[BUGS] Deferrable constraint execution not respecting "initially immediate"?

fbd@datasapiens.com writes:
> I am testing PG on this query :
> CREATE TABLE T_UNIK (ID INT UNIQUE);
> INSERT INTO T_UNIK VALUES (1), (2), (3), (4), (5);
> UPDATE T_UNIK SET ID = ID + 1;

> I know that PG is unable to do this set based operation properly because it
> does it row by row (which is a nonsense since it works on many RDBMS)

The solution for that is documented: declare the unique constraint as
deferrable.

regression=# CREATE TABLE T_UNIK (ID INT UNIQUE deferrable );
CREATE TABLE
regression=# 

​​

INSERT INTO T_UNIK VALUES (1), (2), (3), (4), (5);
INSERT 0 5
regression=# U

​​

PDATE T_UNIK SET ID = ID + 1;
UPDATE 5