Postgres 8.4

By using db<>fiddle, you agree to license everything you submit by Creative Commons CC0.

create table demo ( id bigint, value int)
;

CREATE TABLE

insert into demo(value)
  select generate_series(1,10000)
;

INSERT 0 10000

create index demo_idx
  on demo(value, id)
;

CREATE INDEX

vacuum analyze demo;

VACUUM

explain --(verbose)
select id from demo
  where value = 42
;

QUERY PLAN

Index Scan using demo_idx on demo  (cost=0.00..8.27 rows=1 width=8)

  Index Cond: (value = 42)

EXPLAIN