On Wed, Oct 12, 2016 at 03:51:33PM +0200, Wolfgang Bumiller wrote: > On October 5, 2016 at 6:55 PM Ben Pfaff <b...@ovn.org> wrote: > > I don't know what you're trying to deal with. The autogenerated code > > provides a C view of all of the features that the underlying database > > does. If you need something else, then it probably means extending the > > database schema, at which point the autogenerated code will give a view > > of whatever you add to the schema. > > I was just worried that the schema would be involved in interface/rpc > code which could potentially break tools built with the old schema. > (Considering it comes with a checksum) > But I don't see another option. > > Would you generally prefer an additional boolean flag for a change like > this or perhaps add -1 special value for the ingress_policing_rate. > A quick glance at the existing schema didn't point out many existing > special values other than a semi intuitive active_timeout where 0 means > default and -1 means disabled. In the case of ingress_policing_rate 0 > would mean disabled and -1 would mean untouched.
Yes, we're very concerned about schema backward compatibility. Adding special interpretations, or adding columns, doesn't break this kind of backward compatibility. I have two thoughts here. One would be to use -1, as you say. These columns currently have a constraint "minInteger": 0, which prevents -1 from being used. That could prevent downgrading from a newer to an older schema if the -1 value were actually in use. That is probably a minor concern. The other possibility I'm thinking of is to add an ingress_qos column to the Port table, which would resemble the qos column except that it would be used on ingress. Then we could define a collection of ingress qdiscs like those used for egress, one of which would be a "noop" qdisc. This is more future proof and does not have downgrade issues, although it is a little more work. _______________________________________________ discuss mailing list discuss@openvswitch.org http://openvswitch.org/mailman/listinfo/discuss
