I'm running postgresql 10.12 on Ubuntu 18.04.
I'd like to experiment with a software package that uses postgres. This means I should figure out how to set up users, passwords and databases under postgres.
Postgres is running, but there's no way to log in to it.
I'm pretty sure there is a user called 'postgres'.
Logging in as this user without providing a password fails.
Also, attempting to use the passwords 'postgres' or 'root' fail.
How do I change the password for the user 'postgres' without being able to access the database?
This is a newbie-level recipe to modify initial password, which works on all fresh installations of the postgresql package on Linux Debian/Ubuntu and derivatives.
Go to the shell and switch user to postgres
(in user shell) sudo su - postgres
connect to the postgres database as postgres user
(in postgres shell) psql postgres postgres
now you can modify password of postgres user
(in postgres psql) ALTER USER postgres PASSWORD 'newsecret';
quit psql
(in postgres psql) \q
quit postgres shell
(in postgres shell) exit
test connection with new password
(in user shell) psql -h localhost postgres postgres
Note on remote postgres servers
In step 1 above, you can use ssh or kubectl exec or anything like that, if you have this kind of access.
Best Practice note
Above recipe (though it answers the OP question) is not a good practice. The best approach is:
Read and understand client auth -> https://www.postgresql.org/docs/current/client-authentication.html
Do not use postgres database user (or any other superuser!) for applications/development. Create your own user instead. For the simplest setup, use this:
(in psql shell)
CREATE USER myapp PASSWORD 'secret';
CREATE DATABASE myapp;
ALTER DATABASE myapp OWNER TO myapp;
-- alternative if you want to keep default ownership:
-- GRANT ALL ON DATABASE myapp TO myapp;
This should be done instead of modifying postgres user and/or postgres database.
I am new to technologies , please do not judge my question too strong :).
I installed in My Ubuntu 18.04 PostgreSQL 10.7. To be able to enter my DB I need to enter the following commands from my terminal. sudo -u postgres psql.
Is there any shortened way where I can connect it from my Ubuntu User account. For example. if I input psql it will open database environment where I can type PostgreSQL commands.
Thank you.
Just execute this command in your terminal :
alias psql='sudo -u postgres psql'
So the next time, you input psql and execute, you will be in database environment.
I see two options:
1) Create alias for this command sudo -u postgres psql .
2) Go to psql and create new superuser and database for it:
CREATE ROLE username SUPERUSER;
ALTER ROLE username WITH LOGIN;
CREATE DATABASE username;
You shouldn't be using the superuser account for your normal database work. That is as if you were using root for everything in Linux.
You need to create a regular user with the privileges to create or modify tables in your database. This can be done by granting the user all privileges on the database (which is not the same as making that user a superuser) or make that user the owner of that database.
As documented in the manual psql tries to connect to a database with the name of the current Linux user and with a database user with the name of the current Linux user. So if you want to keep things simple create a user with your regular Linux user's name and an database that is owned by that user:
create user rob password 'somepassword';
create database rob owner = rob;
Assuming your Linux user is rob, then all you need to do is:
psql
and you are connected to a database where you can create and manage tables.
Depending on how you installed Postgres, you might need to adjust pg_hba.conf to allow rob to log in directly.
Again: please do NOT use the superuser account for your normal work.
I'm trying to execute following Postgres 9.6 commands over JDBC connection
CREATE USER my_db WITH SUPERUSER PASSWORD 'my_db';
CREATE DATABASE my_db;
GRANT ALL PRIVILEGES ON DATABASE my_db TO my_db;
\connect my_db; -- THIS ONE FAILS
SET ROLE my_db;
CREATE SCHEMA my_db AUTHORIZATION my_db;
"\connect" command fails as not recognized. Is there way to connect other database staying within the same JDBC connection?
UPD: "CONNECT TO ..." and "EXEC SQL CONNECT TO ..." also fail.
Backslash commands are not PostgreSQL SQL commands, they're commands in the psql command-line utility. Behind the scenes, \connect just closes the connection and opens a new one.
PostgreSQL its self does not have any way to switch databases on a connection.
Disconnect and reconnect to the other DB.
I'm trying to set up a Heroku environment for python development following instructions on https://github.com/heroku/python-getting-started. When I run createdb python_getting_started:
I'm first prompted to give in a password: I entered the password of the user "postgres" in Postgres
I get an error message:
createdb database creation failed: ERROR: permission denied to create database
Don't really how to solve this one. The user "postgres" is allowed to create a database. I checked with \du that it is a Superuser and it has Create DB rights. What's going on here? Which user is Windows using to try to create a Postgres DB?
