Re: Extensions versus pg_upgrade

On Tue, Feb 8, 2011 at 10:25 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> Robert Haas <robertmhaas@gmail.com> writes:
>> On Tue, Feb 8, 2011 at 9:48 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
>>> Like ALTER THING SET SCHEMA, ALTER THING SET EXTENSION is implicitly
>>> assuming that there can be only one owning extension for an object.
>
>> I would assume that we would enforce that constraint anyway.  No?
>> Otherwise when you drop one of the two extensions, what happens to the
>> object?  Seems necessary for sanity.
>
> Not sure --- what about nested extensions, for instance?  Or you could
> think about objects that are shared between two extensions, and go away
> only if all those extensions are dropped.  (RPM has exactly that
> behavior for files owned by multiple packages, to take a handy example.)
>
> My point is that the current restriction to just one containing
> extension seems to me to be an implementation restriction, rather than
> something inherent in the concept of extensions.  I have no intention of
> trying to relax that restriction in the near future --- I'm just
> pointing out that it could become an interesting thing to do.

OK.  My point was that I think we should definitely *enforce* that
restriction until we have a very clear vision of what it means to do
anything else, so it sounds like we're basically in agreement.

--
Robert Haas
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