nova-manage db archive_deleted_rows doesn't delete rows from the nova_cell0 database

Issue

• Our database is growing to a very large size and we might need to truncate tables to keep it within a reasonable size.

• There is a lot of deleted records in the instances table of the nova_cell0 database:

MariaDB [nova_cell0]> select count(*) from instances where deleted_at is not null;
+----------+
| count(*) |
+----------+
|   708405 |
+----------+

• There is a lot of deleted records in the instance_system_metadata table of the nova_cell0 database:

MariaDB [nova_cell0]> select count(*) from instance_system_metadata;
+----------+
| count(*) |
+----------+
| 18086868 |
+----------+

• nova-manage db archive_deleted_rows doesn't have any effect