+    StorageBase::ensureOpened(StorageBase::readAllMethodName);
 
-    if (*mode != Mode::full) {                      //there is a room for optimization
-        *mode = Mode::full;                         //I can read and deserialize only those values
-        *cache = DataBase::Table<K, V>::readAll();  //that are missing in the cache
+    if (*mode != Mode::full) {              //there is a room for optimization
+        *mode = Mode::full;                 //I can read and deserialize only those values
+        *cache = Storage<K, V>::readAll();  //that are missing in the cache
         abscent->clear();
         *sizeDifference = 0;
     }
@@ -188,27 +167,32 @@ std::map<K, V> DataBase::Cache<K, V>::readAll() const {
 }
 
 template<class K, class V>
-void DataBase::Cache<K, V>::replaceAll(const std::map<K, V>& data) {
-    DataBase::Table<K, V>::replaceAll(data);
+void LMDBDataBase::Cache<K, V>::replaceAll(const std::map<K, V>& data) {
+    Storage<K, V>::replaceAll(data);
     *cache = data;
+
+    if (*mode != Mode::full) {
+        *mode = Mode::full;
+        abscent->clear();
+        *sizeDifference = 0;
+    }
 }
 
 template<class K, class V>
-uint32_t DataBase::Cache<K, V>::addRecords(const std::map<K, V>& data, bool overwrite) {
-    uint32_t newSize = DataBase::Table<K, V>::addRecords(data, overwrite);
+uint32_t LMDBDataBase::Cache<K, V>::addRecords(const std::map<K, V>& data, bool overwrite) {
+    uint32_t newSize = Storage<K, V>::addRecords(data, overwrite);
 
     Mode& m = *mode;
-    if (m == Mode::nothing) {
+    if (m == Mode::nothing)
         m = Mode::size;
-    }
+
     std::map<K, V>& c = *cache;
     std::set<K>& a = *abscent;
     for (const std::pair<const K, V>& pair : data) {
         std::pair<typename std::map<K, V>::iterator, bool> res = c.insert(pair);
         if (!res.second) {
-            if (overwrite) {
+            if (overwrite)
                 res.first->second = pair.second;
-            }
         } else if (m != Mode::full) {
             a.erase(pair.first);
         }
@@ -226,31 +210,27 @@ uint32_t DataBase::Cache<K, V>::addRecords(const std::map<K, V>& data, bool over
 }
 
 template<class K, class V>
-void DataBase::Cache<K, V>::removeRecord(const K& key) {
-    if (!DataBase::Table<K, V>::db->opened) {
-        throw Closed("removeRecord", DataBase::Table<K, V>::db->name, DataBase::Table<K, V>::name);
-    }
+void LMDBDataBase::Cache<K, V>::removeRecord(const K& key) {
+    StorageBase::ensureOpened(StorageBase::removeRecordMethodName);
 
     typename std::pair<typename std::set<K>::const_iterator, bool> pair = abscent->insert(key);
-    if (!pair.second) {
-        throw NotFound(DataBase::_Table::toString(key), DataBase::Table<K, V>::db->name, DataBase::Table<K, V>::name);
-    }
+    if (!pair.second)
+        StorageBase::throwNotFound(StorageBase::toString(key));
 
-    Table<K, V>::removeRecord(key);
-    if (cache->erase(key) == 0) {   //if it was not cached and we are now in size mode then the sizeDifference would decrease
+    Storage<K, V>::removeRecord(key);
+    if (cache->erase(key) == 0)     //if it was not cached and we are now in size mode then the sizeDifference would decrease
         handleMode();
-    }
-    if (*mode != Mode::full) {
+
+    if (*mode != Mode::full)
         abscent->insert(key);
-    }
 }
 
 template<class K, class V>
-uint32_t DataBase::Cache<K, V>::count() const {
+uint32_t LMDBDataBase::Cache<K, V>::count() const {
     switch (*mode) {
         case Mode::nothing:
         {
-            uint32_t sz = DataBase::Table<K, V>::count();
+            uint32_t sz = Storage<K, V>::count();
             *sizeDifference = sz - cache->size();
             if (sz == 0) {
                 *mode = Mode::full;
@@ -264,11 +244,13 @@ uint32_t DataBase::Cache<K, V>::count() const {
             return cache->size() + *sizeDifference;
         case Mode::full:
             return cache->size();
+        default:
+            return 0;   //unreachable, no such state, just to suppress the waring
     }
 }
 
 template<class K, class V>
-void DataBase::Cache<K, V>::handleMode() const {
+void LMDBDataBase::Cache<K, V>::handleMode() const {
     if (*mode == Mode::size) {
         --(*sizeDifference);
         if (*sizeDifference == 0) {
@@ -279,8 +261,8 @@ void DataBase::Cache<K, V>::handleMode() const {
 }
 
 template<class K, class V>
-int DataBase::Cache<K, V>::drop(MDB_txn * transaction) {
-    int res = DataBase::Table<K, V>::drop(transaction);
+int LMDBDataBase::Cache<K, V>::drop(MDB_txn * transaction) {
+    int res = Storage<K, V>::drop(transaction);
     cache->clear();
     abscent->clear();
     *mode = Mode::full;
@@ -288,4 +270,4 @@ int DataBase::Cache<K, V>::drop(MDB_txn * transaction) {
     return res;
 }
 
-#endif //DATABASE_CACHE_HPP
+#endif //LMDBDATABASE_CACHE_HPP
diff --git a/database.cpp b/database.cpp
index fc114dc..87f4419 100644
--- a/database.cpp
+++ b/database.cpp
@@ -16,30 +16,30 @@
 
 #include "database.h"
 #include "exceptions.h"
-#include "table.h"
+#include "storage.h"
 
-DataBase::DataBase(const QString& p_name, uint16_t mapSize):
+LMDBDataBase::DataBase::DataBase(const QString& p_name, uint16_t mapSize):
     name(p_name.toStdString()),
     opened(false),
     size(mapSize),
     environment(),
-    tables()
-{
-}
+    tables(),
+    transactions(new Transactions())
+{}
 
-DataBase::~DataBase()
-{
+LMDBDataBase::DataBase::~DataBase() {
     close();
-    for (const std::pair<const std::string, _Table*>& pair : tables) {
+
+    delete transactions;
+
+    for (const std::pair<const std::string, StorageBase*>& pair : tables)
         delete pair.second;
-    }
 }
 
-void DataBase::close()
-{
+void LMDBDataBase::DataBase::close() {
     if (opened) {
-        for (const std::pair<const std::string, _Table*>& pair : tables) {
-            _Table* table = pair.second;
+        for (const std::pair<const std::string, StorageBase*>& pair : tables) {
+            StorageBase* table = pair.second;
             mdb_dbi_close(environment, table->dbi);
         }
         mdb_env_close(environment);
@@ -47,8 +47,7 @@ void DataBase::close()
     }
 }
 
-void DataBase::open()
-{
+void LMDBDataBase::DataBase::open() {
     if (!opened) {
         mdb_env_create(&environment);
         QString path = createDirectory();
@@ -60,40 +59,34 @@ void DataBase::open()
         MDB_txn *txn;
         mdb_txn_begin(environment, NULL, 0, &txn);
 
-        for (const std::pair<const std::string, _Table*>& pair : tables) {
-            _Table* table = pair.second;
+        for (const std::pair<const std::string, StorageBase*>& pair : tables) {
+            StorageBase* table = pair.second;
             int rc = table->createTable(txn);
-            if (rc) {
+            if (rc)
                 throw Unknown(name, mdb_strerror(rc));
-            }
-
         }
         mdb_txn_commit(txn);
         opened = true;
     }
 }
 
-bool DataBase::removeDirectory()
-{
-    if (opened) {
+bool LMDBDataBase::DataBase::removeDirectory() {
+    if (opened)
         throw Opened(name, "remove database directory");
-    }
+
     QString path(QStandardPaths::writableLocation(QStandardPaths::CacheLocation));
     path += "/" + getName();
     QDir cache(path);
 
-    if (cache.exists()) {
+    if (cache.exists())
         return cache.removeRecursively();
-    } else {
+    else
         return true;
-    }
 }
 
-QString DataBase::createDirectory()
-{
-    if (opened) {
+QString LMDBDataBase::DataBase::createDirectory() {
+    if (opened)
         throw Opened(name, "create database directory");
-    }
 
     QString path(QStandardPaths::writableLocation(QStandardPaths::CacheLocation));
     path += "/" + getName();
@@ -101,44 +94,100 @@ QString DataBase::createDirectory()
 
     if (!cache.exists()) {
         bool res = cache.mkpath(path);
-        if (!res) {
+        if (!res)
             throw Directory(path.toStdString());
-        }
     }
 
     return path;
 }
 
+QString LMDBDataBase::DataBase::getName() const {
+    return QString::fromStdString(name);}
 
-QString DataBase::getName() const
-{
-    return QString::fromStdString(name);
-}
+bool LMDBDataBase::DataBase::ready() const {
+    return opened;}
 
-bool DataBase::ready() const
-{
-    return opened;
-}
-
-void DataBase::drop()
-{
-    if (!opened) {
+void LMDBDataBase::DataBase::drop() {
+    if (!opened)
         throw Closed("drop", name);
-    }
 
     MDB_txn *txn;
     int rc = mdb_txn_begin(environment, NULL, 0, &txn);
-    if (rc) {
+    if (rc)
         throw Unknown(name, mdb_strerror(rc));
-    }
-    for (const std::pair<const std::string, _Table*>& pair : tables) {
+
+    for (const std::pair<const std::string, StorageBase*>& pair : tables) {
         rc = pair.second->drop(txn);
-        if (rc) {
+        if (rc)
             throw Unknown(name, mdb_strerror(rc), pair.first);
-        }
     }
 
     mdb_txn_commit(txn);
 }
 
+LMDBDataBase::TransactionID LMDBDataBase::DataBase::beginReadOnlyTransaction() const {
+    return beginReadOnlyTransaction(emptyName);}
 
