Re: Planner mis-estimation using nested loops followup - Mailing list pgsql-performance

From Scott Marlowe
Subject Re: Planner mis-estimation using nested loops followup
Date
Msg-id dcc563d10803181246sbdc7425u838ff2baf70faeb6@mail.gmail.com
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In response to Re: Planner mis-estimation using nested loops followup  ("Chris Kratz" <chris.kratz@vistashare.com>)
Responses Re: Planner mis-estimation using nested loops followup
List pgsql-performance
On Tue, Mar 18, 2008 at 9:58 AM, Chris Kratz <chris.kratz@vistashare.com> wrote:
> Y, turning nested loops off in specific cases has increased performance
> greatly.  It didn't fix the planner mis-estimation, just the plan it chose.
> It's certainly not a panacea, but it's something we now try early on when
> trying to speed up a query that matches these characteristics.

I have to admit I've had one or two reporting queries in the past that
turning off nested_loop was the only reasonable fix due to
misestimation.  I'd tried changing the stats targets etc and nothing
really worked reliably to prevent the nested_loop from showing up in
the wrong places.

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