Re: Delete query takes exorbitant amount of time

From: Karim Nassar <karim(dot)nassar(at)acm(dot)org>
To: Simon Riggs <simon(at)2ndquadrant(dot)com>
Cc: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Christopher Kings-Lynne <chriskl(at)familyhealth(dot)com(dot)au>, pgsql-performance(at)postgresql(dot)org
Subject: Re: Delete query takes exorbitant amount of time
Date: 2005-03-25 21:47:44
Message-ID: 1111787264.9168.7.camel@k2.cet.nau.edu
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On Fri, 2005-03-25 at 15:10 +0000, Simon Riggs wrote:
> Karim: Did this happen? If not, can you drop and re-create and confirm
> that you get the WARNING? If not, we have problems.

No. Nor do I think that I should. SERIAL is shortcut for INTEGER, no? I
think there is some other (TBD) problem causing my big seq scan.

orfs=# ALTER TABLE measurement DROP CONSTRAINT measurement_id_int_sensor_meas_type_fkey;
ALTER TABLE
orfs=# ALTER TABLE ONLY measurement ADD CONSTRAINT measurement_id_int_sensor_meas_type_fkey
orfs-# FOREIGN KEY (id_int_sensor_meas_type) REFERENCES int_sensor_meas_type(id_int_sensor_meas_type);
ALTER TABLE
orfs=#

The add constraint statement comes directly from a pg_dump.

For clarity, the table/indexes were created as such:

CREATE TABLE int_sensor_meas_type(
id_int_sensor_meas_type SERIAL PRIMARY KEY,
id_sensor integer NOT NULL REFERENCES sensor,
id_meas_type integer NOT NULL REFERENCES meas_type UNIQUE);

CREATE TABLE measurement (
id_measurement SERIAL PRIMARY KEY,
id_int_sensor_meas_type integer NOT NULL REFERENCES int_sensor_meas_type,
datetime timestamp WITH TIME ZONE NOT NULL,
value numeric(15,5) NOT NULL,
created timestamp with time zone NOT NULL DEFAULT now(),
created_by TEXT NOT NULL REFERENCES public.person(id_person));

CREATE INDEX measurement__id_int_sensor_meas_type_idx ON measurement(id_int_sensor_meas_type);

Regards,
--
Karim Nassar
Department of Computer Science
Box 15600, College of Engineering and Natural Sciences
Northern Arizona University, Flagstaff, Arizona 86011
Office: (928) 523-5868 -=- Mobile: (928) 699-9221

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