Re: ModifyTable overheads in generic plans

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Robert Haas <robertmhaas(at)gmail(dot)com>
Cc: Amit Langote <amitlangote09(at)gmail(dot)com>, Heikki Linnakangas <hlinnaka(at)iki(dot)fi>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>, David Rowley <dgrowleyml(at)gmail(dot)com>, "Tsunakawa, Takayuki" <tsunakawa(dot)takay(at)jp(dot)fujitsu(dot)com>
Subject: Re: ModifyTable overheads in generic plans
Date: 2021-04-07 18:02:16
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Robert Haas <robertmhaas(at)gmail(dot)com> writes:
> On Wed, Apr 7, 2021 at 12:34 PM Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>> Indeed, that's a pretty impressive comparison.

> +1. That looks like a big improvement.

> In a vacuum, you'd hope that partitioning a table would make things
> faster rather than slower, when only one partition is implicated. Or
> at least that the speed would stay about the same. And, while this is
> a lot better, we're clearly not there yet. So I hope that, in future
> releases, we can continue to find ways to whittle down the overhead.

Note that this test case includes plan_cache_mode = force_generic_plan,
so it's deliberately kneecapping our ability to tell that "only one
partition is implicated". I think things would often be better in
production cases. No argument that there's not work left to do, though.

regards, tom lane

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