postgres query 100w 条数据，使用select和explain select的用时

select count(*) from managers;

select * from managers where first_name = 'jim' or last_name='jim';

select * from managers where  last_name='jim';

select * from managers where  first_name='jim';

select * from managers where last_name = 'PHRZO';

explain select * from managers where last_name = 'PHRZO';

select * from managers where last_name like '%HRZO%';