QUERY PLAN
Aggregate (cost=18.71..18.72 rows=1 width=8)
-> Sort (cost=18.69..18.69 rows=1 width=590)
Sort Key: a.created_at DESC
-> Nested Loop Anti Join (cost=0.15..18.68 rows=1 width=590)
Join Filter: (l.id = r.user_id)
-> Nested Loop Left Join (cost=0.15..10.52 rows=11 width=12)
-> Seq Scan on tbl_announcements a (cost=0.00..1.01 rows=1 width=12)
Filter: (created_at > '2016-10-14 22:23:37+08'::timestamp with time zone)
-> Index Only Scan using tbl_read_announcement_pkey on tbl_read_announcement r (cost=0.15..8.17 rows=1 width=8)
Index Cond: ((announcement_id = a.id) AND (user_id = 1000))
-> Materialize (cost=0.00..7.99 rows=1 width=4)
-> Seq Scan on tbl_logins l (cost=0.00..7.99 rows=1 width=4)
Filter: (id = 1000)