PostgreSQL benchmark for database index on the Django' `auth_user.is_staff` field

gistfile1.sql

database=> SELECT COUNT(*) FROM auth_user;
 count 
-------
  1076
(1 row)

database=> EXPLAIN SELECT COUNT(*) FROM auth_user WHERE is_staff = False;
                            QUERY PLAN                             
-------------------------------------------------------------------
 Aggregate  (cost=26.80..26.81 rows=1 width=0)
   ->  Seq Scan on auth_user  (cost=0.00..24.04 rows=1103 width=0)
         Filter: (NOT is_staff)
(3 rows)

database=> EXPLAIN SELECT COUNT(*) FROM auth_user WHERE is_staff = True;
                           QUERY PLAN                           
----------------------------------------------------------------
 Aggregate  (cost=24.04..24.05 rows=1 width=0)
   ->  Seq Scan on auth_user  (cost=0.00..24.04 rows=1 width=0)
         Filter: is_staff
(3 rows)

database=> CREATE INDEX auth_user_is_staff ON auth_user (is_staff);
CREATE INDEX

database=> EXPLAIN SELECT COUNT(*) FROM auth_user WHERE is_staff = False;
                            QUERY PLAN                             
-------------------------------------------------------------------
 Aggregate  (cost=26.45..26.46 rows=1 width=0)
   ->  Seq Scan on auth_user  (cost=0.00..23.76 rows=1075 width=0)
         Filter: (NOT is_staff)
(3 rows)

database=> EXPLAIN SELECT COUNT(*) FROM auth_user WHERE is_staff = True;
                                        QUERY PLAN                                        
------------------------------------------------------------------------------------------
 Aggregate  (cost=8.27..8.28 rows=1 width=0)
   ->  Index Scan using auth_user_is_staff on auth_user  (cost=0.00..8.27 rows=1 width=0)
         Index Cond: (is_staff = true)
         Filter: is_staff
(4 rows)