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[[Category:Database management systems]]
 
[[Category:Database management systems]]
[[Category:Web Server]]
 
 
[[it:PostgreSQL]]
 
[[it:PostgreSQL]]
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[[ja:PostgreSQL]]
 
[[ru:PostgreSQL]]
 
[[ru:PostgreSQL]]
[[zh-CN:PostgreSQL]]
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[[zh-hans:PostgreSQL]]
{{Poor writing|excessive use of lists, please use them only when there are items to list.}}
+
{{Related articles start}}
 +
{{Related|PhpPgAdmin}}
 +
{{Related articles end}}
 +
[http://www.postgresql.org/ PostgreSQL] is an open source, community driven, standard compliant object-relational database system.
  
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]].
+
This document describes how to set up PostgreSQL. It also describes how to configure PostgreSQL to be accessible from a remote client. Among other applications, PostgreSQL can be substituted for MySQL as part of the [[LAMP]] web stack.
  
Several sections have instructions stating "become the postgres user". If sudo is installed, execute the following to get a shell as the postgres user:
+
== Installing PostgreSQL ==
sudo -i -u postgres
 
  
Otherwise su can be used:
+
[[Install]] the {{Pkg|postgresql}} package. Then [[Users_and_groups#Other_examples_of_user_management|set a password]] for the newly created ''postgres'' user.
su root
 
su - postgres
 
  
==Installing PostgreSQL==
+
Then, switch to the default PostgreSQL user ''postgres'' by executing the following command:
*Install {{Pkg|postgresql}}
 
# pacman -S postgresql
 
*Configure the PGROOT
 
Edit the /etc/conf.d/postgresql (if you don't know what value to put just uncomment the line)
 
  
*Reboot the system to automatically create the file tmpfiles.d for /run/postgresql
+
* If you have [[sudo]] and your username is in {{ic|sudoers}}:
*Create the data directory (acordingly  with the PGROOT variable set before in the config file)
 
# mkdir /var/lib/postgres/data
 
*Set /var/lib/postgres/data ownership to user 'postgres'
 
# chown -c postgres:postgres /var/lib/postgres/data
 
*As user 'postgres' start the database
 
$ initdb -D '/var/lib/postgres/data'
 
*Start PostgreSQL
 
# systemctl start postgresql
 
*(Optional) Add PostgreSQL to the list of daemons that start on system startup
 
# systemctl enable postgresql
 
  
==Creating Your First Database/User==
+
:{{bc|$ sudo -u postgres -i}}
*Become the postgres user. Add a new database-user using the [http://www.postgresql.org/docs/9.0/static/app-createuser.html 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).
+
* Otherwise:
  
e.g. to create a superuser
+
:{{bc|<nowiki>
 +
$ su
 +
# su -l postgres
 +
</nowiki>}}
  
{{hc|$ createuser -s -U postgres --interactive|
+
See {{man|1|su}} or {{man|8|sudo|url=https://www.sudo.ws/man/sudo.man.html}} for their usage.
Enter name of role to add: myUsualArchLoginName}}
 
  
*Create a new database over which the above user has read/write privileges using the [http://www.postgresql.org/docs/9.0/static/app-createdb.html createdb] command.
+
{{Note|Commands that should be run as the postgres user are prefixed by {{ic|[postgres]$}} in this article.}}
  
From your login shell ('''not''' the postrgres user's)
+
Before PostgreSQL can function correctly, the database cluster must be initialized:
  
  $ createdb myDatabaseName
+
[postgres]$ initdb --locale $LANG -E UTF8 -D '/var/lib/postgres/data'
  
==Familiarizing Yourself with PostgreSQL==
+
Where:
  
===Access the database shell===
+
* the {{ic|--locale}} is the one defined in the file {{ic|/etc/locale.conf}};
*Become the postgres user. Start the primary db shell, [http://www.postgresql.org/docs/8.3/static/app-psql.html 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)
+
* the {{ic|-E}} is the default encoding of the database that will be created in the future;
  $ psql -d myDatabaseName
+
* and {{ic|-D}} is the default location where the database cluster must be stored.
 +
 
 +
Many lines should now appear on the screen with several ending by {{ic|... ok}}:
 +
{{bc|
 +
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_GB.UTF-8".
 +
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
 +
creating template1 database in /var/lib/postgres/data/base/1 ... ok
 +
initializing pg_authid ... ok
 +
[...]
 +
}}
 +
 
 +
If these are the kind of lines you see, then the process succeeded. Return to the regular user using {{ic|exit}}.
 +
 
