Hello Chris, I thought it was a bug in SQLAlchemy code, so I wrote a snippet [1] to check my assumption, but I haven't managed to reproduce the problem with SQLAlchemy versions 0.7.9, 0.7.10 and 0.8.2.
I would suggest you to start from enabling logging of all SQL queries SQLAlchemy issues [2] and, if needed, examining of session/model instance state with pdb. For your second question. You can set a column to its current value by using of literal_column() expression [3]. Can you elaborate a bit more on your use case? Why do you update the table row, but keep the update_at column value unchanged? Thanks, Roman [1] http://paste.openstack.org/show/48335/ [2] https://github.com/openstack/nova/blob/stable/grizzly/nova/openstack/common/db/sqlalchemy/session.py#L296 [3] https://github.com/openstack/cinder/blob/master/cinder/db/sqlalchemy/api.py#L1088 On Sat, Oct 12, 2013 at 2:31 AM, Chris Friesen <chris.frie...@windriver.com>wrote: > Hi, > > I'm using grizzly with sqlalchemy 0.7.9. > > I'm seeing some funny behaviour related to the automatic update of > "updated_at" column for the Service class in the sqlalchemy model. > > I added a new column to the Service class, and I want to be able to update > that column without triggering the automatic update of the "updated_at" > field. > > While trying to do this, I noticed the following behaviour. If I do > > values = {'updated_at': new_value} > self.service_update(context, service, values) > > this sets the "updated_at" column to new_value as expected. However, if I > do > > values = {'updated_at': new_value, 'other_key': other_value} > self.service_update(context, service, values) > > then the other key is set as expected, but "updated_at" gets auto-updated > to the current timestamp. > > The "onupdate" description in the sqlalchemy docs indicates that it "will > be invoked upon update if this column is not present in the SET clause of > the update". Anyone know why it's being invoked even though I'm passing in > an explicit value? > > > On a slightly different note, does anyone have a good way to update a > column in the Service class without triggering the "updated_at" field to be > changed? Is there a way to tell the database "set this column to this > value, and set the updated_at column to its current value"? I don't want > to read the "updated_at" value and then write it back in another operation > since that leads to a potential race with other entities accessing the > database. > > Thanks, > Chris > > ______________________________**_________________ > OpenStack-dev mailing list > OpenStack-dev@lists.openstack.**org <OpenStack-dev@lists.openstack.org> > http://lists.openstack.org/**cgi-bin/mailman/listinfo/**openstack-dev<http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev> >
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