from:"vincent.moreau"

[PERFORM] Execution plan changed after upgrade from 7.3.9 to 8.2.3

2007-03-13 Thread vincent.moreau


Hello,


I have upgraded from 7.3.9 to 8.2.3 and now the application that is 
using Postgres is really slow.
Using pgfouine, I was able to identify a SQL select statement that was 
running in 500 ms before and now that is running in more than 20 seconds !


The reason is that the execution plan is different from the 2 versions.
The difference is the order the tables are joined :

For 8.2.3 :
Seq Scan on lm05_t_tarif_panneau g (cost=0.00..2977.08 rows=18947 
width=43) (actual time=0.006..65.388 rows=4062 loops=280)


For 7.3.9 :
Seq Scan on lm05_t_tarif_panneau g  (cost=0.00..90.00 rows=692 
width=190) (actual time=0.03..206.23 rows=4062 loops=1)


Is there an option in the 8.2.3 to change in order to have the same 
execution plan than before ?
I have compared the 2 postgresql.conf files and there are no differences 
as far as I know.


Thanks for your help.

Best Regards,
Vincent Moreau


For 7.3.9 :

Unique  (cost=232.48..232.51 rows=1 width=497) (actual 
time=524.49..543.00 rows=140 loops=1)



 ->  Seq Scan on 
lm05_t_tarif_panneau g  (cost=0.00..90.00 rows=692 width=190) (actual 
time=0.03..206.23 rows=4062 loops=1)
   Filter: 
(((lrg_min < 1000) AND (lrg_max >= 1000)) OR ((lrg_min < 500) AND 
(lrg_max >= 500)) OR (((
lrg_min)::numeric < 333.) AND ((lrg_max)::numeric >= 
333.)) OR ((lrg_min < 250) AND (lrg_max >= 250)) OR 
((lrg_min < 200) AND (lrg_
max >= 200)) OR (((lrg_min)::numeric < 166.6667) AND 
((lrg_max)::numeric >= 166.6667)) OR (((lrg_min)::numeric < 
142.857142857143) AND ((lr
g_max)::numeric >= 142.857142857143)) OR ((lrg_min < 125) AND (lrg_max 
>= 125)) OR (((lrg_min)::numeric < 111.) AND 
((lrg_max)::numeric >= 111.

)) OR ((lrg_min < 100) AND (lrg_max >= 100)))
 ->  Hash  
(cost=32.35..32.35 rows=1 width=8) (actual time=19.07..19.07 rows=0 
loops=1)
   ->  Nested Loop  
(cost=0.00..32.35 rows=1 width=8) (actual time=17.99..19.07 rows=1 loops=1)
 ->  Seq 
Scan on cm_gestion_modele_ca h  (cost=0.00..27.50 rows=1 width=4) 
(actual time=0.09..17.35 rows=165 loops=1)
   
Filter: ((idmagasin = '011'::character varying) AND (idoav = 
'PC_PLACARD'::character varying) AND (autorise = 1))
 ->  Index 
Scan using lm05_t_modele_cod_modele_key on lm05_t_modele a  
(cost=0.00..4.83 rows=1 width=4) (actual time=0.01..0.01 rows=0 loops=165)
   
Index Cond: ("outer".cod_modele = a.cod_modele)
   
Filter: ((cod_type_ouverture = 'OUV_COU'::character varying) AND 
(cod_type_panneau = 'PAN_MEL'::character varying) AND (cod_fournisseur = 
5132) AND (cod_gamme_prof = 'Design Xtra'::character varying))





For 8.2.3 :

Unique (cost=5278.93..5278.95 rows=1 width=32) (actual 
time=27769.435..27771.863 rows=140 loops=1)


...

