diff --git a/dmp-backend/src/main/java/eu/eudat/dao/DatabaseAccess.java b/dmp-backend/src/main/java/eu/eudat/dao/DatabaseAccess.java
index e5f7aaa32..94d45316c 100644
--- a/dmp-backend/src/main/java/eu/eudat/dao/DatabaseAccess.java
+++ b/dmp-backend/src/main/java/eu/eudat/dao/DatabaseAccess.java
@@ -4,7 +4,7 @@ import eu.eudat.dao.databaselayer.service.DatabaseService;
 import eu.eudat.entities.DataEntity;
 
 
-public class DatabaseAccess<T extends DataEntity<T>> {
+public class DatabaseAccess<T extends DataEntity> {
     private DatabaseService<T> databaseService;
 
     public DatabaseService<T> getDatabaseService() {
diff --git a/dmp-backend/src/main/java/eu/eudat/dao/DatabaseAccessLayer.java b/dmp-backend/src/main/java/eu/eudat/dao/DatabaseAccessLayer.java
index 44f179f0e..f094ea6dc 100644
--- a/dmp-backend/src/main/java/eu/eudat/dao/DatabaseAccessLayer.java
+++ b/dmp-backend/src/main/java/eu/eudat/dao/DatabaseAccessLayer.java
@@ -4,7 +4,7 @@ package eu.eudat.dao;
 import eu.eudat.entities.DataEntity;
 import eu.eudat.queryable.QueryableList;
 
-public interface DatabaseAccessLayer<T extends DataEntity<T>, I> {
+public interface DatabaseAccessLayer<T extends DataEntity, I> {
     T createOrUpdate(T item);
 
     T find(I id);
diff --git a/dmp-backend/src/main/java/eu/eudat/dao/databaselayer/context/DatabaseContext.java b/dmp-backend/src/main/java/eu/eudat/dao/databaselayer/context/DatabaseContext.java
index a72ed4c77..6d1d4c820 100644
--- a/dmp-backend/src/main/java/eu/eudat/dao/databaselayer/context/DatabaseContext.java
+++ b/dmp-backend/src/main/java/eu/eudat/dao/databaselayer/context/DatabaseContext.java
@@ -13,7 +13,7 @@ import javax.persistence.PersistenceContext;
 
 
 @Repository("databaseCtx")
-public class DatabaseContext<T extends DataEntity<T>> {
+public class DatabaseContext<T extends DataEntity> {
 
     @PersistenceContext
     private EntityManager entityManager;
@@ -30,8 +30,8 @@ public class DatabaseContext<T extends DataEntity<T>> {
     @Transactional
     public T createOrUpdate(T item, Class<T> type) {
         EntityManager entityManager = this.entityManager;
-        if (item.getKeys()[0] != null) {
-            T oldItem = entityManager.find(type, item.getKeys()[0]);
+        if (item.getKeys() != null) {
+            T oldItem = entityManager.find(type, item.getKeys());
             if (oldItem != null) {
                 oldItem.update(item);
                 entityManager.merge(oldItem);
diff --git a/dmp-backend/src/main/java/eu/eudat/dao/databaselayer/service/DatabaseService.java b/dmp-backend/src/main/java/eu/eudat/dao/databaselayer/service/DatabaseService.java
index b452284c8..ac997dfaf 100644
--- a/dmp-backend/src/main/java/eu/eudat/dao/databaselayer/service/DatabaseService.java
+++ b/dmp-backend/src/main/java/eu/eudat/dao/databaselayer/service/DatabaseService.java
@@ -11,7 +11,7 @@ import java.util.Set;
 
 
 @Service("databaseService")
-public class DatabaseService<T extends DataEntity<T>> {
+public class DatabaseService<T extends DataEntity> {
 
     private DatabaseContext<T> databaseCtx;
 
diff --git a/dmp-backend/src/main/java/eu/eudat/dao/entities/DMPDao.java b/dmp-backend/src/main/java/eu/eudat/dao/entities/DMPDao.java
index a8077a286..cfb6c1025 100644
--- a/dmp-backend/src/main/java/eu/eudat/dao/entities/DMPDao.java
+++ b/dmp-backend/src/main/java/eu/eudat/dao/entities/DMPDao.java
@@ -17,5 +17,4 @@ public interface DMPDao extends DatabaseAccessLayer<DMP, UUID> {
 
     QueryableList<DMP> getAuthenticated(QueryableList<DMP> query, UserInfo principal);
 