+LMDBDataBase::TransactionID LMDBDataBase::DataBase::beginTransaction() const {
+    return beginTransaction(emptyName);}
+
+void LMDBDataBase::DataBase::abortTransaction(LMDBDataBase::TransactionID id) const {
+    return abortTransaction(id, emptyName);}
+
+void LMDBDataBase::DataBase::commitTransaction(LMDBDataBase::TransactionID id) const {
+    return commitTransaction(id, emptyName);}
+
+
+LMDBDataBase::TransactionID LMDBDataBase::DataBase::beginReadOnlyTransaction(const std::string& storageName) const {
+    if (!opened)
+        throw Closed("beginReadOnlyTransaction", name, storageName);
+
+    MDB_txn* txn;
+    int rc = mdb_txn_begin(environment, NULL, MDB_RDONLY, &txn);
+    if (rc) {
+        mdb_txn_abort(txn);
+        throw Unknown(name, mdb_strerror(rc), storageName);
+    }
+    transactions->emplace(txn);
+    return txn;
+}
+
+LMDBDataBase::TransactionID LMDBDataBase::DataBase::beginTransaction(const std::string& storageName) const {
+    if (!opened)
+        throw Closed("beginTransaction", name, storageName);
+
+    MDB_txn* txn;
+    int rc = mdb_txn_begin(environment, NULL, 0, &txn);
+    if (rc) {
+        mdb_txn_abort(txn);
+        throw Unknown(name, mdb_strerror(rc), storageName);
+    }
+    transactions->emplace(txn);
+    return txn;
+}
+
+void LMDBDataBase::DataBase::abortTransaction(LMDBDataBase::TransactionID id, const std::string& storageName) const {
+    if (!opened)
+        throw Closed("abortTransaction", name, storageName);
+
+    Transactions::iterator itr = transactions->find(id);
+    if (itr == transactions->end())     //TODO may be it's a good idea to make an exception class for this
+        throw Unknown(name, "unable to abort transaction: transaction was not found", storageName);
+
+    mdb_txn_abort(id);
+    transactions->erase(itr);
+}
+
+void LMDBDataBase::DataBase::commitTransaction(LMDBDataBase::TransactionID id, const std::string& storageName) const {
+    if (!opened)
+        throw Closed("abortTransaction", name, storageName);
+
+    Transactions::iterator itr = transactions->find(id);
+    if (itr == transactions->end())     //TODO may be it's a good idea to make an exception class for this
+        throw Unknown(name, "unable to commit transaction: transaction was not found", storageName);
+
+    int rc = mdb_txn_commit(id);
+    transactions->erase(itr);
+    if (rc != MDB_SUCCESS)
+        throw Unknown(name, mdb_strerror(rc), storageName);
+}
diff --git a/database.h b/database.h
index 005c1d9..27f318e 100644
--- a/database.h
+++ b/database.h
@@ -14,28 +14,41 @@
 // You should have received a copy of the GNU General Public License
 // along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
-#ifndef CORE_DATABASE_H
-#define CORE_DATABASE_H
+#ifndef LMDBDATABASE_DATABASE_H
+#define LMDBDATABASE_DATABASE_H
 
 #include <map>
+#include <set>
 #include <string>
 #include <optional>
+#include <limits>
 
 #include <QString>
 #include <QStandardPaths>
 #include <QDir>
+
 #include <lmdb.h>
 
-class DataBase
-{
-    class _Table;
-    template<class T>
-    class Serializer;
+#include "exceptions.h"
+
+namespace LMDBDataBase {
+
+class StorageBase;
+
+template<class T>
+class Serializer;
+
+template <class K, class V>
+class Storage;
+
+template <class K, class V>
+class Cache;
+
+typedef MDB_txn* TransactionID;
+
+class DataBase {
+    friend class StorageBase;
 public:
-    template <class K, class V>
-    class Table;
-    template <class K, class V>
-    class Cache;
 
     DataBase(const QString& name, uint16_t mapSize = 10);
     ~DataBase();
@@ -48,69 +61,74 @@ public:
     QString getName() const;
     void drop();
 
+    TransactionID beginReadOnlyTransaction() const;
+    TransactionID beginTransaction() const;
+    void commitTransaction(TransactionID id) const;
+    void abortTransaction(TransactionID id) const;
 
     template <class K, class V>
-    Table<K, V>* addTable(const std::string& name);
+    Storage<K, V>* addTable(const std::string& name);
 
     template <class K, class V>
     Cache<K, V>* addCache(const std::string& name);
 
     template <class K, class V>
-    Table<K, V>* getTable(const std::string& name);
+    Storage<K, V>* getTable(const std::string& name);
 
     template <class K, class V>
     Cache<K, V>* getCache(const std::string& name);
 
-public:
-    //exceptions
-    class Exception;
-    class Directory;
-    class Closed;
-    class Opened;
-    class NotFound;
-    class Exist;
-    class Unknown;
+private:
+    typedef std::map<std::string, StorageBase*> Tables;
+    typedef std::set<TransactionID> Transactions;
+
+    TransactionID beginReadOnlyTransaction(const std::string& storageName) const;
+    TransactionID beginTransaction(const std::string& storageName) const;
+    void commitTransaction(TransactionID id, const std::string& storageName) const;
+    void abortTransaction(TransactionID id, const std::string& storageName) const;
 
 private:
     std::string name;
     bool opened;
     uint16_t size;
     MDB_env* environment;
-    std::map<std::string, _Table*> tables;
+    Tables tables;
+    Transactions* transactions;
+
+    inline static const std::string emptyName = "";
 };
 
-#include "exceptions.h"
+}
 #include "operators.hpp"
 
 template <class K, class V>
-DataBase::Table<K, V>* DataBase::addTable(const std::string& p_name) {
+LMDBDataBase::Storage<K, V>* LMDBDataBase::DataBase::addTable(const std::string& p_name) {
     if (opened) {
         throw Opened(name, "add table " + p_name);
     }
-    DataBase::Table<K, V>* table = new DataBase::Table<K, V>(p_name, this);
-    tables.insert(std::make_pair(p_name, (_Table*)table));
+    Storage<K, V>* table = new Storage<K, V>(p_name, this);
+    tables.insert(std::make_pair(p_name, (StorageBase*)table));
     return table;
 }
 
 template<class K, class V>
-DataBase::Cache<K, V> * DataBase::addCache(const std::string& p_name) {
+LMDBDataBase::Cache<K, V> * LMDBDataBase::DataBase::addCache(const std::string& p_name) {
     if (opened) {
         throw Opened(name, "add cache " + p_name);
     }
-    DataBase::Cache<K, V>* cache = new DataBase::Cache<K, V>(p_name, this);
-    tables.insert(std::make_pair(p_name, (_Table*)cache));
+    Cache<K, V>* cache = new Cache<K, V>(p_name, this);
+    tables.insert(std::make_pair(p_name, (StorageBase*)cache));
     return cache;
 }
 
 template <class K, class V>
-DataBase::Table<K, V>* DataBase::getTable(const std::string& p_name) {
-    return static_cast<DataBase::Table<K, V>*>(tables.at(p_name));
+LMDBDataBase::Storage<K, V>* LMDBDataBase::DataBase::getTable(const std::string& p_name) {
+    return static_cast<Storage<K, V>*>(tables.at(p_name));
 }
 
 template <class K, class V>
-DataBase::Cache<K, V>* DataBase::getCache(const std::string& p_name) {
-    return static_cast<DataBase::Cache<K, V>*>(tables.at(p_name));
+LMDBDataBase::Cache<K, V>* LMDBDataBase::DataBase::getCache(const std::string& p_name) {
+    return static_cast<Cache<K, V>*>(tables.at(p_name));
 }
 
-
-#endif // CORE_DATABASE_H
+#endif // LMDBDATABASE_DATABASE_H
diff --git a/exceptions.cpp b/exceptions.cpp
index 086649e..16a8010 100644
--- a/exceptions.cpp
+++ b/exceptions.cpp
@@ -16,26 +16,25 @@
 
 #include "exceptions.h"
 
-DataBase::Exception::Exception():
-std::exception()
+LMDBDataBase::Exception::Exception():
+    std::exception()
 {}
 
-DataBase::Exception::~Exception() {}
+LMDBDataBase::Exception::~Exception() {}
 
-const char* DataBase::Exception::what() const noexcept( true )
-{
+const char* LMDBDataBase::Exception::what() const noexcept( true ) {
     std::string* msg = new std::string(getMessage());
     return msg->c_str();
 }
 
-DataBase::Directory::Directory(const std::string& p_path):
+LMDBDataBase::Directory::Directory(const std::string& p_path):
     Exception(),
     path(p_path) {}
 
-std::string DataBase::Directory::getMessage() const {
+std::string LMDBDataBase::Directory::getMessage() const {
     return "Can't create directory for database at " + path;}
 
-DataBase::Closed::Closed(
+LMDBDataBase::Closed::Closed(
     const std::string& p_operation,
     const std::string& p_dbName,
     const std::optional<std::string>& p_tableName
@@ -45,29 +44,28 @@ DataBase::Closed::Closed(
     dbName(p_dbName),
     tableName(p_tableName) {}
 
-std::string DataBase::Closed::getMessage() const {
+std::string LMDBDataBase::Closed::getMessage() const {
     std::string msg = "An attempt to perform operation " + operation
                     + " on closed database " + dbName;
-    if (tableName.has_value()) {
+    if (tableName.has_value())
         msg += + " on table " + tableName.value();
-    }
-    return msg;
 
+    return msg;
 }
 
-DataBase::Opened::Opened(const std::string& p_dbName, const std::string& p_action):
+LMDBDataBase::Opened::Opened(const std::string& p_dbName, const std::string& p_action):
     Exception(),
     dbName(p_dbName),
     action(p_action) {}
 
 
-std::string DataBase::Opened::getMessage() const {
+std::string LMDBDataBase::Opened::getMessage() const {
     return "An attempt to " + action
             + " (the database " + dbName
             + ") but it's can't be done because the DataBase is already opened";
 }
 
-DataBase::NotFound::NotFound(
+LMDBDataBase::NotFound::NotFound(
     const std::string& p_key,
     const std::string& p_dbName,
     const std::string& p_tableName
@@ -77,12 +75,12 @@ DataBase::NotFound::NotFound(
     dbName(p_dbName),
     tableName(p_tableName) {}
 
-std::string DataBase::NotFound::getMessage() const {
+std::string LMDBDataBase::NotFound::getMessage() const {
     return "Element for id " + key + " wasn't found "
             + " in database " + dbName
             + " in table " + tableName;}
 
-DataBase::Exist::Exist(
+LMDBDataBase::Exist::Exist(
     const std::string& p_key,
     const std::string& p_dbName,
     const std::string& p_tableName
@@ -92,14 +90,14 @@ DataBase::Exist::Exist(
     dbName(p_dbName),
     tableName(p_tableName) {}
 
-std::string DataBase::Exist::getMessage() const {
+std::string LMDBDataBase::Exist::getMessage() const {
     return "An attempt to insert element with key " + key
             + " to database " + dbName
             + " to table " + tableName
             + " but it already has an element with given id";
 }
 
