diff --git a/datapipe/store/database.py b/datapipe/store/database.py
index 15f461f3..daf13645 100644
--- a/datapipe/store/database.py
+++ b/datapipe/store/database.py
@@ -3,7 +3,6 @@
 import math
 from typing import Any, Callable, Iterator, cast
 
-import numpy as np
 import pandas as pd
 from opentelemetry import trace
 from sqlalchemy import Column, MetaData, Table, create_engine, func, text
@@ -239,10 +238,12 @@ def update_rows(self, df: DataDF) -> None:
         if df.empty:
             return
 
-        # TODO разобраться, нужен ли этот блок кода, написать тесты на заполнение None/NULL
-        insert_sql = self.dbconn.insert(self.data_table).values(
-            df.fillna(np.nan).replace({np.nan: None}).to_dict(orient="records")
-        )
+        # SQLAlchemy expects Python None for SQL NULL; keep object dtype to avoid
+        # pandas downcasting warnings while preserving scalar values.
+        df_records = df.astype(object)
+        df_records[pd.isna(df_records)] = None
+        records = df_records.to_dict(orient="records")
+        insert_sql = self.dbconn.insert(self.data_table).values(records)
 
         if len(self.data_keys) > 0:
             sql = insert_sql.on_conflict_do_update(
diff --git a/datapipe/store/table_store.py b/datapipe/store/table_store.py
index 8d3d2839..8f3cefcc 100644
--- a/datapipe/store/table_store.py
+++ b/datapipe/store/table_store.py
@@ -45,7 +45,7 @@ def hash_keys(self) -> list[str]:
         return self.primary_keys + self.meta_keys
 
     def hash_rows(self, df: DataDF) -> HashDF:
-        hash_df = df[self.hash_keys]
+        hash_df = df[self.hash_keys].copy()
         hash_df["hash"] = df.apply(lambda x: str(list(x)), axis=1).apply(
             lambda x: int.from_bytes(cityhash.CityHash32(x).to_bytes(4, "little"), "little", signed=True)
         )