-    Long count();
 }
\ No newline at end of file
diff --git a/dmp-backend/src/main/java/eu/eudat/dao/entities/DMPDaoImpl.java b/dmp-backend/src/main/java/eu/eudat/dao/entities/DMPDaoImpl.java
index 959ed94ba..8f208abf1 100644
--- a/dmp-backend/src/main/java/eu/eudat/dao/entities/DMPDaoImpl.java
+++ b/dmp-backend/src/main/java/eu/eudat/dao/entities/DMPDaoImpl.java
@@ -77,8 +77,4 @@ public class DMPDaoImpl extends DatabaseAccess<DMP> implements DMPDao {
         return this.getDatabaseService().getQueryable(DMP.class);
     }
 
-    @Override
-    public Long count() {
-        return this.getDatabaseService().count(DMP.class);
-    }
 }
diff --git a/dmp-backend/src/main/java/eu/eudat/dao/entities/DatasetDao.java b/dmp-backend/src/main/java/eu/eudat/dao/entities/DatasetDao.java
index f6ff6cb24..5cb766447 100644
--- a/dmp-backend/src/main/java/eu/eudat/dao/entities/DatasetDao.java
+++ b/dmp-backend/src/main/java/eu/eudat/dao/entities/DatasetDao.java
@@ -19,5 +19,4 @@ public interface DatasetDao extends DatabaseAccessLayer<Dataset, UUID> {
 
     Dataset find(UUID id, String hint);
 
-    Long count();
 }
\ No newline at end of file
diff --git a/dmp-backend/src/main/java/eu/eudat/dao/entities/DatasetDaoImpl.java b/dmp-backend/src/main/java/eu/eudat/dao/entities/DatasetDaoImpl.java
index ca1c87710..a15177d98 100644
--- a/dmp-backend/src/main/java/eu/eudat/dao/entities/DatasetDaoImpl.java
+++ b/dmp-backend/src/main/java/eu/eudat/dao/entities/DatasetDaoImpl.java
@@ -61,11 +61,6 @@ public class DatasetDaoImpl extends DatabaseAccess<Dataset> implements DatasetDa
         return query;
     }
 
-    @Override
-    public Long count() {
-        return this.getDatabaseService().count(Dataset.class);
-    }
-
     @Override
     public void delete(Dataset item) {
         this.getDatabaseService().delete(item);
diff --git a/dmp-backend/src/main/java/eu/eudat/dao/entities/ProjectDao.java b/dmp-backend/src/main/java/eu/eudat/dao/entities/ProjectDao.java
index 6683ce2f0..0a2f9b6ac 100644
--- a/dmp-backend/src/main/java/eu/eudat/dao/entities/ProjectDao.java
+++ b/dmp-backend/src/main/java/eu/eudat/dao/entities/ProjectDao.java
@@ -14,5 +14,4 @@ public interface ProjectDao extends DatabaseAccessLayer<Project, UUID> {
 
     QueryableList<Project> getAuthenticated(QueryableList<Project> query, UserInfo principal);
 
-    Long count();
 }
\ No newline at end of file
diff --git a/dmp-backend/src/main/java/eu/eudat/dao/entities/ProjectDaoImpl.java b/dmp-backend/src/main/java/eu/eudat/dao/entities/ProjectDaoImpl.java
index 6c208ef10..74e64f236 100644
--- a/dmp-backend/src/main/java/eu/eudat/dao/entities/ProjectDaoImpl.java
+++ b/dmp-backend/src/main/java/eu/eudat/dao/entities/ProjectDaoImpl.java
@@ -44,11 +44,6 @@ public class ProjectDaoImpl extends DatabaseAccess<Project> implements ProjectDa
         return getDatabaseService().getQueryable(Project.class).where((builder, root) -> builder.equal((root.get("id")), id)).getSingle();
     }
 
-    @Override
-    public Long count() {
-        return this.getDatabaseService().count(Project.class);
-    }
-
     @Override
     public void delete(Project item) {
         this.getDatabaseService().delete(item);
diff --git a/dmp-backend/src/main/java/eu/eudat/entities/Credential.java b/dmp-backend/src/main/java/eu/eudat/entities/Credential.java
index ef22f8dba..254ce8188 100644
--- a/dmp-backend/src/main/java/eu/eudat/entities/Credential.java
+++ b/dmp-backend/src/main/java/eu/eudat/entities/Credential.java
@@ -7,7 +7,7 @@ import java.util.UUID;
 
 @Entity
 @Table(name = "\"Credential\"")
-public class Credential implements DataEntity<Credential> {
+public class Credential implements DataEntity<Credential,UUID> {
 