-DataBase::Unknown::Unknown(
+LMDBDataBase::Unknown::Unknown(
     const std::string& p_dbName,
     const std::string& message,
     const std::optional<std::string>& p_tableName
@@ -109,12 +107,11 @@ DataBase::Unknown::Unknown(
     tableName(p_tableName),
     msg(message) {}
 
-std::string DataBase::Unknown::getMessage() const
-{
+std::string LMDBDataBase::Unknown::getMessage() const {
     std::string result = "Unknown error in database " + dbName;
-    if (tableName.has_value()) {
+    if (tableName.has_value())
         result += " in table " + tableName.value();
-    }
+
     result += ": " + msg;
     return result;
 }
diff --git a/exceptions.h b/exceptions.h
index 88c2e6a..87dc438 100644
--- a/exceptions.h
+++ b/exceptions.h
@@ -14,17 +14,16 @@
 // You should have received a copy of the GNU General Public License
 // along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
-#ifndef CORE_DATABASE_EXCEPTIONS_H
-#define CORE_DATABASE_EXCEPTIONS_H
+#ifndef LMDBDATABASE_EXCEPTIONS_H
+#define LMDBDATABASE_EXCEPTIONS_H
 
 #include <stdexcept>
 #include <string>
 #include <optional>
 
-#include "database.h"
+namespace LMDBDataBase {
 
-class DataBase::Exception : public std::exception
-{
+class Exception : public std::exception {
 public:
     Exception();
     virtual ~Exception();
@@ -34,7 +33,7 @@ public:
     const char* what() const noexcept( true );
 };
 
-class DataBase::Directory: public DataBase::Exception {
+class Directory: public Exception {
 public:
     Directory(const std::string& path);
 
@@ -43,7 +42,7 @@ private:
     std::string path;
 };
 
-class DataBase::Closed : public DataBase::Exception {
+class Closed : public Exception {
 public:
     Closed(const std::string& p_operation, const std::string& dbName, const std::optional<std::string>& tableName = std::nullopt);
 
@@ -54,7 +53,7 @@ private:
     std::optional<std::string> tableName;
 };
 
-class DataBase::Opened : public DataBase::Exception {
+class Opened : Exception {
 public:
     Opened(const std::string& dbName, const std::string& action);
 
@@ -64,7 +63,7 @@ private:
     std::string action;
 };
 
-class DataBase::NotFound : public DataBase::Exception {
+class NotFound : public Exception {
 public:
     NotFound(const std::string& key, const std::string& dbName, const std::string& tableName);
 
@@ -75,7 +74,7 @@ private:
     std::string tableName;
 };
 
-class DataBase::Exist : public DataBase::Exception {
+class Exist : public Exception {
 public:
     Exist(const std::string& key, const std::string& dbName, const std::string& tableName);
 
@@ -86,7 +85,7 @@ private:
     std::string tableName;
 };
 
-class DataBase::Unknown : public DataBase::Exception {
+class Unknown : public Exception {
 public:
     Unknown(const std::string& dbName, const std::string& message, const std::optional<std::string>& tableName = std::nullopt);
 
@@ -97,4 +96,6 @@ private:
     std::string msg;
 };
 
-#endif //CORE_DATABASE_EXCEPTIONS_H
+}
+
+#endif //LMDBDATABASE_EXCEPTIONS_H
diff --git a/serializer.h b/serializer.h
index 9ff3c18..8f00db9 100644
--- a/serializer.h
+++ b/serializer.h
@@ -14,8 +14,8 @@
 // You should have received a copy of the GNU General Public License
 // along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
-#ifndef CORE_DATABASE_SERIALIZER_H
-#define CORE_DATABASE_SERIALIZER_H
+#ifndef LMDBDATABASE_SERIALIZER_H
+#define LMDBDATABASE_SERIALIZER_H
 
 #include <cstring>
 
@@ -25,9 +25,10 @@
 
 #include "database.h"
 
+namespace LMDBDataBase {
+
 template<class T>
-class DataBase::Serializer
-{
+class Serializer {
 public:
     Serializer();
     Serializer(const T& value);
@@ -48,6 +49,8 @@ private:
     QDataStream stream;
 };
 
+}
+
 #include "serializer.hpp"
 #include "serializer_uint64.hpp"
 #include "serializer_uint32.hpp"
@@ -63,4 +66,4 @@ private:
 #include "serializer_qstring.hpp"
 #include "serializer_qbytearray.hpp"
 
-#endif // CORE_DATABASE_SERIALIZER_H
+#endif // LMDBDATABASE_SERIALIZER_H
diff --git a/serializer.hpp b/serializer.hpp
index 59305c0..a580a88 100644
--- a/serializer.hpp
+++ b/serializer.hpp
@@ -14,14 +14,13 @@
 // You should have received a copy of the GNU General Public License
 // along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
-
-#ifndef CORE_DATABASE_SERIALIZER_HPP
-#define CORE_DATABASE_SERIALIZER_HPP
+#ifndef LMDBDATABASE_SERIALIZER_HPP
+#define LMDBDATABASE_SERIALIZER_HPP
 
 #include "serializer.h"
 
 template<class T>
-DataBase::Serializer<T>::Serializer() :
+LMDBDataBase::Serializer<T>::Serializer() :
     bytes(),
     buffer(&bytes),
     stream(&buffer)
@@ -30,7 +29,7 @@ DataBase::Serializer<T>::Serializer() :
 }
 
 template<class T>
-DataBase::Serializer<T>::Serializer(const T& value) :
+LMDBDataBase::Serializer<T>::Serializer(const T& value) :
     bytes(),
     buffer(&bytes),
     stream(&buffer)
@@ -40,19 +39,19 @@ DataBase::Serializer<T>::Serializer(const T& value) :
 }
 
 template<class T>
-DataBase::Serializer<T>::~Serializer() {
+LMDBDataBase::Serializer<T>::~Serializer() {
     buffer.close();
 }
 
 template<class T>
-MDB_val DataBase::Serializer<T>::setData(const T& value) {
+MDB_val LMDBDataBase::Serializer<T>::setData(const T& value) {
     clear();
     _setData(value);
     return getData();
 }
 
 template<class T>
-T DataBase::Serializer<T>::deserialize(const MDB_val& value) {
+T LMDBDataBase::Serializer<T>::deserialize(const MDB_val& value) {
     clear();
     bytes.setRawData((char*)value.mv_data, value.mv_size);
     T result;
@@ -62,19 +61,19 @@ T DataBase::Serializer<T>::deserialize(const MDB_val& value) {
 }
 
 template<class T>
-void DataBase::Serializer<T>::_setData(const T& value) {
+void LMDBDataBase::Serializer<T>::_setData(const T& value) {
     stream << value;
 }
 
 template<class T>
-void DataBase::Serializer<T>::clear() {
+void LMDBDataBase::Serializer<T>::clear() {
     if (buffer.pos() > 0) {
         buffer.seek(0);
     }
 }
 
 template<class T>
-MDB_val DataBase::Serializer<T>::getData() {
+MDB_val LMDBDataBase::Serializer<T>::getData() {
     MDB_val val;
 
     val.mv_size = buffer.pos();
@@ -83,4 +82,4 @@ MDB_val DataBase::Serializer<T>::getData() {
     return val;
 }
 
-#endif //CORE_DATABASE_SERIALIZER_HPP
+#endif //LMDBDATABASE_SERIALIZER_HPP
diff --git a/serializer_double.hpp b/serializer_double.hpp
index aaab3b1..6cdbf01 100644
--- a/serializer_double.hpp
+++ b/serializer_double.hpp
@@ -14,13 +14,13 @@
 // You should have received a copy of the GNU General Public License
 // along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
+#ifndef LMDBDATABASE_SERIALIZER_DOUBLE_HPP
+#define LMDBDATABASE_SERIALIZER_DOUBLE_HPP
 
-#ifndef CORE_DATABASE_SERIALIZER_DOUBLE_HPP
-#define CORE_DATABASE_SERIALIZER_DOUBLE_HPP
+namespace LMDBDataBase {
 
 template<>
-class DataBase::Serializer<double>
-{
+class Serializer<double> {
 public:
     Serializer():value(0) {};
     Serializer(const double& p_value):value(p_value) {};
@@ -46,8 +46,9 @@ private:
     double value;
 };
 
+}
 
-#endif //CORE_DATABASE_SERIALIZER_DOUBLE_HPP
+#endif //LMDBDATABASE_SERIALIZER_DOUBLE_HPP
 
 
 
diff --git a/serializer_float.hpp b/serializer_float.hpp
index 6a79946..29ce0e0 100644
--- a/serializer_float.hpp
+++ b/serializer_float.hpp
@@ -14,13 +14,13 @@
 // You should have received a copy of the GNU General Public License
 // along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
+#ifndef LMDBDATABASE_SERIALIZER_FLOAT_HPP
+#define LMDBDATABASE_SERIALIZER_FLOAT_HPP
 
-#ifndef CORE_DATABASE_SERIALIZER_FLOAT_HPP
-#define CORE_DATABASE_SERIALIZER_FLOAT_HPP
+namespace LMDBDataBase {
 
 template<>
-class DataBase::Serializer<float>
-{
+class Serializer<float> {
 public:
     Serializer():value(0) {};
     Serializer(const float& p_value):value(p_value) {};
@@ -46,8 +46,9 @@ private:
     float value;
 };
 
+}
 
-#endif //CORE_DATABASE_SERIALIZER_FLOAT_HPP
+#endif //LMDBDATABASE_SERIALIZER_FLOAT_HPP
 
 
 
diff --git a/serializer_int16.hpp b/serializer_int16.hpp
index 380b184..ff07821 100644
--- a/serializer_int16.hpp
+++ b/serializer_int16.hpp
@@ -14,13 +14,15 @@
 // You should have received a copy of the GNU General Public License
 // along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
+#ifndef LMDBDATABASE_SERIALIZER_INT16_HPP
+#define LMDBDATABASE_SERIALIZER_INT16_HPP
 
-#ifndef CORE_DATABASE_SERIALIZER_INT16_HPP
-#define CORE_DATABASE_SERIALIZER_INT16_HPP
+#include <stdint.h>
+
+namespace LMDBDataBase {
 
 template<>
-class DataBase::Serializer<int16_t>
-{
+class Serializer<int16_t> {
 public:
     Serializer():value(0) {};
     Serializer(const int16_t& p_value):value(p_value) {};
@@ -46,5 +48,6 @@ private:
     int16_t value;
 };
 
