gistfile1.sql

musicbrainz_db=# \d artist_name;
                             Table "musicbrainz_test.artist_name"
  Column  |          Type          |                        Modifiers                         
----------+------------------------+----------------------------------------------------------
 id       | integer                | not null default nextval('artist_name_id_seq'::regclass)
 name     | character varying(255) | not null
 page     | integer                | not null
 refcount | integer                | default 0
Indexes:
    "artist_name_pk" PRIMARY KEY, btree (id)
    "artist_name_idx_name" UNIQUE, btree (name)
    "artist_name_idx_name_txt" gin (to_tsvector('mb_simple'::regconfig, name::text))

musicbrainz_db=# SELECT * FROM artist_name WHERE name = 'Nirvana';
 id | name | page | refcount 
----+------+------+----------
(0 rows)

musicbrainz_db=# INSERT INTO artist_name (name, page) VALUES ('Nirvana', 1234) RETURNING id;
ERROR:  duplicate key value violates unique constraint "artist_name_pk"