Re: Re: parallel distinct union and aggregate support patch

Sorry, this email was marked spam by sohu, so I didn't notice it, and last few months I work hard for merge PostgreSQL 14 to our cluster version(github.com/ADBSQL/AntDB).

I have an idea how to make "Parallel Redistribute" work, even under "Parallel Append" and "Nestloop". but "grouping sets" can not work in parallel mode using "Parallel Redistribute".
Wait days please, path coming soon.

From: David Rowley
Date: 2021-07-06 10:48
To: bucoo(at)sohu(dot)com
CC: David Steele; pgsql-hackers; tgl; Dilip Kumar; Thomas Munro; Tomas Vondra; hlinnaka; robertmhaas; pgsql
Subject: Re: Re: parallel distinct union and aggregate support patch
On Tue, 30 Mar 2021 at 22:33, bucoo(at)sohu(dot)com <bucoo(at)sohu(dot)com> wrote:
> I have written a plan with similar functions, It is known that the following two situations do not work well.

I read through this thread and also wondered about a Parallel
Partition type operator. It also seems to me that if it could be done
this way then you could just plug in existing nodes to get Sorting and
Aggregation rather than having to modify existing nodes to get them to
do what you need.

From what I've seen looking over the thread, a few people suggested
this and I didn't see anywhere where you responded to them about the
idea. Just so you're aware, contributing to PostgreSQL is not a case
of throwing code at a wall and seeing which parts stick. You need to
interact and respond to people reviewing your work. This is especially
true for the people who actually have the authority to merge any of
your work with the main code repo.

It seems to me you might be getting off to a bad start and you might
not be aware of this process. So I hope this email will help put you
on track.

Some of the people that you've not properly responded to include:

Thomas Munro: PostgreSQL committer. Wrote Parallel Hash Join.
Robert Hass: PostgreSQL committer. Wrote much of the original parallel
query code
Heikki Linnakangas: PostgreSQL committer. Worked on many parts of the
planner and executor. Also works for the company that develops
Greenplum, a massively parallel processing RDBMS, based on Postgres.

You might find other information in [1].

If I wanted to do what you want to do, I think those 3 people might be
some of the last people I'd pick to ignore questions from! :-)

Also, I'd say also copying in Tom Lane randomly when he's not shown
any interest in the patch here is likely not a good way of making
forward progress. You might find that it might bubble up on his radar
if you start constructively interacting with the people who have
questioned your design. I'd say that should be your next step.

The probability of anyone merging any of your code without properly
discussing the design with the appropriate people are either very
close to zero or actually zero.

I hope this email helps you get on track.

David

[1] https://www.postgresql.org/community/contributors/