Fix tuple state prefix read/write #372

clickhouse_driver/columns/tuplecolumn.py

@@ -28,6 +28,14 @@ def read_data(self, n_items, buf):
     def read_items(self, n_items, buf):
         return self.read_data(n_items, buf)
 
+    def read_state_prefix(self, buf):
+        for x in self.nested_columns:
+            x.read_state_prefix(buf)
+
+    def write_state_prefix(self, buf):
+        for x in self.nested_columns:
+            x.write_state_prefix(buf)
+
 
 def create_tuple_column(spec, column_by_spec_getter, column_options):
     inner_spec = get_inner_spec('Tuple', spec)

tests/columns/test_tuple.py

@@ -178,3 +178,22 @@ def test_type_mismatch_error(self):
         with self.create_table(columns):
             with self.assertRaises(errors.TypeMismatchError):
                 self.client.execute('INSERT INTO test (a) VALUES', data)
+
+    def test_tuple_of_low_cardinality(self):
+        data = [((1, 2), )]
+        columns = 'a Tuple(LowCardinality(Int32), LowCardinality(Int32))'
+
+        with self.create_table(columns):
+            self.client.execute(
+                'INSERT INTO test (a) VALUES', data
+            )
+
+            query = 'SELECT * FROM test'
+            inserted = self.emit_cli(query)
+            self.assertEqual(
+                inserted,
+                '(1,2)\n'
+            )
+
+            inserted = self.client.execute(query)
+            self.assertEqual(inserted, data)