Re: EXPLAIN times - Mailing list pgsql-general

From Afra
Subject Re: EXPLAIN times
Date
Msg-id 3DBED786.3050101@cse.buffalo.edu
Whole thread Raw
In response to EXPLAIN times  (Afra <aa4@cse.buffalo.edu>)
List pgsql-general
Thank you for the response.

We run VACUUM ANALYZE every night, so we don't think this is a problem.
Postgres was also installed the same ways for both and we fine-tuned
some of the variables in the config files (regarding memory, for example).

Thank you.

Afra

Neil Conway wrote:

> Afra  writes:
>
> >The postgres version for each box is 7.2.1.
>
>
> Upgrading to 7.2.3 would be a good idea (it won't effect this problem,
> it's just a good idea in general).
>
>
> >These are the EXPLAIN results on DB1:
> >
> >NOTICE:  QUERY PLAN:
> >
> >Merge Join  (cost=152183.00..271426.66 rows=9416137 width=105)
> >   ->  Sort  (cost=141295.60..141295.60 rows=613709 width=69)
> >         ->  Seq Scan on ord_contact_name  (cost=0.00..18568.09
> >rows=613709 width=69)
> >   ->  Sort  (cost=10887.40..10887.40 rows=3069 width=36)
> >         ->  Index Scan using dv_job_number_ord_dv_job_num_ke on
> >ord_dv_job_num  (cost=0.00..10709.67 rows=3069 width=36)
> >
> >And the EXPLAIN results on DB2:
> >
> >NOTICE:  QUERY PLAN:
> >
> >Nested Loop  (cost=0.00..9.91 rows=1 width=90)
> >   ->  Index Scan using dv_job_number_ord_dv_job_num_ke on
> >ord_dv_job_num  (cost=0.00..3.89 rows=1 width=40)
> >   ->  Index Scan using ord_obj_guid_ord_contact_name_k on
> >ord_contact_name  (cost=0.00..6.01 rows=1 width=50)
>
>
> Have you run VACUUM ANALYZE on both databases recently? (if you
> haven't, do so). The statistics for DB1 look bizarrely incorrect, so
> I'd suspect that updating them will fix the problem.
>
> Is PostgreSQL configured in the same way on both systems?
>
> Cheers,
>
> Neil
>


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