What happens if filters are applied?
test=# EXPLAIN SELECT * FROM t_data WHERE t = '2016-01-04'; QUERY PLAN ----------------------------------------------------------------- Append (cost=0.00..95.12 rows=23 width=40) -> Seq Scan on t_data (cost=0.00..0.00 rows=1 width=40) Filter: (t = '2016-01-04'::date) -> Seq Scan on t_data_2016 (cost=0.00..25.00 rows=6 width=40) Filter: (t = '2016-01-04'::date) -> Seq Scan on t_data_2015 (cost=0.00..25.00 rows=6 width=40) Filter: (t = '2016-01-04'::date) -> Seq Scan on t_data_2014 (cost=0.00..25.00 rows=6 width=40) Filter: (t = '2016-01-04'::date) -> Seq Scan on t_data_2013 (cost=0.00..20.12 rows=4 width=40) Filter: (t = '2016-01-04'::date) (11 rows)
PostgreSQL will ...