     @Id
     @Column(name = "\"Id\"", updatable = false, nullable = false, columnDefinition = "BINARY(16)")
@@ -119,7 +119,7 @@ public class Credential implements DataEntity<Credential> {
     }
 
     @Override
-    public Object[] getKeys() {
-        return new UUID[]{this.id == null ? null : this.id};
+    public UUID getKeys() {
+        return this.id;
     }
 }
diff --git a/dmp-backend/src/main/java/eu/eudat/entities/DMP.java b/dmp-backend/src/main/java/eu/eudat/entities/DMP.java
index 29e8da2c3..146031b16 100644
--- a/dmp-backend/src/main/java/eu/eudat/entities/DMP.java
+++ b/dmp-backend/src/main/java/eu/eudat/entities/DMP.java
@@ -23,7 +23,7 @@ import java.util.*;
                         @NamedAttributeNode("project"), @NamedAttributeNode("profile"),
                         @NamedAttributeNode("users"), @NamedAttributeNode("organisations"), @NamedAttributeNode("researchers")})
 })
-public class DMP implements Serializable, DataEntity<DMP> {
+public class DMP implements DataEntity<DMP,UUID> {
 
     public enum DMPStatus {
         ACTIVE((short) 0), DELETED((short) 1);
@@ -286,8 +286,8 @@ public class DMP implements Serializable, DataEntity<DMP> {
     }
 
     @Override
-    public Object[] getKeys() {
-        return new UUID[]{this.id == null ? null : this.id};
+    public UUID getKeys() {
+        return this.id;
     }
 
 }
diff --git a/dmp-backend/src/main/java/eu/eudat/entities/DMPOrganisation.java b/dmp-backend/src/main/java/eu/eudat/entities/DMPOrganisation.java
index 2ee1288c9..e3fee9f24 100644
--- a/dmp-backend/src/main/java/eu/eudat/entities/DMPOrganisation.java
+++ b/dmp-backend/src/main/java/eu/eudat/entities/DMPOrganisation.java
@@ -10,7 +10,7 @@ import java.util.UUID;
 
 @Entity
 @Table(name = "\"DMPOrganisation\"")
-public class DMPOrganisation implements Serializable {
+public class DMPOrganisation {
 
     @Id
     @GeneratedValue
diff --git a/dmp-backend/src/main/java/eu/eudat/entities/DataEntity.java b/dmp-backend/src/main/java/eu/eudat/entities/DataEntity.java
index 1be39124a..6ebe0080e 100644
--- a/dmp-backend/src/main/java/eu/eudat/entities/DataEntity.java
+++ b/dmp-backend/src/main/java/eu/eudat/entities/DataEntity.java
@@ -1,7 +1,7 @@
 package eu.eudat.entities;
 
-public interface DataEntity<T> {
+public interface DataEntity<T,K> {
     void update(T entity);
 
-    Object[] getKeys();
+    K getKeys();
 }
diff --git a/dmp-backend/src/main/java/eu/eudat/entities/DataRepository.java b/dmp-backend/src/main/java/eu/eudat/entities/DataRepository.java
index 52c5247c8..6407186b6 100644
--- a/dmp-backend/src/main/java/eu/eudat/entities/DataRepository.java
+++ b/dmp-backend/src/main/java/eu/eudat/entities/DataRepository.java
@@ -12,7 +12,7 @@ import java.util.UUID;
 
 @Entity
 @Table(name = "\"DataRepository\"")
-public class DataRepository implements Serializable, DataEntity<DataRepository> {
+public class DataRepository implements Serializable, DataEntity<DataRepository,UUID> {
 
     @Id
     @GeneratedValue
@@ -147,7 +147,7 @@ public class DataRepository implements Serializable, DataEntity<DataRepository>
     }
 
     @Override
-    public Object[] getKeys() {
-        return new UUID[]{this.id == null ? null : this.id};
+    public UUID getKeys() {
+        return this.id;
     }
 }
diff --git a/dmp-backend/src/main/java/eu/eudat/entities/Dataset.java b/dmp-backend/src/main/java/eu/eudat/entities/Dataset.java
index d8cae40c0..00648db49 100644
--- a/dmp-backend/src/main/java/eu/eudat/entities/Dataset.java
+++ b/dmp-backend/src/main/java/eu/eudat/entities/Dataset.java
@@ -20,7 +20,7 @@ import java.util.*;
                 attributeNodes = {@NamedAttributeNode("services"), @NamedAttributeNode("dataRepositories"), @NamedAttributeNode("externalDatasets"), @NamedAttributeNode("registries"),
                         @NamedAttributeNode("dmp"), @NamedAttributeNode("profile"), @NamedAttributeNode("creator")})
 })
-public class Dataset implements DataEntity<Dataset> {
+public class Dataset implements DataEntity<Dataset,UUID> {
 
     public static Set<String> getHints() {
         return hints;
@@ -313,7 +313,7 @@ public class Dataset implements DataEntity<Dataset> {
     }
 
