Re: BUG #1697: Select getting slower on continously updating data

From: Bruno Wolff III <bruno(at)wolff(dot)to>
To: Bahadur Singh <bahadursingh(at)yahoo(dot)com>
Cc: pgsql-bugs(at)postgresql(dot)org, pgsql-novice(at)postgresql(dot)org, pgsql-performance(at)postgresql(dot)org
Subject: Re: BUG #1697: Select getting slower on continously updating data
Date: 2005-06-03 14:49:51
Message-ID: 20050603144951.GA10195@wolff.to
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On Fri, Jun 03, 2005 at 00:09:00 -0700,
Bahadur Singh <bahadursingh(at)yahoo(dot)com> wrote:
>
> Many thanks for this tip !
> But is this good idea to analyse/vacuuming the
> database tables while updates are taking place..
> Since, I update continuously say (100,000 ) times or
> more the same data set.
>
> This is the result of analyze command.
>
> INFO: analyzing "public.salesarticle"
> INFO: "salesarticle": scanned 3000 of 20850 pages,
> containing 62 live rows and 134938 dead rows; 62 rows
> in sample, 431 estimated total rows
>
> Gesamtlaufzeit der Abfrage: 5531 ms.
> Total Time Taken : 5531 ms.
>
> Can you suggest me some clever way to so, because I
> would prefer to do vaccumming while database is not
> loaded with queries/transactions.

While that may be a nice preference, under your usage pattern that does
not appear to be a good idea. As long as your disk I/O isn't saturated
you want to be running vacuums a lot more often than you are. (Analyze should
only be needed if the distrution of values is changing constantly. An example
would be timestamps indicating when an update occured.)

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