Оператор Postgresql IN Производительность: список против подзапроса

Question

Для списка ~ 700 идентификаторов производительность запросов более 20 раз медленнее, чем передача подзапроса, который возвращает эти 700 идентификаторов. Это должно быть наоборот.

например. (Первый запрос берет под 400мсом, поздний 9600 мс)

select date_trunc('month', day) as month, sum(total) 
from table_x 
where y_id in (select id from table_y where prop = 'xyz') 
and day between '2015-11-05' and '2016-11-04' 
group by month 

является 20x быстрее на моей машине, чем передача массива напрямую:

select date_trunc('month', day) as month, sum(total) 
from table_x 
where y_id in (1625, 1871, ..., 1640, 1643, 13291, 1458, 13304, 1407, 1765) 
and day between '2015-11-05' and '2016-11-04' 
group by month 

Любой идеи, что может быть проблемой или как оптимизировать и получить такую ​​же производительность?

Answer 1

Разница простой фильтр против хэша присоединиться:

explain analyze 
select i 
from t 
where i in (500,501,502,503,504,505,506,507,508,509,510,511,512,513,514,515,516,517,518,519,520,521,522,523,524,525,526,527,528,529,530,531,532,533,534,535,536,537,538,539,540,541,542,543,544,545,546,547,548,549,550,551,552,553,554,555,556,557,558,559,560,561,562,563,564,565,566,567,568,569,570,571,572,573,574,575,576,577,578,579,580,581,582,583,584,585,586,587,588,589,590,591,592,593,594,595,596,597,598,599,600); 
               QUERY PLAN                                                       
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- 
Seq Scan on t (cost=0.00..140675.00 rows=101 width=4) (actual time=0.648..1074.567 rows=101 loops=1) 
    Filter: (i = ANY ('{500,501,502,503,504,505,506,507,508,509,510,511,512,513,514,515,516,517,518,519,520,521,522,523,524,525,526,527,528,529,530,531,532,533,534,535,536,537,538,539,540,541,542,543,544,545,546,547,548,549,550,551,552,553,554,555,556,557,558,559,560,561,562,563,564,565,566,567,568,569,570,571,572,573,574,575,576,577,578,579,580,581,582,583,584,585,586,587,588,589,590,591,592,593,594,595,596,597,598,599,600}'::integer[])) 
    Rows Removed by Filter: 999899 
Planning time: 0.170 ms 
Execution time: 1074.624 ms 

explain analyze 
select i 
from t 
where i in (select i from r); 
                QUERY PLAN              
------------------------------------------------------------------------------------------------------------------- 
Hash Semi Join (cost=3.27..17054.40 rows=101 width=4) (actual time=0.382..240.389 rows=101 loops=1) 
    Hash Cond: (t.i = r.i) 
    -> Seq Scan on t (cost=0.00..14425.00 rows=1000000 width=4) (actual time=0.030..117.193 rows=1000000 loops=1) 
    -> Hash (cost=2.01..2.01 rows=101 width=4) (actual time=0.074..0.074 rows=101 loops=1) 
     Buckets: 1024 Batches: 1 Memory Usage: 12kB 
     -> Seq Scan on r (cost=0.00..2.01 rows=101 width=4) (actual time=0.010..0.035 rows=101 loops=1) 
Planning time: 0.245 ms 
Execution time: 240.448 ms 

Чтобы иметь такую ​​же производительность, присоединяемый к массиву:

explain analyze 
select i 
from 
    t 
    inner join 
    unnest(
     array[500,501,502,503,504,505,506,507,508,509,510,511,512,513,514,515,516,517,518,519,520,521,522,523,524,525,526,527,528,529,530,531,532,533,534,535,536,537,538,539,540,541,542,543,544,545,546,547,548,549,550,551,552,553,554,555,556,557,558,559,560,561,562,563,564,565,566,567,568,569,570,571,572,573,574,575,576,577,578,579,580,581,582,583,584,585,586,587,588,589,590,591,592,593,594,595,596,597,598,599,600]::int[] 
    ) u (i) using (i) 
; 
                 QUERY PLAN              
----------------------------------------------------------------------------------------------------------------------- 
Hash Join (cost=2.25..18178.25 rows=100 width=4) (actual time=0.267..243.768 rows=101 loops=1) 
    Hash Cond: (t.i = u.i) 
    -> Seq Scan on t (cost=0.00..14425.00 rows=1000000 width=4) (actual time=0.022..118.709 rows=1000000 loops=1) 
    -> Hash (cost=1.00..1.00 rows=100 width=4) (actual time=0.063..0.063 rows=101 loops=1) 
     Buckets: 1024 Batches: 1 Memory Usage: 12kB 
     -> Function Scan on unnest u (cost=0.00..1.00 rows=100 width=4) (actual time=0.028..0.041 rows=101 loops=1) 
Planning time: 0.172 ms 
Execution time: 243.816 ms 

Или используйте синтаксис values:

explain analyze 
select i 
from t 
where i = any (values (500),(501),(502),(503),(504),(505),(506),(507),(508),(509),(510),(511),(512),(513),(514),(515),(516),(517),(518),(519),(520),(521),(522),(523),(524),(525),(526),(527),(528),(529),(530),(531),(532),(533),(534),(535),(536),(537),(538),(539),(540),(541),(542),(543),(544),(545),(546),(547),(548),(549),(550),(551),(552),(553),(554),(555),(556),(557),(558),(559),(560),(561),(562),(563),(564),(565),(566),(567),(568),(569),(570),(571),(572),(573),(574),(575),(576),(577),(578),(579),(580),(581),(582),(583),(584),(585),(586),(587),(588),(589),(590),(591),(592),(593),(594),(595),(596),(597),(598),(599),(600)) 
; 
                 QUERY PLAN              
----------------------------------------------------------------------------------------------------------------------- 
Hash Semi Join (cost=2.53..17053.65 rows=101 width=4) (actual time=0.279..239.888 rows=101 loops=1) 
    Hash Cond: (t.i = "*VALUES*".column1) 
    -> Seq Scan on t (cost=0.00..14425.00 rows=1000000 width=4) (actual time=0.022..117.199 rows=1000000 loops=1) 
    -> Hash (cost=1.26..1.26 rows=101 width=4) (actual time=0.059..0.059 rows=101 loops=1) 
     Buckets: 1024 Batches: 1 Memory Usage: 12kB 
     -> Values Scan on "*VALUES*" (cost=0.00..1.26 rows=101 width=4) (actual time=0.002..0.027 rows=101 loops=1) 
Planning time: 0.242 ms 
Execution time: 239.933 ms 

Answer 2

Попробуйте изменить критическую линию к этому:

where y_id = any (values (1625, 1871, ..., 1640, 1643, 13291, 1458, 13304, 1407, 1765))