+}
 
-#endif //CORE_DATABASE_SERIALIZER_INT16_HPP
+#endif //LMDBDATABASE_SERIALIZER_INT16_HPP
diff --git a/serializer_int32.hpp b/serializer_int32.hpp
index da89324..28da663 100644
--- a/serializer_int32.hpp
+++ b/serializer_int32.hpp
@@ -14,13 +14,15 @@
 // You should have received a copy of the GNU General Public License
 // along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
+#ifndef LMDBDATABASE_SERIALIZER_INT32_HPP
+#define LMDBDATABASE_SERIALIZER_INT32_HPP
 
-#ifndef CORE_DATABASE_SERIALIZER_INT32_HPP
-#define CORE_DATABASE_SERIALIZER_INT32_HPP
+#include <stdint.h>
+
+namespace LMDBDataBase {
 
 template<>
-class DataBase::Serializer<int32_t>
-{
+class Serializer<int32_t> {
 public:
     Serializer():value(0) {};
     Serializer(const int32_t& p_value):value(p_value) {};
@@ -46,6 +48,7 @@ private:
     int32_t value;
 };
 
+}
 
 #endif //CORE_DATABASE_SERIALIZER_INT32_HPP
 
diff --git a/serializer_int64.hpp b/serializer_int64.hpp
index d39a368..14c7426 100644
--- a/serializer_int64.hpp
+++ b/serializer_int64.hpp
@@ -14,13 +14,15 @@
 // You should have received a copy of the GNU General Public License
 // along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
+#ifndef LMDBDATABASE_SERIALIZER_INT64_HPP
+#define LMDBDATABASE_SERIALIZER_INT64_HPP
 
-#ifndef CORE_DATABASE_SERIALIZER_INT64_HPP
-#define CORE_DATABASE_SERIALIZER_INT64_HPP
+#include <stdint.h>
+
+namespace LMDBDataBase {
 
 template<>
-class DataBase::Serializer<int64_t>
-{
+class Serializer<int64_t> {
 public:
     Serializer():value(0) {};
     Serializer(const int64_t& p_value):value(p_value) {};
@@ -46,6 +48,7 @@ private:
     int64_t value;
 };
 
+}
 
 #endif //CORE_DATABASE_SERIALIZER_INT64_HPP
 
diff --git a/serializer_int8.hpp b/serializer_int8.hpp
index a1e0404..d6df4c1 100644
--- a/serializer_int8.hpp
+++ b/serializer_int8.hpp
@@ -14,13 +14,15 @@
 // You should have received a copy of the GNU General Public License
 // along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
+#ifndef LMDBDATABASE_SERIALIZER_INT8_HPP
+#define LMDBDATABASE_SERIALIZER_INT8_HPP
 
-#ifndef CORE_DATABASE_SERIALIZER_INT8_HPP
-#define CORE_DATABASE_SERIALIZER_INT8_HPP
+#include <stdint.h>
+
+namespace LMDBDataBase {
 
 template<>
-class DataBase::Serializer<int8_t>
-{
+class Serializer<int8_t> {
 public:
     Serializer():value(0) {};
     Serializer(const int8_t& p_value):value(p_value) {};
@@ -46,8 +48,9 @@ private:
     int8_t value;
 };
 
+}
 
-#endif //CORE_DATABASE_SERIALIZER_INT8_HPP
+#endif //LMDBDATABASE_SERIALIZER_INT8_HPP
 
 
 
diff --git a/serializer_qbytearray.hpp b/serializer_qbytearray.hpp
index 741bf34..bbb8050 100644
--- a/serializer_qbytearray.hpp
+++ b/serializer_qbytearray.hpp
@@ -14,15 +14,15 @@
 // You should have received a copy of the GNU General Public License
 // along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
-
-#ifndef CORE_DATABASE_SERIALIZER_QBYTEARRAY_HPP
-#define CORE_DATABASE_SERIALIZER_QBYTEARRAY_HPP
+#ifndef LMDBDATABASE_SERIALIZER_QBYTEARRAY_HPP
+#define LMDBDATABASE_SERIALIZER_QBYTEARRAY_HPP
 
 #include <QByteArray>
 
+namespace LMDBDataBase {
+
 template<>
-class DataBase::Serializer<QByteArray>
-{
+class Serializer<QByteArray> {
 public:
     Serializer():value() {};
     Serializer(const QByteArray& p_value):value(p_value) {};
@@ -50,8 +50,9 @@ private:
     QByteArray value;
 };
 
+}
 
-#endif //CORE_DATABASE_SERIALIZER_QBYTEARRAY_HPP
+#endif //LMDBDATABASE_SERIALIZER_QBYTEARRAY_HPP
 
 
 
diff --git a/serializer_qstring.hpp b/serializer_qstring.hpp
index 72c33dd..6073435 100644
--- a/serializer_qstring.hpp
+++ b/serializer_qstring.hpp
@@ -14,16 +14,16 @@
 // You should have received a copy of the GNU General Public License
 // along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
-
-#ifndef CORE_DATABASE_SERIALIZER_QSTRING_HPP
-#define CORE_DATABASE_SERIALIZER_QSTRING_HPP
+#ifndef LMDBDATABASE_SERIALIZER_QSTRING_HPP
+#define LMDBDATABASE_SERIALIZER_QSTRING_HPP
 
 #include <QString>
 #include <QByteArray>
 
+namespace LMDBDataBase {
+
 template<>
-class DataBase::Serializer<QString>
-{
+class Serializer<QString> {
 public:
     Serializer():value() {};
     Serializer(const QString& p_value):value(p_value.toUtf8()) {};
@@ -49,8 +49,9 @@ private:
     QByteArray value;
 };
 
+}
 
-#endif //CORE_DATABASE_SERIALIZER_QSTRING_HPP
+#endif //LMDBDATABASE_SERIALIZER_QSTRING_HPP
 
 
 
diff --git a/serializer_stdstring.hpp b/serializer_stdstring.hpp
index a17a6f1..9fdc152 100644
--- a/serializer_stdstring.hpp
+++ b/serializer_stdstring.hpp
@@ -14,13 +14,15 @@
 // You should have received a copy of the GNU General Public License
 // along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
+#ifndef LMDBDATABASE_SERIALIZER_STDSTRING_HPP
+#define LMDBDATABASE_SERIALIZER_STDSTRING_HPP
 
-#ifndef CORE_DATABASE_SERIALIZER_STDSTRING_HPP
-#define CORE_DATABASE_SERIALIZER_STDSTRING_HPP
+#include <string>
+
+namespace LMDBDataBase {
 
 template<>
-class DataBase::Serializer<std::string>
-{
+class Serializer<std::string> {
 public:
     Serializer():value() {};
     Serializer(const std::string& p_value):value(p_value) {};
@@ -46,8 +48,9 @@ private:
     std::string value;
 };
 
+}
 
-#endif //CORE_DATABASE_SERIALIZER_STDSTRING_HPP
+#endif //LMDBDATABASE_SERIALIZER_STDSTRING_HPP
 
 
 
diff --git a/serializer_uint16.hpp b/serializer_uint16.hpp
index b5df796..ea3324c 100644
--- a/serializer_uint16.hpp
+++ b/serializer_uint16.hpp
@@ -14,13 +14,15 @@
 // You should have received a copy of the GNU General Public License
 // along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
+#ifndef LMDBDATABASE_SERIALIZER_UINT16_HPP
+#define LMDBDATABASE_SERIALIZER_UINT16_HPP
 
-#ifndef CORE_DATABASE_SERIALIZER_UINT16_HPP
-#define CORE_DATABASE_SERIALIZER_UINT16_HPP
+#include <stdint.h>
+
+namespace LMDBDataBase {
 
 template<>
-class DataBase::Serializer<uint16_t>
-{
+class Serializer<uint16_t> {
 public:
     Serializer():value(0) {};
     Serializer(const uint16_t& p_value):value(p_value) {};
@@ -46,7 +48,8 @@ private:
     uint16_t value;
 };
 
+}
 
-#endif //CORE_DATABASE_SERIALIZER_UINT16_HPP
+#endif //LMDBDATABASE_SERIALIZER_UINT16_HPP
 
 
diff --git a/serializer_uint32.hpp b/serializer_uint32.hpp
index 590ecb2..bd07534 100644
--- a/serializer_uint32.hpp
+++ b/serializer_uint32.hpp
@@ -14,13 +14,15 @@
 // You should have received a copy of the GNU General Public License
 // along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
+#ifndef LMDBDATABASE_SERIALIZER_UINT32_HPP
+#define LMDBDATABASE_SERIALIZER_UINT32_HPP
 
-#ifndef CORE_DATABASE_SERIALIZER_UINT32_HPP
-#define CORE_DATABASE_SERIALIZER_UINT32_HPP
+#include <stdint.h>
+
+namespace LMDBDataBase {
 
 template<>
-class DataBase::Serializer<uint32_t>
-{
+class Serializer<uint32_t> {
 public:
     Serializer():value(0) {};
     Serializer(const uint32_t& p_value):value(p_value) {};
@@ -46,5 +48,6 @@ private:
     uint32_t value;
 };
 
+}
 
-#endif //CORE_DATABASE_SERIALIZER_UINT32_HPP
+#endif //LMDBDATABASE_SERIALIZER_UINT32_HPP
diff --git a/serializer_uint64.hpp b/serializer_uint64.hpp
index 6edbbb5..9015378 100644
--- a/serializer_uint64.hpp
+++ b/serializer_uint64.hpp
@@ -14,13 +14,15 @@
 // You should have received a copy of the GNU General Public License
 // along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
+#ifndef LMDBDATABASE_SERIALIZER_UINT64_HPP
+#define LMDBDATABASE_SERIALIZER_UINT64_HPP
 
-#ifndef CORE_DATABASE_SERIALIZER_UINT64_HPP
-#define CORE_DATABASE_SERIALIZER_UINT64_HPP
+#include <stdint.h>
+
+namespace LMDBDataBase {
 
 template<>
-class DataBase::Serializer<uint64_t>
-{
+class Serializer<uint64_t> {
 public:
     Serializer():value(0) {};
     Serializer(const uint64_t& p_value):value(p_value) {};
@@ -46,6 +48,7 @@ private:
     uint64_t value;
 };
 
+}
 
-#endif //CORE_DATABASE_SERIALIZER_UINT64_HPP
+#endif //LMDBDATABASE_SERIALIZER_UINT64_HPP
 
diff --git a/serializer_uint8.hpp b/serializer_uint8.hpp
index bb1fc7e..ba2526c 100644
--- a/serializer_uint8.hpp
+++ b/serializer_uint8.hpp
@@ -14,13 +14,15 @@
 // You should have received a copy of the GNU General Public License
 // along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
+#ifndef LMDBDATABASE_SERIALIZER_UINT8_HPP
+#define LMDBDATABASE_SERIALIZER_UINT8_HPP
 
