diff --git a/qlib/data/cache.py b/qlib/data/cache.py
index 2d0b8a7cd..3e0680e74 100644
--- a/qlib/data/cache.py
+++ b/qlib/data/cache.py
@@ -237,7 +237,7 @@ class CacheUtils:
             lock.acquire()
         except redis_lock.AlreadyAcquired:
             raise QlibCacheException(
-                f"""It sees the key(lock:{repr(lock_name)[1:-1]}-wlock) of the redis lock has existed in your redis db now. 
+                f"""It sees the key(lock:{repr(lock_name)[1:-1]}-wlock) of the redis lock has existed in your redis db now.
                     You can use the following command to clear your redis keys and rerun your commands:
                     $ redis-cli
                     > select {C.redis_task_db}
@@ -784,10 +784,10 @@ class DiskDatasetCache(DatasetCache):
         def build_index_from_data(data, start_index=0):
             if data.empty:
                 return pd.DataFrame()
-            line_data = data.iloc[:, 0].fillna(0).groupby("datetime").count()
+            line_data = data.groupby("datetime").size()
             line_data.sort_index(inplace=True)
             index_end = line_data.cumsum()
-            index_start = index_end.shift(1).fillna(0)
+            index_start = index_end.shift(1, fill_value=0)
 
             index_data = pd.DataFrame()
             index_data["start"] = index_start