From: Mike Rylander <mrylander@gmail.com>
To: Gary Stainburn <gary.stainburn@ringways.co.uk>
To: pgsql-sql <pgsql-sql@postgresql.org>
Subject: Re: Speed up slow select - was gone blind
Date: Fri, 1 Apr 2005 12:46:37 +0000
Message-ID: <b918cf3d050401044677139922@mail.gmail.com> (raw)
In-Reply-To: <200504011332.33404.gary.stainburn@ringways.co.uk>
References: <200504011332.33404.gary.stainburn@ringways.co.uk>
Can you send the EXPLAIN ANALYZE of each? We can't really tell where
the slowdown is without that.
On Apr 1, 2005 12:32 PM, Gary Stainburn <gary.stainburn@ringways.co.uk> wrote:
> 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
>
> This email does not contain private or confidential material as it
> may be snooped on by interested government parties for unknown
> and undisclosed purposes - Regulation of Investigatory Powers Act, 2000
>
> ---------------------------(end of broadcast)---------------------------
> TIP 9: the planner will ignore your desire to choose an index scan if your
> joining column's datatypes do not match
>
--
Mike Rylander
mrylander@gmail.com
GPLS -- PINES Development
Database Developer
http://open-ils.org
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To: pgsql-sql@postgresql.org
Cc: mrylander@gmail.com, gary.stainburn@ringways.co.uk
Subject: Re: Speed up slow select - was gone blind
In-Reply-To: <b918cf3d050401044677139922@mail.gmail.com>
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