Re: [HACKERS] path toward faster partition pruning

From: Amit Langote <Langote_Amit_f8(at)lab(dot)ntt(dot)co(dot)jp>
To: David Rowley <david(dot)rowley(at)2ndquadrant(dot)com>, Alvaro Herrera <alvherre(at)alvh(dot)no-ip(dot)org>
Cc: Amit Langote <amitlangote09(at)gmail(dot)com>, "pgsql-hackers(at)postgresql(dot)org" <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: [HACKERS] path toward faster partition pruning
Date: 2018-04-09 09:27:32
Message-ID: c2838545-0e77-3c08-cd14-1c3bbf9eb62d@lab.ntt.co.jp
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Hi David.

On 2018/04/09 12:48, David Rowley wrote:
> While looking at the docs in [1], I saw that we still mention:
>
> 4. Ensure that the constraint_exclusion configuration parameter is not
> disabled in postgresql.conf. If it is, queries will not be optimized
> as desired.
>
> This is no longer true. The attached patch removed it.
>
> [1] https://www.postgresql.org/docs/10/static/ddl-partitioning.htm
Thanks. I was aware of the changes that would need to be made, but you
beat me to writing the patch itself.

About the patch:

While the users no longer need to enable constraint_exclusion true for
select queries, one would still need it for update/delete queries, because
the new pruning logic only gets invoked for the former. Alas...

Also, further down on that page, there is a 5.10.4 Partitioning and
Constraint Exclusion sub-section. I think it would also need some tweaks
due to new developments.

I updated your patch to fix that. Please take a look.

Thanks,
Amit

Attachment Content-Type Size
v2-0001-Remove-mention-of-constraint_exclusion-in-partiti.patch text/plain 2.1 KB

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