diff --git a/src/django_clickhouse/clickhouse_models.py b/src/django_clickhouse/clickhouse_models.py
index af0bc3d..327cb7c 100644
--- a/src/django_clickhouse/clickhouse_models.py
+++ b/src/django_clickhouse/clickhouse_models.py
@@ -9,6 +9,7 @@ from typing import List, Tuple
 from django.db.models import Model as DjangoModel
 from django.utils.timezone import now
 from infi.clickhouse_orm.database import Database
+from infi.clickhouse_orm.engines import CollapsingMergeTree
 from infi.clickhouse_orm.models import Model as InfiModel, ModelBase as InfiModelBase
 from six import with_metaclass
 from statsd.defaults.django import statsd
@@ -91,8 +92,11 @@ class ClickHouseModel(with_metaclass(ClickHouseModelMeta, InfiModel)):
     def _prepare_val_for_eq(self, field_name, field, val):
         if isinstance(val, datetime.datetime):
             return val.replace(microsecond=0)
-        elif field_name == '_version':
-            return True  # Независимо от версии должно сравнение быть истиной
+
+        # Sign column for collapsing should be ignored
+        if isinstance(self.engine, CollapsingMergeTree) and field_name == self.engine.sign_col:
+            return True
+
         return val
 
     def __eq__(self, other):
@@ -184,4 +188,6 @@ class ClickHouseModel(with_metaclass(ClickHouseModelMeta, InfiModel)):
         if last_sync_time is None:
             return True
 
+        print(last_sync_time)
+
         return (last_sync_time - datetime.datetime.now()).total_seconds() >= cls.get_sync_delay()
diff --git a/src/django_clickhouse/compatibility.py b/src/django_clickhouse/compatibility.py
deleted file mode 100644
index e69de29..0000000
diff --git a/tests/clickhouse_models.py b/tests/clickhouse_models.py
index 3ee3b3f..362e648 100644
--- a/tests/clickhouse_models.py
+++ b/tests/clickhouse_models.py
@@ -1,3 +1,5 @@
+from enum import Enum
+
 from django_clickhouse.clickhouse_models import ClickHouseModel
 from django_clickhouse.engines import MergeTree, CollapsingMergeTree
 from infi.clickhouse_orm import fields
@@ -25,4 +27,4 @@ class ClickHouseCollapseTestModel(ClickHouseModel):
     value = fields.Int32Field()
     sign = fields.Int8Field()
 
-    engine = CollapsingMergeTree('created_date', ('id',), 'sign')
\ No newline at end of file
+    engine = CollapsingMergeTree('created_date', ('id',), 'sign')
diff --git a/tests/test_clickhouse_models.py b/tests/test_clickhouse_models.py
new file mode 100644
index 0000000..a757f72
--- /dev/null
+++ b/tests/test_clickhouse_models.py
@@ -0,0 +1,29 @@
+import datetime
+
+from django.test import TestCase
+
+from tests.clickhouse_models import ClickHouseTestModel
+
+
+class ClickHouseModelTest(TestCase):
+    def setUp(self):
+        self.storage = ClickHouseTestModel.get_storage()
+        self.storage.flush()
+
+    def test_need_sync(self):
+        # sync is disabled by default
+        self.assertFalse(ClickHouseTestModel.need_sync())
+
+        # There were no syncs. So it should be done
+        ClickHouseTestModel.sync_enabled = True
+        self.assertTrue(ClickHouseTestModel.need_sync())
+
+        # Time hasn't passed - no sync
+        self.storage.set_last_sync_time(ClickHouseTestModel.get_import_key(), datetime.datetime.now())
+        self.assertFalse(ClickHouseTestModel.need_sync())
+
+        # Time has passed
+        sync_delay = ClickHouseTestModel.get_sync_delay()
+        self.storage.set_last_sync_time(ClickHouseTestModel.get_import_key(),
+                                        datetime.datetime.now() - datetime.timedelta(seconds=sync_delay))
+        self.assertFalse(ClickHouseTestModel.need_sync())