     @Override
-    public Object[] getKeys() {
-        return new UUID[]{this.id == null ? null : this.id};
+    public UUID getKeys() {
+        return this.id;
     }
 }
diff --git a/dmp-backend/src/main/java/eu/eudat/entities/DatasetProfile.java b/dmp-backend/src/main/java/eu/eudat/entities/DatasetProfile.java
index bdb5c79d4..4ecafda14 100644
--- a/dmp-backend/src/main/java/eu/eudat/entities/DatasetProfile.java
+++ b/dmp-backend/src/main/java/eu/eudat/entities/DatasetProfile.java
@@ -13,7 +13,7 @@ import java.util.UUID;
 
 @Entity
 @Table(name = "\"DatasetProfile\"")
-public class DatasetProfile implements Serializable, DataEntity<DatasetProfile> {
+public class DatasetProfile implements DataEntity<DatasetProfile,UUID> {
 
     @Id
     @GeneratedValue
@@ -132,7 +132,7 @@ public class DatasetProfile implements Serializable, DataEntity<DatasetProfile>
     }
 
     @Override
-    public Object[] getKeys() {
-        return new UUID[]{this.id == null ? null : this.id};
+    public UUID getKeys() {
+        return this.id;
     }
 }
diff --git a/dmp-backend/src/main/java/eu/eudat/entities/DatasetProfileRuleset.java b/dmp-backend/src/main/java/eu/eudat/entities/DatasetProfileRuleset.java
index 42fd02b92..223c86411 100644
--- a/dmp-backend/src/main/java/eu/eudat/entities/DatasetProfileRuleset.java
+++ b/dmp-backend/src/main/java/eu/eudat/entities/DatasetProfileRuleset.java
@@ -11,7 +11,7 @@ import java.util.UUID;
 
 @Entity
 @Table(name = "\"DatasetProfileRuleset\"")
-public class DatasetProfileRuleset implements Serializable {
+public class DatasetProfileRuleset {
 
     @Id
     @GeneratedValue
diff --git a/dmp-backend/src/main/java/eu/eudat/entities/DatasetRegistry.java b/dmp-backend/src/main/java/eu/eudat/entities/DatasetRegistry.java
index 9628ac2d0..a223c8a2f 100644
--- a/dmp-backend/src/main/java/eu/eudat/entities/DatasetRegistry.java
+++ b/dmp-backend/src/main/java/eu/eudat/entities/DatasetRegistry.java
@@ -11,7 +11,7 @@ import java.util.UUID;
 
 @Entity
 @Table(name = "\"DatasetRegistry\"")
-public class DatasetRegistry implements Serializable {
+public class DatasetRegistry {
 
     @Id
     @GeneratedValue
diff --git a/dmp-backend/src/main/java/eu/eudat/entities/DatasetService.java b/dmp-backend/src/main/java/eu/eudat/entities/DatasetService.java
index 872abb822..259589db2 100644
--- a/dmp-backend/src/main/java/eu/eudat/entities/DatasetService.java
+++ b/dmp-backend/src/main/java/eu/eudat/entities/DatasetService.java
@@ -11,7 +11,7 @@ import java.util.UUID;
 
 @Entity
 @Table(name = "\"DatasetService\"")
-public class DatasetService implements Serializable {
+public class DatasetService {
 
     @Id
     @GeneratedValue
diff --git a/dmp-backend/src/main/java/eu/eudat/entities/ExternalDataset.java b/dmp-backend/src/main/java/eu/eudat/entities/ExternalDataset.java
index 334c07c22..ebe7e438e 100644
--- a/dmp-backend/src/main/java/eu/eudat/entities/ExternalDataset.java
+++ b/dmp-backend/src/main/java/eu/eudat/entities/ExternalDataset.java
@@ -10,7 +10,7 @@ import java.util.UUID;
 
 @Entity
 @Table(name = "\"ExternalDataset\"")
-public class ExternalDataset implements DataEntity<ExternalDataset> {
+public class ExternalDataset implements DataEntity<ExternalDataset,UUID> {
 
     @Id
     @GeneratedValue
@@ -104,7 +104,7 @@ public class ExternalDataset implements DataEntity<ExternalDataset> {
     }
 