-#ifndef CORE_DATABASE_SERIALIZER_UINT8_HPP
-#define CORE_DATABASE_SERIALIZER_UINT8_HPP
+#include <stdint.h>
+
+namespace LMDBDataBase {
 
 template<>
-class DataBase::Serializer<uint8_t>
-{
+class Serializer<uint8_t> {
 public:
     Serializer():value(0) {};
     Serializer(const uint8_t& p_value):value(p_value) {};
@@ -46,8 +48,9 @@ private:
     uint8_t value;
 };
 
+}
 
-#endif //CORE_DATABASE_SERIALIZER_UINT8_HPP
+#endif //LMDBDATABASE_SERIALIZER_UINT8_HPP
 
 
 
diff --git a/storage.cpp b/storage.cpp
new file mode 100644
index 0000000..213a0f2
--- /dev/null
+++ b/storage.cpp
@@ -0,0 +1,121 @@
+// Squawk messenger. 
+// Copyright (C) 2019  Yury Gubich <blue@macaw.me>
+// 
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+// 
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+// 
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+#include "storage.h"
+
+LMDBDataBase::StorageBase::StorageBase(const std::string& p_name, DataBase* parent):
+    dbi(),
+    db(parent),
+    name(p_name)
+{}
+
+LMDBDataBase::StorageBase::~StorageBase() {}
+
+void LMDBDataBase::StorageBase::drop() {
+    ensureOpened(dropMethodName);
+
+    MDB_txn *txn;
+    int rc = mdb_txn_begin(db->environment, NULL, 0, &txn);
+    if (rc) {
+        mdb_txn_abort(txn);
+        throw Unknown(db->name, mdb_strerror(rc), name);
+    }
+    rc = drop(txn);
+    if (rc) {
+        mdb_txn_abort(txn);
+        throw Unknown(db->name, mdb_strerror(rc), name);
+    }
+
+    mdb_txn_commit(txn);
+}
+
+int LMDBDataBase::StorageBase::drop(MDB_txn* transaction) {
+    return mdb_drop(transaction, dbi, 0);
+}
+
+const std::string & LMDBDataBase::StorageBase::dbName() const {
+    return db->name;}
+
+bool LMDBDataBase::StorageBase::isDBOpened() const {
+    return db->opened;}
+
+void LMDBDataBase::StorageBase::ensureOpened(const std::string& methodName) const {
+    if (!db->opened)
+        throw Closed(methodName, db->name, name);
+}
+
+uint32_t LMDBDataBase::StorageBase::count() const {
+    ensureOpened(countMethodName);
+
+    MDB_txn *txn;
+    MDB_stat stat;
+    int rc = mdb_txn_begin(db->environment, NULL, MDB_RDONLY, &txn);
+    if (rc) {
+        mdb_txn_abort(txn);
+        throw Unknown(db->name, mdb_strerror(rc), name);
+    }
+
+    rc = mdb_stat(txn, dbi, &stat);
+    if (rc) {
+        mdb_txn_abort(txn);
+        throw Unknown(db->name, mdb_strerror(rc), name);
+    }
+    uint32_t amount = stat.ms_entries;
+    mdb_txn_abort(txn);
+    return amount;
+}
+
+void LMDBDataBase::StorageBase::throwDuplicateOrUnknown(int rc, TransactionID txn, const std::string& key) const {
+    abortTransaction(txn);
+    if (rc == MDB_KEYEXIST)
+        throwDuplicate(key);
+    else
+        throwUnknown(rc);
+}
+
+void LMDBDataBase::StorageBase::throwNotFoundOrUnknown(int rc, LMDBDataBase::TransactionID txn, const std::string& key) const {
+    abortTransaction(txn);
+    if (rc == MDB_NOTFOUND)
+        throwNotFound(key);
+    else
+        throwUnknown(rc);
+}
+
+void LMDBDataBase::StorageBase::throwUnknown(int rc, LMDBDataBase::TransactionID txn) const {
+    abortTransaction(txn);
+    throwUnknown(rc);
+}
+
+void LMDBDataBase::StorageBase::throwUnknown(int rc) const {
+    throw Unknown(db->name, mdb_strerror(rc), name);}
+
+void LMDBDataBase::StorageBase::throwDuplicate(const std::string& key) const {
+    throw Exist(key, db->name, name);}
+
+void LMDBDataBase::StorageBase::throwNotFound(const std::string& key) const {
+    throw NotFound(key, db->name, name);}
+
+LMDBDataBase::TransactionID LMDBDataBase::StorageBase::beginReadOnlyTransaction() const {
+    return db->beginReadOnlyTransaction(name);}
+
+LMDBDataBase::TransactionID LMDBDataBase::StorageBase::beginTransaction() const {
+    return db->beginTransaction(name);}
+
+void LMDBDataBase::StorageBase::abortTransaction(LMDBDataBase::TransactionID id) const {
+    db->abortTransaction(id);}
+
+void LMDBDataBase::StorageBase::commitTransaction(LMDBDataBase::TransactionID id) const {
+    db->commitTransaction(id);}
diff --git a/table.h b/storage.h
similarity index 51%
rename from table.h
rename to storage.h
index 8279237..19990c1 100644
--- a/table.h
+++ b/storage.h
@@ -14,30 +14,61 @@
 // You should have received a copy of the GNU General Public License
 // along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
-#ifndef CORE_TABLE_H
-#define CORE_TABLE_H
+#ifndef LMDBDATABASE_STORAGE_H
+#define LMDBDATABASE_STORAGE_H
 
 #include "database.h"
 #include "serializer.h"
 
-class DataBase::_Table {
+namespace LMDBDataBase {
+
+class StorageBase {
     friend class DataBase;
 protected:
-    _Table(const std::string& name, DataBase* parent);
-    virtual ~_Table();
+    StorageBase(const std::string& name, DataBase* parent);
+    virtual ~StorageBase();
 
     virtual int createTable(MDB_txn * transaction) = 0;
     virtual int drop(MDB_txn * transaction);
 
+    bool isDBOpened() const;
+    const std::string& dbName() const;
+
+    void ensureOpened(const std::string& methodName) const;
+    void throwDuplicateOrUnknown(int rc, TransactionID txn, const std::string& key) const;
+    void throwNotFoundOrUnknown(int rc, TransactionID txn, const std::string& key) const;
+    void throwUnknown(int rc, TransactionID txn) const;
+    void throwUnknown(int rc) const;
+    void throwDuplicate(const std::string& key) const;
+    void throwNotFound(const std::string& key)const ;
+
 public:
     virtual void drop();
     virtual uint32_t count() const;
 
+    TransactionID beginReadOnlyTransaction() const;
+    TransactionID beginTransaction() const;
+    void commitTransaction(TransactionID id) const;
+    void abortTransaction(TransactionID id) const;
+
 protected:
     MDB_dbi dbi;
     DataBase* db;
     const std::string name;
 
+    inline static const std::string dropMethodName = "drop";
+    inline static const std::string countMethodName = "count";
+
+    inline static const std::string addRecordMethodName = "addRecord";
+    inline static const std::string forceRecordMethodName = "forceRecord";
+    inline static const std::string changeRecordMethodName = "changeRecord";
+    inline static const std::string removeRecordMethodName = "removeRecord";
+    inline static const std::string checkRecordMethodName = "checkRecord";
+    inline static const std::string getRecordMethodName = "getRecord";
+    inline static const std::string readAllMethodName = "readAllRecord";
+    inline static const std::string replaceAllMethodName = "replaceAll";
+    inline static const std::string addRecordsMethodName = "addRecords";
+
 protected:
     template <class T>
     int makeTable(MDB_txn* transaction);
@@ -47,14 +78,14 @@ protected:
 };
 
 template <class K, class V>
-class DataBase::Table : public DataBase::_Table {
+class Storage : public StorageBase {
     friend class DataBase;
 protected:
-    Table(const std::string& name, DataBase* parent);
-    ~Table() override;
+    Storage(const std::string& name, DataBase* parent);
+    ~Storage() override;
 
 public:
-    using DataBase::_Table::drop;
+    using StorageBase::drop;
     virtual void addRecord(const K& key, const V& value);
     virtual bool forceRecord(const K& key, const V& value);     //returns true if there was addition, false if change
     virtual void changeRecord(const K& key, const V& value);
@@ -72,6 +103,8 @@ protected:
     int createTable(MDB_txn* transaction) override;
 };
 
