From: "Joel Fradkin" <jfradkin@wazagua.com>
To: "'Michael Fuhr'" <mike@fuhr.org>
Cc: <pgsql-sql@postgresql.org>
Subject: Re: MSSQL versus Postgres timing
Date: Tue, 1 Feb 2005 14:26:07 -0500
Message-ID: <000101c50893$e25da5d0$797ba8c0@jfradkin>
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With seq scan on.
-----Original Message-----
From: Michael Fuhr [mailto:mike@fuhr.org] 
Sent: Tuesday, February 01, 2005 12:07 PM
To: Joel Fradkin
Cc: pgsql-sql@postgresql.org
Subject: Re: [SQL] MSSQL versus Postgres timing

On Tue, Feb 01, 2005 at 11:54:11AM -0500, Joel Fradkin wrote:
> 
> A table with 645,000 records for associates has view (basically select *
> from tblassociates where clientnum = 'test')
> 
> This is taking 13 seconds in postgres and 3 seconds in MSSQL.

Please post the EXPLAIN ANALYZE output for the slow query, once
with enable_seqscan on and once with it off.  For example:

SET enable_seqscan TO on;  -- if not already on
EXPLAIN ANALYZE SELECT * FROM tblassociates WHERE clientnum = 'test';

SET enable_seqscan TO off;
EXPLAIN ANALYZE SELECT * FROM tblassociates WHERE clientnum = 'test';

> Be glad to provide the view and tables etc.

Please do -- it might help us spot something that could be improved.
What version of PostgreSQL are you using?

-- 
Michael Fuhr
http://www.fuhr.org/~mfuhr/

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QUERY PLAN
"Merge Join  (cost=3D47489.81..47975.65 rows=3D3758 width=3D111) (actual =
time=3D27167.305..29701.080 rows=3D85694 loops=3D1)"
"  Merge Cond: (""outer"".locationid =3D ""inner"".locationid)"
"  ->  Sort  (cost=3D1168.37..1169.15 rows=3D312 width=3D48) (actual =
time=3D261.096..262.410 rows=3D402 loops=3D1)"
"        Sort Key: l.locationid"
"        ->  Index Scan using ix_tbllocation on tbllocation l  =
(cost=3D0.00..1155.44 rows=3D312 width=3D48) (actual =
time=3D213.107..259.160 rows=3D402 loops=3D1)"
"              Index Cond: ('SAKS'::text =3D (clientnum)::text)"
"  ->  Sort  (cost=3D46321.45..46535.47 rows=3D85611 width=3D74) (actual =
time=3D26906.148..27689.258 rows=3D85695 loops=3D1)"
"        Sort Key: a.locationid"
"        ->  Merge Right Join  (cost=3D38119.24..39307.55 rows=3D85611 =
width=3D74) (actual time=3D22236.915..25384.945 rows=3D99139 loops=3D1)"
"              Merge Cond: (((""outer"".clientnum)::text =3D =
""inner"".""?column10?"") AND (""outer"".id =3D ""inner"".jobtitleid))"
"              ->  Index Scan using ix_tbljobtitle_id on tbljobtitle jt  =
(cost=3D0.00..338.90 rows=3D6337 width=3D37) (actual =
time=3D164.976..2290.760 rows=3D5662 loops=3D1)"
"                    Filter: (1 =3D presentationid)"
"              ->  Sort  (cost=3D38119.24..38333.26 rows=3D85611 =
width=3D52) (actual time=3D20667.645..21031.627 rows=3D99139 loops=3D1)"
"                    Sort Key: (a.clientnum)::text, a.jobtitleid"
"                    ->  Seq Scan on tblassociate a  =
(cost=3D0.00..31105.34 rows=3D85611 width=3D52) (actual =
time=3D14.768..16024.395 rows=3D99139 loops=3D1)"
"                          Filter: ((clientnum)::text =3D 'SAKS'::text)"
"Total runtime: 30319.859 ms"

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