Re: BUG #15670: alter table .. add column if not exists ... references ...; adds a FK constraint on each execution

PG Bug reporting form <noreply@postgresql.org> writes:
> I don't know if this is the expected behavior but when I execute this
> script:
> alter table test2 add column if not exists test1_fk integer not null
> references test1(id);
> alter table test2 add column if not exists test1_fk integer not null
> references test1(id);
> alter table test2 add column if not exists test1_fk integer not null
> references test1(id);
> I end up with 3 FK constrains:

Yeah, this is the same problem previously reported at bug #15180,

https://www.postgresql.org/message-id/flat/152509815280.19803.16118194452213577808%40wrigleys.postgresql.org

We had a sketch for a fix but discussion seems to have trailed off :-(

            regards, tom lane