 +
As root, [[start]] and [[enable]] {{ic|postgresql.service}}.
 +
 
 +
{{Tip|If you change the root to something other than {{ic|/var/lib/postgres}}, you will have to edit the service file. If the root is under {{ic|home}}, make sure to set {{ic|ProtectHome}} to false.}}
 +
 
 +
{{Warning|If the database resides on a [[Btrfs]] file system, you should consider disabling [[Btrfs#Copy-on-Write (CoW)|Copy-on-Write]] for the directory before creating any database.  If the database resides on a [[ZFS]] file system, you should consult [[ZFS#Database]] before creating any database.}}
 +
 
 +
== Create your first database/user ==
 +
 
 +
{{Tip|If you create a PostgreSQL user with the same name as your Linux username, it allows you to access the PostgreSQL database shell without having to specify a user to login (which makes it quite convenient).}}
 +
 
 +
Become the postgres user. Add a new database user using the [http://www.postgresql.org/docs/current/static/app-createuser.html createuser] command:
 +
 
 +
[postgres]$ createuser --interactive
 +
 
 +
Create a new database over which the above user has read/write privileges using the [http://www.postgresql.org/docs/current/static/app-createdb.html createdb] command (execute this command from your login shell if the database user has the same name as your Linux user, otherwise add {{ic|-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, [http://www.postgresql.org/docs/current/static/app-psql.html psql], where you can do all your creation of databases/tables, deletion, set permissions, and run raw SQL commands. Use the {{ic|-d}} option to connect to the database you created (without specifying a database, {{ic|psql}} will try to access a database that matches your username).
 +
 
 +
[postgres]$ psql -d myDatabaseName
  
 
Some helpful commands:
 
Some helpful commands:
  
*Connect to a particular database
+
Get help:
 +
 
 +
=> \help
 +
 
 +
Connect to a particular database:
 +
 
 
  => \c <database>
 
  => \c <database>
*List all users and their permission levels
+
 
 +
List all users and their permission levels:
 +
 
 
  => \du
 
  => \du
*Shows summary information about all tables in the current database
+
 
 +
Show summary information about all tables in the current database:
 +
 
 
  => \dt
 
  => \dt
*exit/quit the psql shell
+
 
 +
Exit/quit the {{ic|psql}} shell:
 +
 
 
  => \q or CTRL+d
 
  => \q or CTRL+d
  
There are of course many more meta-commands, but these should help you get started.
+
There are of course many more meta-commands, but these should help you get started. To see all meta-commands run:
 +
 
 +
=> \?
 +
 
 +
== Optional configuration ==
 +
 
 +
=== Configure PostgreSQL to be accessible from remote hosts ===
 +
 
 +
The PostgreSQL database server configuration file is {{ic|postgresql.conf}}. This file is located in the data directory of the server, typically {{ic|/var/lib/postgres/data}}. This folder also houses the other main configuration files, including the {{ic|pg_hba.conf}}.
 +
 
 +
{{Note|By default, this folder will not be browsable or searchable by a regular user. This is why {{ic|find}} and {{ic|locate}} are not finding the configuration files.}}
  
==Configure PostgreSQL to be accessible from remote hosts==
+
Edit the file {{ic|/var/lib/postgres/data/postgresql.conf}}. In the connections and authentications section, add the {{ic|listen_addresses}} line to your needs:
The PostgreSQL database server configuration file is <code>postgresql.conf</code>. This file is located in the data directory of the server, typically <code>/var/lib/postgres/data</code>. This folder also houses the other main config files, including the <code>pg_hba.conf</code>.
 
  
{{Note | By default this folder will not even be browseable (or searchable) by a regular user, if you are wondering why `find` or `locate` is not finding the conf files, this is the reason (threw me for a loop the first time I installed).}}
+
listen_addresses = 'localhost,''my_local_ip_address'''
 +
#You can use '*' to listen on all local addresses
 +
 
 +
Take a careful look at the other lines.
 +
 
 +
Host-based authentication is configured in {{ic|/var/lib/postgres/data/pg_hba.conf}}. This file controls which hosts are allowed to connect. Note that the defaults '''allow any local user to connect as any database user''', including the database superuser. Add a line like the following:
  
#As root user edit the file<br><pre># vim /var/lib/postgres/data/postgresql.conf</pre>
 
#In the connections and authentications section uncomment or edit the <code>listen_addresses</code> line to your needs<br><pre>listen_addresses = '*'</pre>and take a careful look at the other lines.
 