-> Hash Join (cost=6.31..3055.59 rows=115 width=47) (actual 
time=58.096..67.787 rows=48 loops=280)


Hash Cond: (g.cod_modele = a.cod_modele)

-> Seq Scan on lm05_t_tarif_panneau g (cost=0.00..2977.08 rows=18947 
width=43) (actual time=0.006..65.388 rows=4062 loops=280)


Filter: (((lrg_min < 1000) AND (lrg_max >= 1000)) OR ((lrg_min < 500) 
AND (lrg_max >= 500)) OR (((lrg_min)::numeric < 333.) AND 
((lrg_max)::numeric >= 333.)) OR ((lrg_min < 250) AND 
(lrg_max >= 250)) OR ((lrg_min < 200) AND (lrg_max >= 200)) OR 
(((lrg_min)::numeric < 166.6667) AND ((lrg_max)::numeric >= 
166.6667)) OR (((lrg_min)::numeric < 142.857142857143) AND 
((lrg_max)::numeric >= 142.857142857143)) OR ((lrg_min < 125) AND 
(lrg_max >= 125)) OR (((lrg_min)::numeric < 111.) AND 
((lrg_max)::numeric >= 111.)) OR ((lrg_min < 100) AND 
(lrg_max >= 100)))


-> Hash (cost=6.30..6.30 rows=1 width=4) (actual time=0.135..0.135 
rows=1 loops=1)


-> Seq Scan on lm05_t_modele a (cost=0.00..6.30 rows=1 width=4) (actual 
time=0.053..0.124 rows=1 loops=1)


Filter: (((cod_type_ouverture)::text = 'OUV_COU'::text) AND 
((cod_type_panneau)::text = 'PAN_MEL'::text) AND (cod_fournisseur = 
5132) AND ((cod_gamme_prof)::text = 'Design Xtra'::text))


-> Seq Scan on mag_gestion_modele_mag i (cost=0.00..8.78 rows=165 
width=4) (actual time=0.053..0.214 rows=165 loops=1120)


Filter: (((idmagasin)::text = '011'::text) AND ((idoav)::text = 
'PC_PLACARD'::text) AND (selection = 1))




Ce message et toutes les pièces jointes sont établis à l'attention exclusive de 
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Re: [PERFORM] Execution plan changed after upgrade from 7.3.9 to 8.2.3

2007-03-13 Thread vincent.moreau

I have attached the requested information.

You will see that the query is quite messy and could be easily improved.
Unfortunately, it came from a third party application and we do not have 
access to the source code.

Thanks for your help,

Best Regards,
Vincent




Michael Fuhr wrote:
> On Tue, Mar 13, 2007 at 09:19:47AM +0100, [EMAIL PROTECTED] wrote:
>   
>> Is there an option in the 8.2.3 to change in order to have the same 
>> execution plan than before ?
>> 
>
> Let's see if we can figure out why 8.2.3 is choosing a bad plan.
> Have you run ANALYZE on the tables in 8.2.3?  Could you post the
> query and the complete output of EXPLAIN ANALYZE (preferably without
> wrapping) for both versions?
>
>   


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-bash-2.05b$ psql CCM 
Welcome to psql 8.2.3, the PostgreSQL interactive terminal.

Type:  \copyright for distribution terms
   \h for help with SQL commands
   \? for help with psql commands
   \g or terminate with semicolon to execute query
   \q to quit

CCM=# VACUUM FULL ANALYZE ;
VACUUM
CCM=# explain ANALYZE SELECT distinct C.cod_couleur_panneau, 
C.cod_couleur_panneau, cast ('LM05' as varchar), cast ('OMM_TEINTE' as 
varchar), cast ('IM' as varchar) FROM lm05_t_modele AS A, 
lm05_t_couleur_panneau AS C, lm05_t_infos_modele AS D, lm05_t_tarif_panneau AS 
G , lm05_t_composition AS E , lm05_t_couleur_profile AS F , 
cm_gestion_modele_ca as H, mag_gestion_modele_mag as I WHERE 
A.cod_type_ouverture = 'OUV_COU' AND A.cod_type_panneau = 'PAN_MEL' AND 
A.cod_modele = C.cod_modele AND A.cod_modele = D.cod_modele AND A.cod_modele = 
G.cod_modele AND G.cod_tarif_panneau = C.cod_tarif_panneau AND A.cod_modele = 
E.cod_modele AND nb_vantaux >= 2 AND A.cod_modele = F.cod_modele AND 
F.couleur_profile = 'acajou mat' AND F.cod_tarif_profile = G.cod_tarif_profile 
AND A.cod_fournisseur = '5132' AND A.cod_gamme_prof = 'Design Xtra' AND 
C.ht_min < 2000 AND C.ht_max >= 2000 AND D.largeur_maxi_rail >= 1000 AND 
C.cod_aspect = 'tons bois et cuirs' AND C.cod_gamme_panneau = 'BOIS et CUIR 
XTRA 3' AND ((G.lrg_min < 1000 AND G.lrg_max >= 1000) OR (G.lrg_min < 500 AND 
G.lrg_max >= 500) OR (G.lrg_min < 333. AND G.lrg_max >= 
333.) OR (G.lrg_min < 250 AND G.lrg_max >= 250) OR (G.lrg_min < 200 
AND G.lrg_max >= 200) OR (G.lrg_min < 166.6667 AND G.lrg_max >= 
166.6667) OR (G.lrg_min < 142.857142857143 AND G.lrg_max >= 
142.857142857143) OR (G.lrg_min < 125 AND G.lrg_max >= 125) OR (G.lrg_min < 
111. AND G.lrg_max >= 111.) OR (G.lrg_min < 100 AND 
G.lrg_max >= 100)) AND H.idmagasin = '011' AND H.idoav='PC_PLACARD' AND 
H.cod_modele = A.cod_modele AND H.autorise = 1 AND I.idmagasin = '011' AND 
I.idoav='PC_PLACARD' AND I.cod_modele = A.cod_modele AND I.selection = 1;

