Re: ALTER COLUMN TYPE vs. domain constraints

Michael Paquier <michael(dot)paquier(at)gmail(dot)com> writes:
> On Fri, Oct 27, 2017 at 11:15 AM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>> We could consider back-patching the attached to cover this, but
>> I'm not entirely sure it's worth the trouble, because I haven't
>> thought of any non-silly use-cases in the absence of domains
>> over composite. Comments?

> There are no real complaints about the current behavior, aren't there?
> So only patching HEAD seems enough to me.

Yeah, we can leave it till someone does complain.

> You have added a comment on the constraint to make sure that it
> remains up on basically this ALTER TYPE. Querying pg_obj_description
> would make sure that the comment on the constraint is still here.

Done.

> +RebuildDomainConstraintComment(AlteredTableInfo *tab, int pass, Oid objid,
> + List *domname, char *conname)
> There is much duplication with RebuildConstraintComment. Why not
> grouping both under say RebuildObjectComment()?

True. I'd originally expected the code to differ more, but we can
merge these easily enough.

> I would think about
> having cmd->objtype and cmd->object passed as arguments, and then
> remove rel and domname from the existing arguments.

Doing it like that requires the callers to do work (to prepare the object
ID data structure) that's wasted if there's no comment, which most often
there wouldn't be, I suspect. Seems better to just pass the info the
caller does have and let this function do the rest.

Pushed, thanks for reviewing!

regards, tom lane