In PostgreSQL, a user and a role are actually the same thing —
the difference is only permissions.

• CREATE USER xyz is really just CREATE ROLE xyz LOGIN;
• That means: the role can log in (has the LOGIN attribute).
• If you run CREATE ROLE xyz; without LOGIN, it’s a group role (can’t log in).

So when you ran:

CREATE USER user WITH PASSWORD 'something';

PostgreSQL internally ran:

CREATE ROLE user LOGIN PASSWORD 'something';

✅ That’s correct — your PostgreSQL user (role) was successfully created.

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⚙️ Why the output said “CREATE ROLE”

That’s normal and expected in PostgreSQL.
Even when you write CREATE USER, it outputs CREATE ROLE.

So your user is created and working. 🎉

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🔍 Let’s Verify

Run these commands to confirm:

sudo -i -u postgres
psql

Then inside psql:

\du

This lists all database roles (users).

You should see something like:

Role name | Attributes               | Member of
-----------+--------------------------+-----------
postgres  | Superuser, Create role... |
user      | Login                    | {}

(user here is your Ubuntu username, or whatever you used)

Exit:

\q
exit

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✅ So, to directly answer your question:

Whether user created or I have to create role for same username as Ubuntu?

Answer:
You already created it. PostgreSQL users are roles with login privileges.
No need to create anything else. ✅

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🔒 Optional — make sure your user can connect to iotdb

We can grant privileges again explicitly (safe to repeat):

sudo -i -u postgres
psql

Then inside psql:

GRANT ALL PRIVILEGES ON DATABASE iotdb TO user;
\q
exit