From: | Amit Langote <Langote_Amit_f8(at)lab(dot)ntt(dot)co(dot)jp> |
---|---|
To: | David Rowley <david(dot)rowley(at)2ndquadrant(dot)com> |
Cc: | PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: Partial Aggregation / GROUP BY before JOIN |
Date: | 2015-09-28 10:17:01 |
Message-ID: | 5609139D.3080809@lab.ntt.co.jp |
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Lists: | pgsql-hackers |
On 2015/09/28 17:04, David Rowley wrote:
> On 28 September 2015 at 20:36, Amit Langote <Langote_Amit_f8(at)lab(dot)ntt(dot)co(dot)jp>
> wrote:
>
>>
>> Did you perhaps attach a version of the patch you didn't intend to?
>>
>
> Oops. It seems so.
>
> Please find the correct version attached.
Thanks, this one works fine.
By the way, you may have noticed that the append_rel_list would be broken
if the proposed optimization is applied to a appendrel parent.
CREATE TABLE sale_1() INHERITS(sale);
CREATE TABLE sale_2() INHERITS(sale);
EXPLAIN SELECT count(*) FROM sale;
QUERY PLAN
------------------------------------------------------
Finalize Aggregate (cost=0.01..0.02 rows=1 width=0)
-> Result (cost=0.00..0.01 rows=1 width=0)
One-Time Filter: false
(3 rows)
Moreover, would partial aggregation work below Append?
Thanks,
Amit
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