Re: check constraint problem during COPY while pg_upgrade-ing

I have noticed another problem during pg_upgrade on a 9.1
cluster with 9.4 as the target.

Consider this sort of table

        create table therapy (
                pk serial primary key,
                description text,
                is_ongoing boolean not null,
                ts_end timestamp with time zone
        );

Now, business rules say that a particular therapy is either
ongoing or not. The end of therapy can be known or not.

However, if the therapy is ongoing the ts_end must be either
NULL or "in the future" at row INSERT/UPDATE time.