Re: Is disableing nested_loops a bad idea ? - Mailing list pgsql-performance

From Kevin Grittner
Subject Re: Is disableing nested_loops a bad idea ?
Date
Msg-id 4C91E28C0200002500035868@gw.wicourts.gov
Whole thread Raw
In response to Re: Is disableing nested_loops a bad idea ?  (Franck Routier <franck.routier@axege.com>)
List pgsql-performance
Franck Routier <franck.routier@axege.com> wrote:

> So I wanted to better understand to what extend using a
> sledgehammer will impact me :-)

Disabling it globally is likely to significantly hurt some queries.
Before resorting to that, you might decrease effective_cache_size,
increase random_page_cost, and (most importantly) do whatever you
can to improve statistics.  Where those fail, and disabling nested
loops helps, I concur with the advice to only do that for specific
queries, taking care to reset it afterward.

In other words, use that sledgehammer with great care, don't just
swing it around wildly....  ;-)

-Kevin

pgsql-performance by date:

Previous
From: Anssi Kääriäinen
Date:
Subject: Re: Performance problem with joined aggregate query
Next
From: Merlin Moncure
Date:
Subject: Re: Performance problem with joined aggregate query