This document describes how to set up PostgreSQL. It also describes how to configure PostgreSQL to be accessible from a remote client. If you need help setting up the rest of a web stack, see the LAMP page and follow all of the sections except the one related to MySQL.
Several sections have instructions stating "become the postgres user". If sudo is installed, execute the following to get a shell as the postgres user:
sudo -i -u postgres
Otherwise su can be used:
su root su - postgres
- 1 Installing PostgreSQL
- 2 Creating Your First Database/User
- 3 Familiarizing Yourself with PostgreSQL
- 4 Configure PostgreSQL to be accessible from remote hosts
- 5 Configure PostgreSQL to Work With PHP
- 6 Change Default Data Dir (Optional)
- 7 Change Default Encoding of New Databases To UTF-8 (Optional)
- 8 Installing phpPgAdmin (optional)
- 9 Installing pgAdmin (optional)
- 10 Upgrading Postgresql
- 11 More Resources
- Install postgresql
$ sudo pacman -S postgresql
- Start the PostgreSQL server (The first time that this is run it will create the data directory and users needed to run the server. As such you will see a lot of output.)
$ sudo /etc/rc.d/postgresql start
- (Optional) Add postgresql to the list of daemons that start on system startup in the /etc/rc.conf file
Creating Your First Database/User
- Become the postgres user. Add a new database user using the createuser command.
If you create a user as per your login user ($USER) it allows you to access the postgresql database shell without having to specify a user to login (which makes it quite convenient).
- Create a new database over which the above user has read/write privileges using the createdb command.
Familiarizing Yourself with PostgreSQL
Access the database shell
- Become the postgres user. Start the primary db shell, psql, where you can do all your creation of databases/tables, deletion, set permissions, and run raw SQL commands.
Some helpful commands:
- Connect to a particular database
=> \c <database>
- List all users and their permission levels
- Shows summary information about all tables in the current database
- exit/quit the psql shell
=> \q or CTRL+d
There are of course many more meta-commands, but these should help you get started.
Configure PostgreSQL to be accessible from remote hosts
The PostgreSQL database server configuration file is
postgresql.conf. This file is located in the data directory of the server, typically
/var/lib/postgres/data. This folder also houses the other main config files, including the
- As root user edit the file
$ sudo vim /var/lib/postgres/data/postgresql.conf
- In the connections and authentications section uncomment or edit the
listen_addressesline to your needs
listen_addresses = '*'and take a careful look at the other lines.
- Hereafter insert the following line in the host-based authentication file
/var/lib/postgres/data/pg_hba.conf. This file controls which hosts are allowed to connect, so be careful.
# IPv4 local connections: host all all your_desired_ip_address/32 trust
your_desired_ip_address is the IP address of the client.
- After this you should restart the daemon process for the changes to take effect with
$ sudo /etc/rc.d/postgresql restart
For troubleshooting take a look in the server log file
Configure PostgreSQL to Work With PHP
- Install the PHP-PostgreSQL modules
# pacman -S php-pgsql
- Open the file
/etc/php/php.iniwith your editor of choice, e.g.,
# vim /etc/php/php.ini
- Find the line that starts with, ";extension=pgsql.so" and change it to, "extension=pgsql.so". (Just remove the preceding ";"). If you need PDO, do the same thing with ";extension=pdo.so" and ";extension=pdo_pgsql.so". If these lines are not present, add them. These lines may be in the "Dynamic Extensions" section of the file, or toward the very end of the file.
- Restart the Apache web server
# /etc/rc.d/httpd restart
Change Default Data Dir (Optional)
By default, when installing PostgreSQL the directory were all your newly created databases will be stored is
/var/lib/postgresql/data. If you want to change this behavior, you have to follow these steps:
- Create the new directory and assign it to user
postgres(you eventually have to become root):
# mkdir /mypath/mydatadir # chown postgres:postgres /mypath/mydatadir
- Become the postgres user, and initialize the new cluster:
$ initdb -D /mypath/mydatadir
/etc/conf.d/postgresqland change the PGROOT variable to point at your new data directory.
