Re: slow query - Mailing list pgsql-sql

From A. Kretschmer
Subject Re: slow query
Date
Msg-id 20070405051127.GA24814@a-kretschmer.de
Whole thread Raw
In response to slow query  (Sumeet <asumeet@gmail.com>)
Responses Re: slow query  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-sql
am  Wed, dem 04.04.2007, um 23:17:54 -0400 mailte Sumeet folgendes:
> sm=> explain analyze select * from ma limit 10;
>                                                              QUERY
> PLAN                                                             
>
-------------------------------------------------------------------------------------------------------------------------------------
>  Limit  (cost=0.00..0.45 rows=10 width=76) (actual time=21985.292..22204.340
> rows=10 loops=1)
>    ->  Seq Scan on ma  (cost=0.00..2181956.92 rows=48235392 width=76) (actual
> time=21985.285..22204.308 rows=10 loops=1)
>  Total runtime: 22204.476 ms
> (3 rows)

which version?

I have 8.1 and on a table with 1.9 million records i got:


scholl=# explain analyse select * from bde_meldungen limit 10;
QUERYPLAN
 

----------------------------------------------------------------------------------------------------------------------------Limit
(cost=0.00..0.34 rows=10 width=157) (actual time=19.570..19.660 rows=10 loops=1)  ->  Seq Scan on bde_meldungen
(cost=0.00..65748.33rows=1957933 width=157) (actual time=19.565..19.587 rows=10 loops=1)Total runtime: 19.845 ms
 
(3 rows)


If I remember correctly, since 8.0 or 8.1 we have a massive improvement with
LIMIT.


Andreas
-- 
Andreas Kretschmer
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