#Hereafter insert the following line in the host-based authentication file <code>/var/lib/postgres/data/pg_hba.conf</code>. This file controls which hosts are allowed to connect, '''so be careful'''.
 
 
  # IPv4 local connections:
 
  # IPv4 local connections:
  host  all  all  your_desired_ip_address/32  trust
+
  host  all  all  ''my_remote_client_ip_address''/32  md5
where <code>your_desired_ip_address</code> is the IP address of the client.
+
 
#After this you should restart the daemon process for the changes to take effect with<br><pre># rc.d restart postgresql</pre>
+
where {{ic|my_remote_client_ip_address}} is the IP address of the client.
 +
 
 +
See the documentation for [http://www.postgresql.org/docs/current/static/auth-pg-hba-conf.html pg_hba.conf].
 +
 
 +
After this you should [[restart]] {{ic|postgresql.service}} for the changes to take effect.
  
{{Note | Postgresql uses port 5432 by default for remote connections. So make sure this port is open and able to receive incoming connections}}
+
{{Note|PostgreSQL uses port {{ic|5432}} by default for remote connections. Make sure this port is open and able to receive incoming connections.}}
  
For troubleshooting take a look in the server log file
+
For troubleshooting take a look in the server log file:
tail /var/log/postgresql.log
 
  
==Configure PostgreSQL to Work With PHP==
+
$ journalctl -u postgresql
#Install the PHP-PostgreSQL modules<pre># pacman -S php-pgsql </pre>
 
#Open the file '''<code>/etc/php/php.ini</code>''' with your editor of choice, e.g.,<pre># vim /etc/php/php.ini</pre>
 
#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<pre># rc.d restart httpd</pre>
 
  
==Change Default Data Dir (Optional)==
+
=== Configure PostgreSQL authenticate against PAM ===
The default directory where all your newly created databases will be stored is <code>/var/lib/postgres/data</code>. To change this, follow these steps:
 
  
Create the new directory and assign it to user <code>postgres</code> (you eventually have to become root):
+
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.
  mkdir -p ''/pathto/pgroot/data''
+
 
  chown -R postgres:postgres ''/pathto/pgroot''
+
For example, the same configuration as above, but with PAM enabled:
Become the postgres user(change to root, then postgres user), and initialize the new cluster:
+
 
  initdb -D ''/pathto/pgroot/data''
+
# IPv4 local connections:
Edit <code>/etc/conf.d/postgresql</code> and change the PGROOT variable(optionally PGLOG) to point to your new pgroot directory.
+
host  all  all  ''my_remote_client_ip_address''/32  pam
  #PGROOT="/var/lib/postgres/"
+
 
PGROOT="''/pathto/pgroot/''"
+
The PostgreSQL server is however running without root privileges and will not be able to access {{ic|/etc/shadow}}. We can work around that by allowing the postgres group to access this file:
If using systemd, copy <code>/usr/lib/systemd/system/postgresql.service</code> to <code>/etc/systemd/system/postgresql.service</code> and change the default PGROOT path.
+
 
  #Environment=PGROOT=/var/lib/postgres/
+
setfacl -m g:postgres:r /etc/shadow
  Environment=PGROOT=''/pathto/pgroot/''
+
 
You will also need to change the default PIDFile path.
+
=== Change default data directory ===
 +
 
 +
The default directory where all your newly created databases will be stored is {{ic|/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
 +
 
 +
Some variables need to be overridden in the configuration, as described in [[Systemd#Editing provided units]]. First, run:
 +
 
 +
  # systemctl edit postgresql.service
 +
 
 +
Systemctl will open a drop-in configuration file in your editor. Write the following in that file:
 +
 
 +
  [Service]
 +
  Environment=PGROOT=''/pathto/pgroot''
 
  PIDFile=''/pathto/pgroot/''data/postmaster.pid
 
  PIDFile=''/pathto/pgroot/''data/postmaster.pid
  
==Change Default Encoding of New Databases To UTF-8 (Optional)==
+
If you want to use {{ic|/home}} directory for default directory or for tablespaces, add one more line in this file:
When creating a new database (e.g. with <code>createdb blog</code>) 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:
+
 
 +
ProtectHome=false
 +
 
 +
=== Change default encoding of new databases to UTF-8 ===
 +
 
 +
{{Note|If you ran {{ic|initdb}} with {{ic|-E UTF8}} these steps are not required.}}
 +
 
 +
When creating a new database (e.g. with {{ic|createdb blog}}) PostgreSQL actually copies a template database. There are two predefined templates: {{ic|template0}} is vanilla, while {{ic|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 {{ic|template1}}. To do this, log into PostgreSQL shell ({{ic|psql}}) and execute the following:
 +
 
