PostgreSQL is an open source, community driven, standard compliant object-relational database system.
- 1 Installing PostgreSQL
- 2 Initial configuration
- 3 Create your first database/user
- 4 Familiarize with PostgreSQL
- 5 Optional configuration
- 5.1 Restricts access rights to the database superuser by default
- 5.2 Configure PostgreSQL to be accessible exclusively through UNIX Sockets
- 5.3 Configure PostgreSQL to be accessible from remote hosts
- 5.4 Configure PostgreSQL authenticate against PAM
- 5.5 Change default data directory
- 5.6 Change default encoding of new databases to UTF-8
- 6 Administration tools
- 7 Upgrading PostgreSQL
- 8 Troubleshooting
Install the package. It will also create a system user called postgres.
[postgres]$in this article.
You can switch to the PostgreSQL user by executing the following command:
$ sudo -u postgres -i
- Otherwise using su:
$ su # su -l postgres
You can also run oneshot commands:
- Using sudo:
$ sudo -u postgres command
- Using su:
# su -c command postgres
Seeor for their usage.
Before PostgreSQL can function correctly, the database cluster must be initialized:
[postgres]$ initdb -D '/var/lib/postgres/data'
-D is the default location where the database cluster must be stored (see #Change default data directory if you want to use a different one).
Note that by default, the locale and the encoding for the database cluster are derived from your current environment (using $LANG value).  However, depending on your settings and use cases this might not be what you want, and you can override the defaults using:
--locale locale, where locale is to be chosen amongst the ones defined in the file
Cthat are also accepted);
-E encondingfor the encoding (which must match the chosen locale);
[postgres]$ initdb --locale en_US.UTF-8 -E UTF8 -D '/var/lib/postgres/data'
Many lines should now appear on the screen with several ending by
The files belonging to this database system will be owned by user "postgres". This user must also own the server process. The database cluster will be initialized with locale "en_US.UTF-8". The default database encoding has accordingly been set to "UTF8". The default text search configuration will be set to "english". Data page checksums are disabled. fixing permissions on existing directory /var/lib/postgres/data ... ok creating subdirectories ... ok selecting default max_connections ... 100 selecting default shared_buffers ... 128MB selecting dynamic shared memory implementation ... posix creating configuration files ... ok running bootstrap script ... ok performing post-bootstrap initialization ... ok syncing data to disk ... ok WARNING: enabling "trust" authentication for local connections You can change this by editing pg_hba.conf or using the option -A, or --auth-local and --auth-host, the next time you run initdb. Success. You can now start the database server using: pg_ctl -D /var/lib/postgres/ -l logfile start
If these are the kind of lines you see, then the process succeeded. Return to the regular user using
WARNING, see local users configuration.
/var/lib/postgres, you will have to edit the service file. If the root is under
home, make sure to set
Create your first database/user
Become the postgres user. Add a new database user using the createuser command:
[postgres]$ createuser --interactive
Create a new database over which the above user has read/write privileges using the createdb command (execute this command from your login shell if the database user has the same name as your Linux user, otherwise add
-U database-username to the following command):
$ createdb myDatabaseName
Familiarize with PostgreSQL
Access the database shell
Become the postgres user. Start the primary database shell, psql, where you can do all your creation of databases/tables, deletion, set permissions, and run raw SQL commands. Use the
-d option to connect to the database you created (without specifying a database,
psql will try to access a database that matches your username).
[postgres]$ psql -d myDatabaseName
Some helpful commands:
Connect to a particular database:
=> \c <database>
List all users and their permission levels:
Show summary information about all tables in the current database:
=> \q or CTRL+d
There are of course many more meta-commands, but these should help you get started. To see all meta-commands run:
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 configuration files, including the
pg_hba.conf which defines authentication settings, for both local users and other hosts ones.
locateare not finding the configuration files.
Restricts access rights to the database superuser by default
pg_hba.conf allow any local user to connect as any database user, including the database superuser.