-#include "table.hpp"
+}
 
-#endif // CORE_TABLE_H
+#include "storage.hpp"
+
+#endif // LMDBDATABASE_STORAGE_H
diff --git a/storage.hpp b/storage.hpp
new file mode 100644
index 0000000..198fcf1
--- /dev/null
+++ b/storage.hpp
@@ -0,0 +1,291 @@
+// Squawk messenger.
+// Copyright (C) 2019  Yury Gubich <blue@macaw.me>
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+#ifndef LMDBDATABASE_STORAGE_HPP
+#define LMDBDATABASE_STORAGE_HPP
+
+#include "storage.h"
+#include "exceptions.h"
+
+template<class K, class V>
+LMDBDataBase::Storage<K, V>::Storage(const std::string& p_name, DataBase* parent):
+    StorageBase(p_name, parent),
+    keySerializer(new Serializer<K>()),
+    valueSerializer(new Serializer<V>())
+{}
+
+template<class K, class V>
+LMDBDataBase::Storage<K, V>::~Storage() {
+    delete valueSerializer;
+    delete keySerializer;
+}
+
+template<class K, class V>
+void LMDBDataBase::Storage<K, V>::addRecord(const K& key, const V& value) {
+    ensureOpened(addRecordMethodName);
+
+    TransactionID txn = beginTransaction();
+    MDB_val lmdbKey = keySerializer->setData(key);
+    MDB_val lmdbData = valueSerializer->setData(value);
+
+    int rc = mdb_put(txn, dbi, &lmdbKey, &lmdbData, MDB_NOOVERWRITE);
+    if (rc != MDB_SUCCESS)
+        throwDuplicateOrUnknown(rc, txn, toString(key));
+
+    commitTransaction(txn);
+}
+
+template<class K, class V>
+bool LMDBDataBase::Storage<K, V>::forceRecord(const K& key, const V& value) {
+    ensureOpened(forceRecordMethodName);
+
+    bool added;
+    TransactionID txn = beginTransaction();
+    MDB_val lmdbKey = keySerializer->setData(key);
+    MDB_val lmdbData;
+
+    int rc = mdb_get(txn, dbi, &lmdbKey, &lmdbData);
+    switch (rc) {
+        case MDB_SUCCESS:
+            added = false;
+            break;
+        case MDB_NOTFOUND:
+            added = true;
+            break;
+        default:
+            added = false;
+            throwUnknown(rc, txn);
+    }
+
+    lmdbData = valueSerializer->setData(value);
+    rc = mdb_put(txn, dbi, &lmdbKey, &lmdbData, 0);
+    if (rc != MDB_SUCCESS)
+        throwUnknown(rc, txn);
+
+    commitTransaction(txn);
+
+    return added;
+}
+
+template<class K, class V>
+void LMDBDataBase::Storage<K, V>::changeRecord(const K& key, const V& value) {
+    ensureOpened(changeRecordMethodName);
+
+    TransactionID txn = beginTransaction();
+    MDB_val lmdbKey = keySerializer->setData(key);
+    MDB_val lmdbData = valueSerializer->setData(value);
+
+    int rc = mdb_put(txn, dbi, &lmdbKey, &lmdbData, 0);
+    if (rc != MDB_SUCCESS)
+        throwUnknown(rc, txn);
+
+    commitTransaction(txn);
+}
+
+template<class K, class V>
+V LMDBDataBase::Storage<K, V>::getRecord(const K& key) const {
+    ensureOpened(getRecordMethodName);
+
+    TransactionID txn = beginReadOnlyTransaction();
+    MDB_val lmdbKey = keySerializer->setData(key);
+    MDB_val lmdbData;
+
+    int rc = mdb_get(txn, dbi, &lmdbKey, &lmdbData);
+    if (rc != MDB_SUCCESS)
+        throwNotFoundOrUnknown(rc, txn, toString(key));
+
+    V value = valueSerializer->deserialize(lmdbData);
+    abortTransaction(txn);
+
+    return value;
+}
+
+template<class K, class V>
+bool LMDBDataBase::Storage<K, V>::checkRecord(const K& key) const {
+    ensureOpened(checkRecordMethodName);
+
+    TransactionID txn = beginReadOnlyTransaction();
+    MDB_val lmdbKey = keySerializer->setData(key);
+    MDB_val lmdbData;
+
+    int rc = mdb_get(txn, dbi, &lmdbKey, &lmdbData);
+    abortTransaction(txn);
+
+    if (rc == MDB_SUCCESS)
+        return true;
+
+    if (rc != MDB_NOTFOUND)
+        throwUnknown(rc);
+
+    return false;
+}
+
+template<class K, class V>
+std::map<K, V> LMDBDataBase::Storage<K, V>::readAll() const {
+    ensureOpened(readAllMethodName);
+
+    TransactionID txn = beginReadOnlyTransaction();
+    std::map<K, V> result;
+    MDB_cursor* cursor;
+    MDB_val lmdbKey, lmdbData;
+
+    int rc = mdb_cursor_open(txn, dbi, &cursor);
+    if (rc != MDB_SUCCESS)
+        throwUnknown(rc, txn);
+
+    rc = mdb_cursor_get(cursor, &lmdbKey, &lmdbData, MDB_FIRST);
+    while (rc == MDB_SUCCESS) {
+        K key = keySerializer->deserialize(lmdbKey);
+        V value = valueSerializer->deserialize(lmdbData);
+        result.insert(std::make_pair(key, value));
+        rc = mdb_cursor_get(cursor, &lmdbKey, &lmdbData, MDB_NEXT);
+    }
+
+    abortTransaction(txn);
+    if (rc != MDB_NOTFOUND)
+        throwUnknown(rc);
+
+    return result;
+}
+
+template<class K, class V>
+void LMDBDataBase::Storage<K, V>::replaceAll(const std::map<K, V>& data) {
+    ensureOpened(replaceAllMethodName);
+
+    TransactionID txn = beginTransaction();
+    int rc = drop(txn);
+    if (rc != MDB_SUCCESS)
+        throwUnknown(rc, txn);
+
+    MDB_val lmdbKey, lmdbData;
+    for (const std::pair<const K, V>& pair : data) {
+        lmdbKey = keySerializer->setData(pair.first);
+        lmdbData = valueSerializer->setData(pair.second);
+
+        rc = mdb_put(txn, dbi, &lmdbKey, &lmdbData, MDB_NOOVERWRITE);
+        if (rc != MDB_SUCCESS)
+            throwUnknown(rc, txn);
+    }
+    commitTransaction(txn);
+}
+
+template<class K, class V>
+uint32_t LMDBDataBase::Storage<K, V>::addRecords(const std::map<K, V>& data, bool overwrite) {
+    ensureOpened(addRecordsMethodName);
+
+    TransactionID txn = beginTransaction();
+    MDB_val lmdbKey, lmdbData;
+    int rc;
+
+    for (const std::pair<const K, V>& pair : data) {
+        lmdbKey = keySerializer->setData(pair.first);
+        lmdbData = valueSerializer->setData(pair.second);
+
+        rc = mdb_put(txn, dbi, &lmdbKey, &lmdbData, overwrite ? 0 : MDB_NOOVERWRITE);
+        if (rc != MDB_SUCCESS)
+            throwUnknown(rc, txn);
+    }
+
+    MDB_stat stat;
+    rc = mdb_stat(txn, dbi, &stat);
+    if (rc != MDB_SUCCESS)
+        throwUnknown(rc, txn);
+
+    uint32_t amount = stat.ms_entries;
+    commitTransaction(txn);
+
+    return amount;
+}
+
+template<class K, class V>
+void LMDBDataBase::Storage<K, V>::removeRecord(const K& key) {
+    ensureOpened(removeRecordMethodName);
+
+    TransactionID txn = beginTransaction();
+    MDB_val lmdbKey = keySerializer->setData(key);
+    int rc = mdb_del(txn, dbi, &lmdbKey, NULL);
+    if (rc != MDB_SUCCESS)
+        throwNotFoundOrUnknown(rc, txn, toString(key));
+
+    commitTransaction(txn);
+}
+
+template<class K, class V>
+int LMDBDataBase::Storage<K, V>::createTable(MDB_txn* transaction) {
+    return makeTable<K>(transaction);
+}
+
+template<class K>
+inline int LMDBDataBase::StorageBase::makeTable(MDB_txn* transaction) {
+    return mdb_dbi_open(transaction, name.c_str(), MDB_CREATE, &dbi);
+}
+
+template<>
+inline int LMDBDataBase::StorageBase::makeTable<uint64_t>(MDB_txn* transaction) {
+    return mdb_dbi_open(transaction, name.c_str(), MDB_CREATE | MDB_INTEGERKEY, &dbi);
+}
+
+template<>
+inline int LMDBDataBase::StorageBase::makeTable<uint32_t>(MDB_txn* transaction) {
+    return mdb_dbi_open(transaction, name.c_str(), MDB_CREATE | MDB_INTEGERKEY, &dbi);
+}
+
+template<>
+inline int LMDBDataBase::StorageBase::makeTable<uint16_t>(MDB_txn* transaction) {
+    return mdb_dbi_open(transaction, name.c_str(), MDB_CREATE | MDB_INTEGERKEY, &dbi);
+}
+
+template<>
+inline int LMDBDataBase::StorageBase::makeTable<uint8_t>(MDB_txn* transaction) {
+    return mdb_dbi_open(transaction, name.c_str(), MDB_CREATE | MDB_INTEGERKEY, &dbi);
+}
+
+template<>
+inline int LMDBDataBase::StorageBase::makeTable<int64_t>(MDB_txn* transaction) {
+    return mdb_dbi_open(transaction, name.c_str(), MDB_CREATE | MDB_INTEGERKEY, &dbi);
+}
+
+template<>
+inline int LMDBDataBase::StorageBase::makeTable<int32_t>(MDB_txn* transaction) {
+    return mdb_dbi_open(transaction, name.c_str(), MDB_CREATE | MDB_INTEGERKEY, &dbi);
+}
+
+template<>
+inline int LMDBDataBase::StorageBase::makeTable<int16_t>(MDB_txn* transaction) {
+    return mdb_dbi_open(transaction, name.c_str(), MDB_CREATE | MDB_INTEGERKEY, &dbi);
+}
+
+template<>
+inline int LMDBDataBase::StorageBase::makeTable<int8_t>(MDB_txn* transaction) {
+    return mdb_dbi_open(transaction, name.c_str(), MDB_CREATE | MDB_INTEGERKEY, &dbi);
+}
+
+template<class T>
+inline std::string LMDBDataBase::StorageBase::toString(const T& value) {
+    return std::to_string(value);
+}
+
+template<>
+inline std::string LMDBDataBase::StorageBase::toString(const QString& value) {
+    return value.toStdString();
+}
+
+template<>
+inline std::string LMDBDataBase::StorageBase::toString(const std::string& value) {
+    return value;
+}
+
+#endif //LMDBDATABASE_STORAGE_HPP
diff --git a/table.cpp b/table.cpp
deleted file mode 100644
index 80ac7bc..0000000
--- a/table.cpp
+++ /dev/null
@@ -1,72 +0,0 @@
-// Squawk messenger. 
-// Copyright (C) 2019  Yury Gubich <blue@macaw.me>
-// 
-// This program is free software: you can redistribute it and/or modify
-// it under the terms of the GNU General Public License as published by
-// the Free Software Foundation, either version 3 of the License, or
-// (at your option) any later version.
-// 
-// This program is distributed in the hope that it will be useful,
-// but WITHOUT ANY WARRANTY; without even the implied warranty of
-// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-// GNU General Public License for more details.
-// 
-// You should have received a copy of the GNU General Public License
-// along with this program.  If not, see <http://www.gnu.org/licenses/>.
-
-#include "table.h"
-
-DataBase::_Table::_Table(const std::string& p_name, DataBase* parent):
-    dbi(),
-    db(parent),
-    name(p_name)
-{
-}
-
-DataBase::_Table::~_Table() {}
-
-
-void DataBase::_Table::drop()
-{
-    if (!db->opened) {
-        throw Closed("drop", db->name, name);
-    }
-
-    MDB_txn *txn;
-    int rc = mdb_txn_begin(db->environment, NULL, 0, &txn);
-    if (rc) {
-        mdb_txn_abort(txn);
-        throw Unknown(db->name, mdb_strerror(rc), name);
-    }
-    rc = drop(txn);
-    if (rc) {
-        mdb_txn_abort(txn);
-        throw Unknown(db->name, mdb_strerror(rc), name);
-    }
-
-    mdb_txn_commit(txn);
-}
-
-int DataBase::_Table::drop(MDB_txn* transaction)
-{
-    return mdb_drop(transaction, dbi, 0);
-}
-
-uint32_t DataBase::_Table::count() const
-{
-    if (!db->opened) {
-        throw Closed("count", db->name, name);
-    }
-
-    MDB_txn *txn;
-    MDB_stat stat;
-    int rc = mdb_txn_begin(db->environment, NULL, 0, &txn);
-    rc = mdb_stat(txn, dbi, &stat);
-    if (rc) {
-        mdb_txn_abort(txn);
-        throw Unknown(db->name, mdb_strerror(rc), name);
-    }
-    uint32_t amount = stat.ms_entries;
-    mdb_txn_abort(txn);
-    return amount;
-}
diff --git a/table.hpp b/table.hpp
deleted file mode 100644
index 49cb38e..0000000
--- a/table.hpp
+++ /dev/null
@@ -1,385 +0,0 @@
-// Squawk messenger.
-// Copyright (C) 2019  Yury Gubich <blue@macaw.me>
-//
-// This program is free software: you can redistribute it and/or modify
-// it under the terms of the GNU General Public License as published by
-// the Free Software Foundation, either version 3 of the License, or
-// (at your option) any later version.
-//