 +
First, we need to drop {{ic|template1}}. Templates cannot be dropped, so we first modify it so it is an ordinary database:
  
1. 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';
 
  UPDATE pg_database SET datistemplate = FALSE WHERE datname = 'template1';
2. Now we can drop it:
+
 
 +
Now we can drop it:
 +
 
 
  DROP DATABASE template1;
 
  DROP DATABASE template1;
3. The next step is to create a new database from template0, with a new default encoding:
+
 
 +
The next step is to create a new database from {{ic|template0}}, with a new default encoding:
 +
 
 
  CREATE DATABASE template1 WITH TEMPLATE = template0 ENCODING = 'UNICODE';
 
  CREATE DATABASE template1 WITH TEMPLATE = template0 ENCODING = 'UNICODE';
4. Now modify template1 so it is actually a template:
+
 
 +
Now modify {{ic|template1}} so it is actually a template:
 +
 
 
  UPDATE pg_database SET datistemplate = TRUE WHERE datname = 'template1';
 
  UPDATE pg_database SET datistemplate = TRUE WHERE datname = 'template1';
6. (OPTIONAL) If you do not want anyone connecting to this template, set datallowconn to FALSE:
+
 
 +
Optionally, if you do not want anyone connecting to this template, set {{ic|datallowconn}} to {{ic|FALSE}}:
 +
 
 
  UPDATE pg_database SET datallowconn = FALSE WHERE datname = 'template1';
 
  UPDATE pg_database SET datallowconn = FALSE WHERE datname = 'template1';
  
Now you can create a new database by running from regular shell:
+
{{Note|This last step can create problems when upgrading via {{ic|pg_upgrade}}.}}
  su -
+
 
  su - postgres
+
Now you can create a new database:
  createdb blog;
+
 
 +
  [postgres]$ createdb blog
 +
 
 +
If you log back in to {{ic|psql}} and check the databases, you should see the proper encoding of your new database:
 +
 
 +
{{hc|\l|<nowiki>
 +
                              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    |
 +
</nowiki>}}
 +
 
 +
== Administration tools ==
 +
 
 +
* {{App|[[phpPgAdmin]]|Web-based administration tool for PostgreSQL.|http://phppgadmin.sourceforge.net|{{Pkg|phppgadmin}}}}
 +
* {{App|pgAdmin|GUI-based administration tool for PostgreSQL.|http://www.pgadmin.org/|{{Pkg|pgadmin3}}}}
 +
 
 +
== Setup HHVM to work with PostgreSQL ==
 +
 
 +
{{Out of date|hhvm-pgsql fails to compile against HHVM 3.7.0, but upstream has not resolved the problem yet. See https://github.com/PocketRent/hhvm-pgsql/issues/82|section=Setting up HHVM}}
 +
 
 +
  $ git clone https://github.com/PocketRent/hhvm-pgsql.git
 +
$ cd hhvm-pgsql
 +
 
 +
If you do not use a nightly build, then run this command (verified on HHVM 3.6.1) to avoid compile errors:
 +
 
 +
  $ git checkout tags/3.6.0
 +
 
 +
Then build the extension (if you do not need an improved support for Hack language, then remove -DHACK_FRIENDLY=ON):
  
If you log in back to psql and check the databases, you should see the proper encoding of your new database:
+
  $ hphpize
\l
+
  $ cmake -DHACK_FRIENDLY=ON .
returns
+
  $ make
                              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)==
+
Then copy the built extension:
[[Phppgadmin]] ([http://phppgadmin.sourceforge.net website]) is a web-based administration tool for PostgreSQL.
 
  
#Make sure that the [community] repo is enabled.
+
# cp pgsql.so /etc/hhvm/
#Install the package via Pacman<pre># pacman -S phppgadmin</pre>
 
  
==Installing pgAdmin (optional)==
+
Add to /etc/hhvm/server.ini:
[http://www.pgadmin.org/ pgAdmin] is a GUI-based administration tool for PostgreSQL.
 
