Great, it solved the issue. Seems problematic that the planner do full scans on all partitions in the first case isnt it ? Seems like a bug ?
2018-02-04 16:54 GMT+02:00 Andreas Kretschmer <andreas@xxxxxxxxxxxxxxx>:
Am 04.02.2018 um 13:19 schrieb Mariel Cherkassky:
I checked the plan of the next query :
explain select count(*) from log_full where end_date between to_date('2017/12/03','YY/MM/DD') and to_date('2017/12/03','YY/MM/DD ');
can you rewrite the query to
... where end_date between '2017/12/03' and '2017/12/03'
simple test-case:
test=*# \d+ t
Table "public.t"
Column | Type | Collation | Nullable | Default | Storage | Stats target | Description
--------+------+-----------+----------+---------+---------+- -------------+-------------
d | date | | | | plain | |
Partition key: RANGE (d)
Partitions: t_01 FOR VALUES FROM ('2018-02-04') TO ('2018-02-05'),
t_02 FOR VALUES FROM ('2018-02-05') TO ('2018-02-06')
test=*# explain analyse select * from t where d between to_date('2018/02/04','YY/MM/DD') and to_date('2018/02/04','YY/MM/DD ');
QUERY PLAN
------------------------------------------------------------ ------------------------------ ------------------------------ ---------
Append (cost=0.00..122.00 rows=26 width=4) (actual time=0.006..0.006 rows=0 loops=1)
-> Seq Scan on t_01 (cost=0.00..61.00 rows=13 width=4) (actual time=0.004..0.004 rows=0 loops=1)
Filter: ((d >= to_date('2018/02/04'::text, 'YY/MM/DD'::text)) AND (d <= to_date('2018/02/04'::text, 'YY/MM/DD'::text)))
-> Seq Scan on t_02 (cost=0.00..61.00 rows=13 width=4) (actual time=0.001..0.001 rows=0 loops=1)
Filter: ((d >= to_date('2018/02/04'::text, 'YY/MM/DD'::text)) AND (d <= to_date('2018/02/04'::text, 'YY/MM/DD'::text)))
Planning time: 0.241 ms
Execution time: 0.042 ms
(7 rows)
test=*# explain analyse select * from t where d between '2018/02/04' and '2018/02/04';
QUERY PLAN
------------------------------------------------------------ ------------------------------ ------------
Append (cost=0.00..48.25 rows=13 width=4) (actual time=0.005..0.005 rows=0 loops=1)
-> Seq Scan on t_01 (cost=0.00..48.25 rows=13 width=4) (actual time=0.004..0.004 rows=0 loops=1)
Filter: ((d >= '2018-02-04'::date) AND (d <= '2018-02-04'::date))
Planning time: 0.203 ms
Execution time: 0.030 ms
(5 rows)
test=*#
maybe the planner should be smart enough to do that for you, but obvously he can't. So it's a workaround, but it seems to solve the problem.
Regards, Andreas
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