Re: speeding up COUNT and DISTINCT queries - Mailing list pgsql-performance

From Chad Thompson
Subject Re: speeding up COUNT and DISTINCT queries
Date
Msg-id 0ca601c2e8ea$6f7783d0$32021aac@chad
Whole thread Raw
In response to speeding up COUNT and DISTINCT queries  (Max Baker <max@warped.org>)
Responses Re: speeding up COUNT and DISTINCT queries  (Max Baker <max@warped.org>)
List pgsql-performance
Ive found that group by works faster than distinct.

Try
EXPLAIN ANALYZE  select mac from node group by mac;

HTH
Chad

----- Original Message -----
From: "Max Baker" <max@warped.org>
To: "PostgreSQL Performance Mailing List" <pgsql-performance@postgresql.org>
Sent: Wednesday, March 12, 2003 3:38 PM
Subject: [PERFORM] speeding up COUNT and DISTINCT queries


> I'm looking for a general method to
> speed up DISTINCT and COUNT queries.
>
>
> mydatabase=> EXPLAIN ANALYZE  select distinct(mac) from node;
> NOTICE:  QUERY PLAN:
>
> Unique  (cost=110425.67..110514.57 rows=3556 width=6) (actual
> time=45289.78..45598.62 rows=25334 loops=1)
>   ->  Sort  (cost=110425.67..110425.67 rows=35561 width=6) (actual
>   time=45289.77..45411.53 rows=34597 loops=1)
>           ->  Seq Scan on node  (cost=0.00..107737.61 rows=35561
>           width=6) (actual time=6.73..44383.57 rows=34597 loops=1)
>
>           Total runtime: 45673.19 msec
>                          ouch.
>
> I run VACCUUM ANALYZE once a day.
>
> Thanks,
> max
>
> ---------------------------(end of broadcast)---------------------------
> TIP 3: if posting/reading through Usenet, please send an appropriate
> subscribe-nomail command to majordomo@postgresql.org so that your
> message can get through to the mailing list cleanly
>


pgsql-performance by date:

Previous
From: Rod Taylor
Date:
Subject: Re: speeding up COUNT and DISTINCT queries
Next
From: Jean-Luc Lachance
Date:
Subject: Re: speeding up COUNT and DISTINCT queries