Hi all,
I found a runtime pruning test case which may be a problem as follows:
----
create table t1 (id int, dt date) partition by range(dt);
create table t1_1 partition of t1 for values from ('2019-01-01') to
('2019-04-01');
create table t1_2 partition of t1 for values from ('2019-04-01') to
('2019-07-01');
create table t1_3 partition of t1 for values from ('2019-07-01') to
('2019-10-01');
create table t1_4 partition of t1 for values from ('2019-10-01') to
('2020-01-01');
In this example, current_date is 2019-04-16.
postgres=# explain select * from t1 where dt = current_date + 400;
QUERY PLAN
------------------------------------------------------------
Append (cost=0.00..198.42 rows=44 width=8)
Subplans Removed: 3
-> Seq Scan on t1_1 (cost=0.00..49.55 rows=11 width=8)
Filter: (dt = (CURRENT_DATE + 400))
(4 rows)
postgres=# explain analyze select * from t1 where dt = current_date + 400;
QUERY PLAN
---------------------------------------------------------------------------------------
Append (cost=0.00..198.42 rows=44 width=8) (actual time=0.000..0.001 rows=0
loops=1)
Subplans Removed: 3
-> Seq Scan on t1_1 (cost=0.00..49.55 rows=11 width=8) (never executed)
Filter: (dt = (CURRENT_DATE + 400))
Planning Time: 0.400 ms
Execution Time: 0.070 ms
(6 rows)
----
I realized t1_1 was not scanned actually since "never executed"
was displayed in the plan using EXPLAIN ANALYZE. But I think
"One-Time Filter: false" and "Subplans Removed: ALL" or something
like that should be displayed instead.
What do you think?
Best regards,
Yuzuko Hosoya
NTT Open Source Software Center
