Idempotency for all DDL statements

Hello everyone. This is my first time posting in -hackers, so please keep
this in mind.

I would like to formally request the addition of "IF EXISTS", "IF NOT
EXISTS", "OR REPLACE", and any other CINE variants to DDL statements that
currently do not feature an idempotent construct.

The lack of an idempotent option in statements such as "CREATE TRIGGER" for
example is particularly painful when performing upgrades on sizable
schemas.

I understand that there may be some difficulties in providing this to
various database objects. That said, I believe IMHO that this would be a
huge win for the community at large. Could I request DDL idempotency as an
addition to the development roadmap?

Thanks,

Kenaniah