  

  

  QUERY PLAN  

  

  

--
--
--
--
--

 Unique  (cost=5276.93..5276.95 rows=1 width=32) (actual 
time=28977.716..28980.225 rows=140 loops=1)
   ->  Sort  (cost=5276.93..5276.94 rows=1 width=32) (actual 
time=28977.712..28978.464 rows=1400 loops=1)
 Sort Key: c.cod_couleur_panneau, c.cod_couleur_panneau, 
'LM05'::character varying, 'OMM_TEINTE'::character varying, 'IM'::character 
varying
 ->  Nested Loop  (cost=6.31..5276.92 rows=1 width=32) (actual 
time=111.982..28945.37

Re: [PERFORM] Execution plan changed after upgrade from 7.3.9 to 8.2.3

2007-03-13 Thread vincent.moreau


Thanks for the update.

The following did not change anything in the execution plan

ALTER TABLE lm05_t_tarif_panneau ALTER COLUMN lrg_min SET STATISTICS 1000
ALTER TABLE lm05_t_tarif_panneau ALTER COLUMN lrg_max SET STATISTICS 1000
ANALYZE lm05_t_tarif_panneau

I was able to improve response time by creating indexes, but I would 
like to avoid changing the database structure because it is not 
maintained by ourseleves, but by the  third party vendor.




Richard Huxton wrote:

[EMAIL PROTECTED] wrote:

I have attached the requested information.

You will see that the query is quite messy and could be easily improved.
Unfortunately, it came from a third party application and we do not 
have access to the source code.


->  Hash Join  (cost=6.31..3056.17 rows=116 width=47) (actual 
time=60.055..70.078 rows=48 loops=280)

Hash Cond: (g.cod_modele = a.cod_modele)
->  Seq Scan on lm05_t_tarif_panneau g  (cost=0.00..2977.08 
rows=19097 width=43) (actual time=0.008..67.670 rows=4062 loops=280)


It does seem to be running that sequential scan 280 times, which is a 
strange choice to say the least.


Obvious thing #1 is to look at I'd say is the stats on lrg_min,lrg_max 
- try something like:

ALTER TABLE lm05_t_tarif_panneau ALTER COLUMN lrg_min SET STATISTICS 
You can set  up to 1000 (and then the same for lrg_max of course).
Analyse the table again and see if that gives it a clue.

Second thing might be to try indexes on lrg_min and lrg_max and see if 
the bitmap code in 8.2 helps things.


Very strange plan.