-// This program is distributed in the hope that it will be useful,
-// but WITHOUT ANY WARRANTY; without even the implied warranty of
-// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-// GNU General Public License for more details.
-//
-// You should have received a copy of the GNU General Public License
-// along with this program.  If not, see <http://www.gnu.org/licenses/>.
-
-#ifndef CORE_TABLE_HPP
-#define CORE_TABLE_HPP
-
-#include "table.h"
-#include "exceptions.h"
-
-template<class K, class V>
-DataBase::Table<K, V>::Table(const std::string& p_name, DataBase* parent):
-    _Table(p_name, parent),
-    keySerializer(new Serializer<K>()),
-    valueSerializer(new Serializer<V>())
-{
-}
-
-template<class K, class V>
-DataBase::Table<K, V>::~Table() {
-    delete valueSerializer;
-    delete keySerializer;
-}
-
-template<class K, class V>
-void DataBase::Table<K, V>::addRecord(const K& key, const V& value) {
-    if (!db->opened) {
-        throw Closed("addRecord", db->name, name);
-    }
-
-    MDB_val lmdbKey = keySerializer->setData(key);
-    MDB_val lmdbData = valueSerializer->setData(value);
-    MDB_txn *txn;
-    int rc = mdb_txn_begin(db->environment, NULL, 0, &txn);
-    if (rc != MDB_SUCCESS) {
-        mdb_txn_abort(txn);
-        throw Unknown(db->name, mdb_strerror(rc), name);
-    }
-
-    rc = mdb_put(txn, dbi, &lmdbKey, &lmdbData, MDB_NOOVERWRITE);
-    if (rc != 0) {
-        mdb_txn_abort(txn);
-        if (rc == MDB_KEYEXIST) {
-            throw Exist(toString(key), db->name, name);
-        } else {
-            throw Unknown(db->name, mdb_strerror(rc), name);
-        }
-    } else {
-        mdb_txn_commit(txn);
-    }
-}
-
-template<class K, class V>
-bool DataBase::Table<K, V>::forceRecord(const K& key, const V& value) {
-    if (!db->opened) {
-        throw Closed("forceRecord", db->name, name);
-    }
-
-    bool added;
-    MDB_val lmdbKey = keySerializer->setData(key);
-    MDB_val lmdbData;
-    MDB_txn *txn;
-    int rc = mdb_txn_begin(db->environment, NULL, 0, &txn);
-    if (rc != MDB_SUCCESS) {
-        mdb_txn_abort(txn);
-        throw Unknown(db->name, mdb_strerror(rc), name);
-    }
-
-    rc = mdb_get(txn, dbi, &lmdbKey, &lmdbData);
-    if (rc == 0) {
-        added = false;
-    } else if (rc == MDB_NOTFOUND) {
-        added = true;
-    } else {
-        mdb_txn_abort(txn);
-        throw Unknown(db->name, mdb_strerror(rc), name);
-    }
-    lmdbData = valueSerializer->setData(value);
-    rc = mdb_put(txn, dbi, &lmdbKey, &lmdbData, 0);
-    if (rc != 0) {
-        mdb_txn_abort(txn);
-        throw Unknown(db->name, mdb_strerror(rc), name);
-    } else {
-        mdb_txn_commit(txn);
-    }
-
-    return added;
-}
-
-template<class K, class V>
-void DataBase::Table<K, V>::changeRecord(const K& key, const V& value) {
-    if (!db->opened) {
-        throw Closed("changeRecord", db->name, name);
-    }
-
-    MDB_val lmdbKey = keySerializer->setData(key);
-    MDB_val lmdbData = valueSerializer->setData(value);
-    MDB_txn *txn;
-
-    int rc = mdb_txn_begin(db->environment, NULL, 0, &txn);
-    if (rc != MDB_SUCCESS) {
-        mdb_txn_abort(txn);
-        throw Unknown(db->name, mdb_strerror(rc), name);
-    }
-
-    rc = mdb_put(txn, dbi, &lmdbKey, &lmdbData, 0);
-    if (rc != 0) {
-        mdb_txn_abort(txn);
-        if (rc) {
-            throw Unknown(db->name, mdb_strerror(rc), name);
-        }
-    } else {
-        mdb_txn_commit(txn);
-    }
-}
-
-template<class K, class V>
-V DataBase::Table<K, V>::getRecord(const K& key) const {
-    if (!db->opened) {
-        throw Closed("getRecord", db->name, name);
-    }
-
-    MDB_val lmdbKey = keySerializer->setData(key);
-    MDB_val lmdbData;
-
-    MDB_txn *txn;
-    int rc = mdb_txn_begin(db->environment, NULL, MDB_RDONLY, &txn);
-    if (rc != MDB_SUCCESS) {
-        mdb_txn_abort(txn);
-        throw Unknown(db->name, mdb_strerror(rc), name);
-    }
-
-    rc = mdb_get(txn, dbi, &lmdbKey, &lmdbData);
-    if (rc) {
-        mdb_txn_abort(txn);
-        if (rc == MDB_NOTFOUND) {
-            throw NotFound(toString(key), db->name, name);
-        } else {
-            throw Unknown(db->name, mdb_strerror(rc), name);
-        }
-    } else {
-        V value = valueSerializer->deserialize(lmdbData);
-        mdb_txn_abort(txn);
-
-        return value;
-    }
-}
-
-template<class K, class V>
-bool DataBase::Table<K, V>::checkRecord(const K& key) const {
-    if (!db->opened) {
-        throw Closed("checkRecord", db->name, name);
-    }
-
-    MDB_val lmdbKey = keySerializer->setData(key);
-    MDB_val lmdbData;
-
-    MDB_txn *txn;
-    int rc = mdb_txn_begin(db->environment, NULL, MDB_RDONLY, &txn);
-    if (rc != MDB_SUCCESS) {
-        mdb_txn_abort(txn);
-        throw Unknown(db->name, mdb_strerror(rc), name);
-    }
-
-    rc = mdb_get(txn, dbi, &lmdbKey, &lmdbData);
-    mdb_txn_abort(txn);
-
-    if (rc) {
-        if (rc == MDB_NOTFOUND) {
-            return false;
-        } else {
-            throw Unknown(db->name, mdb_strerror(rc), name);
-        }
-    } else {
-        return true;
-    }
-}
-
-template<class K, class V>
-std::map<K, V> DataBase::Table<K, V>::readAll() const {
-    if (!db->opened) {
-        throw Closed("readAll", db->name, name);
-    }
-
-    std::map<K, V> result;
-    MDB_txn *txn;
-    MDB_cursor* cursor;
-    MDB_val lmdbKey, lmdbData;
-    int rc = mdb_txn_begin(db->environment, NULL, MDB_RDONLY, &txn);
-    if (rc != MDB_SUCCESS) {
-        mdb_txn_abort(txn);
-        throw Unknown(db->name, mdb_strerror(rc), name);
-    }
-    rc = mdb_cursor_open(txn, dbi, &cursor);
-    if (rc != MDB_SUCCESS) {
-        mdb_txn_abort(txn);
-        throw Unknown(db->name, mdb_strerror(rc), name);
-    }
-    rc = mdb_cursor_get(cursor, &lmdbKey, &lmdbData, MDB_FIRST);
-    while (rc == MDB_SUCCESS) {
-        K key = keySerializer->deserialize(lmdbKey);
-        V value = valueSerializer->deserialize(lmdbData);
-        result.insert(std::make_pair(key, value));
-        rc = mdb_cursor_get(cursor, &lmdbKey, &lmdbData, MDB_NEXT);
-    }
-
-    mdb_txn_abort(txn);
-    if (rc != MDB_NOTFOUND) {
-        throw Unknown(db->name, mdb_strerror(rc), name);
-    }
-
-    return result;
-}
-
-template<class K, class V>
-void DataBase::Table<K, V>::replaceAll(const std::map<K, V>& data) {
-    if (!db->opened) {
-        throw Closed("replaceAll", db->name, name);
-    }
-
-    MDB_txn *txn;
-    int rc = mdb_txn_begin(db->environment, NULL, 0, &txn);
-    if (rc) {
-        mdb_txn_abort(txn);
-        throw Unknown(db->name, mdb_strerror(rc), name);
-    }
-    rc = drop(txn);
-    if (rc) {
-        mdb_txn_abort(txn);
-        throw Unknown(db->name, mdb_strerror(rc), name);
-    }
-
-    MDB_val lmdbKey, lmdbData;
-    for (const std::pair<const K, V>& pair : data) {
-        lmdbKey = keySerializer->setData(pair.first);
-        lmdbData = valueSerializer->setData(pair.second);
-
-        rc = mdb_put(txn, dbi, &lmdbKey, &lmdbData, MDB_NOOVERWRITE);
-        if (rc != 0) {
-            mdb_txn_abort(txn);
-            throw Unknown(db->name, mdb_strerror(rc), name);
-        }
-    }
-    mdb_txn_commit(txn);
-}
-
-template<class K, class V>
-uint32_t DataBase::Table<K, V>::addRecords(const std::map<K, V>& data, bool overwrite) {
-    if (!db->opened) {
-        throw Closed("addRecords", db->name, name);
-    }
-
-    MDB_txn *txn;
-    int rc = mdb_txn_begin(db->environment, NULL, 0, &txn);
-    if (rc) {
-        mdb_txn_abort(txn);
-        throw Unknown(db->name, mdb_strerror(rc), name);
-    }
-
-    MDB_val lmdbKey, lmdbData;
-    for (const std::pair<const K, V>& pair : data) {
-        lmdbKey = keySerializer->setData(pair.first);
-        lmdbData = valueSerializer->setData(pair.second);
-
-        rc = mdb_put(txn, dbi, &lmdbKey, &lmdbData, overwrite ? 0 : MDB_NOOVERWRITE);
-        if (rc != 0) {
-            mdb_txn_abort(txn);
-            throw Unknown(db->name, mdb_strerror(rc), name);
-        }
-    }
-
-    MDB_stat stat;
-    rc = mdb_stat(txn, dbi, &stat);
-    if (rc) {
-        mdb_txn_abort(txn);
-        throw Unknown(db->name, mdb_strerror(rc), name);
-    }
-    uint32_t amount = stat.ms_entries;
-
-    mdb_txn_commit(txn);
-    return amount;
-}
-
-template<class K, class V>
-void DataBase::Table<K, V>::removeRecord(const K& key) {
-    if (!db->opened) {
-        throw Closed("removeRecord", db->name, name);
-    }
-
-    MDB_val lmdbKey = keySerializer->setData(key);
-
-    MDB_txn *txn;
-    int rc;
-    mdb_txn_begin(db->environment, NULL, 0, &txn);
-    rc = mdb_del(txn, dbi, &lmdbKey, NULL);
-    if (rc) {
-        mdb_txn_abort(txn);
-        if (rc == MDB_NOTFOUND) {
-            throw NotFound(toString(key), db->name, name);
-        } else {
-            throw Unknown(db->name, mdb_strerror(rc), name);
-        }
-    } else {
-        mdb_txn_commit(txn);
-    }
-}
-
-template<class K, class V>
-int DataBase::Table<K, V>::createTable(MDB_txn* transaction) {
-    return makeTable<K>(transaction);
-}
-
-template<class K>
-inline int DataBase::_Table::makeTable(MDB_txn* transaction) {
-    return mdb_dbi_open(transaction, name.c_str(), MDB_CREATE, &dbi);
-}
-
-template<>
-inline int DataBase::_Table::makeTable<uint64_t>(MDB_txn* transaction) {
-    return mdb_dbi_open(transaction, name.c_str(), MDB_CREATE | MDB_INTEGERKEY, &dbi);
-}
-
-template<>
-inline int DataBase::_Table::makeTable<uint32_t>(MDB_txn* transaction) {
-    return mdb_dbi_open(transaction, name.c_str(), MDB_CREATE | MDB_INTEGERKEY, &dbi);
-}
-
-template<>
-inline int DataBase::_Table::makeTable<uint16_t>(MDB_txn* transaction) {
-    return mdb_dbi_open(transaction, name.c_str(), MDB_CREATE | MDB_INTEGERKEY, &dbi);
-}
-
-template<>
-inline int DataBase::_Table::makeTable<uint8_t>(MDB_txn* transaction) {
-    return mdb_dbi_open(transaction, name.c_str(), MDB_CREATE | MDB_INTEGERKEY, &dbi);
-}
-
-template<>
-inline int DataBase::_Table::makeTable<int64_t>(MDB_txn* transaction) {
-    return mdb_dbi_open(transaction, name.c_str(), MDB_CREATE | MDB_INTEGERKEY, &dbi);
-}
-
-template<>
-inline int DataBase::_Table::makeTable<int32_t>(MDB_txn* transaction) {
-    return mdb_dbi_open(transaction, name.c_str(), MDB_CREATE | MDB_INTEGERKEY, &dbi);
-}
-
-template<>
-inline int DataBase::_Table::makeTable<int16_t>(MDB_txn* transaction) {
-    return mdb_dbi_open(transaction, name.c_str(), MDB_CREATE | MDB_INTEGERKEY, &dbi);
-}
-
-template<>
-inline int DataBase::_Table::makeTable<int8_t>(MDB_txn* transaction) {
-    return mdb_dbi_open(transaction, name.c_str(), MDB_CREATE | MDB_INTEGERKEY, &dbi);
-}
-
-template<class T>
-inline std::string DataBase::_Table::toString(const T& value) {
-    return std::to_string(value);
-}
-
-template<>
-inline std::string DataBase::_Table::toString(const QString& value) {
-    return value.toStdString();
-}
-
-template<>
-inline std::string DataBase::_Table::toString(const std::string& value) {
-    return value;
-}
-
-#endif //CORE_TABLE_HPP
diff --git a/test/basic.cpp b/test/basic.cpp
index 2ee0262..cc92a5f 100644
--- a/test/basic.cpp
+++ b/test/basic.cpp
@@ -1,7 +1,7 @@
 #include <gtest/gtest.h>
 
