Tom Lane wrote:
- Can domains have operators, or are operators defined on types?
I think the current state of play is that you can have such things but
the system will only consider them for exact type matches, so you might
need more explicit casts than you ordinarily would.
Turns out it's even smarter than that; it seems to coerce when it's unambiguous:
create domain birthdate as date;
create function date_dist(birthdate, birthdate) returns integer as $$
select 123;
$$ language sql;
create operator <-> (
procedure = date_dist,
leftarg = birthdate,
rightarg = birthdate);
select '2012-01-01'::birthdate <-> '2012-01-01'::birthdate;
-- 123
select '2012-01-01'::date <-> '2012-01-01'::date ;
-- 123
create domain activity_date as date;
create function date_dist(activity_date, activity_date)
returns integer as $$
select 432;
$$ language sql;
create operator <-> (
procedure = date_dist,
leftarg = activity_date,
rightarg = activity_date);
select '2012-01-01'::activity_date <-> '2012-01-01'::activity_date;
-- 432
select '2012-01-01'::birthdate <-> '2012-01-01'::birthdate;
-- 123
select '2012-01-01'::date <-> '2012-01-01'::date ;
-- ERROR: operator is not unique: date <-> date
--
Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org)
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-hackers
