Deleting a branch set for translations export generates a OOPS

Branch deletion should check for all the foreign references before trying to remove the branch (and I believe it does that already for things like MPs, so it just needs extending). It should be safe to unset a translations_branch when branch is being removed, provided we warn users about it.

Danilo, somewhat cheeky passing the buck as this should really have been done as part of the translation work.

Reproducing this issue is not trivial. It is really helpful to include an oops-id, so that we can look up the exact cause of the failure. I had assumed it was the existence of the BranchJob, but that can't be it, because those are deleted at branch deletion time.

Example OOPS: OOPS-1643EB2211

I hope you don't mind that I deleted the branch for good afterwards after having manually disabled the translation export.

To clarify the "cheeky" bit: is there any reason why we wouldn't go and remove all the branch references automatically? If we did that, we wouldn't even have problems with BuildQueue stuff that Paul (I think) hit recently.

Tim, if you feel that's a bad idea, then I'd agree we should move this bug back to Launchpad Translations (so, please do it if you don't see anything generic in your future ;). Still, I personally prefer generic solutions since the rest of LP is going to keep breaking branch deletion as they introduce more features that depend on branches.

On Fri, 23 Jul 2010 21:55:07 you wrote:
> To clarify the "cheeky" bit: is there any reason why we wouldn't go and
> remove all the branch references automatically? If we did that, we
> wouldn't even have problems with BuildQueue stuff that Paul (I think)
> hit recently.
>
> Tim, if you feel that's a bad idea, then I'd agree we should move this
> bug back to Launchpad Translations (so, please do it if you don't see
> anything generic in your future ;). Still, I personally prefer generic
> solutions since the rest of LP is going to keep breaking branch deletion
> as they introduce more features that depend on branches.

We don't want general automagical resolution.

There are some places where there are links to branches where the links just
need to be NULLed out, like series linked branches.

When a branch is stacked on, we don't want to allow the main branch to be
deleted.

Other cases we have cascading deletes, like in the situation with the
BranchRevision table.

Before we make a generalised answer, I'd like to get our DBA and Architect
position on more general cascading deletes. These type of thinks should be
added in when the table is being linked.

Also I actually added a test that needs to be updated whenever anyone adds a
reference to the Branch table, extract shown here:

> == Branch references ==
>
> When new references to the branch table are added, these need to be
> taken into consideration with branch deletion.
>
> The current references to the branch table are shown here.

productseries.translations_branch was added, but the developer did not
actually read the text and take the new reference into consideration for the
branch deletion code.