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Thread: Optimize querry sql

Optimize querry sql

From
"Stanislas de Larocque"
Date:
Hi,

I had errors in my last emails. sorry

I want to optimize my query sql (execution time : 2665 ms) :

SELECT b.idxreseller, sum(a.nbrq), b.namereseller from stat a
,reseller b where b.asp=6 and a.idxreseller=b.reseller and
a.month=date_part('month',now() - interval '1 month') and
a.year=date_part('year',now() - interval '1 month') GROUP BY
b.idxreseller,b.namereseller limit 15;


Explain analyse :

Limit  (cost=1057.15..1057.16 rows=1 width=27) (actual
time=2655.083..2655.176 rows=15 loops=1)  ->  HashAggregate  (cost=1057.15..1057.16 rows=1 width=27) (actual
time=2655.074..2655.132 rows=15 loops=1)        ->  Nested Loop  (cost=0.00..1057.14 rows=1 width=27) (actual
time=0.646..2464.563 rows=18543 loops=1)              ->  Seq Scan on stat a  (cost=0.00..1042.98 rows=1
width=8) (actual time=0.273..1239.510 rows=24881 loops=1)                    Filter: (((month)::double precision =
date_part('month'::text, (now() - '1 mon'::interval))) AND
((year)::double precision = date_part('year'::text, (now() - '1
mon'::interval))))              ->  Index Scan using reseller_pkey on reseller b
(cost=0.00..14.15 rows=1 width=23) (actual time=0.034..0.038 rows=1
loops=24881)                    Index Cond: ("outer".idxrreseller = b.idxreseller)                    Filter: (asp =
6)Totalruntime: 2655.713 ms 




dns=> \d stat;                          Table «public.stat»
idxreseller | integer | not nullidxdo   | integer | not nullidxd       | integer | not nullnbrq         | integer |
default0month         | integer | default date_part('month'::text, (now() - 
'1 mon'::interval))year        | integer | default date_part('year'::text, (now() - '1
mon'::interval))

Index :  «stat_dns_domaine_idx_idxr_idxreseller» btree (dxreseller)  «stat_dns_domaine_idx_month_year_idxres» btree
(month,year, idxreseller) 




\d reseller;                                      Table «public.reseller»
idxreseller    | integer | not null default
nextval(('idxrevendeur_seq'::text)::regclass)namereseller     | text    |asp              | integer |
Index :  «reseller_pkey» PRIMARY KEY, btree (idxreseller)


Have you advices ?

Thank you

Stan

Re: Optimize querry sql

From
hubert depesz lubaczewski
Date:
On Fri, Sep 14, 2007 at 03:02:59PM +0200, Stanislas de Larocque wrote:
> I want to optimize my query sql (execution time : 2665 ms) :
SELECT   b.idxreseller,   sum(a.nbrq),   b.namereseller
from   stat a,   reseller b
where    b.asp=6    and a.idxreseller=b.reseller    and a.month=date_part('month',now() - interval '1 month')    and
a.year=date_part('year',now()- interval '1 month')
 
GROUP BY   b.idxreseller,b.namereseller limit 15;

1. cast all date_parts to int4, like in:   a.month = cast( date_part('month',now() - interval '1 month') as int4)
2. why there is a limit without any order by?
3. change it to get namereseller from subselect, not from join.

depesz

-- 
quicksil1er: "postgres is excellent, but like any DB it requires a
highly paid DBA.  here's my CV!" :)
http://www.depesz.com/ - blog dla ciebie (i moje CV)

Re: Optimize querry sql

From
"Stanislas de Larocque"
Date:
Hi,

I deleted the fonction date_part and now the time of the querry is : 464 ms !!!


Limit  (cost=1373.32..1373.50 rows=15 width=27) (actual
time=463.762..463.857 rows=15 loops=1)  ->  HashAggregate  (cost=1373.32..1408.52 rows=2816 width=27)
(actual time=463.755..463.820 rows=15 loops=1)        ->  Hash Join  (cost=149.72..1189.22 rows=24546 width=27)
(actual time=42.106..348.561 rows=18543 loops=1)              Hash Cond: ("outer".idxreseller = "inner".idxreseller)
         ->  Seq Scan on stat a  (cost=0.00..545.27 rows=24877
 
width=8) (actual time=0.054..167.340 rows=24881 loops=1)                    Filter: ((month = 8) AND (year = 2007))
        ->  Hash  (cost=142.68..142.68 rows=2816 width=23)
 
(actual time=41.954..41.954 rows=2816 loops=1)                    ->  Seq Scan on reseller b  (cost=0.00..142.68
rows=2816 width=23) (actual time=0.035..28.447 rows=2816 loops=1)                          Filter: (asp = 6)Total
runtime:464.337 ms
 

Have you advices to optimize the query please ?

Stan

2007/9/14, hubert depesz lubaczewski <depesz@depesz.com>:
> On Fri, Sep 14, 2007 at 03:02:59PM +0200, Stanislas de Larocque wrote:
> > I want to optimize my query sql (execution time : 2665 ms) :
> SELECT
>     b.idxreseller,
>     sum(a.nbrq),
>     b.namereseller
> from
>     stat a,
>     reseller b
> where
>      b.asp=6
>      and a.idxreseller=b.reseller
>      and a.month=date_part('month',now() - interval '1 month')
>      and a.year=date_part('year',now() - interval '1 month')
> GROUP BY
>     b.idxreseller,b.namereseller limit 15;
>
> 1. cast all date_parts to int4, like in:
>     a.month = cast( date_part('month',now() - interval '1 month') as int4)
> 2. why there is a limit without any order by?
> 3. change it to get namereseller from subselect, not from join.
>
> depesz
>
> --
> quicksil1er: "postgres is excellent, but like any DB it requires a
> highly paid DBA.  here's my CV!" :)
> http://www.depesz.com/ - blog dla ciebie (i moje CV)
>


-- 
Stanislas de Larocque
dllstan@gmail.com
06 63 64 00 47

Re: Optimize querry sql

From
hubert depesz lubaczewski
Date:
On Mon, Sep 17, 2007 at 09:17:58AM +0200, Stanislas de Larocque wrote:
> Have you advices to optimize the query please ?

for some many rows the 400ms looks quite reasonable.

the best thing you can make to speed things up is to calculate the
counts with triggers.

depesz

-- 
quicksil1er: "postgres is excellent, but like any DB it requires a
highly paid DBA.  here's my CV!" :)
http://www.depesz.com/ - blog dla ciebie (i moje CV)