Re: bad plan - Mailing list pgsql-performance

From Richard Huxton
Subject Re: bad plan
Date
Msg-id 422D8F0E.8000906@archonet.com
Whole thread Raw
In response to bad plan  (Gaetano Mendola <mendola@bigfoot.com>)
Responses Re: bad plan
List pgsql-performance
Gaetano Mendola wrote:
> running a 7.4.5 engine, I'm facing this bad plan:
>
> empdb=# explain analyze SELECT name,url,descr,request_status,url_status,size_mb,estimated_start,request_time_stamp
> empdb-#                    FROM v_sc_user_request
> empdb-#                    WHERE
> empdb-#                         login = 'babinow1'
> empdb-#                    LIMIT 10 ;

>                      ->  Subquery Scan vsp  (cost=985.73..1016.53 rows=1103 width=12) (actual time=25.328..1668.754
rows=493loops=31) 
>                            ->  Merge Join  (cost=985.73..1011.01 rows=1103 width=130) (actual time=25.321..1666.666
rows=493loops=31) 
>                                  Merge Cond: ("outer".id_program = "inner".id_program)

The problem to address is in this subquery. That's a total of 31 x
(1668.754 - 25.328) = 50seconds (about).

Since your query is so simple, I'm guessing v_sc_user_request is a view.
Can you provide the definition?
--
   Richard Huxton
   Archonet Ltd

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