#Install the package via Pacman<pre># pacman -S pgadmin3</pre>
 
  
==Upgrading PostgreSQL ==
+
extension_dir = /etc/hhvm
 +
hhvm.extensions[pgsql] = pgsql.so
  
=== Quick Guide ===
+
== Upgrading PostgreSQL ==
This is for upgrading from 9.1 to 9.2.
 
  
  sudo pacman -S --needed postgresql-old-upgrade
+
Upgrading major PostgreSQL versions (i.e. from {{ic|9.''x''}} to {{ic|9.''y''}}) requires some extra maintenance.
  sudo -u postgres mv /var/lib/postgres/data /var/lib/postgres/data-9.1
 
  sudo -u postgres mkdir /var/lib/postgres/data
 
  sudo -u postgres initdb -D /var/lib/postgres/data
 
  sudo -u postgres pg_upgrade \
 
    -b /opt/pgsql-9.1/bin/ \
 
    -B /usr/bin/ \
 
    -d /var/lib/postgres/data-9.1 \
 
    -D /var/lib/postgres/data
 
  
If the "pg_upgrade" step fails with:
+
{{Note|Official PostgreSQL [http://www.postgresql.org/docs/current/static/upgrading.html upgrade documentation] should be followed.}}
* ''cannot write to log file pg_upgrade_internal.log<br /> Failure, exiting'' <br />Make sure you're in a directory that the "postgres" user has enough rights to write the log file to (<code>/tmp</code> for example). Or use "su - postgres" instead of "sudo -u postgres".
 
* ''LC_COLLATE error that says that old and new values are different''<br />Figure out what the old COLLATE was, C or en_US.UTF-8 for example.
 
* ''There seems to be a postmaster servicing the old cluster.<br/>Please shutdown that postmaster and try again.''<br/>Make sure postgres isn't running. If you still get the error then chances are these an old PID file you need to clear out.
 
  > sudo -u postgres ls -l /var/lib/postgres/data-9.1
 
    total 88
 
    -rw------- 1 postgres postgres    4 Mar 25  2012 PG_VERSION
 
    drwx------ 8 postgres postgres  4096 Jul 17 00:36 base
 
    drwx------ 2 postgres postgres  4096 Jul 17 00:38 global
 
    drwx------ 2 postgres postgres  4096 Mar 25  2012 pg_clog
 
    -rw------- 1 postgres postgres  4476 Mar 25  2012 pg_hba.conf
 
    -rw------- 1 postgres postgres  1636 Mar 25  2012 pg_ident.conf
 
    drwx------ 4 postgres postgres  4096 Mar 25  2012 pg_multixact
 
    drwx------ 2 postgres postgres  4096 Jul 17 00:05 pg_notify
 
    drwx------ 2 postgres postgres  4096 Mar 25  2012 pg_serial
 
    drwx------ 2 postgres postgres  4096 Jul 17 00:53 pg_stat_tmp
 
    drwx------ 2 postgres postgres  4096 Mar 25  2012 pg_subtrans
 
    drwx------ 2 postgres postgres  4096 Mar 25  2012 pg_tblspc
 
    drwx------ 2 postgres postgres  4096 Mar 25  2012 pg_twophase
 
    drwx------ 3 postgres postgres  4096 Mar 25  2012 pg_xlog
 
    -rw------- 1 postgres postgres 19169 Mar 25  2012 postgresql.conf
 
    -rw------- 1 postgres postgres    48 Jul 17 00:05 postmaster.opts
 
    -rw------- 1 postgres postgres    80 Jul 17 00:05 postmaster.pid  # <-- This is the problem
 
 
 
  > sudo -u postgres mv /var/lib/postgres/data-9.1/postmaster.pid /tmp
 
* ''ERROR: could not access file "$libdir/postgis-2.0": No such file or directory'' <br> Retrieve postgis-2.0.so from postgis package for version postgresql 9.1 () and copy it to /opt/pgsql-9.1/lib (make sure the privileges are right)
 
  
=== Detailed Instructions ===
+
{{Warning|The following instructions could cause data loss. '''Use at your own risk'''.}}
{{Warning|Official PostgreSQL [http://www.postgresql.org/docs/current/static/upgrading.html upgrade] documentation should be followed.}}
 
  
Note that these instructions could cause data loss. '''Use at your own risk'''.
+
It is recommended to add the following to your {{ic|/etc/pacman.conf}} file:
  
It is recommended to add the following to your <code>/etc/pacman.conf</code> file:
 
 
  IgnorePkg = postgresql postgresql-libs
 
  IgnorePkg = postgresql postgresql-libs
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 (e.g., 9.0.3 to 9.0.4) are safe to perform. However, if you do an accidental upgrade to a different major version (e.g., 9.0.X to 9.1.X), 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 the [http://www.postgresql.org/support/versioning versioning policy].
+
 
 +
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 {{ic|pacman.conf}}.  Minor version upgrades (e.g. 9.0.3 to 9.0.4) are safe to perform. However, if you do an accidental upgrade to a different major version (e.g. 9.0.x to 9.1.x), you might not be able to access any of your data. Always check the [http://www.postgresql.org/ 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 [http://www.postgresql.org/support/versioning versioning policy].
  
