From: Anssi Kääriäinen <anssi.kaariainen@thl.fi>
To: Pavel Stehule <pavel.stehule@gmail.com>
Cc: pgsql-performance@postgresql.org <pgsql-performance@postgresql.org>
Subject: Re: Disabling nested loops - worst case performance
Date: Fri, 18 Mar 2011 12:58:48 +0200
Message-ID: <4D833AE8.9020608@thl.fi> (raw)
In-Reply-To: <AANLkTi=kdWVCKBZPUHFE-8pd8MLzCDVjVpG14iRtkyGf@mail.gmail.com>
References: <4D8306A7.7020205@thl.fi>
<AANLkTi=kdWVCKBZPUHFE-8pd8MLzCDVjVpG14iRtkyGf@mail.gmail.com>
On 03/18/2011 09:02 AM, Pavel Stehule wrote:
> for example queries with LIMIT clause can be significantly faster with
> nested loop. But you don't need to disable nested loop globally.
>
> You can wrap your query to sql functions and disable nested loop just
> for these functions.
Thank you for your help, the LIMIT example was something I was not aware of.
The problem is we are replacing an old database, and we need to
replicate certain views for external users. Minimal impact for these
users is required. Maybe it would be best to create special user
accounts for these external users and disable nested loops only for
those accounts. Otherwise we will disable nested loops when absolutely
necessary.
- Anssi
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To: pgsql-performance@postgresql.org
Cc: anssi.kaariainen@thl.fi, pavel.stehule@gmail.com
Subject: Re: Disabling nested loops - worst case performance
In-Reply-To: <4D833AE8.9020608@thl.fi>
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