Change Default Encoding of New Databases To UTF-8 (Optional)
When creating a new database (e.g. with
createdb blog) PostgreSQL actually copies a template database. There are two predefined templates: template0 is vanilla, while template1 is meant as an on-site template changeable by the administrator and is used by default. In order to change the encoding of new database, one of the options is to change on-site template1. To do this, log into PostgresSQL shell (psql) and execute the following:
1. First, we need to drop template1. Templates can't be dropped, so we first modify it so it's an ordinary database:
UPDATE pg_database SET datistemplate = FALSE WHERE datname = 'template1';
2. Now we can drop it:
DROP DATABASE template1;
3. The next step is to create a new database from template0, with a new default encoding:
CREATE DATABASE template1 WITH TEMPLATE = template0 ENCODING = 'UNICODE';
4. Now modify template1 so it's actually a template:
UPDATE pg_database SET datistemplate = TRUE WHERE datname = 'template1';
5. (RECOMMENDED) PostgreSQL documentation advises to VACUUM FREEZE the template:
\c template1 VACUUM FREEZE;
6. (OPTIONAL) If you don't want anyone connecting to this template, set datallowconn to FALSE:
UPDATE pg_database SET datallowconn = FALSE WHERE datname = 'template1';
Now you can create a new database by running from regular shell:
su - su - postgres createdb blog;
If you log in back to psql and check the databases, you should see the proper encoding of your new database:
List of databases Name | Owner | Encoding | Collation | Ctype | Access privileges -----------+----------+-----------+-----------+-------+---------------------- blog | postgres | UTF8 | C | C | postgres | postgres | SQL_ASCII | C | C | template0 | postgres | SQL_ASCII | C | C | =c/postgres : postgres=CTc/postgres template1 | postgres | UTF8 | C | C |
Installing phpPgAdmin (optional)
phpPgAdmin is a web-based administration tool for PostgreSQL.
- Make sure that the [community] repo is enabled.
- Install the package via Pacman
# pacman -S phppgadmin
Installing pgAdmin (optional)
pgAdmin is a GUI-based administration tool for PostgreSQL.
- Install the package via Pacman
# pacman -S pgadmin3
First thing: these instructions could cause data loss. Use at your own risk. They work for me, but things change and nothing is guaranteed.
I would highly suggest adding the line
IgnorePkg = postgresql
to /etc/pacman.conf. This will make sure that you don't accidentally upgrade the database to an incompatible version. If you did an accidental upgrade you might not be able to access any of your data. Always check the Postgresql home page (http://www.postgresql.org/) to be sure of what steps are required for each upgrade. For a bit about why this is the case see this.
How to dump all of your data, upgrade PostgreSQL, and then restore all of your data (this may not be necessary for every upgrade, see #2 above)
Become the root user
Become the postgres user
Change the current directory to one that the postgres user can write to
eg. cd ~/data/
Dump the current contents of the database
pg_dumpall > pgs_db.out
Unless you have a .pgpass file setup, you will be required to enter your password a few times (the number of times is roughly equal to the number of databases that you have + 2). One problem occurs if you don't have a password defined for the postgres user but you require local users to authenticate. In this case you will be asked to give a password that doesn't exist. To work around this problem, add a line to your pg_hba.conf file to trust the postgres user. You can remove this line after the upgrade is complete. So, the first line of the 'local' section of pg_hba.conf would look something like this:
local all postgres trust
Log out of the postgres user and return to superuser
Stop the PostgreSQL server
Move Postgresql's data directory
mv /var/lib/postgres /var/lib/postgres_old
pacman -S postgresql
Start the PostgreSQL server (this will create all needed files and directories)
Become the postgres user
Change the current directory to the directory that you dumped the data out to (in step 4 above)
eg. cd /var/lib/postgres_old/data/
Restore the database
psql -e template1 -f pgs_db.out