Re: ALTER TABLE ... IF EXISTS feature?

On Fri, Nov 5, 2010 at 1:31 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> Daniel Farina <drfarina@acm.org> writes:
>> On Fri, Nov 5, 2010 at 11:04 AM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
>>> Daniel Farina <drfarina@acm.org> writes:
>>>> pg_dump --clean will successfully and silently wipe out a foreign key
>>>> right now, should it exist,
>>>
>>> No, it will not, because we don't use CASCADE in the drop commands.
>
>> I know it does not use CASCADE, but if I understand it correctly,
>> foreign keys are dropped between tables, and then the tables are
>> dropped. (effectively a manual cascade)
>
> You're missing the point.  The scenario I'm concerned about is:
>
>        source database contained table foo
>
>        target database contains table foo, and table bar, and
>        bar has an FK reference to foo
>

I think that's intended and okay to fail, and would continue to fail
post-patch, if I understand what I am doing correctly (always
suspect).

The only condition where this should be emitted is when all the
dependent objects are going to be dropped anyway.

fdr