Use PostgreSQL Relational Databases on Ubuntu 9.04 (Jaunty)
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The PostgreSQL relational database system is a fast, scalable, and standards-compliant open source database platform. This guide will help you install and configure PostgreSQL on Ubuntu 9.04 (Jaunty). We assume you’ve followed the steps detailed in our getting started guide, and that you’re logged into your Linode as root via SSH.
Make sure your package repositories and installed programs are up to date by issuing the following commands:
apt-get update apt-get upgrade --show-upgraded
Issue the following command to install PostgreSQL and required dependencies:
apt-get install postgresql
The current version of the database server will be installed, along with several supporting packages.
Creating a Database
Switch to the “postgres” user and create a database by issuing the following commands:
su - postgres createdb mytestdb
Connect to the test database by issuing the following command:
You should see output similar to the following:
[email protected]:~$ psql mytestdb Welcome to psql 8.3.7, the PostgreSQL interactive terminal. Type: \copyright for distribution terms \h for help with SQL commands \? for help with psql commands \g or terminate with semicolon to execute query \q to quit mytestdb=#
This is the PostgreSQL client shell; you may use it to issue SQL statements. To see a list of available commands, use the following command in the shell:
You may find more information on a specific command by adding it after the
To create a table in your test database called “employees”, issue the following command:
CREATE TABLE employees (employee_id int, first_name varchar, last_name varchar);
To insert a record into the table, you would issue a statement like this:
INSERT INTO employees VALUES (1, 'Jack', 'Sprat');
To see the contents of the “employees” table, you would issue a SELECT statement similar to the following:
SELECT * FROM employees;
This would produce output similar to the following:
mytestdb=# SELECT * FROM employees; employee_id | first_name | last_name -------------+------------+----------- 1 | Jack | Sprat (1 row)
To exit the
psql shell, issue this command:
Creating PostgreSQL Users (Roles)
PostgreSQL refers to users as “roles”, which may have different privileges on your databases. If a user is classified as a “superuser” it will have administrative access to the database system. To add a new user to PostgreSQL, issue the following command as the “postgres” user:
createuser alison --pwprompt
You will be asked to specify several values for the new user. To delete this user, issue the following command:
By default, PostgreSQL uses
ident authentication. This means database connections will be granted to local system users that own or have privileges on the database being connected to. Such authentication is useful in cases where a particular system user will be running a program (local scripts, CGI/FastCGI processes owned by separate users, etc). However, you may wish to change this behavior to require passwords. To do so, edit the file
/etc/postgresql/8.4/main/pg_hba.conf as root or the postgres user. Find the following line:
local all all ident sameuser
Change it to the following to use password authentication:
local all all md5
To grant all privileges on the table
employees to a user named
alison, issue the following commands:
psql mytestdb GRANT ALL ON employees TO alison;
To use the database
alison, issue the following command:
psql -U alison -W mytestdb
You will be prompted to enter the password for the
alison user and given
psql shell access to the database.
You may wish to consult the following resources for additional information on this topic. While these are provided in the hope that they will be useful, please note that we cannot vouch for the accuracy or timeliness of externally hosted materials.
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