Django annotate with standard deviation

I´m trying to annotate a queryset by the Standard deviation.

I found this post How to perform STD

And read this documentation about querysets

I tried this:

from django.db.models import StdDev
ventas_producto = ventas.values("prod_codigo").annotate(uds_std=StdDev("uds"))

But I get the following error:

Exception Type: OperationalError Exception Value: no such function: STDDEV_POP

Any clues? Thanks!