Misleading sentence about default privileges

On Thu, Jun 17, 2021 at 09:07:11AM +0000, PG Doc comments form wrote:

You can change default privileges only for objects that will be created by

yourself or by roles that you are a member of.

Yet, altering the default privileges `for role`'s that I am a member of
(i.e. `target_role` in docs), does not affect privileges granted on objects
created by other members of said role.

Seeing as separating Users (roles with log-in privilege) from Roles
(containing concrete grants, unable to log in) seems a common, and
recommendable pattern, I believe the statement is quite misleading.

For an example of expected behaviour, see this Stack Overflow question:
https://stackoverflow.com/questions/56237907/why-doesnt-alter-default-privileges-work-as-expected

The only scenario I can think of where the statement makes sense seems quite
foreign to me:
Scenario: I, say `role_a`, have log-in, and am also a member of another
Role, say `role_b`, which also has login. Only objects created directly by
`role_b` (i.e. not any of its members) are affected.

I suggest adding something like the following to the documentation:

" Note that only object created directly by _*target_role*_ , i.e. not any
of its members, will have privileges granted. "

I researched this. What it is saying is that you can modify the
defaults for your own role, or roles you are a member of. The defaults
are applied based on the active role at the time you create an object.
Here is an example run as the postgres user:

CREATE ROLE demo NOLOGIN;

--> ALTER DEFAULT PRIVILEGES FOR ROLE demo GRANT SELECT ON TABLES TO PUBLIC;

CREATE TABLE test1 (x INTEGER);

--> SET ROLE demo;

CREATE TABLE test2 (x INTEGER);
\dp test1
Access privileges
Schema | Name | Type | Access privileges | Column privileges |
Policies
--------+-------+-------+-------------------+-------------------+----------

public | test1 | table | | |

\dp test2
Access privileges
Schema | Name | Type | Access privileges | Column privileges |
Policies
--------+-------+-------+-------------------+-------------------+----------

public | test2 | table | =r/demo +| |
--> | | | demo=arwdDxt/demo | |

I am trying to think of wording that would make this documentation
section clearer, but I can't think of anything. Maybe the entire
concept of "active role at time of object creation" needs to be
explained more, since there is a lot of focus on owner without the idea
that this is really the active role.

--
Bruce Momjian <bruce@momjian.us> https://momjian.us
EDB https://enterprisedb.com

If only the physical world exists, free will is an illusion.