 
There are two main ways to upgrade your PostgreSQL database. Read the official documentation for details.
 
There are two main ways to upgrade your PostgreSQL database. Read the official documentation for details.
  
For those wishing to use <code>pg_upgrade</code>, a {{Pkg|postgresql-old-upgrade}} package is available in the repositories 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. When you are ready to perform the upgrade, you can do
+
For those wishing to use {{ic|pg_upgrade}}, a {{Pkg|postgresql-old-upgrade}} 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.  
pacman -Syu postgresql postgresql-libs postgresql-old-upgrade
 
Note also that the data 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 database must be initialized by starting the server, as described near the top of this page.  The server then needs to be stopped before running pg_upgrade.
 
  
# rc.d stop postgresql
+
When you are ready, upgrade the following packages: {{Pkg|postgresql}}, {{Pkg|postgresql-libs}}, and {{Pkg|postgresql-old-upgrade}}. Note that the data directory does not change from version to version, so before running {{ic|pg_upgrade}}, it is necessary to rename your existing data directory and migrate into a new directory. The new database must be initialized, as described near the top of this page.
# su - postgres -c 'mv /var/lib/postgres/data /var/lib/postgres/olddata'
 
# rc.d start postgresql
 
# rc.d stop postgresql
 
  
Reference the [http://www.postgresql.org/docs/current/static/pgupgrade.html upstream pg_upgrade documentation] for details.
+
# systemctl stop postgresql.service
 +
# su -l postgres -c 'mv /var/lib/postgres/data /var/lib/postgres/olddata'
 +
# su -l postgres -c 'initdb --locale en_US.UTF-8 -E UTF8 -D /var/lib/postgres/data'
  
The upgrade invocation will likely look something like the following (run as the postgres user). '''Do not run this command blindly without understanding what it does!'''
+
The upgrade invocation will likely look something like the following. '''Do not run this command blindly without understanding what it does!''' Reference the [http://www.postgresql.org/docs/current/static/pgupgrade.html upstream pg_upgrade documentation] for details.
  
  # su - postgres -c 'pg_upgrade -d /var/lib/postgres/olddata/ -D /var/lib/postgres/data/ -b /opt/pgsql-8.4/bin/ -B /usr/bin/'
+
  # su -l postgres -c 'pg_upgrade -d /var/lib/postgres/olddata/ -D /var/lib/postgres/data/ -b /opt/pgsql-9.4/bin/ -B /usr/bin/'
  
You could also do something like this (after the upgrade and install of postgresql-old-upgrade)
+
=== Manual dump and reload ===
  
  # rc.d stop postgresql
+
You could also do something like this (after the upgrade and install of {{Pkg|postgresql-old-upgrade}}).
  # /opt/pgsql-8.4/bin/pg_ctl -D /var/lib/postgres/olddata/ start
+
 
  # pg_dumpall >> old_backup.sql
+
{{Note|Below are the commands for PostgreSQL 9.4. You can find similar commands in {{ic|/opt/}} for PostgreSQL 9.2.}}
  # /opt/pgsql-8.4/bin/pg_ctl -D /var/lib/postgres/olddata/ stop
+
 
  # rc.d start postgresql
+
  # systemctl stop postgresql.service
 +
  # /opt/pgsql-9.4/bin/pg_ctl -D /var/lib/postgres/olddata/ start
 +
  # /opt/pgsql-9.4/bin/pg_dumpall >> old_backup.sql
 +
  # /opt/pgsql-9.4/bin/pg_ctl -D /var/lib/postgres/olddata/ stop
 +
  # systemctl start postgresql.service
 
  # psql -f old_backup.sql postgres
 
  # psql -f old_backup.sql postgres
  
==Troubleshooting==
+
== Troubleshooting ==
 +
 
 +
=== Improve performance of small transactions ===
  
===Improve performance of small transactions===
+
If you are using PostgresSQL on a local machine for development and it seems slow, you could try turning [http://www.postgresql.org/docs/current/static/runtime-config-wal.html#GUC-SYNCHRONOUS-COMMIT synchronous_commit off] in the configuration. Beware of the [http://www.postgresql.org/docs/current/static/runtime-config-wal.html#GUC-SYNCHRONOUS-COMMIT caveats], however.
  
