diff --git a/mayan/apps/documents/managers.py b/mayan/apps/documents/managers.py
index a783670af0..d6d3dc7946 100644
--- a/mayan/apps/documents/managers.py
+++ b/mayan/apps/documents/managers.py
@@ -20,7 +20,7 @@ class DocumentManager(models.Manager):
             stale_stub_document.delete(trash=False)
 
     def get_by_natural_key(self, uuid):
-        return self.get(uuid=uuid)
+        return self.model.passthrough.get(uuid=uuid)
 
     def get_queryset(self):
         return TrashCanQuerySet(
@@ -32,6 +32,19 @@ class DocumentManager(models.Manager):
             document.invalidate_cache()
 
 
+class DocumentVersionManager(models.Manager):
+    def get_by_natural_key(self, checksum, document_natural_key):
+        Document = apps.get_model(
+            app_label='documents', model_name='Document'
+        )
+        try:
+            document = Document.objects.get_by_natural_key(document_natural_key)
+        except Document.DoesNotExist:
+            raise self.model.DoesNotExist
+
+        return document.versions.get(checksum=checksum)
+
+
 class DocumentTypeManager(models.Manager):
     def check_delete_periods(self):
         logger.info('Executing')
diff --git a/mayan/apps/documents/models.py b/mayan/apps/documents/models.py
index afdaeb4e06..f98afd2b5f 100644
--- a/mayan/apps/documents/models.py
+++ b/mayan/apps/documents/models.py
@@ -33,8 +33,9 @@ from .events import (
 )
 from .literals import DEFAULT_DELETE_PERIOD, DEFAULT_DELETE_TIME_UNIT
 from .managers import (
-    DocumentManager, DocumentTypeManager, DuplicatedDocumentManager,
-    PassthroughManager, RecentDocumentManager, TrashCanManager
+    DocumentManager, DocumentVersionManager, DocumentTypeManager,
+    DuplicatedDocumentManager, PassthroughManager, RecentDocumentManager,
+    TrashCanManager
 )
 from .permissions import permission_document_view
 from .settings import (
@@ -415,6 +416,8 @@ class DocumentVersion(models.Model):
         verbose_name = _('Document version')
         verbose_name_plural = _('Document version')
 
+    objects = DocumentVersionManager()
+
     def __str__(self):
         return self.get_rendered_string()
 
@@ -505,6 +508,10 @@ class DocumentVersion(models.Model):
             context=Context({'instance': self})
         )
 
+    def natural_key(self):
+        return (self.checksum,) + self.document.natural_key()
+    natural_key.dependencies = ['documents.Document']
+
     def invalidate_cache(self):
         storage_documentimagecache.delete(self.cache_filename)
         for page in self.pages.all():
diff --git a/mayan/apps/metadata/managers.py b/mayan/apps/metadata/managers.py
index 68775323ab..2a07fc459a 100644
--- a/mayan/apps/metadata/managers.py
+++ b/mayan/apps/metadata/managers.py
@@ -24,6 +24,17 @@ class MetadataTypeManager(models.Manager):
 
 
 class DocumentTypeMetadataTypeManager(models.Manager):
+    def get_by_natural_key(self, metadata_type_name, document_natural_key):
+        Document = apps.get_model(
+            app_label='documents', model_name='Document'
+        )
+        try:
+            document = Document.objects.get_by_natural_key(document_natural_key)
+        except Document.DoesNotExist:
+            raise self.model.DoesNotExist
+
+        return document.metadata.get(metadata_type_name=metadata_type_name)
+
     def get_metadata_types_for(self, document_type):
         DocumentType = apps.get_model(
             app_label='metadata', model_name='MetadataType'
diff --git a/mayan/apps/metadata/models.py b/mayan/apps/metadata/models.py
index b7e5a21503..89d312d1b0 100644
--- a/mayan/apps/metadata/models.py
+++ b/mayan/apps/metadata/models.py
@@ -111,7 +111,7 @@ class MetadataType(models.Model):
         ).exists()
 
     def natural_key(self):
-        return (self.name,)
+        return self.name
 
     def validate_value(self, document_type, value):
         # Check default
@@ -189,6 +189,10 @@ class DocumentMetadata(models.Model):
 
         return super(DocumentMetadata, self).delete(*args, **kwargs)
 
+    def natural_key(self):
+        return (self.metadata_type.name,) + self.document.natural_key()
+    natural_key.dependencies = ['documents.Document', 'metadata.MetadataType']
+
     @property
     def is_required(self):
         return self.metadata_type.get_required_for(
diff --git a/mayan/apps/ocr/managers.py b/mayan/apps/ocr/managers.py
index fb547a3648..20de7b30b6 100644
--- a/mayan/apps/ocr/managers.py
+++ b/mayan/apps/ocr/managers.py
@@ -90,3 +90,16 @@ class DocumentPageOCRContentManager(models.Manager):
             post_document_version_ocr.send(
                 sender=document_version.__class__, instance=document_version
             )
+
+
+class DocumentTypeSettingsManager(models.Manager):
+    def get_by_natural_key(self, document_type_natural_key):
+        DocumentType = apps.get_model(
+            app_label='documents', model_name='DocumentType'
+        )
+        try:
+            document_type = DocumentType.objects.get_by_natural_key(document_type_natural_key)
+        except DocumentType.DoesNotExist:
+            raise self.model.DoesNotExist
+
+        return document_type.ocr_settings
diff --git a/mayan/apps/ocr/models.py b/mayan/apps/ocr/models.py
index 0d0b099627..293d6ff82b 100644
--- a/mayan/apps/ocr/models.py
+++ b/mayan/apps/ocr/models.py
@@ -6,7 +6,9 @@ from django.utils.translation import ugettext_lazy as _
 
 from documents.models import DocumentPage, DocumentType, DocumentVersion
 
-from .managers import DocumentPageOCRContentManager
+from .managers import (
+    DocumentPageOCRContentManager, DocumentTypeSettingsManager
+)
 
 
 class DocumentTypeSettings(models.Model):
@@ -22,10 +24,17 @@ class DocumentTypeSettings(models.Model):
         verbose_name=_('Automatically queue newly created documents for OCR.')
     )
 
+    objects = DocumentTypeSettingsManager()
+
     class Meta:
         verbose_name = _('Document type settings')
         verbose_name_plural = _('Document types settings')
 
+    def natural_key(self):
+        return self.document_type.natural_key()
+    natural_key.dependencies = ['documents.DocumentType']
+
+
 
 @python_2_unicode_compatible
 class DocumentPageOCRContent(models.Model):