Re: Proposal: Partitioning Advisor for PostgreSQL

From: Ashutosh Bapat <ashutosh(dot)bapat(at)enterprisedb(dot)com>
To: Julien Rouhaud <rjuju123(at)gmail(dot)com>
Cc: Yuzuko Hosoya <hosoya(dot)yuzuko(at)lab(dot)ntt(dot)co(dot)jp>, PostgreSQL Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org>
Subject: Re: Proposal: Partitioning Advisor for PostgreSQL
Date: 2018-06-12 08:10:30
Message-ID: CAFjFpRe397P0vVS9BqgeK76S9WUf6KpuOsxVQN1Re3CWABRZ5g@mail.gmail.com
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On Tue, Jun 12, 2018 at 12:21 AM, Julien Rouhaud <rjuju123(at)gmail(dot)com> wrote:
>
> I both like and dislike this idea. The good thing is that it's way
> less hacky than what we did in our prototype, and it's also working
> out of the box. However, the problem I have with this approach is
> that the generated plans will be quite different from real
> partitioning, The main features such as partition pruning or
> partition-wise join will probably work, but you'll always have a
> ForeignScan as the primary path and I think that it'll drastically
> limit the planner and the usability.

AFAIR, there is a hook using which we can change the EXPLAIN output,
so we could change the ForeignScan label. But I don't remember that
hook top of my head and a brief look at Explain code didn't reveal
anything. May be there isn't any hook. We may be able add one in that
case or use CustomScan or something like that. I agree that seeing a
ForeignScan in the plan is not a good thing.

Anyway, the work involved in my proposal may not be worth the utility
we get out of this extension, so may not be worth pursuing it further.

--
Best Wishes,
Ashutosh Bapat
EnterpriseDB Corporation
The Postgres Database Company

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