Re: Add column if not exists (CINE)

On Wed, Jul 21, 2010 at 2:53 PM, Bernd Helmle <mailings(at)oopsware(dot)de> wrote:
>
>
> --On 1. Mai 2010 23:09:23 -0400 Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
>
>> On Wed, Apr 28, 2010 at 9:15 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>>>>
>>>> CREATE OR REPLACE is indeed much more complicated.  In fact, for
>>>> tables, I maintain that you'll need to link with -ldwim to make it
>>>> work properly.
>>>
>>> This may in fact be an appropriate way to handle the case for tables,
>>> given the complexity of their definitions.
>>
>> Patch attached.
>
> I had an initial look at Robert's patch. Patch applies cleanly,
> documentation and regression tests included, everything works as expected.
> When looking at the functionality there's one thing that strikes me a
> little:
>
> bernd(at)localhost:bernd #*= CREATE TABLE IF NOT EXISTS foo(id int);
> ERROR:  duplicate key value violates unique constraint
> "pg_type_typname_nsp_index"
> DETAIL:  Key (typname, typnamespace)=(foo, 2200) already exists.
>
> This is what you get from concurrent CINE commands. The typname thingie
> might be confusing by unexperienced users, but i think its hard to do
> anything about it ?

I get the same error message from concurrent CREATE TABLE commands
even without CINE...

S1:
rhaas=# begin;
BEGIN
rhaas=# create table foo (id int);
CREATE TABLE

S2:
rhaas=# begin;
BEGIN
rhaas=# create table foo (id int);
<blocks>

S1:
rhaas=# commit;
COMMIT

S2:
ERROR: duplicate key value violates unique constraint
"pg_type_typname_nsp_index"
DETAIL: Key (typname, typnamespace)=(foo, 2200) already exists.

I agree it would be nice to fix this. I'm not sure how hard it is. I
don't think it's the job of this patch. :-)

--
Robert Haas
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