ERROR: must be superuser to alter superusers - postgresql-8.4

Question

Unfortunately, I have removed super user privileges from postgres user in PostgreSQL. And currently I have not any super user in PostgreSQL. And i want to make superuser. So how can i make it ? Every time I am trying to make postgres to super user. I am facing this problem.
Error : must be superuser to alter superusers.

Answer 1

(assuming you have root access on Ubuntu machine)
To enter psql as super user you need to:
sudo -u postgres psql
as suggested in this SO post here
If there is no user called postgres you need to create it on system first, with:
sudo adduser newuser
Else, if you have problems with password not accepted or not created at all you can follow (Ubuntu 14.04 related) instructions here or for more on user accounts look here

Answer 2

For me helps:
sudo -u gleb psql postgres
where gleb is my mac system user

Answer 3

Adding to Craig Ringer's answer, here is the procedure for MacOS and Brew if you accidentally downgrade your only PostgreSQL user:
brew services stop postgresql
Wait a few seconds and/or check Activity Monitor to make sure "postgres" is no longer running.
/usr/local/Cellar/postgresql/10.4/bin/postgres --single -D /usr/local/var/postgres
backend> ALTER USER "yourname" with superuser; or whatever privilege you need to fix
CTRL-D
brew services start postgresql

Answer 4

You're going to have to stop the database system and start a stand-alone back-end, which always unconditionally runs as a superuser.
You can use this backend to ALTER the user you wish to give superuser rights to. Then shut the standalone backend down and start the database normally.
It is important that you completely stop the database server before entering single user mode. PostgreSQL single user mode will refuse to start if there's a postmaster, but to be sure you should make sure there are no PostgreSQL processes running on your system. Under (almost) no circumstances should you ever delete postmaster.pid - that's pretty much guaranteed to result in database corruption if there's still any PostgreSQL process accessing that data directory.
Exactly how to start a standalone back-end depends a bit on your OS/distro and how you installed PostgreSQL. You haven't included this info, so I can only really point you at the manual for the postgres back-end executable.
Make a backup first.
In the single-user mode, the session user will be set to the user with ID 1, and implicit superuser powers are granted to this user. This user does not actually have to exist, so the single-user mode can be used to manually recover from certain kinds of accidental damage to the system catalogs.
See the section Options for Single User mode and, toward the bottom, Usage. You'll want to run the postgres backend with --single, as the unix user that owns the database files, with the path to the datadir. On a typical Linux PostgreSQL install this might be something like:
sudo systemctl stop postgresql-9.3.service
sudo -u postgres /usr/pgsql-9.3/bin/postgres --single -D /var/lib/pgsql/9.3/data
Your datadir and postgres executable location are quite possibly different. The above is for a Fedora system running with PGDG PostgreSQL packages from http://yum.postgresql.org/ .

Answer 5

Assuming that your system user is 'ec2-user'
So try this to enter as superuser
psql -U ec2-user postgres
This will enter you as ec2-user as superuser using postgres db
Now, change postgres user roles to superuser
ALTER USER postgres WITH SUPERUSER;
Quit from above console and now you can open psql using postgres user as superuser
psql -U postgres
Note: I tested this on PostgreSQL 12.5

Answer 6

SELECT usename AS role_name,
CASE
WHEN usesuper AND usecreatedb THEN
CAST('superuser, create database' AS pg_catalog.text)
WHEN usesuper THEN
CAST('superuser' AS pg_catalog.text)
WHEN usecreatedb THEN
CAST('create database' AS pg_catalog.text)
ELSE
CAST('' AS pg_catalog.text)
END role_attributes
FROM pg_catalog.pg_user
ORDER BY role_name desc;
log with root_user then give superuser to postgres