     @Override
-    public Object[] getKeys() {
-        return new UUID[]{this.id == null ? null : this.id};
+    public UUID getKeys() {
+        return this.id;
     }
 }
diff --git a/dmp-backend/src/main/java/eu/eudat/entities/Invitation.java b/dmp-backend/src/main/java/eu/eudat/entities/Invitation.java
index 57764e202..04503cca6 100644
--- a/dmp-backend/src/main/java/eu/eudat/entities/Invitation.java
+++ b/dmp-backend/src/main/java/eu/eudat/entities/Invitation.java
@@ -9,7 +9,7 @@ import java.util.UUID;
 
 @Entity
 @Table(name = "\"Invitation\"")
-public class Invitation implements DataEntity<Invitation> {
+public class Invitation implements DataEntity<Invitation,UUID> {
 
     @Id
     @GeneratedValue
@@ -100,7 +100,7 @@ public class Invitation implements DataEntity<Invitation> {
     }
 
     @Override
-    public Object[] getKeys() {
-        return new UUID[]{this.id == null ? null : this.id};
+    public UUID getKeys() {
+        return this.id;
     }
 }
diff --git a/dmp-backend/src/main/java/eu/eudat/entities/Organisation.java b/dmp-backend/src/main/java/eu/eudat/entities/Organisation.java
index 910005dc5..7916166f8 100644
--- a/dmp-backend/src/main/java/eu/eudat/entities/Organisation.java
+++ b/dmp-backend/src/main/java/eu/eudat/entities/Organisation.java
@@ -13,7 +13,7 @@ import java.util.UUID;
 
 @Entity
 @Table(name = "\"Organisation\"")
-public class Organisation implements Serializable, DataEntity<Organisation> {
+public class Organisation implements Serializable, DataEntity<Organisation,UUID> {
 
     @Id
     @GeneratedValue
@@ -151,7 +151,7 @@ public class Organisation implements Serializable, DataEntity<Organisation> {
     }
 
     @Override
-    public Object[] getKeys() {
-        return new UUID[]{this.id == null ? null : this.id};
+    public UUID getKeys() {
+        return this.id;
     }
 }
diff --git a/dmp-backend/src/main/java/eu/eudat/entities/Project.java b/dmp-backend/src/main/java/eu/eudat/entities/Project.java
index 1d9c0fd18..de8bd0a42 100644
--- a/dmp-backend/src/main/java/eu/eudat/entities/Project.java
+++ b/dmp-backend/src/main/java/eu/eudat/entities/Project.java
@@ -15,7 +15,7 @@ import java.util.UUID;
 
 @Entity
 @Table(name = "\"Project\"")
-public class Project implements DataEntity<Project> {
+public class Project implements DataEntity<Project,UUID> {
 
     public enum Status {
         ACTIVE((short) 1), INACTIVE((short) 0), DELETED((short) 99);
@@ -248,7 +248,7 @@ public class Project implements DataEntity<Project> {
     }
 
     @Override
-    public Object[] getKeys() {
-        return new UUID[]{this.id == null ? null : this.id};
+    public UUID getKeys() {
+        return this.id;
     }
 }
diff --git a/dmp-backend/src/main/java/eu/eudat/entities/Registry.java b/dmp-backend/src/main/java/eu/eudat/entities/Registry.java
index 57a1a882b..80e601592 100644
--- a/dmp-backend/src/main/java/eu/eudat/entities/Registry.java
+++ b/dmp-backend/src/main/java/eu/eudat/entities/Registry.java
@@ -12,7 +12,7 @@ import java.util.UUID;
 
 @Entity
 @Table(name = "\"Registry\"")
-public class Registry implements DataEntity<Registry> {
+public class Registry implements DataEntity<Registry,UUID> {
 
 
     @Id
@@ -149,7 +149,7 @@ public class Registry implements DataEntity<Registry> {
     }
 
     @Override
-    public Object[] getKeys() {
-        return new UUID[]{this.id == null ? null : this.id};
+    public UUID getKeys() {
+        return this.id;
     }
 }
diff --git a/dmp-backend/src/main/java/eu/eudat/entities/Researcher.java b/dmp-backend/src/main/java/eu/eudat/entities/Researcher.java
index de296f2f9..f37a4a5b8 100644
--- a/dmp-backend/src/main/java/eu/eudat/entities/Researcher.java
+++ b/dmp-backend/src/main/java/eu/eudat/entities/Researcher.java
@@ -12,7 +12,7 @@ import java.util.UUID;
 
 @Entity
 @Table(name = "\"Researcher\"")
-public class Researcher implements DataEntity<Researcher> {
+public class Researcher implements DataEntity<Researcher,UUID> {
 
