From: Richard Huxton <dev@archonet.com>
To: firerox@centrum.cz
Cc: tv@fuzzy.cz
Cc: pgsql-performance@postgresql.org
Subject: Re: slow full table update
Date: Wed, 12 Nov 2008 17:45:55 +0000
Message-ID: <491B1653.3040600@archonet.com> (raw)
In-Reply-To: <200811121825.26487@centrum.cz>
References: <200811101729.14977@centrum.cz>
<200811101730.11057@centrum.cz>
<200811101730.15902@centrum.cz>
<61593.89.102.139.23.1226335300.squirrel@sq.gransy.com>
<200811121725.30238@centrum.cz>
<63509.89.102.139.23.1226508479.squirrel@sq.gransy.com>
<200811121825.26487@centrum.cz>
firerox@centrum.cz wrote:
> Hi,
>
> I've changed settings,
> but with no effect on speed.
>
> I try explain query with this result
> for 10.000 rows > update songs set views = 0 where sid > 20000 and sid < 30000
>
> Bitmap Heap Scan on songs (cost=151.59..6814.29 rows=8931 width=526) (actual time=4.848..167.855 rows=8945 loops=1)
This query says t is taking 167 milli-seconds, not 10 minutes as your
first message said. Is this query actually slow?
>
> Recheck Cond: ((sid > 20000) AND (sid < 30000))
>
> -> Bitmap Index Scan on pk_songs2 (cost=0.00..151.59 rows=8931 width=0) (actual time=4.071..4.071 rows=9579 loops=1)
>
> Index Cond: ((sid > 20000) AND (sid < 30000))
>
> Is there a way to run this query on sigle throughpass with no Recheck Cond?
Only a sequential scan.
--
Richard Huxton
Archonet Ltd
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To: pgsql-performance@postgresql.org
Cc: dev@archonet.com, firerox@centrum.cz, tv@fuzzy.cz
Subject: Re: slow full table update
In-Reply-To: <491B1653.3040600@archonet.com>
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