From: Bruce Momjian <bruce@momjian.us>
To: stefan.keller@ost.ch
To: pgsql-docs@lists.postgresql.org
Cc: Tomas Vondra <tomas.vondra@enterprisedb.com>
Subject: Re: Empty values of pg_stats_ext when table is empty
Date: Wed, 17 Aug 2022 10:32:55 -0400
Message-ID: <Yvz8F7z+u9Fuxg4P@momjian.us> (raw)
In-Reply-To: <163577298184.680.6561061840343770915@wrigleys.postgresql.org>
References: <163577298184.680.6561061840343770915@wrigleys.postgresql.org>
On Mon, Nov 1, 2021 at 01:23:01PM +0000, PG Doc comments form wrote:
> The following documentation comment has been logged on the website:
>
> Page: https://www.postgresql.org/docs/14/view-pg-stats-ext.html
> Description:
>
> When table mytable is being inherited it may not contain any data but still
> return row sets from the inheriting tables. Now doing CREATE STATISTICS on
> mytable will work but won't have any values.
>
> This is very difficult to realize from a user's perspective and can be
> either considered a feature or a bug, i.e. being enhanced.
>
> Given this is considered as a feature, I suggest to add a comment at the end
> of this documentation
> https://www.postgresql.org/docs/current/view-pg-stats-ext.html like this:
>
> <<
> Note then there are no values when the table is empty which happens when
> there are tables which inherit from it.
> <<
>
> I could also think of a run-time warning?
I talked to Tomas Vondra and he says there will be proper parent
statistics in PG 15, due to be released in the next 1-2 months. Here is
the PG 15 release note item:
https://www.postgresql.org/docs/15/release-15.html
Allow extended statistics to record statistics for a parent with all its
children (Tomas Vondra, Justin Pryzby)
Regular statistics already tracked parent and parent/all-children
statistics separately.
--
Bruce Momjian <bruce@momjian.us> https://momjian.us
EDB https://enterprisedb.com
Indecision is a decision. Inaction is an action. Mark Batterson
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Reply to all the recipients using the --to and --cc options:
reply via email
To: pgsql-docs@postgresql.org
Cc: bruce@momjian.us, stefan.keller@ost.ch, pgsql-docs@lists.postgresql.org, tomas.vondra@enterprisedb.com
Subject: Re: Empty values of pg_stats_ext when table is empty
In-Reply-To: <Yvz8F7z+u9Fuxg4P@momjian.us>
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
This inbox is served by DDX for PostgreSQL; see mirroring instructions
for how to clone and mirror all data and code used for this inbox