Re: [HACKERS] Partition-wise aggregation/grouping

From: Jeevan Chalke <jeevan(dot)chalke(at)enterprisedb(dot)com>
To: Ashutosh Bapat <ashutosh(dot)bapat(at)enterprisedb(dot)com>
Cc: Robert Haas <robertmhaas(at)gmail(dot)com>, Dilip Kumar <dilipbalaut(at)gmail(dot)com>, David Rowley <david(dot)rowley(at)2ndquadrant(dot)com>, Rajkumar Raghuwanshi <rajkumar(dot)raghuwanshi(at)enterprisedb(dot)com>, PostgreSQL Hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: [HACKERS] Partition-wise aggregation/grouping
Date: 2018-03-13 14:13:05
Message-ID: CAM2+6=XpUzoELzjT1ZSZRWzB4Cmp7A83aWpXUATXnxckfO+ckw@mail.gmail.com
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Hi,

I have resolved all the comments/issues reported in this new patch-set.

Changes done by Ashutosh Bapat for splitting out create_grouping_paths()
into separate functions so that partitionwise aggregate code will use them
were based on my partitionwise aggregate changes. Those were like
refactoring changes. And thus, I have refactored them separately and before
any partitionwise changes (see
0005-Split-create_grouping_paths-and-Add-GroupPathExtraDa.patch). And then
I have re-based all partitionwise changes over it including all fixes.

The patch-set is complete now. But still, there is a scope of some comment
improvements due to all these refactorings. I will work on it. Also, need
to update few documentations and indentations etc. Will post those changes
in next patch-set. But meanwhile, this patch-set is ready to review.

On Tue, Mar 13, 2018 at 9:12 AM, Ashutosh Bapat <
ashutosh(dot)bapat(at)enterprisedb(dot)com> wrote:

> On Mon, Mar 12, 2018 at 7:49 PM, Jeevan Chalke
> <jeevan(dot)chalke(at)enterprisedb(dot)com> wrote:
> >
> >
> > On Mon, Mar 12, 2018 at 6:07 PM, Ashutosh Bapat
> > <ashutosh(dot)bapat(at)enterprisedb(dot)com> wrote:
> >>
> >> On Fri, Mar 9, 2018 at 4:21 PM, Ashutosh Bapat
> >>
> We don't need UpperRelationKind member in that structure. That will be
> provided by the RelOptInfo passed.
>
> The problem here is the extra information required for grouping is not
> going to be the same for that needed for window aggregate and
> certainly not for ordering. If we try to jam everything in the same
> structure, it will become large with many members useless for a given
> operation. A reader will not have an idea about which of them are
> useful and which of them are not. So, instead we should try some
> polymorphism. I think we can pass a void * to GetForeignUpperPaths()
> and corresponding FDW hook knows what to cast it to based on the
> UpperRelationKind passed.
>

Yep. Done this way.

>
> BTW, the patch has added an argument to GetForeignUpperPaths() but has
> not documented the change in API. If we go the route of polymorphism,
> we will need to document the mapping between UpperRelationKind and the
> type of structure passed in.
>

Oops. Will do that in next patchset.

Thanks for pointing out, I have missed this at first place it self.

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

Attachment Content-Type Size
partition-wise-agg-v17.tar.gz application/gzip 34.9 KB

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