Re: partition table slow planning

>*Can we know why this is happening?*

Please give us - more info about your system:
- PG version?
- number of partitions?
- any other important?

for example - in PG 11.2 Changes:
"Improve planning speed for large inheritance or partitioning table groups
(Amit Langote, Etsuro Fujita)"
https://www.postgresql.org/docs/current/release-11-2.html

Imre

Jatinder Sandhu <jatinder(dot)sandhu(at)flightnetwork(dot)com> ezt írta (időpont:
2019. júl. 24., Sze, 9:22):

>
>
> We encounter a issue when we do query on partition table directly with
> proper partition key provide. postgres able to find problem partition but
> when I do explain plan it showing 95% spend on planning the execution .
> Here is example
> itinerary=# EXPLAIN ANALYZE SELECT * FROM itinerary WHERE destination
> ='GRJ' AND departure_date = '2020-01-01' AND month_day = 101
> itinerary-# ;
>
> QUERY PLAN
>
> -----------------------------------------------------------------------------------------------------------------------------------------------------------------------
> Append (cost=0.29..13.79 rows=11 width=1024) (actual time=0.033..0.037
> rows=1 loops=1)
> -> Index Scan using itinerary_101_destination_departure_date_idx on
> itinerary_101 (cost=0.29..13.73 rows=11 width=1024) (actual
> time=0.033..0.036 rows=1 loops=1)
> Index Cond: (((destination)::text = 'GRJ'::text) AND
> ((departure_date)::text = '2020-01-01'::text))
> Filter: (month_day = 101)
>
> * Planning Time: 51.677 ms* Execution Time: 0.086 ms
>
>
> When I do query on directly on the partition table it is quite fast
> itinerary=# EXPLAIN ANALYZE SELECT * FROM itinerary_101 WHERE destination
> ='GRJ' AND departure_date = '2020-01-01' AND month_day = 101
> itinerary-# ;
>
> QUERY PLAN
>
> -----------------------------------------------------------------------------------------------------------------------------------------------------------------
> Index Scan using itinerary_101_destination_departure_date_idx on
> itinerary_101 (cost=0.29..13.73 rows=11 width=1024) (actual
> time=0.043..0.048 rows=1 loops=1)
> Index Cond: (((destination)::text = 'GRJ'::text) AND
> ((departure_date)::text = '2020-01-01'::text))
> Filter: (month_day = 101)
>
> * Planning Time: 0.191 ms* Execution Time: 0.074 ms
> (5 rows)
>
> itinerary=#
>
> *Can we know why this is happening?*
>
>
>
>
>
>