Re: ALTER TABLE ... IF EXISTS feature?

Robert Haas  writes:
> On Nov 5, 2010, at 10:49 AM, Tom Lane  wrote:
>> I think you've phrased the question backwards.  Why *should* we support
>> that large increment of complexity?  The use-cases seem pretty few and
>> far between.

> Obviously we have different definitions of "a large increment in complexity".

Well,

(1) the proposal affects a large number of commands

(2) in some cases the correct behavior isn't obvious (I note Daniel's
example had *two* IF EXISTS options in one command...)

(3) it raises the bar of expectation for every future ALTER command

That spells "large maintenance burden" to me, even if any one command
would be relatively simple to fix.  And we haven't even reached the
question of whether pg_dump could use these things usefully; I suspect
that the bottom-line issue there might be something else entirely.
		regards, tom lane