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Re: Bad plan for join to aggregate of join.
- From: Mischa Sandberg <mischa(at)ca(dot)sophos(dot)com>
- To: pgsql-performance(at)postgresql(dot)org
- Subject: Re: Bad plan for join to aggregate of join.
- Date: Tue, 12 Sep 2006 17:51:27 -0700
- Message-id: <4507560F(dot)9020906(at)ca(dot)sophos(dot)com>
Tom Lane wrote:
Mischa Sandberg <mischa(at)ca(dot)sophos(dot)com> writes:can PG see that a join on an grouped-by field can be pushed down into the query as an indexable filter?No. The GROUP BY serves as a partial optimization fence. If you're concerned about the speed of this query, I recommend making a different view in which 'message' is joined inside the GROUP BY.
Thanks.
- References:
- Abysmal hash join
- From: Florian Weimer
- Bad plan for join to aggregate of join.
- From: Mischa Sandberg
- Re: Bad plan for join to aggregate of join.
- From: Tom Lane
- Abysmal hash join
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