     @Id
     @GeneratedValue
@@ -150,7 +150,7 @@ public class Researcher implements DataEntity<Researcher> {
     }
 
     @Override
-    public Object[] getKeys() {
-        return new UUID[]{this.id == null ? null : this.id};
+    public UUID getKeys() {
+        return this.id;
     }
 }
diff --git a/dmp-backend/src/main/java/eu/eudat/entities/Service.java b/dmp-backend/src/main/java/eu/eudat/entities/Service.java
index 3a8f16ff1..0c03a245e 100644
--- a/dmp-backend/src/main/java/eu/eudat/entities/Service.java
+++ b/dmp-backend/src/main/java/eu/eudat/entities/Service.java
@@ -12,7 +12,7 @@ import java.util.UUID;
 
 @Entity
 @Table(name = "\"Service\"")
-public class Service implements DataEntity<Service> {
+public class Service implements DataEntity<Service, UUID> {
 
     @Id
     @GeneratedValue
@@ -150,7 +150,7 @@ public class Service implements DataEntity<Service> {
     }
 
     @Override
-    public Object[] getKeys() {
-        return new UUID[]{this.id == null ? null : this.id};
+    public UUID getKeys() {
+        return this.id;
     }
 }
diff --git a/dmp-backend/src/main/java/eu/eudat/entities/UserDMP.java b/dmp-backend/src/main/java/eu/eudat/entities/UserDMP.java
index ab145e910..a2235a940 100644
--- a/dmp-backend/src/main/java/eu/eudat/entities/UserDMP.java
+++ b/dmp-backend/src/main/java/eu/eudat/entities/UserDMP.java
@@ -7,7 +7,7 @@ import java.util.UUID;
 
 @Entity
 @Table(name = "\"UserDMP\"")
-public class UserDMP implements DataEntity<UserDMP> {
+public class UserDMP implements DataEntity<UserDMP, UUID> {
 
     public enum UserDMPRoles {
         OWNER(0), USER(1);
@@ -90,7 +90,7 @@ public class UserDMP implements DataEntity<UserDMP> {
     }
 
     @Override
-    public Object[] getKeys() {
-        return new UUID[]{this.id == null ? null : this.id};
+    public UUID getKeys() {
+        return this.id;
     }
 }
diff --git a/dmp-backend/src/main/java/eu/eudat/entities/UserInfo.java b/dmp-backend/src/main/java/eu/eudat/entities/UserInfo.java
index 58e2ddfbc..07d98095f 100644
--- a/dmp-backend/src/main/java/eu/eudat/entities/UserInfo.java
+++ b/dmp-backend/src/main/java/eu/eudat/entities/UserInfo.java
@@ -17,7 +17,7 @@ import java.util.UUID;
                 name = "userInfo",
                 attributeNodes = {@NamedAttributeNode("userRoles"), @NamedAttributeNode("credentials")})
 })
-public class UserInfo implements DataEntity<UserInfo> {
+public class UserInfo implements DataEntity<UserInfo, UUID> {
 
     @Id
     @GeneratedValue
@@ -173,7 +173,7 @@ public class UserInfo implements DataEntity<UserInfo> {
     }
 
     @Override
-    public Object[] getKeys() {
-        return new UUID[]{this.id == null ? null : this.id};
+    public UUID getKeys() {
+        return this.id;
     }
 }
diff --git a/dmp-backend/src/main/java/eu/eudat/entities/UserRole.java b/dmp-backend/src/main/java/eu/eudat/entities/UserRole.java
index f63e8d4e6..0f0f76668 100644
--- a/dmp-backend/src/main/java/eu/eudat/entities/UserRole.java
+++ b/dmp-backend/src/main/java/eu/eudat/entities/UserRole.java
@@ -8,7 +8,7 @@ import java.util.UUID;
 
 @Entity
 @Table(name = "\"UserRole\"")
-public class UserRole implements DataEntity<UserRole> {
+public class UserRole implements DataEntity<UserRole, UUID> {
 
     @Id
     @GeneratedValue
@@ -53,7 +53,7 @@ public class UserRole implements DataEntity<UserRole> {
     }
 
     @Override
-    public Object[] getKeys() {
-        return new UUID[]{this.id == null ? null : this.id};
+    public UUID getKeys() {
+        return this.id;
     }
 }
diff --git a/dmp-backend/src/main/java/eu/eudat/entities/UserToken.java b/dmp-backend/src/main/java/eu/eudat/entities/UserToken.java
index d53b68d3a..940812b84 100644
--- a/dmp-backend/src/main/java/eu/eudat/entities/UserToken.java
+++ b/dmp-backend/src/main/java/eu/eudat/entities/UserToken.java
@@ -7,7 +7,7 @@ import java.util.UUID;
 
