From: | "Kevin Grittner" <Kevin(dot)Grittner(at)wicourts(dot)gov> |
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To: | "Franck Routier" <franck(dot)routier(at)axege(dot)com>, "pgsql-performance" <pgsql-performance(at)postgresql(dot)org> |
Subject: | Re: Is disableing nested_loops a bad idea ? |
Date: | 2010-09-16 14:25:32 |
Message-ID: | 4C91E28C0200002500035868@gw.wicourts.gov |
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Lists: | pgsql-performance |
Franck Routier <franck(dot)routier(at)axege(dot)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
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