This is likely not what you want, so in order to restrict global access to the postgress user, change the following line:
# TYPE DATABASE USER ADDRESS METHOD # "local" is for Unix domain socket connections only local all all trust
# TYPE DATABASE USER ADDRESS METHOD # "local" is for Unix domain socket connections only local all postgres peer
You might later add additional lines depending on your needs or software ones.
Configure PostgreSQL to be accessible exclusively through UNIX Sockets
In the connections and authentications section of your configuration, set:
listen_addresses = ''
This will disable network listening completely.
After this you should restart
postgresql.service for the changes to take effect.
Configure PostgreSQL to be accessible from remote hosts
In the connections and authentications section, set the
listen_addresses line to your needs:
listen_addresses = 'localhost,my_local_ip_address'
You can use
'*' to listen on all available addresses.
5432by default for remote connections. Make sure this port is open in your firewall and able to receive incoming connections. You can also change it in the configuration file, right below
Then add a line like the following to the authentication config:
# TYPE DATABASE USER ADDRESS METHOD # IPv4 local connections: host all all ip_address/32 md5
ip_address is the IP address of the remote client.
See the documentation for pg_hba.conf.
After this you should restart
postgresql.service for the changes to take effect.
For troubleshooting take a look in the server log file:
$ journalctl -u postgresql.service
Configure PostgreSQL authenticate against PAM
PostgreSQL offers a number of authentication methods. If you would like to allow users to authenticate with their system password, additional steps are necessary. First you need to enable PAM for the connection.
For example, the same configuration as above, but with PAM enabled:
# IPv4 local connections: host all all my_remote_client_ip_address/32 pam
The PostgreSQL server is however running without root privileges and will not be able to access
/etc/shadow. We can work around that by allowing the postgres group to access this file:
# setfacl -m g:postgres:r /etc/shadow
Change default data directory
The default directory where all your newly created databases will be stored is
/var/lib/postgres/data. To change this, follow these steps:
Create the new directory and make the postgres user its owner:
# mkdir -p /pathto/pgroot/data # chown -R postgres:postgres /pathto/pgroot
Become the postgres user, and initialize the new cluster:
[postgres]$ initdb -D /pathto/pgroot/data
postgresql.service to create a drop-in file and override the
PIDFile settings. For example:
[Service] Environment=PGROOT=/pathto/pgroot PIDFile=/pathto/pgroot/data/postmaster.pid
If you want to use
/home directory for default directory or for tablespaces, add one more line in this file:
Change default encoding of new databases to UTF-8
-E UTF8or while using an UTF-8 locale, these steps are not required.
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 a new database, one of the options is to change on-site
template1. To do this, log into PostgreSQL shell (
psql) and execute the following:
First, we need to drop
template1. Templates cannot be dropped, so we first modify it so it is an ordinary database:
UPDATE pg_database SET datistemplate = FALSE WHERE datname = 'template1';
Now we can drop it:
DROP DATABASE template1;
The next step is to create a new database from
template0, with a new default encoding:
CREATE DATABASE template1 WITH TEMPLATE = template0 ENCODING = 'UNICODE';
template1 so it is actually a template:
UPDATE pg_database SET datistemplate = TRUE WHERE datname = 'template1';
Optionally, if you do not want anyone connecting to this template, set
UPDATE pg_database SET datallowconn = FALSE WHERE datname = 'template1';
Now you can create a new database:
[postgres]$ createdb blog
If you log back in 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 |
- Adminer — Web-based database management tool for multiple database systems.
- https://www.adminer.org || AUR
- phpPgAdmin — Web-based administration tool for PostgreSQL.
- pgAdmin — GUI-based administration tool for PostgreSQL.
- pgModeler — Graphical schema designer for PostgreSQL.
- https://pgmodeler.io/ || AUR
Upgrading major PostgreSQL versions requires some extra maintenance.
