Slow execution time when querying view with WHERE clause
| От | Mike Mascari |
|---|---|
| Тема | Slow execution time when querying view with WHERE clause |
| Дата | |
| Msg-id | 41A25C3B.3040608@mascari.com обсуждение исходный текст |
| Ответы |
Re: Slow execution time when querying view with WHERE clause
(Mike Mascari <mascarm@mascari.com>)
Re: Slow execution time when querying view with WHERE clause (Tom Lane <tgl@sss.pgh.pa.us>) |
| Список | pgsql-performance |
I have the following view:
create or replace view market.p_areas as
select a.*
from _areas a
where a.area in (
select b.area
from _bins b, _inventories i, _offers o, _pricemembers p
where b.bin = i.bin and
i.inventory = o.inventory and
o.pricegroup = p.pricegroup and
p.buyer in (
select s.store
from _stores s, _webusers w
where w.webuser = getWebuser() and
w.company = s.company
union
select s.store
from _stores s, _companies c
where s.company = c.company and
c.companyid = 'DEFAULT'
)
);
When I query the view without a where clause I get:
explain analyze select * from p_areas;
QUERY PLAN
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Hash Join (cost=1273.12..1276.31 rows=47 width=163) (actual time=438.739..439.574 rows=34 loops=1)
Hash Cond: ("outer".area = "inner".area)
-> Seq Scan on _areas a (cost=0.00..2.48 rows=48 width=163) (actual time=0.015..0.169 rows=48 loops=1)
-> Hash (cost=1273.01..1273.01 rows=47 width=8) (actual time=438.532..438.532 rows=0 loops=1)
-> HashAggregate (cost=1273.01..1273.01 rows=47 width=8) (actual time=438.286..438.395 rows=34 loops=1)
-> Hash Join (cost=558.53..1266.68 rows=2532 width=8) (actual time=160.923..416.968 rows=5264
loops=1)
Hash Cond: ("outer".bin = "inner".bin)
-> Hash Join (cost=544.02..1207.86 rows=2531 width=8) (actual time=156.097..356.560 rows=5264
loops=1)
Hash Cond: ("outer".inventory = "inner".inventory)
-> Seq Scan on _inventories i (cost=0.00..265.96 rows=11396 width=16) (actual
time=0.010..44.047rows=11433 loops=1)
-> Hash (cost=537.14..537.14 rows=2751 width=8) (actual time=155.891..155.891 rows=0
loops=1)
-> Hash Join (cost=13.96..537.14 rows=2751 width=8) (actual time=11.967..136.598
rows=5264loops=1)
Hash Cond: ("outer".pricegroup = "inner".pricegroup)
-> Seq Scan on _offers o (cost=0.00..379.24 rows=15524 width=16) (actual
time=0.008..50.335rows=15599 loops=1)
-> Hash (cost=13.94..13.94 rows=9 width=8) (actual time=11.861..11.861 rows=0
loops=1)
-> Hash IN Join (cost=8.74..13.94 rows=9 width=8) (actual
time=10.801..11.801rows=12 loops=1)
Hash Cond: ("outer".buyer = "inner".store)
-> Seq Scan on _pricemembers p (cost=0.00..4.07 rows=207
width=16)(actual time=0.011..0.548 rows=207 loops=1)
-> Hash (cost=8.72..8.72 rows=8 width=8) (actual
time=10.687..10.687rows=0 loops=1)
-> Subquery Scan "IN_subquery" (cost=8.60..8.72 rows=8
width=8)(actual time=10.645..10.654 rows=1 loops=1)
-> Unique (cost=8.60..8.64 rows=8 width=8) (actual
time=10.631..10.636rows=1 loops=1)
-> Sort (cost=8.60..8.62 rows=8 width=8)
(actualtime=10.625..10.627 rows=1 loops=1)
Sort Key: store
-> Append (cost=2.86..8.48 rows=8
width=8)(actual time=10.529..10.583 rows=1 loops=1)
-> Subquery Scan "*SELECT* 1"
(cost=2.86..5.15rows=5 width=8) (actual time=10.222..10.222 rows=0 loops=1)
-> Hash Join (cost=2.86..5.10
rows=5width=8) (actual time=10.214..10.214 rows=0 loops=1)
Hash Cond:
("outer".company= "inner".company)
-> Seq Scan on _stores s
(cost=0.00..2.13 rows=13 width=16) (actual time=0.019..0.059 rows=13 loops=1)
-> Hash
(cost=2.85..2.85rows=1 width=8) (actual time=10.031..10.031 rows=0 loops=1)
-> Seq Scan on
_webusersw (cost=0.00..2.85 rows=1 width=8) (actual time=10.023..10.023 rows=0 loops=1)
Filter:
(webuser= getwebuser())
-> Subquery Scan "*SELECT* 2"
(cost=1.08..3.33rows=3 width=8) (actual time=0.298..0.349 rows=1 loops=1)
-> Hash Join (cost=1.08..3.30
rows=3width=8) (actual time=0.287..0.335 rows=1 loops=1)
Hash Cond:
("outer".company= "inner".company)
-> Seq Scan on _stores s
(cost=0.00..2.13 rows=13 width=16) (actual time=0.008..0.048 rows=13 loops=1)
-> Hash
