Re: CONSTRAINT does not show when applying a EXCLUDE constraint - Mailing list pgsql-general

Richard Broersma <richard.broersma@gmail.com> writes:
> On Mon, Dec 27, 2010 at 12:50 PM, InterRob <rob.marjot@gmail.com> wrote:
>> pgsql Command "\d test" produces the following:
>>        Table "public.test"
>>    Column   |  Type   | Modifiers
>> ------------+---------+-----------
>>  object_id  | integer |
>>  subject_id | integer |
>> Indexes:
>>     "EXCL_double_combi" EXCLUDE USING btree (imm_least(subject_id,
>> object_id) WITH =, imm_greatest(subject_id, object_id) WITH =)

> I see.  Since exclusion constraints is a rather new feature, psql may
> need some tweaking to report these constraints as constraints

No, the behavior is entirely intentional.  Compare what it's always been
for primary keys:

regression=# create table foo (f1 int primary key);
NOTICE:  CREATE TABLE / PRIMARY KEY will create implicit index "foo_pkey" for table "foo"
CREATE TABLE
regression=# \d foo
      Table "public.foo"
 Column |  Type   | Modifiers
--------+---------+-----------
 f1     | integer | not null
Indexes:
    "foo_pkey" PRIMARY KEY, btree (f1)

regression=#

BTW, I fail to see the point of using EXCLUDE in this particular way.
You'd get the same results, more efficiently, with a plain UNIQUE
constraint on the two function expressions.  EXCLUDE is really only
interesting for cases where the behavior you want doesn't conform to
btree semantics.

            regards, tom lane