- Official PostgreSQL upgrade documentation should be followed.
- From version
10.0onwards PostgreSQL changed its versioning scheme. Earlier upgrade from version
9.ywas considered as major upgrade. Now upgrade from version
10.yis considered as minor upgrade and upgrade from version
11.yis considered as major upgrade.
It is recommended to add the following to your
IgnorePkg = postgresql*
This will ensure you do not accidentally upgrade the database to an incompatible version. When an upgrade is available, pacman will notify you that it is skipping the upgrade because of the entry in
pacman.conf. Minor version upgrades are safe to perform. However, if you do an accidental upgrade to a different major version, you might not be able to access any of your data. Always check the PostgreSQL home page to be sure of what steps are required for each upgrade. For a bit about why this is the case, see the versioning policy.
There are two main ways to upgrade your PostgreSQL database. Read the official documentation for details.
For those wishing to use
pg_upgrade, a package is available that will always run one major version behind the real PostgreSQL package. This can be installed side-by-side with the new version of PostgreSQL.
Note that the databases cluster directory does not change from version to version, so before running
pg_upgrade, it is necessary to rename your existing data directory and migrate into a new directory. The new databases cluster must be initialized, as described in the #Installing PostgreSQL section.
When you are ready, stop the postgresql service, upgrade the following packages:, , and . Finally upgrade the databases cluster.
Stop and make sure PostgreSQL is stopped:
# systemctl stop postgresql.service # systemctl status postgresql.service
Upgrade the packages:
# pacman -S postgresql postgresql-libs postgresql-old-upgrade
Rename the databases cluster directory, and create an empty one:
# mv /var/lib/postgres/data /var/lib/postgres/olddata # mkdir /var/lib/postgres/data /var/lib/postgres/tmp # chown postgres:postgres /var/lib/postgres/data /var/lib/postgres/tmp [postgres]$ initdb -D '/var/lib/postgres/data'
Upgrade the cluster:
[postgres]$ cd /var/lib/postgres/tmp [postgres]$ pg_upgrade -b /opt/pgsql-9.6/bin -B /usr/bin -d /var/lib/postgres/olddata -D /var/lib/postgres/data
pg_upgrade will perform the upgrade and create some scripts in
/var/lib/postgres/tmp/. Follow the instructions given on screen and act accordingly. You may delete the
/var/lib/postgres/tmp directory once the upgrade is completely over.
Start the cluster:
# systemctl start postgresql.service
Manual dump and reload
You could also do something like this (after the upgrade and install of).
- Below are the commands for PostgreSQL 9.6. You can find similar commands in
/opt/for PostgreSQL 9.2.
- If you had customized your
pg_hba.conffile, you may have to temporarily modify it to allow full access to old database cluster from local system. After upgrade is complete set your customization to new database cluster as well and restart
# systemctl stop postgresql.service # mv /var/lib/postgres/data /var/lib/postgres/olddata # mkdir /var/lib/postgres/data # chown postgres:postgres /var/lib/postgres/data [postgres]$ initdb -D '/var/lib/postgres/data' [postgres]$ /opt/pgsql-9.6/bin/pg_ctl -D /var/lib/postgres/olddata/ start [postgres]$ pg_dumpall -f /tmp/old_backup.sql [postgres]$ /opt/pgsql-9.6/bin/pg_ctl -D /var/lib/postgres/olddata/ stop # systemctl start postgresql.service [postgres]$ psql -f /tmp/old_backup.sql postgres
Improve performance of small transactions
synchronous_commit = off
Prevent disk writes when idle
PostgreSQL periodically updates its internal "statistics" file. By default, this file is stored on disk, which prevents disks from spinning down on laptops and causes hard drive seek noise. It is simple and safe to relocate this file to a memory-only file system with the following configuration option:
stats_temp_directory = '/run/postgresql'
Cannot connect to database through pg_connect()
php.ini file uncommenting the lines
extension=pgsql, then restart