Re: Rewriting DISTINCT and losing performance

[Richard Huxton <dev(at)archonet(dot)com>]

Chuck D. wrote:
>                 Table "geo.city"
>    Column   |          Type          | Modifiers
> ------------+------------------------+-----------
>  city_id    | integer                | not null
>  state_id   | smallint               |
>  country_id | smallint               |
>  latitude   | numeric(9,7)           |
>  longitude  | numeric(10,7)          |
>  city_name  | character varying(100) |
> Indexes:
>     "city_pk" PRIMARY KEY, btree (city_id)
>     "idx_city_country_id" btree (country_id) CLUSTER
> Foreign-key constraints:
>     "city_state_id_fk" FOREIGN KEY (state_id) REFERENCES geo.state(state_id)
> ON UPDATE CASCADE ON DELETE CASCADE

Any good reason why country_id is NULLable?

--
  Richard Huxton
  Archonet Ltd