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Re: mal advice in FAQ 4.1. - Mailing list pgsql-hackers

From Nikolay Samokhvalov
Subject Re: mal advice in FAQ 4.1.
Date
Msg-id e431ff4c0710090552y79af2b31gb159eb8e9ccf9bd6@mail.gmail.com
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In response to mal advice in FAQ 4.1.  ("Pavel Stehule" <pavel.stehule@gmail.com>)
Responses Re: mal advice in FAQ 4.1.
Re: mal advice in FAQ 4.1.
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Hubert recently posted his thoughts on this topic: http://www.depesz.com/index.php/2007/09/16/my-thoughts-on-getting-random-row/

I've encountered with this problem several times in web development and every time found out that the best (in terms of performance) solution is to use some pseudo random approach (such as ">= random() limit 1" or "limit 1 offset random()*N" or even pre-caching rows on app side).

On 10/9/07, Pavel Stehule <pavel.stehule@gmail.com> wrote:
Hello

I found lot of slow queries in some databases which I checked based on
advice 4.1. from FAQ,

To SELECT a random row, use:
    SELECT col
    FROM tab
    ORDER BY random()
    LIMIT 1;

It's robust and slow on bigger tables. Can we add some better solutions?


--
Best regards,
Nikolay

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