my_db=> explain select value from my_table;
 Seq Scan on my_table  (cost=0.00..94431870.58 rows=5441724758 width=4)

my_db=> explain select max(value) from my_table;
 Finalize Aggregate  (cost=48518318.76..48518318.77 rows=1 width=4)
   ->  Gather  (cost=48518317.93..48518318.74 rows=8 width=4)
         Workers Planned: 8
         ->  Partial Aggregate  (cost=48517317.93..48517317.94 rows=1 width=4)
               ->  Parallel Seq Scan on my_table  (cost=0.00..46816778.95 rows=680215595 width=4)

my_db=> d my_table
 id       | bigint                         | not null default nextval('my_table_id_seq'::regclass)
 datetime | timestamp(0) without time zone | not null
 value    | real                           | not null
 my_id    | smallint                       | not null
 my_flag  | boolean                        | not null

my_db=> d my_table_id_seq
 sequence_name | name    | my_table_id_seq
 last_value    | bigint  | 4971842011
 start_value   | bigint  | 1
 increment_by  | bigint  | 1
 max_value     | bigint  | 9223372036854775807
 min_value     | bigint  | 1
 cache_value   | bigint  | 1
 log_cnt       | bigint  | 22
 is_cycled     | boolean | f
 is_called     | boolean | t