Update many rows with minimal footprint on the server

[raratiru]

Quoting this solution for efficiently updating or deleting in batches, should it be needed…
(Just ran out of memory)

@charettes

chunk_size = 1000
queryset = (
    Model.objects.filter(
        is_expired=True,
    )
    .order_by()
    .values_list("pk", flat=True)
)
while True:
    deleted, _ = Model.objects.filter(
        pk__in=queryset[:chunk_size]
    ).delete()
    if not deleted:
        break