further clarification: alter table alter column set not null - table scan is skipped

agora inbox for pgsql-docs@postgresql.org  
help / color / mirror / Atom feed

From: PG Doc comments form <noreply@postgresql.org>
To: pgsql-docs@lists.postgresql.org
Cc: psy2000usa@yahoo.com
Subject: further clarification: alter table alter column set not null - table scan is skipped
Date: Wed, 30 Jul 2025 04:52:16 +0000
Message-ID: <175385113607.786.16774570234342968908@wrigleys.postgresql.org> (raw)

The following documentation comment has been logged on the website:

Page: https://www.postgresql.org/docs/17/docguide.html
Description:

Hello there,
I like PostgreSQL a lot so this is my way of giving back.

The "table scan is skipped" optimization can use some clarification
https://www.postgresql.org/docs/current/sql-altertable.html#SQL-ALTERTABLE-DESC-SET-DROP-NOT-NULL
My proposal is "then the table scan is skipped if the alter statement
doesn't drop the constraint."

The reason behind the proposal is documented here
https://dev.to/andrewpsy/the-set-not-null-downtime-trap-in-postgresql-1o71

Thank you for working on such an awesome project.
Cheers,
Andrew

view thread (7+ messages)  latest in thread

Message-ID: <175385113607.786.16774570234342968908@wrigleys.postgresql.org>
Permalink:  ../175385113607.786.16774570234342968908@wrigleys.postgresql.org/
Also on:    postgresql.org/message-id/175385113607.786.16774570234342968908@wrigleys.postgresql.org

reply

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: noreply@postgresql.org, pgsql-docs@lists.postgresql.org, psy2000usa@yahoo.com
  Subject: Re: further clarification: alter table alter column set not null - table scan is skipped
  In-Reply-To: <175385113607.786.16774570234342968908@wrigleys.postgresql.org>

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

This inbox is served by agora; see mirroring instructions
for how to clone and mirror all data and code used for this inbox