Re: Partition-wise aggregation/grouping

From: Jeevan Chalke <jeevan(dot)chalke(at)enterprisedb(dot)com>
To: Dilip Kumar <dilipbalaut(at)gmail(dot)com>
Cc: David Rowley <david(dot)rowley(at)2ndquadrant(dot)com>, Ashutosh Bapat <ashutosh(dot)bapat(at)enterprisedb(dot)com>, Rajkumar Raghuwanshi <rajkumar(dot)raghuwanshi(at)enterprisedb(dot)com>, PostgreSQL Hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Partition-wise aggregation/grouping
Date: 2017-10-27 11:01:26
Message-ID: CAM2+6=UAMJybYwVi36+NkkduhpJK5rsf40JeGiXxx8R3YdXjWQ@mail.gmail.com
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Hi,

Attached new patch-set here. Changes include:

1. Added separate patch for costing Append node as discussed up-front in the
patch-set.
2. Since we now cost Append node, we don't need
partition_wise_agg_cost_factor
GUC. So removed that. The remaining patch hence merged into main
implementation
patch.
3. Updated rows in test-cases so that we will get partition-wise plans.

Thanks

On Wed, Oct 18, 2017 at 9:53 AM, Dilip Kumar <dilipbalaut(at)gmail(dot)com> wrote:

> On Tue, Oct 17, 2017 at 10:44 PM, Jeevan Chalke
> <jeevan(dot)chalke(at)enterprisedb(dot)com> wrote:
> >
>
> > I didn't get what you mean by regression here. Can you please explain?
> >
> > I see that PWA plan is selected over regular plan when enabled on the
> basis
> > of costing.
> > Regular planning need a Result node due to which costing increases where
> as
> > PWA don't need that and thus wins.
>
> Sorry for not clearly explaining, I meant that with normal plan
> execution time is 263.678 ms whereas with PWA its 339.929 ms.
>
> I only set enable_partition_wise_agg=on and it switched to PWA and
> execution time increased by 30%.
> I understand that the this is the worst case for PWA where
> FinalizeAggregate is getting all the tuple.
>
> --
> Regards,
> Dilip Kumar
> EnterpriseDB: http://www.enterprisedb.com
>

--
Jeevan Chalke
Technical Architect, Product Development
EnterpriseDB Corporation
The Enterprise PostgreSQL Company

Attachment Content-Type Size
partition-wise-agg-v6.tar.gz application/x-gzip 33.8 KB

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