 @Entity
 @Table(name = "\"UserToken\"")
-public class UserToken implements DataEntity<UserToken> {
+public class UserToken implements DataEntity<UserToken, UUID> {
 
     @Id
     @Column(name = "\"Token\"", updatable = false, nullable = false, columnDefinition = "BINARY(16)")
@@ -62,7 +62,7 @@ public class UserToken implements DataEntity<UserToken> {
     }
 
     @Override
-    public Object[] getKeys() {
-        return new UUID[]{this.token == null ? null : this.token};
+    public UUID getKeys() {
+        return this.token;
     }
 }
diff --git a/dmp-backend/src/main/java/eu/eudat/managers/DashBoardManager.java b/dmp-backend/src/main/java/eu/eudat/managers/DashBoardManager.java
index 12f9b865c..a109c12b4 100644
--- a/dmp-backend/src/main/java/eu/eudat/managers/DashBoardManager.java
+++ b/dmp-backend/src/main/java/eu/eudat/managers/DashBoardManager.java
@@ -11,9 +11,9 @@ public class DashBoardManager {
 
     public DashBoardStatistics getStatistics(DatasetDao datasetRepository, DMPDao dataManagementPlanRepository, ProjectDao projectRepository) {
         DashBoardStatistics statistics = new DashBoardStatistics();
-        statistics.setTotalDataManagementPlanCount(dataManagementPlanRepository.count());
-        statistics.setTotalDataSetCount(datasetRepository.count());
-        statistics.setTotalProjectCount(projectRepository.count());
+        statistics.setTotalDataManagementPlanCount(dataManagementPlanRepository.asQueryable().count());
+        statistics.setTotalDataSetCount(datasetRepository.asQueryable().count());
+        statistics.setTotalProjectCount(projectRepository.asQueryable().count());
         return statistics;
     }
 
diff --git a/dmp-backend/src/main/java/eu/eudat/managers/PaginationManager.java b/dmp-backend/src/main/java/eu/eudat/managers/PaginationManager.java
index d4dad79f7..6473fc8b9 100644
--- a/dmp-backend/src/main/java/eu/eudat/managers/PaginationManager.java
+++ b/dmp-backend/src/main/java/eu/eudat/managers/PaginationManager.java
@@ -10,14 +10,14 @@ import java.util.Collection;
 
 public class PaginationManager {
 
-    public static <T extends DataEntity<T>> QueryableList<T> applyPaging(QueryableList<T> items, TableRequest tableRequest) throws Exception {
+    public static <T extends DataEntity> QueryableList<T> applyPaging(QueryableList<T> items, TableRequest tableRequest) throws Exception {
         if (tableRequest.getOrderings() != null) applyOrder(items, tableRequest);
         if (tableRequest.getLength() != null) items.take(tableRequest.getLength());
         if (tableRequest.getOffset() != null) items.skip(tableRequest.getOffset());
         return items;
     }
 
-    public static <T extends DataEntity<T>> void applyOrder(QueryableList<T> items, TableRequest tableRequest) throws Exception {
+    public static <T extends DataEntity> void applyOrder(QueryableList<T> items, TableRequest tableRequest) throws Exception {
         ColumnOrderings columnOrderings = tableRequest.getOrderings();
         for (Ordering ordering : columnOrderings.getFieldOrderings()) {
             if (ordering.getOrderByType() == Ordering.OrderByType.ASC)
@@ -29,7 +29,7 @@ public class PaginationManager {
         return;
     }
 
-    private static <T extends DataEntity<T>> void applyAscOrder(QueryableList<T> items, Ordering ordering) {
+    private static <T extends DataEntity> void applyAscOrder(QueryableList<T> items, Ordering ordering) {
         if (ordering.getColumnType() == Ordering.ColumnType.COUNT) {
             items.orderBy((builder, root) -> builder.asc(builder.size(root.<Collection>get(ordering.getFieldName()))));
         } else if (ordering.getColumnType() == Ordering.ColumnType.JOIN_COLUMN) {
@@ -40,7 +40,7 @@ public class PaginationManager {
         }
     }
 