 #include "database.h"
-#include "table.h"
+#include "storage.h"
 #include "cache.h"
 
 #include <QString>
@@ -18,7 +18,7 @@ protected:
 
     static void SetUpTestSuite() {
         if (db == nullptr) {
-            db = new DataBase("testBase");
+            db = new LMDBDataBase::DataBase("testBase");
             db->addTable<uint32_t, uint32_t>("table1");
             db->addTable<QString, QString>("table2");
             db->addCache<int8_t, std::string>("cache1");
@@ -32,15 +32,15 @@ protected:
         db = nullptr;
     }
 
-    static DataBase* db;
+    static LMDBDataBase::DataBase* db;
 
-    DataBase::Table<uint32_t, uint32_t>* t1;
-    DataBase::Table<QString, QString>* t2;
-    DataBase::Cache<int8_t, std::string>* c1;
+    LMDBDataBase::Storage<uint32_t, uint32_t>* t1;
+    LMDBDataBase::Storage<QString, QString>* t2;
+    LMDBDataBase::Cache<int8_t, std::string>* c1;
 };
 
 
-DataBase* DataBaseTest::db = nullptr;
+LMDBDataBase::DataBase* DataBaseTest::db = nullptr;
 
 TEST_F(DataBaseTest, RemovingDirectory) {
     EXPECT_EQ(db->removeDirectory(), true);
@@ -88,7 +88,7 @@ TEST_F(DataBaseTest, AddingRepeatingIntegerKey) {
     bool thrown = false;
     try {
         t1->addRecord(3, 24);
-    } catch (const DataBase::Exist e) {
+    } catch (const LMDBDataBase::Exist e) {
         thrown = true;
     }
     ASSERT_EQ(thrown, true) << "The expected behaviour is to throw exception on duplicate, but it didn't happened";
@@ -100,7 +100,7 @@ TEST_F(DataBaseTest, AddingRepeatingStringKey) {
     bool thrown = false;
     try {
         t2->addRecord("sdfhga", "world");
-    } catch (const DataBase::Exist e) {
+    } catch (const LMDBDataBase::Exist e) {
         thrown = true;
     }
     ASSERT_EQ(thrown, true) << "The expected behaviour is to throw exception on duplicate, but it didn't happened";
@@ -112,7 +112,7 @@ TEST_F(DataBaseTest, AddingRepeatingCacheKey) {
     bool thrown = false;
     try {
         c1->addRecord(-4, "world");
-    } catch (const DataBase::Exist e) {
+    } catch (const LMDBDataBase::Exist e) {
         thrown = true;
     }
     ASSERT_EQ(thrown, true) << "The expected behaviour is to throw exception on duplicate, but it didn't happened";
@@ -124,7 +124,7 @@ TEST_F(DataBaseTest, GettingNotExistingKeys) {
     bool thrown = false;
     try {
         QString wrong = t2->getRecord("almonds");
-    } catch (const DataBase::NotFound e) {
+    } catch (const LMDBDataBase::NotFound e) {
         thrown = true;
     }
     ASSERT_EQ(thrown, true) << "The expected behaviour is to throw exception on duplicate, but it didn't happened";
@@ -132,7 +132,7 @@ TEST_F(DataBaseTest, GettingNotExistingKeys) {
     thrown = false;
     try {
         uint32_t wrong = t1->getRecord(64);
-    } catch (const DataBase::NotFound e) {
+    } catch (const LMDBDataBase::NotFound e) {
         thrown = true;
     }
     ASSERT_EQ(thrown, true) << "The expected behaviour is to throw exception on duplicate, but it didn't happened";
@@ -140,7 +140,7 @@ TEST_F(DataBaseTest, GettingNotExistingKeys) {
     thrown = false;
     try {
         std::string wrong = c1->getRecord(21);
-    } catch (const DataBase::NotFound e) {
+    } catch (const LMDBDataBase::NotFound e) {
         thrown = true;
     }
     ASSERT_EQ(thrown, true) << "The expected behaviour is to throw exception on duplicate, but it didn't happened";
@@ -151,7 +151,7 @@ TEST_F(DataBaseTest, Persistence) {
     db->close();
     delete db;
 
-    db = new DataBase("testBase");
+    db = new LMDBDataBase::DataBase("testBase");
     t1 = db->addTable<uint32_t, uint32_t>("table1");
     t2 = db->addTable<QString, QString>("table2");
     c1 = db->addCache<int8_t, std::string>("cache1");
@@ -175,7 +175,7 @@ TEST_F(DataBaseTest, Persistence) {
     bool thrown = false;
     try {
         QString wrong = t2->getRecord("cats");
-    } catch (const DataBase::NotFound e) {
+    } catch (const LMDBDataBase::NotFound e) {
         thrown = true;
     }
     ASSERT_EQ(thrown, true) << "The expected behaviour is to throw exception on duplicate, but it didn't happened";
@@ -183,7 +183,7 @@ TEST_F(DataBaseTest, Persistence) {
     thrown = false;
     try {
         uint32_t wrong = t1->getRecord(7893);
-    } catch (const DataBase::NotFound e) {
+    } catch (const LMDBDataBase::NotFound e) {
         thrown = true;
     }
     ASSERT_EQ(thrown, true) << "The expected behaviour is to throw exception on duplicate, but it didn't happened";
@@ -191,7 +191,7 @@ TEST_F(DataBaseTest, Persistence) {
     thrown = false;
     try {
         std::string wrong = c1->getRecord(89);
-    } catch (const DataBase::NotFound e) {
+    } catch (const LMDBDataBase::NotFound e) {
         thrown = true;
     }
     ASSERT_EQ(thrown, true) << "The expected behaviour is to throw exception on duplicate, but it didn't happened";