Difference between revisions of "PostgreSQL"

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m (Quick guide: since the initdb was probably done with UTF-8 instead of default 'C', this should be the default option here.)
m (use the same style for commands that should be run as postgres user)
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[[ru:PostgreSQL]]
 
[[ru:PostgreSQL]]
 
[[zh-CN:PostgreSQL]]
 
[[zh-CN:PostgreSQL]]
{{Poor writing|excessive use of lists, please use them only when there are items to list.}}
+
{{Related articles start}}
 
+
{{Related|PhpPgAdmin}}
PostgreSQL is an open source, community driven, standard compliant object-relational database system.
+
{{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. 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]].
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== Before you start ==
 
== Before you start ==
  
Several sections have instructions stating "become the postgres user". Execute the following to get a shell as the postgres user:
+
Several sections have instructions stating "become the ''postgres'' user". Commands that should be run as the ''postgres'' user are prefixed by {{ic|[postgres]$}} in this article.
su root
+
su - postgres
+
  
Otherwise sudo can be used:
+
Execute the following as root to get a shell as the postgres user:
 +
# su - postgres
  
  sudo -i -u postgres
+
If you use sudo, you can use the following:
 +
  $ sudo -i -u postgres
 +
 
 +
The postgres [[Users and groups|user]] will automatically be created by installing PostgreSQL.
  
 
== Installing PostgreSQL ==
 
== Installing PostgreSQL ==
  
[[pacman|Install]] {{Pkg|postgresql}} from the [[official repositories]]. Before PostgreSQL can function correctly, the '''postgres''' user needs to be given ownership of several files and directories, and the database cluster must be initialized. The following steps set sane defaults.
+
[[pacman|Install]] {{Pkg|postgresql}} from the [[official repositories]].  
  
Create "volatile and temporary files and directories". For details, see [[Systemd#Temporary_files]]:
+
Before PostgreSQL can function correctly the database cluster must be initialized by the ''postgres'' user. Become the ''postgres'' user and run the following commmand:
# systemd-tmpfiles --create postgresql.conf
+
  [postgres]$ initdb --locale en_US.UTF-8 -E UTF8 -D '/var/lib/postgres/data'
 
+
Create a directory to house the database cluster, give it correct permissions and initialize the database cluster:
+
# mkdir /var/lib/postgres/data
+
# chown -c -R postgres:postgres /var/lib/postgres
+
  # sudo su - postgres -c "initdb --locale en_US.UTF-8 -E UTF8 -D '/var/lib/postgres/data'"
+
  
 
Start PostgreSQL and, optionally, add it to the list of daemons that start on system startup:
 
Start PostgreSQL and, optionally, add it to the list of daemons that start on system startup:
 
  # systemctl start postgresql
 
  # systemctl start postgresql
 
  # systemctl enable postgresql
 
  # systemctl enable postgresql
 +
 +
{{Warning|If the database resides on a [[Btrfs]] file system, you should consider disabling [[Btrfs#Copy-On-Write_.28CoW.29|Copy-on-Write]] for the directory before creating any database.}}
  
 
== Create your first database/user ==
 
== Create your first database/user ==
  
Become the postgres user. Add a new database-user using the [http://www.postgresql.org/docs/9.0/static/app-createuser.html createuser] command.
+
{{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).}}
 
+
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).
+
 
+
e.g. to create a superuser
+
 
+
{{hc|$ createuser -s -U postgres --interactive|
+
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.
+
  
From your login shell ('''not''' the postrgres user's):
+
Become the ''postgres'' user. Add a new database user using the [http://www.postgresql.org/docs/9.0/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/9.0/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
 
  $ createdb myDatabaseName
  
Line 58: Line 51:
  
 
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)
 
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)
  $ psql -d myDatabaseName
+
  [postgres]$ psql -d myDatabaseName
  
 
Some helpful commands:
 
Some helpful commands:
Line 75: Line 68:
 
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.
  
== Configure PostgreSQL to be accessible from remote hosts ==
+
== 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 config files, including the {{ic|pg_hba.conf}}.
 