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Re: [PERFORM] Execution plan changed after upgrade from 7.3.9 to 8.2.3

2007-03-13 Thread vincent.moreau

Here it is :

CCM=# SHOW enable_mergejoin;
enable_mergejoin
--
on
(1 row)

CCM=#

Alvaro Herrera wrote:
> [EMAIL PROTECTED] wrote:
>   
>> I have attached the requested information.
>>
>> You will see that the query is quite messy and could be easily improved.
>> Unfortunately, it came from a third party application and we do not have 
>> access to the source code.
>> 
>
> There are only nested loops and hash joins, while the other plan seems
> to be more elaborate -- I wonder if you have disabled bitmap scan, merge
> joins, in 8.2?   Try a SHOW enable_mergejoin in psql.
>
>   

Ce message et toutes les pièces jointes sont établis à l'attention exclusive de 
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erreur, merci de le détruire et d'en avertir immédiatement l'expéditeur. 
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---(end of broadcast)---
TIP 9: In versions below 8.0, the planner will ignore your desire to
   choose an index scan if your joining column's datatypes do not
   match

Re: [PERFORM] Execution plan changed after upgrade from 7.3.9 to 8.2.3

2007-03-13 Thread vincent.moreau

All planner types were enabled.

CCM=# select * from pg_settings where name like 'enable_%';
   name| setting | unit |  category 
  |   short_desc   | extra_desc | 
context | vartype | source  | min_val | max_val 
---+-+--+-+++-+-+-+-+-
 enable_bitmapscan | on  |  | Query Tuning / Planner Method 
Configuration | Enables the planner's use of bitmap-scan plans.|
| user| bool| default | | 
 enable_hashagg| on  |  | Query Tuning / Planner Method 
Configuration | Enables the planner's use of hashed aggregation plans. |
| user| bool| default | | 
 enable_hashjoin   | on  |  | Query Tuning / Planner Method 
Configuration | Enables the planner's use of hash join plans.  |
| user| bool| default | | 
 enable_indexscan  | on  |  | Query Tuning / Planner Method 
Configuration | Enables the planner's use of index-scan plans. |
| user| bool| default | | 
 enable_mergejoin  | on  |  | Query Tuning / Planner Method 
Configuration | Enables the planner's use of merge join plans. |
| user| bool| default | | 
 enable_nestloop   | on  |  | Query Tuning / Planner Method 
Configuration | Enables the planner's use of nested-loop join plans.   |
| user| bool| default | | 
 enable_seqscan| on  |  | Query Tuning / Planner Method 
Configuration | Enables the planner's use of sequential-scan plans.|
| user| bool| default | | 
 enable_sort   | on  |  | Query Tuning / Planner Method 
Configuration | Enables the planner's use of explicit sort steps.  |
| user| bool| default | | 
 enable_tidscan| on  |  | Query Tuning / Planner Method 
Configuration | Enables the planner's use of TID scan plans.   |
| user| bool| default | | 
(9 rows)



I was able to improve response time by seting enable_seqscan to off

Here is the new analyze result :

CCM=# explain ANALYZE SELECT distinct C.cod_couleur_panneau, 
C.cod_couleur_panneau, cast ('LM05' as varchar), cast ('OMM_TEINTE' as 
varchar), cast ('IM' as varchar) FROM lm05_t_modele AS A, 
lm05_t_couleur_panneau AS C, lm05_t_infos_modele AS D, 
lm05_t_tarif_panneau AS G , lm05_t_composition AS E , 
lm05_t_couleur_profile AS F , cm_gestion_modele_ca as H, 
mag_gestion_modele_mag as I WHERE A.cod_type_ouverture = 'OUV_COU' AND 
A.cod_type_panneau = 'PAN_MEL' AND A.cod_modele = C.cod_modele AND 
A.cod_modele = D.cod_modele AND A.cod_modele = G.cod_modele AND 
G.cod_tarif_panneau = C.cod_tarif_panneau AND A.cod_modele = 
E.cod_modele AND nb_vantaux >= 2 AND A.cod_modele = F.cod_modele AND 
F.couleur_profile = 'acajou mat' AND F.cod_tarif_profile = 
G.cod_tarif_profile AND A.cod_fournisseur = '5132' AND A.cod_gamme_prof 
= 'Design Xtra' AND C.ht_min < 2000 AND C.ht_max >= 2000 AND 
D.largeur_maxi_rail >= 1000 AND C.cod_aspect = 'tons bois et cuirs' AND 
C.cod_gamme_panneau = 'BOIS et CUIR XTRA 3' AND ((G.lrg_min < 1000 AND 
G.lrg_max >= 1000) OR (G.lrg_min < 500 AND G.lrg_max >= 500) OR 
(G.lrg_min < 333. AND G.lrg_max >= 333.) OR 
(G.lrg_min < 250 AND G.lrg_max >= 250) OR (G.lrg_min < 200 AND G.lrg_max 
 >= 200) OR (G.lrg_min < 166.6667 AND G.lrg_max >= 
166.6667) OR (G.lrg_min < 142.857142857143 AND G.lrg_max >= 
142.857142857143) OR (G.lrg_min < 125 AND G.lrg_max >= 125) OR 
(G.lrg_min < 111. AND G.lrg_max >= 111.) OR 
(G.lrg_min < 100 AND G.lrg_max >= 100)) AND H.idmagasin = '011' AND 
H.idoav='PC_PLACARD' AND H.cod_modele = A.cod_modele AND H.autorise = 1 
AND I.idmagasin = '011' AND I.idoav='PC_PLACARD' AND I.cod_modele = 
A.cod_modele AND I.selection = 1;


