From: Bricklen Anderson <BAnderson@PresiNET.com>
To: Colton A Smith <smith@cs.utk.edu>
Cc: pgsql-performance@postgresql.org
Subject: Re: poor performance involving a small table
Date: Mon, 30 May 2005 15:00:37 -0700
Message-ID: <429B8D05.5040705@PresiNET.com> (raw)
In-Reply-To: <Pine.GSO.4.62.0505261052180.25866@hydra3>
References: <Pine.GSO.4.62.0505261052180.25866@hydra3>
Colton A Smith wrote:
>
> Hi:
>
> I have a table called sensors:
>
> Table "public.sensor"
> Column | Type | Modifiers
> -----------------+--------------------------+-------------------------------------------------
>
> sensor_id | integer | not null default
> nextval('sensor_id_seq'::text)
> sensor_model_id | integer | not null
> serial_number | character varying(50) | not null
> purchase_date | timestamp with time zone | not null
> variable_id | integer | not null
> datalink_id | integer | not null
> commentary | text |
> Indexes:
> "sensor_pkey" PRIMARY KEY, btree (sensor_id)
> Foreign-key constraints:
> "datalink_id_exists" FOREIGN KEY (datalink_id) REFERENCES
> datalink(datalink_id) ON DELETE RESTRICT
> "sensor_model_id_exists" FOREIGN KEY (sensor_model_id) REFERENCES
> sensor_model(sensor_model_id) ON DELETE RESTRICT
> "variable_id_exists" FOREIGN KEY (variable_id) REFERENCES
> variable(variable_id) ON DELETE RESTRICT
>
>
> Currently, it has only 19 rows. But when I try to delete a row, it takes
> forever. I tried restarting the server. I tried a full vacuum to no
> avail. I tried the following:
>
> explain analyze delete from sensor where sensor_id = 12;
> QUERY PLAN
> ------------------------------------------------------------------------------------------------
>
> Seq Scan on sensor (cost=0.00..1.25 rows=1 width=6) (actual
> time=0.055..0.068 rows=1 loops=1)
> Filter: (sensor_id = 12)
> Total runtime: 801641.333 ms
> (3 rows)
>
> Can anybody help me out? Thanks so much!
>
I'd say the obvious issue would be your foreign keys slowing things down. Have
you analyzed the referenced tables, and indexed the columns on the referenced
tables?
--
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To: pgsql-performance@postgresql.org
Cc: BAnderson@PresiNET.com, smith@cs.utk.edu
Subject: Re: poor performance involving a small table
In-Reply-To: <429B8D05.5040705@PresiNET.com>
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