The PostgreSQL relational database system is a fast, scalable, and stadards-compliant open source database platform. This guide will help you install and configure PostgreSQL on CentOS 5. We assume you've followed the steps detailed in our getting started guide, and that you're logged into your Linode VPS as root via SSH.
Make sure your system is up to date by issuing the following command:
Issue the following command to install PostgreSQL and required dependencies:
yum install postgresql postgresql-server
The current version of the database server will be installed, along with several supporting packages. Start the database server with the following commands:
/sbin/chkconfig --levels 235 postgresql on service postgresql start
Set a password for the "postgres" user by issuing the following commands (be sure to subtitute your postgres password for "CHANGME" below):
passwd postgres su - postgres psql -d template1 -c "ALTER USER postgres WITH PASSWORD 'CHANGEME';"
You should pick a password consisting of numbers, letters, and non-alphanumeric characters. As with other account passwords, it should be a minimum of eight characters in length.
Create a database and connect to it with psql by issuing the following commands:
createdb mytestdb psql mytestdb
You should see output similar to the following:
-bash-3.2$ psql mytestdb Welcome to psql 8.1.21, 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:
To get help on a specific command enter it after \h, as shown below for the "SELECT" command:
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:
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 /var/lib/pgsql/data/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
As root, restart the Postgresql service:
service postgresql restart
Resume these instructions as the postgres user:
su - postgres
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 "mytestdb" as "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.
PostgreSQL listens for connections on localhost, and it is not advised to reconfigure it to listen on public IP addresses. If you would like to access your databases remotely using a graphical tool, please follow one of these guides:
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.
This guide is licensed under a Creative Commons Attribution-NoDerivs 3.0 United States License.
Last edited by Sharon Campbell on Tuesday, September 24th, 2013 (r3689).