Re: partition pruning - Mailing list pgsql-performance

suganthi Sekar wrote:
>  i am using Postgresql 11, i have 2 partition table , when i joined both table in query 
> a table  its goes exact partition table  , but other table scan all partition
> 
> please clarify on this .
> 
> i have enabled below parameter on in configuration file
> Note  :  alter system set enable_partitionwise_join  to 'on';
> 
> 
> Example : 
> 
> explain analyze
> select * from call_report1 as a  inner join  call_report2 as b on a.call_id=b.call_id
>  where a.call_created_date ='2017-11-01' and '2017-11-30'
> 
> 
> 
>  "Hash Right Join  (cost=8.19..50.47 rows=2 width=3635) (actual time=0.426..0.447 rows=7 loops=1)"
> "  Hash Cond: (b.call_id = a.call_id)"
> "  ->  Append  (cost=0.00..41.81 rows=121 width=2319) (actual time=0.040..0.170 rows=104 loops=1)"
> "        ->  Seq Scan on call_report2 b  (cost=0.00..0.00 rows=1 width=528) (actual time=0.010..0.010 rows=0
loops=1)"
> "        ->  Seq Scan on call_report2_201803 b_1  (cost=0.00..10.30 rows=30 width=2334) (actual time=0.029..0.031
rows=14loops=1)"
 
> "        ->  Seq Scan on call_report2_201711 b_2  (cost=0.00..10.30 rows=30 width=2334) (actual time=0.014..0.015
rows=7loops=1)"
 
> "        ->  Seq Scan on call_report2_201712 b_3  (cost=0.00..10.30 rows=30 width=2334) (actual time=0.017..0.047
rows=34loops=1)"
 
> "        ->  Seq Scan on call_report2_201801 b_4  (cost=0.00..10.30 rows=30 width=2334) (actual time=0.017..0.058
rows=49loops=1)"
 
> "  ->  Hash  (cost=8.17..8.17 rows=2 width=1314) (actual time=0.104..0.104 rows=7 loops=1)"
> "        Buckets: 1024  Batches: 1  Memory Usage: 12kB"
> "        ->  Append  (cost=0.00..8.17 rows=2 width=1314) (actual time=0.053..0.060 rows=7 loops=1)"
> "              ->  Seq Scan on call_report1 a  (cost=0.00..0.00 rows=1 width=437) (actual time=0.022..0.022 rows=0
loops=1)"
> "                    Filter: ((call_created_date >= '2017-11-01'::date) AND (call_created_date <=
'2017-11-30'::date))"
> "              ->  Index Scan using idx_call_report1_201711_ccd on call_report1_201711 a_1  (cost=0.14..8.16 rows=1
width=2190)(actual time=0.029..0.034 rows=7 loops=1)"
 
> "                    Index Cond: ((call_created_date >= '2017-11-01'::date) AND (call_created_date <=
'2017-11-30'::date))"
> "Planning Time: 20.866 ms"
> "Execution Time: 1.205 ms"

There is no condition on the table "call_report2" in your query,
so it is not surprising that all partitions are scanned, right?

You have to add a WHERE condition that filters on the partitioning
column(s) of "call_report2".

Yours,
Laurenz Albe
-- 
Cybertec | https://www.cybertec-postgresql.com