QUERY PLAN


---
---
---
---
--
Unique (cost=75413.95..75413.97 rows=1 width=32) (actual 
time=1232.497..1234.961 rows=140 loops=1)
-> Sort (cost=75413.95..75413.96 rows=1 width=32) (actual 
time=1232.494..1233

Re: [PERFORM] Execution plan changed after upgrade from 7.3.9 to 8.2.3

2007-03-13 Thread vincent.moreau

Increasing the default_statistics_target to 1000 did not help.
It just make the vacuum full analyze to take longer to complete.

Here is the output :

CCM=# VACUUM FULL ANALYZE ;
VACUUM
CCM=# explain ANALYZE SELECT distinct C.cod_couleur_panneau, 
C.cod_couleur_panneau, cast ('LM05' as varchar), cast ('OMM_TEINTE' as 
varchar), cast ('IM' as varchar) FROM lm05_t_modele AS A, 
lm05_t_couleur_panneau AS C, lm05_t_infos_modele AS D, 
lm05_t_tarif_panneau AS G , lm05_t_composition AS E , 
lm05_t_couleur_profile AS F , cm_gestion_modele_ca as H, 
mag_gestion_modele_mag as I WHERE A.cod_type_ouverture = 'OUV_COU' AND 
A.cod_type_panneau = 'PAN_MEL' AND A.cod_modele = C.cod_modele AND 
A.cod_modele = D.cod_modele AND A.cod_modele = G.cod_modele AND 
G.cod_tarif_panneau = C.cod_tarif_panneau AND A.cod_modele = 
E.cod_modele AND nb_vantaux >= 2 AND A.cod_modele = F.cod_modele AND 
F.couleur_profile = 'acajou mat' AND F.cod_tarif_profile = 
G.cod_tarif_profile AND A.cod_fournisseur = '5132' AND A.cod_gamme_prof 
= 'Design Xtra' AND C.ht_min < 2000 AND C.ht_max >= 2000 AND 
D.largeur_maxi_rail >= 1000 AND C.cod_aspect = 'tons bois et cuirs' AND 
C.cod_gamme_panneau = 'BOIS et CUIR XTRA 3' AND ((G.lrg_min < 1000 AND 
G.lrg_max >= 1000) OR (G.lrg_min < 500 AND G.lrg_max >= 500) OR 
(G.lrg_min < 333. AND G.lrg_max >= 333.) OR 
(G.lrg_min < 250 AND G.lrg_max >= 250) OR (G.lrg_min < 200 AND G.lrg_max 
 >= 200) OR (G.lrg_min < 166.6667 AND G.lrg_max >= 
166.6667) OR (G.lrg_min < 142.857142857143 AND G.lrg_max >= 
142.857142857143) OR (G.lrg_min < 125 AND G.lrg_max >= 125) OR 
(G.lrg_min < 111. AND G.lrg_max >= 111.) OR 
(G.lrg_min < 100 AND G.lrg_max >= 100)) AND H.idmagasin = '011' AND 
H.idoav='PC_PLACARD' AND H.cod_modele = A.cod_modele AND H.autorise = 1 
AND I.idmagasin = '011' AND I.idoav='PC_PLACARD' AND I.cod_modele = 
A.cod_modele AND I.selection = 1;