Most PostgreSQL utilities by default use your current OS session login for database connections.
You need to either set environment variable PGUSER to postgres or use createdb -U postgres python_getting_started.
You can read more about createdb parameters here, tho admittedly it does not mention default values.
EDIT: It actually does mention that it uses libpq defaults, and those are:
user
PostgreSQL user name to connect as. Defaults to be the same as the operating system name of the user running the application.
I am pretty much confused about root user,super user,user and permissions! I am not able to create a database inside user "athleticu". Following are the commands I used:-
athleticu#ip-172-30-4-103:/home/ubuntu$ createdb -T template0 simple_db1
createdb: database creation failed: ERROR: permission denied to create database
athleticu#ip-172-30-4-103:/home/ubuntu$ sudo createdb -T template0 simple_db1
sudo: unable to resolve host ip-172-30-4-103
createdb: could not connect to database template1: FATAL: role "root" does not exist
Please somebody clarify my doubts and tell me what should I write!
Hey I have already solved this. What you have to do is to first login as postgres user as follows:
$ su postgres
$ psql
postgres=# alter user athleticu createdb;
ALTER ROLE
Hope it helps you :)
Type \du in psql and you will see a list of all the registered users and what type of privileges each one has.
In order to grant privileges to the user which is logged in (eg 'user1'), I had to sign out and log in using one of the superuser roles in that list (eg. 'user2'), using the following command:
psql -U 'user2' -h localhost 'database2'
where 'database2' is the name of the one that specific superuser 'user2' has privileges to.
Once you are logged in as a superuser, you can grant privileges to 'user1' by:
ALTER ROLE user1 WITH CREATEDB
or
ALTER ROLE user1 WITH SUPERUSER
Then sign in again as user1, who is now a superuser.
This blog was helpful as well as this link.
Currently, this worked for me:
sudo su postgres
psql
ALTER USER username WITH CREATEDB;
\q
exit
The root user is an account on the system independent from Postgres. There is only one root user.
A superuser is an account in Postgres with access to everything. There may be many superusers.
System accounts and Postgres accounts are different things, although unless you specify a Postgres username when you connect to the database (through utilities like psql, createdb, dropdb, or otherwise), it will use the current system user's name in hopes that there is a corresponding Postgres account with the same name. The root user does not, by default, have a corresponding account in Postgres.
When you install Postgres on *nix, it creates both a superuser named postgres and a system user named postgres.
Therefore, when you need to do something with Postgres as the built-in superuser, you have two options:
You may sudo su - postgres to become the postgres system user and execute your command (createdb, psql, etc). Because the system user has the same name as the database superuser, your command will connect as the appropriate account.
You may specify the username to execute as with the -U switch, eg psql -U postgres ....
Depending on your Postgres server's authentication settings, you may be required to enter a password with either or both connection methods.
What you can do when you have fresh installation of PostgreSQL is create your user with some rights (see createuser documentation):
my-user> sudo su - postgres -c "createuser <my-user> --createdb"
This will allow my-user to create DBs just like so:
my-user> createdb <my-db>
If you want the my-user to be able to do anything just use the --superuser flag instead:
my-user> sudo su - postgres -c "createuser <my-user> --superuser"
I got the same error and I found out that the reason was that I was trying to create a database outside of psql as a user which did not exist for postgresql. I found out about it and solved it by taking the following steps:
In my terminal I logged in as postgres user (the root user by default for postgresql) by typing sudo -u postgres psql
While inside the psql I typed \du to see all users and their privileges. I found out that I had only one user (the postgres one) and I had to create another superuser which had the same username as my Linux user (george)
I typed (still inside psql) CREATE USER george SUPERUSER; and this way I created a new super user called george.
I exited psql (by typing \q) and I was now able from outside psql, meaning from my terminal, to run created db <database name> with no issues at all.
Error ? You are trying to perform database actions( Creating Database, creating Roles) using a user that doesn't have the permission for those types of actions you are trying to perform.
solution ? Simply login to your database on the command line, i.e for PostgreSQL one will use "sudo -u postgres psql", then confirm that users specific assigned roles using the command "\du", most probably he/she doesn't have the necessary permissions to perform the actions you wanted. Then simply assign the roles you want the user to perform ,i.e create Database or simply make user "Superuser" by following along(https://chartio.com/resources/tutorials/how-to-change-a-user-to-superuser-in-postgresql/)