Re: ALTER command reworks

On Mon, Aug 13, 2012 at 3:35 PM, Kohei KaiGai <kaigai@kaigai.gr.jp> wrote:
> The attached patch is a refreshed version of ALTER command
> reworks towards the latest tree. Here is few big changes except
> for code integration of the code to rename event triggers.

This seems to have bit-rotted a bit.  Please rebase.

> BTW, I had to adjust between oid of pg_largeobject_metadata
> and pg_largeobject on three points of this patch, like:
>
>         if (classId == LargeObjectRelationId)
>             classId = LargeObjectMetadataRelationId;
>
> When we supported largeobject permission features, we put
> special handling to track dependency of its ownership.
> The pg_depend records oid of pg_largeobject, instead of
> pg_largeobject_metadata. Thus, we cannot use classId of
> ObjectAddress being returned from get_object_address()
> as an argument of heap_open() as is, if it indicates oid of
> pg_largeobject.
>
> Was it a right decision to track dependency of large object using
> oid of pg_largeobject, instead of pg_largeobject_metadata?
> IIRC, the reason why we used oid of pg_largeobject is backward
> compatibility for applications that tries to reference pg_depend
> with built-in oids.

I think it was a terrible decision and I'm pretty sure I said as much
at the time, but I lost the argument, so I'm inclined to think we're
stuck with continuing to support that kludge.

Some other preliminary comments:

- Surely you need to take AccessExclusiveLock on the object being
renamed, not just ShareUpdateExclusiveLock.
- I don't think it's acceptable to assemble the object-type
"object-name" already exists message using getObjectDescription();
it's not good for translators.  Use an array of messages, one per
object-type, as we have done in other cases.
- I would like to handle either the RENAME case or the ALTER OWNER
case in one patch, and the other in a follow-on patch.  Can you pick
one to do first and remove everything related to the other one?

-- 
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company