actually working in-memory conversion to hdf5 file

utils/df_utils.py

@@ -25,10 +25,20 @@ def to_excel_binary(df, **kwargs):
         res = out.getvalue()
     return res
 
-def to_hdf_binary(df, key="df", **kwargs):
-    with BytesIO() as out:
-        df.to_hdf(out, key, **kwargs)
-        res = out.getvalue()
+
+
+from pandas import HDFStore
+
+
+def to_hdf_binary(df):
+    with HDFStore(
+        "wontbewritten.h5",
+        mode="a",
+        driver="H5FD_CORE",
+        driver_core_backing_store=0
+    ) as out:
+        out["/data"] = df
+        res = out._handle.get_file_image()
     return res