Re: ALTER TABLE ... IF EXISTS feature?

On Wed, Nov 24, 2010 at 4:30 PM, Bruce Momjian <bruce@momjian.us> wrote:
> Robert Haas wrote:
>> With respect to the syntax itself, I have mixed feelings.  On the one
>> hand, I'm a big fan of CREATE IF NOT EXISTS and DROP IF EXISTS
>> precisely because I believe they handle many common cases that people
>> want in real life without much hullabaloo.  But, there's clearly some
>> limit to what can reasonably be done this way.  At some point, what
>> you really want is some kind of meta-language where you can write
>> things like:
>>
>> IF EXISTS TABLE t1 THEN
>>    ALTER TABLE t1 DROP CONSTRAINT IF EXISTS t1_constr;
>> END IF;
>
> FYI, I have felt this way for a while.  IF EXISTS seemed like something
> that should never have been added as an inline SQL command option; it
> just crept in, and kept growing.

Okay, that being the case: would it make sense to have pg_dump emit DO
blocks? I have a feeling this might draw fire, but I don't see any
reason why the mechanism would not work to more or less equivalent
effect. Certainly making dumps harder to use for those who insist on
disabling PL/PGSQL is probably a negative side effect, if one can
identify this hypothetical class of person.

fdr