(cost=1.07..1.07rows=1 width=8) (actual time=0.111..0.111 rows=0 loops=1)
-> Seq Scan on
_companiesc (cost=0.00..1.07 rows=1 width=8) (actual time=0.059..0.080 rows=1 loops=1)
Filter:
((companyid)::text= 'DEFAULT'::text)
-> Hash (cost=13.01..13.01 rows=601 width=16) (actual time=4.735..4.735 rows=0 loops=1)
-> Seq Scan on _bins b (cost=0.00..13.01 rows=601 width=16) (actual time=0.054..2.846
rows=601loops=1)
Total runtime: 441.685 ms
(41 rows)
---
When I query the view with a simple filter, I get:
explain analyze select * from p_areas where deactive is null;
QUERY PLAN
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Nested Loop IN Join (cost=8.60..524.28 rows=1 width=163) (actual time=1023.291..20025.620 rows=34 loops=1)
Join Filter: ("outer".area = "inner".area)
-> Seq Scan on _areas a (cost=0.00..2.48 rows=1 width=163) (actual time=0.037..0.804 rows=48 loops=1)
Filter: (deactive IS NULL)
-> Nested Loop (cost=8.60..25530.60 rows=2532 width=8) (actual time=0.345..402.775 rows=3408 loops=48)
-> Nested Loop (cost=8.60..16893.61 rows=2531 width=8) (actual time=0.304..264.929 rows=3408 loops=48)
-> Merge Join (cost=8.60..2912.00 rows=2751 width=8) (actual time=0.258..120.841 rows=3408 loops=48)
Merge Cond: ("outer".pricegroup = "inner".pricegroup)
-> Nested Loop IN Join (cost=8.60..1837.73 rows=9 width=8) (actual time=0.216..4.612 rows=8
loops=48)
Join Filter: ("outer".buyer = "inner".store)
-> Index Scan using i_pricemembers3 on _pricemembers p (cost=0.00..10.96 rows=207
width=16)(actual time=0.022..1.045 rows=138 loops=48)
-> Subquery Scan "IN_subquery" (cost=8.60..8.72 rows=8 width=8) (actual time=0.011..0.017
rows=1loops=6606)
-> Unique (cost=8.60..8.64 rows=8 width=8) (actual time=0.006..0.010 rows=1
loops=6606)
-> Sort (cost=8.60..8.62 rows=8 width=8) (actual time=0.003..0.004 rows=1
loops=6606)
Sort Key: store
-> Append (cost=2.86..8.48 rows=8 width=8) (actual time=7.667..7.757
rows=1loops=1)
-> Subquery Scan "*SELECT* 1" (cost=2.86..5.15 rows=5 width=8)
(actualtime=7.362..7.362 rows=0 loops=1)
-> Hash Join (cost=2.86..5.10 rows=5 width=8) (actual
time=7.355..7.355rows=0 loops=1)
Hash Cond: ("outer".company = "inner".company)
-> Seq Scan on _stores s (cost=0.00..2.13 rows=13
width=16)(actual time=0.013..0.054 rows=13 loops=1)
-> Hash (cost=2.85..2.85 rows=1 width=8) (actual
time=7.163..7.163rows=0 loops=1)
-> Seq Scan on _webusers w (cost=0.00..2.85
rows=1width=8) (actual time=7.154..7.154 rows=0 loops=1)
Filter: (webuser = getwebuser())
-> Subquery Scan "*SELECT* 2" (cost=1.08..3.33 rows=3 width=8)
(actualtime=0.295..0.381 rows=1 loops=1)
-> Hash Join (cost=1.08..3.30 rows=3 width=8) (actual
time=0.286..0.368rows=1 loops=1)
Hash Cond: ("outer".company = "inner".company)
-> Seq Scan on _stores s (cost=0.00..2.13 rows=13
width=16)(actual time=0.008..0.080 rows=13 loops=1)
-> Hash (cost=1.07..1.07 rows=1 width=8) (actual
time=0.116..0.116rows=0 loops=1)
-> Seq Scan on _companies c (cost=0.00..1.07
rows=1width=8) (actual time=0.062..0.083 rows=1 loops=1)
Filter: ((companyid)::text =
'DEFAULT'::text)
-> Index Scan using i_offers4 on _offers o (cost=0.00..1007.93 rows=15524 width=16) (actual
time=0.023..67.183rows=10049 loops=48)
-> Index Scan using i_inventories1 on _inventories i (cost=0.00..5.07 rows=1 width=16) (actual
time=0.025..0.029rows=1 loops=163561)
Index Cond: (i.inventory = "outer".inventory)
-> Index Scan using i_bins1 on _bins b (cost=0.00..3.40 rows=1 width=16) (actual time=0.021..0.026 rows=1
loops=163561)
Index Cond: (b.bin = "outer".bin)
Total runtime: 20027.414 ms
(36 rows)
---
That's a slow-down on execution time by a factor of 50, even
though the row count was the same: 34. In fact, it's MUCH
faster to do:
create temporary table foo as
select * from p_areas;
select * from foo
where deactive is null;
The database has been analyzed.
Any tips would be greatly appreciated.
Mike Mascari
P.S.: I turned off word-wrap in my mail client for this post.
Is that the right thing to do for analyze output?
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