[ovs-dev] [gc 13/13] ovsdb: Implement garbage collection.

[Ethan Jackson]

> When I spoke to our controller team, they said that our controllers
> sometimes construct QoS and Queue records without connecting them to the
> rest of the database in the same transaction.  In turn the controllers
> do this because they usually want to attach the same QoS record to
> multiple physical interfaces, because we want the same queues on all of
> the physical interfaces.  This sounded reasonable to me.

Sounds reasonable to me too.  I was just curious.

>> I think it's fine how it is, but my inclination would be to make
>> isRoot = false the default and force the user to specify true on root
>> nodes.  Most nodes we create will not be root nodes, so it seems a bit
>> less error prone.
>
> I agree.  The reason that I adopted "isRoot": true as the default is to
> avoid changing the interpretation of existing schemas.  If "isRoot":
> false is the default, then we need to know whether a schema or a
> database (since a database includes a schema) is written in the old form
> or the new form when we read it.  Otherwise, every record in an old
> database will always be discarded, since the old database has no root
> set at all!

Haha good point.

>
> Another approach, which had not occurred to me before now, would be to
> use "true" as the default if a schema does not have any tables with
> "isRoot" explicitly specified (for compatibility), and "false"
> otherwise.  Do you like that better?  If you do, then I will implement
> it that way instead.

If it's relatively easy to do that sounds like a good idea to me.  I'd
prefer the default do the right thing if possible.  If it's too much
work I wouldn't bother though, we can always change it later if it
becomes a problem.  We don't add tables that often anyways.

> +    the <ref table="Open_vSwitch"/> table are automatically deleted
> +    from the database, except for records in a few distinguished
> +    ``root set'' tables noted below.
> +  </p>

The diff looks good.  I made a minor comment about the wording of the
above sentence which you may not have noticed:
I would phrase this as "except for a few records in a distinguished"

I'm not married to that wording so if you think it's fine how it is
just mention it.

Ethan