[chousuke]

I'm just not sure how it's confusing? PostgreSQL users aren't "tied" to system accounts either. You can have any number of PostgreSQL users that have no system equivalent.

In fact, the process seems to be exactly the same as with MySQL: I just tried installing the MariaDB server (dnf install mariadb-server), and it didn't prompt me for an admin user; instead, I can directly connect to the database as root using sudo, so in this case it appears to be doing the exact same thing that PostgreSQL does.

It just happens to be that by default the "postgres" superuser has a corresponding "postgres" system user that can log in via OS authentication, so you need to switch to the postgres user instead of root.

EDIT: Maybe some of the confusion stems from the fact that the documentation you linked seems to assume that the database is created according to convention to run as the "postgres" user (as it usually is). If your user didn't have the required permission to switch to the postgres user, they wouldn't be able to install the database as said user in the first place.

If you install PostgreSQL as your own user (which is not a good idea if you have any other option), you will not need to switch users as you will obviously have access to the database files and can do whatever you want, anyway.

[mgkimsal]

"Maybe some of the confusion stems from the fact that the documentation you linked seems to assume that the database is created according to convention to run as the "postgres" user (as it usually is)".

The entire point was a reply to someone saying "it's confusing". I'm pointing out how it's confusing, and you come back with that either that 1) MySQL is confusing or 2) you don't think it's confusing. Then you point to documentation which you admit might be a point of confusion.

I've had people say "I installed postgres - here's the password". Then... I can't log in. Because I can't switch to the postgres user. Or they created some login that I can't use. Or something else... because it's somewhat confusing, unless you do this (postgres administration) as part of your regular/periodic work.

re: "I just installed Maria"... If someone uses common default package managers to set up mysql/Maria, and also for postgres, you'll be able to connect to mysql/Maria from any account. You'll only be able to connect to postgres if you switch to the postgres user.

Again - point of the comment was agreeing with an earlier comment that "this is confusing". You seem to acknowledge that it can be confusing.

[chousuke]

> I've had people say "I installed postgres - here's the password". Then... I can't log in. Because I can't switch to the postgres user.

You don't need to switch to the postgres user if you have another database user and password.

Are you talking about a situation where someone has installed a PostgreSQL server but hasn't configured PostgreSQL to allow password authentication? The server admin needs to allow that explicitly, because some distributions don't allow password authentication even on localhost by default, but honestly, it's all very well documented.

> If someone uses common default package managers to set up mysql/Maria, and also for postgres, you'll be able to connect to mysql/Maria from any account.

This is not the case on Fedora at least, since fresh out of the package the MySQL root user has no password; the only way to connect is via local system authentication as the root user.