From: Gary Stainburn <gary.stainburn@ringways.co.uk>
To: pgsql-sql@postgresql.org
Subject: Speed up slow select - was gone blind
Date: Fri, 1 Apr 2005 13:32:33 +0100
Message-ID: <200504011332.33404.gary.stainburn@ringways.co.uk> (raw)
Hi folks.
I've got my select working now, but I haven't received the speed
increase I'd expected. It replaced an earlier select which combined a
single explicit join with multiple froms.
The first select is the old one, the second one is the new one (with a
new join). The new one takes 24 seconds to run while the old one took
29.
How can I redo the select to improve the speed, or what else can I do to
optimaise the database?
original (ugly)
~~~~~
SELECT r.r_id, r.r_registration, r.r_chassis, r.r_vehicle, r.r_fuel,
r.r_pack_mats, r.r_delivery,
(date(r.r_delivery) - date(now())) AS r_remaining,
r.r_created, r.r_completed, r.r_salesman, r.salesman_name,
d.d_des, de.de_des,
u.u_id, u.u_userid, u.u_username, u.u_salesman, u.u_target,
t.t_id, t.t_des,
s.s_id, s.s_des,
c.c_id, c.c_des,
co.com_count, co.com_unseen
FROM (SELECT r.r_id, r.r_t_id, r.r_d_id, r.r_de_id, r.r_s_id,
r.r_registration, r.r_chassis, r.r_c_id, r.r_vehicle,
r.r_fuel, r.r_pack_mats, r.r_delivery, r.r_salesman,
r.r_created, r.r_completed, r.r_u_id,
u.u_username AS salesman_name
FROM (requests r LEFT JOIN users u ON
((r.r_salesman = u.u_id)))) r,
users u,
request_types t,
request_states s,
dealerships d,
departments de,
customers c,
comment_tallies co
WHERE (r.r_d_id = d.d_id) AND
(r.r_s_id = s.s_id) AND
(r.r_c_id = c.c_id) AND
(r.r_t_id = t.t_id) AND
(r.r_d_id = d.d_id) AND
(r.r_de_id = de.de_id) AND
(r.r_u_id = u.u_id) AND
(r.r_id = co.r_id))
ORDER BY r.r_id;
new
~~~
SELECT r.r_id, r.r_registration, r.r_chassis, r.r_vehicle, r.r_fuel,
r.r_pack_mats, r.r_delivery,
(date(r.r_delivery) - date(now())) AS r_remaining, r.r_created,
r.r_completed, r.r_salesman,
sm.u_username as salesman_name,
d.d_des, de.de_des,
u.u_id, u.u_userid, u.u_username, u.u_salesman, u.u_target,
t.t_id, t.t_des,
s.s_id, s.s_des,
c.c_id, c.c_des,
co.com_count, co.com_unseen,
pl.pl_id, pl.pl_desc as plates
FROM requests r
left outer join users sm on sm.u_id = r.r_salesman
left outer join users u on r.r_u_id = u.u_id
left outer join request_types t on r.r_t_id = t.t_id
left outer join request_states s on r.r_s_id = s.s_id
left outer join dealerships d on r.r_d_id = d.d_id
left outer join departments de on r.r_de_id = de.de_id
left outer join customers c on r.r_c_id = c.c_id
left outer join comment_tallies co on r.r_id = co.r_id
left outer join plates pl on r.r_plates = pl.pl_id
ORDER BY r.r_id;
--
Gary Stainburn
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To: pgsql-sql@postgresql.org
Cc: gary.stainburn@ringways.co.uk
Subject: Re: Speed up slow select - was gone blind
In-Reply-To: <200504011332.33404.gary.stainburn@ringways.co.uk>
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