-    private static <T extends DataEntity<T>> void applyDescOrder(QueryableList<T> items, Ordering ordering) {
+    private static <T extends DataEntity> void applyDescOrder(QueryableList<T> items, Ordering ordering) {
         if (ordering.getColumnType() == Ordering.ColumnType.COUNT) {
             items.orderBy((builder, root) -> builder.desc(builder.size(root.<Collection>get(ordering.getFieldName()))));
         } else if (ordering.getColumnType() == Ordering.ColumnType.JOIN_COLUMN) {
diff --git a/dmp-backend/src/main/java/eu/eudat/queryable/QueryableList.java b/dmp-backend/src/main/java/eu/eudat/queryable/QueryableList.java
index e208cccf6..054c6ad6b 100644
--- a/dmp-backend/src/main/java/eu/eudat/queryable/QueryableList.java
+++ b/dmp-backend/src/main/java/eu/eudat/queryable/QueryableList.java
@@ -13,7 +13,7 @@ import java.util.List;
 import java.util.Set;
 import java.util.concurrent.CompletableFuture;
 
-public interface QueryableList<T extends DataEntity<T>> {
+public interface QueryableList<T extends DataEntity> {
     QueryableList<T> where(SinglePredicate<T> predicate);
 
     <R> List<R> select(SelectPredicate<T, R> predicate);
diff --git a/dmp-backend/src/main/java/eu/eudat/queryable/hibernatequeryablelist/QueryableHibernateList.java b/dmp-backend/src/main/java/eu/eudat/queryable/hibernatequeryablelist/QueryableHibernateList.java
index f68a60f2e..c09a986a8 100644
--- a/dmp-backend/src/main/java/eu/eudat/queryable/hibernatequeryablelist/QueryableHibernateList.java
+++ b/dmp-backend/src/main/java/eu/eudat/queryable/hibernatequeryablelist/QueryableHibernateList.java
@@ -21,12 +21,12 @@ import java.util.Set;
 import java.util.concurrent.CompletableFuture;
 import java.util.stream.Collectors;
 
-public class QueryableHibernateList<T extends DataEntity<T>> implements QueryableList<T> {
+public class QueryableHibernateList<T extends DataEntity> implements QueryableList<T> {
 
     private EntityManager manager;
-    private CriteriaQuery<T> query;
+    private CriteriaQuery query;
     private Class<T> tClass;
-    private Root<T> root;
+    private Root root;
     private Root<T> nestedQueryRoot;
     private Subquery<T> subquery;
     private List<SinglePredicate<T>> singlePredicates = new LinkedList<>();
@@ -61,7 +61,7 @@ public class QueryableHibernateList<T extends DataEntity<T>> implements Queryabl
 
     public QueryableHibernateList<T> setEntity(Class<T> type) {
         CriteriaBuilder builder = this.manager.getCriteriaBuilder();
-        this.query = builder.createQuery(type);
+        this.query = builder.createTupleQuery();
         this.root = this.query.from(this.tClass);
         return this;
     }
@@ -170,7 +170,7 @@ public class QueryableHibernateList<T extends DataEntity<T>> implements Queryabl
         if (this.offset != null) typedQuery.setFirstResult(this.offset);
         if (this.length != null) typedQuery.setMaxResults(this.length);
         if (this.hint != null && this.hints.contains(hint)) {
-            List ids = typedQuery.getResultList().stream().map(item -> item.getKeys()[0]).collect(Collectors.toList());
+            List ids = typedQuery.getResultList().stream().map(item -> item.getKeys()).collect(Collectors.toList());
             if (ids != null && !ids.isEmpty()) typedQuery = queryWithHint(ids);
         }
         return typedQuery.getResultList();
@@ -184,7 +184,7 @@ public class QueryableHibernateList<T extends DataEntity<T>> implements Queryabl
         if (this.length != null) typedQuery.setMaxResults(this.length);
         return CompletableFuture.supplyAsync(() -> {
             if (this.hint != null && this.hints.contains(hint)) {
-                List ids = typedQuery.getResultList().stream().map(item -> item.getKeys()[0]).collect(Collectors.toList());
+                List ids = typedQuery.getResultList().stream().map(item -> item.getKeys()).collect(Collectors.toList());
                 if (ids != null && !ids.isEmpty()) return queryWithHint(ids).getResultList();
             }
             return typedQuery.getResultList();
@@ -236,7 +236,6 @@ public class QueryableHibernateList<T extends DataEntity<T>> implements Queryabl
         CriteriaBuilder criteriaBuilder = this.manager.getCriteriaBuilder();
         CriteriaQuery<T> criteriaQuery = criteriaBuilder.createQuery(tClass);
         Root<T> criteriaRoot = criteriaQuery.from(this.tClass);
-
         criteriaQuery.where(criteriaRoot.get("id").in(ids));
         if (!this.orderings.isEmpty())
             criteriaQuery.orderBy(this.generateOrderPredicates(this.orderings, criteriaRoot));