QUERY PLAN



--
--
--
--
--
--
Unique (cost=5275.40..5275.42 rows=1 width=32) (actual 
time=21566.453..21568.917 rows=140 loops=1)
-> Sort (cost=5275.40..5275.41 rows=1 width=32) (actual 
time=21566.450..21567.212 rows=1400 loops=1)
Sort Key: c.cod_couleur_panneau, c.cod_couleur_panneau, 
'LM05'::character varying, 'OMM_TEINTE'::character varyin
g, 'IM'::character varying
-> Nested Loop (cost=105.58..5275.39 rows=1 width=32) (actual 
time=94.901..21534.435 rows=1400 loops=1)
Join Filter: (a.cod_modele = d.cod_modele)
-> Nested Loop (cost=105.58..5267.27 rows=1 width=60) (actual 
time=94.700..21213.793 rows=1400 loops=1)
Join Filter: (a.cod_modele = e.cod_modele)
-> Nested Loop (cost=105.58..5245.28 rows=1 width=56) (actual 
time=93.912..20996.857 rows=280 loops
=1)
Join Filter: (h.cod_modele = a.cod_modele)
-> Nested Loop (cost=105.58..4731.94 rows=1 width=52) (actual 
time=86.994..19181.638 rows=280
loops=1)
Join Filter: (i.cod_modele = a.cod_modele)
-> Nested Loop (cost=105.58..4721.10 rows=1 width=48) (actual 
time=86.651..19091.147 ro
ws=280 loops=1)
Join Filter: ((a.cod_modele = c.cod_modele) AND 
((g.cod_tarif_panneau)::text = (c.c
od_tarif_panneau)::text) AND ((f.cod_tarif_profile)::text = 
(g.cod_tarif_profile)::text))
-> Hash Join (cost=99.26..1665.04 rows=1 width=84) (actual 
time=25.598..31.845 ro
ws=280 loops=1)
Hash Cond: (c.cod_modele = f.cod_modele)
-> Seq Scan on lm05_t_couleur_panneau c (cost=0.00..1565.60 rows=4 width=62
) (actual time=23.817..29.048 rows=280 loops=1)
Filter: ((ht_min < 2000) AND (ht_max >= 2000) AND ((cod_aspect)::text =
'tons bois et cuirs'::text) AND ((cod_gamme_panneau)::text = 'BOIS et 
CUIR XTRA 3'::text))
-> Hash (cost=98.86..98.86 rows=32 width=22) (actual time=1.653..1.653 rows
=32 loops=1)
-> Seq Scan on lm05_t_couleur_profile f (cost=0.00..98.86 rows=32 wid
th=22) (actual time=1.159..1.614 rows=32 loops=1)
Filter: ((couleur_profile)::text = 'acajou mat'::text)
-> Hash Join (cost=6.31..3054.10 rows=112 width=48) (actual 
time=58.304..68.027 r
ows=48 loops=280)
Hash Cond: (g.cod_modele = a.cod_modele)
-> Seq Scan on lm05_t_tarif_panneau g (cost=0.00..2977.08 rows=18557 width=
44) (actual time=0.009..65.642 rows=4062 loops=280)
Filter: (((lrg_min < 1000) AND (lrg_max >= 1000)) OR ((lrg_min < 500) A
ND (lrg_max >= 500)) OR (((lrg_min)::numeric < 333.) AND 
((lrg_max)::numeric >= 333.)) OR

Re: [PERFORM] Execution plan changed after upgrade from 7.3.9 to 8.2.3

2007-03-13 Thread vincent.moreau


Thanks for the advice Tom !

Setting enable_nestloop = off did improve the query a much better way 
than setting enable_seqscan to off.


It does not screw the costs either (I had very odd costs with 
enable_seqscan to off like this : Nested Loop  
(cost=41665.30..42197.96 rows=1 width=96)


Is there a "performance risk" to have enable_nestloop = off for other 
queries ?


If I had the choice, should I go for index creation for the specific 
tables or should I tweak the optimizer with enable_nestloop = off ?



Thanks again to all of you for your help.

Best Regards,
Vincent

Tom Lane wrote:

<[EMAIL PROTECTED]> writes:
  

I was able to improve response time by seting enable_seqscan to off



enable_nestloop = off would probably be a saner choice, at least for
this particular query.

regards, tom lane

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