If you are using PostgresSQL on a local machine for development and it seems slow, you could try turning [http://www.postgresql.org/docs/current/static/runtime-config-wal.html#GUC-SYNCHRONOUS-COMMIT synchronous_commit off] in the configuration (<code>/var/lib/postgres/data/postgresql.conf</code>). Beware of the [http://www.postgresql.org/docs/current/static/runtime-config-wal.html#GUC-SYNCHRONOUS-COMMIT caveats], however.
+
{{hc|/var/lib/postgres/data/postgresql.conf|2=
 +
synchronous_commit = off
 +
}}
  
<pre>synchronous_commit = off</pre>
+
=== Prevent disk writes when idle ===
  
===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:
  
PostgreSQL periodically updates its internal "statistics" file. By default, this file is stored on disk, which prevents disks spinning down on laptops and causes hard drive seek noise. It's simple and safe to relocate this file to a memory-only file system with the following configuration option:
+
{{hc|/var/lib/postgres/data/postgresql.conf|2=
 +
stats_temp_directory = '/run/postgresql'
 +
}}
  
<pre>stats_temp_directory = '/run/postgresql'</pre>
+
===  Cannot connect to database through pg_connect()  ===
  
==See also==
+
Install {{Pkg|php-pgsql}} and edit the {{ic|php.ini}} file uncommenting the lines {{ic|1=extension=pdo_pgsql.so}}  and {{ic|1=extension=pgsql.so}}, then restart {{ic|httpd}}.
*[http://www.postgresql.org/ Official PostgreSQL Homepage]
 

Latest revision as of 17:07, 17 May 2017

Related articles

PostgreSQL is an open source, community driven, standard compliant object-relational database system.

This document describes how to set up PostgreSQL. It also describes how to configure PostgreSQL to be accessible from a remote client. Among other applications, PostgreSQL can be substituted for MySQL as part of the LAMP web stack.

Installing PostgreSQL

Install the postgresql package. Then set a password for the newly created postgres user.

Then, switch to the default PostgreSQL user postgres by executing the following command:

  • If you have sudo and your username is in sudoers:
$ sudo -u postgres -i
  • Otherwise:
$ su
# su -l postgres

See su(1) or sudo(8) for their usage.

Note: Commands that should be run as the postgres user are prefixed by [postgres]$ in this article.

Before PostgreSQL can function correctly, the database cluster must be initialized:

[postgres]$ initdb --locale $LANG -E UTF8 -D '/var/lib/postgres/data'

Where:

  • the --locale is the one defined in the file /etc/locale.conf;
  • the -E is the default encoding of the database that will be created in the future;
  • and -D is the default location where the database cluster must be stored.

Many lines should now appear on the screen with several ending by ... ok:

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_GB.UTF-8".
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
creating template1 database in /var/lib/postgres/data/base/1 ... ok
initializing pg_authid ... ok
[...]

If these are the kind of lines you see, then the process succeeded. Return to the regular user using exit.

As root, start and enable postgresql.service.

Tip: If you change the root to something other than /var/lib/postgres, you will have to edit the service file. If the root is under home, make sure to set ProtectHome to false.
Warning: If the database resides on a Btrfs file system, you should consider disabling Copy-on-Write for the directory before creating any database. If the database resides on a ZFS file system, you should consult ZFS#Database before creating any database.

Create your first database/user

Tip: If you create a PostgreSQL user with the same name as your Linux username, it allows you to access the PostgreSQL database shell without having to specify a user to login (which makes it quite convenient).

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:

Get help:

=> \help

Connect to a particular database:

=> \c <database>

List all users and their permission levels:

=> \du

Show summary information about all tables in the current database:

=> \dt

Exit/quit the psql shell:

=> \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:

=> \?

Optional configuration

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 configuration files, including the pg_hba.conf.

Note: By default, this folder will not be browsable or searchable by a regular user. This is why find and locate are not finding the configuration files.

Edit the file /var/lib/postgres/data/postgresql.conf. In the connections and authentications section, add the listen_addresses line to your needs:

listen_addresses = 'localhost,my_local_ip_address'
#You can use '*' to listen on all local addresses

Take a careful look at the other lines.

Host-based authentication is configured in /var/lib/postgres/data/pg_hba.conf. This file controls which hosts are allowed to connect. Note that the defaults allow any local user to connect as any database user, including the database superuser. Add a line like the following:

# IPv4 local connections:
host   all   all   my_remote_client_ip_address/32   md5

where my_remote_client_ip_address is the IP address of the client.

See the documentation for pg_hba.conf.

After this you should restart postgresql.service for the changes to take effect.

