Re: Very slow inner join query Unacceptable latency. - Mailing list pgsql-performance

On Thu, May 23, 2013 at 12:21 PM,  <fburgess@radiantblue.com> wrote:
>
> But what negative impact is disabling hash joins?
>

doing it just for a single query, could be a tool for solving
particular problems.
setting it in postgresql.conf, therefore affecting all queries, is
like using a hammer to change tv channel... it will cause more
problems than the one it solves.

what you can do is:

1) execute:

SET enable_hashjoin TO OFF;
SELECT here
RESET enable_hashjoin TO ON;

2) in a function:

CREATE FUNCTION do_something() RETURNS bigint AS
$$
   SELECT here
$$ LANGUAGE sql SET enable_hashjoin TO OFF STABLE;

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Jaime Casanova         www.2ndQuadrant.com
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