Skip site navigation (1) Skip section navigation (2)

Re: Disabling nested loops - worst case performance

From: Anssi Kääriäinen <anssi(dot)kaariainen(at)thl(dot)fi>
To: Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com>
Cc: "pgsql-performance(at)postgresql(dot)org" <pgsql-performance(at)postgresql(dot)org>
Subject: Re: Disabling nested loops - worst case performance
Date: 2011-03-18 10:58:48
Message-ID: 4D833AE8.9020608@thl.fi (view raw or flat)
Thread:
Lists: pgsql-performance
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

In response to

pgsql-performance by date

Next:From: Thomas KellererDate: 2011-03-18 11:14:05
Subject: Re: Disabling nested loops - worst case performance
Previous:From: Vitalii TymchyshynDate: 2011-03-18 10:52:03
Subject: Re: Disabling nested loops - worst case performance

Privacy Policy | About PostgreSQL
Copyright © 1996-2014 The PostgreSQL Global Development Group