Note: PostgreSQL uses port 5432 by default for remote connections. Make sure this port is open and able to receive incoming connections.

For troubleshooting take a look in the server log file:

$ journalctl -u postgresql

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

Some variables need to be overridden in the configuration, as described in Systemd#Editing provided units. First, run:

# systemctl edit postgresql.service

Systemctl will open a drop-in configuration file in your editor. Write the following in that file:

[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:

ProtectHome=false

Change default encoding of new databases to UTF-8

Note: If you ran initdb with -E UTF8 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';

Now modify 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 datallowconn to FALSE:

UPDATE pg_database SET datallowconn = FALSE WHERE datname = 'template1';
Note: This last step can create problems when upgrading via pg_upgrade.

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:

\l
                              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     |

Administration tools

  • phpPgAdmin — Web-based administration tool for PostgreSQL.
http://phppgadmin.sourceforge.net || phppgadmin
  • pgAdmin — GUI-based administration tool for PostgreSQL.
http://www.pgadmin.org/ || pgadmin3

Setup HHVM to work with PostgreSQL

Tango-view-refresh-red.pngThis article or section is out of date.Tango-view-refresh-red.png

Reason: hhvm-pgsql fails to compile against HHVM 3.7.0, but upstream has not resolved the problem yet. See https://github.com/PocketRent/hhvm-pgsql/issues/82 (Discuss in Talk:PostgreSQL#Setting up HHVM)
$ git clone https://github.com/PocketRent/hhvm-pgsql.git
$ cd hhvm-pgsql

If you do not use a nightly build, then run this command (verified on HHVM 3.6.1) to avoid compile errors:

$ git checkout tags/3.6.0

Then build the extension (if you do not need an improved support for Hack language, then remove -DHACK_FRIENDLY=ON):

$ hphpize
$ cmake -DHACK_FRIENDLY=ON .
$ make

Then copy the built extension:

# cp pgsql.so /etc/hhvm/

Add to /etc/hhvm/server.ini:

extension_dir = /etc/hhvm
hhvm.extensions[pgsql] = pgsql.so

Upgrading PostgreSQL

Upgrading major PostgreSQL versions (i.e. from 9.x to 9.y) requires some extra maintenance.

Note: Official PostgreSQL upgrade documentation should be followed.
Warning: The following instructions could cause data loss. Use at your own risk.

It is recommended to add the following to your /etc/pacman.conf file:

IgnorePkg = postgresql postgresql-libs

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 (e.g. 9.0.3 to 9.0.4) are safe to perform. However, if you do an accidental upgrade to a different major version (e.g. 9.0.x to 9.1.x), 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 postgresql-old-upgrade 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.

When you are ready, upgrade the following packages: postgresql, postgresql-libs, and postgresql-old-upgrade. Note that the data 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 database must be initialized, as described near the top of this page.

# systemctl stop postgresql.service
# su -l postgres -c 'mv /var/lib/postgres/data /var/lib/postgres/olddata'
# su -l postgres -c 'initdb --locale en_US.UTF-8 -E UTF8 -D /var/lib/postgres/data'

The upgrade invocation will likely look something like the following. Do not run this command blindly without understanding what it does! Reference the upstream pg_upgrade documentation for details.

# su -l postgres -c 'pg_upgrade -d /var/lib/postgres/olddata/ -D /var/lib/postgres/data/ -b /opt/pgsql-9.4/bin/ -B /usr/bin/'

Manual dump and reload

You could also do something like this (after the upgrade and install of postgresql-old-upgrade).

Note: Below are the commands for PostgreSQL 9.4. You can find similar commands in /opt/ for PostgreSQL 9.2.
# systemctl stop postgresql.service
# /opt/pgsql-9.4/bin/pg_ctl -D /var/lib/postgres/olddata/ start
# /opt/pgsql-9.4/bin/pg_dumpall >> old_backup.sql
# /opt/pgsql-9.4/bin/pg_ctl -D /var/lib/postgres/olddata/ stop
# systemctl start postgresql.service
# psql -f old_backup.sql postgres

Troubleshooting

Improve performance of small transactions

If you are using PostgresSQL on a local machine for development and it seems slow, you could try turning synchronous_commit off in the configuration. Beware of the caveats, however.

/var/lib/postgres/data/postgresql.conf
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:

/var/lib/postgres/data/postgresql.conf
stats_temp_directory = '/run/postgresql'

Cannot connect to database through pg_connect()

Install php-pgsql and edit the php.ini file uncommenting the lines extension=pdo_pgsql.so and extension=pgsql.so, then restart httpd.