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 config files, including the {{ic|pg_hba.conf}}.
Line 81: Line 76:
 
{{Note|By default this folder will not even be browseable (or searchable) by a regular user, if you are wondering why {{ic|find}} or {{ic|locate}} is not finding the conf files, this is the reason.}}
 
{{Note|By default this folder will not even be browseable (or searchable) by a regular user, if you are wondering why {{ic|find}} or {{ic|locate}} is not finding the conf files, this is the reason.}}
  
As root user edit the file {{ic|/var/lib/postgres/data/postgresql.conf}}.
+
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:
In the connections and authentications section uncomment or edit the {{ic|listen_addresses}} line to your needs:
+
  listen_addresses = 'localhost,my_remote_ip_address'
  listen_addresses = '*'
+
 
Take a careful look at the other lines.
 
Take a careful look at the other lines.
Hereafter insert the following line in the host-based authentication file {{ic|/var/lib/postgres/data/pg_hba.conf}}. This file controls which hosts are allowed to connect, so '''be careful'''.
+
 
 +
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:
 
  # IPv4 local connections:
 
  # IPv4 local connections:
  host  all  all  your_desired_ip_address/32  trust
+
  host  all  all  ''my_remote_ip_address''/32  md5
 
where {{ic|your_desired_ip_address}} is the IP address of the client.
 
where {{ic|your_desired_ip_address}} is the IP address of the client.
 +
 +
See the documentation for [http://www.postgresql.org/docs/9.3/static/auth-pg-hba-conf.html pg_hba.conf].
 +
 
After this you should restart the daemon process for the changes to take effect with:
 
After this you should restart the daemon process for the changes to take effect with:
 
  # systemctl restart postgresql
 
  # systemctl restart postgresql
Line 95: Line 93:
  
 
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
+
  $ tail /var/log/postgresql.log
 
+
== Configure PostgreSQL to work with PHP==
+
 
+
Install the PHP-PostgreSQL modules {{Pkg|php-pgsql}}.
+
Edit the file {{ic|/etc/php/php.ini}}. Find the line that starts with:
+
;extension=pgsql.so
+
Change it to:
+
extension=pgsql.so
+
If you need PDO, do the same thing with {{ic|;extension=pdo.so}} and {{ic|;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:
+
# systemctl restart httpd
+
  
== Change default data dir (optional) ==
+
=== 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:
 
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 assign it to user {{ic|postgres}} (you eventually have to become root):
+
Create the new directory and make the ''postgres'' user its owner:
  mkdir -p /pathto/pgroot/data
+
  # mkdir -p /pathto/pgroot/data
  chown -R postgres:postgres /pathto/pgroot
+
  # chown -R postgres:postgres /pathto/pgroot
Become the postgres user(change to root, then postgres user), and initialize the new cluster:
+
Become the ''postgres'' user, and initialize the new cluster:
  initdb -D /pathto/pgroot/data
+
  [postgres]$ initdb -D /pathto/pgroot/data
If not using systemd, edit {{ic|/etc/conf.d/postgresql}} and change the PGROOT variable(optionally PGLOG) to point to your new pgroot directory:
+
If enabled, disable {{ic|postgres.service}}. Copy {{ic|/usr/lib/systemd/system/postgresql.service}} to {{ic|/etc/systemd/system/postgresql.service}} and edit it to change the default {{ic|PGROOT}} and {{ic|PIDFile}} paths.
#PGROOT="/var/lib/postgres/"
+
PGROOT="''/pathto/pgroot/''"
+
If using systemd, edit {{ic|/etc/systemd/system/multi-user.target.wants/postgresql.service}}, which links to {{ic|/usr/lib/systemd/system/postgresql.service}}, and change the default PGROOT path.
+
#Environment=PGROOT=/var/lib/postgres/
+
 
  Environment=PGROOT=''/pathto/pgroot/''
 
  Environment=PGROOT=''/pathto/pgroot/''
You will also need to change the default PIDFile path.
+
...
  PIDFile=/pathto/pgroot/data/postmaster.pid
+
  PIDFile=''/pathto/pgroot/''data/postmaster.pid
  
== Change default encoding of new databases to UTF-8 (optional) ==
+
=== Change default encoding of new databases to UTF-8 ===
{{Note|If you ran initdb with -E UTF8 these steps are not required}}
+
{{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: 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:
 
When creating a new database (e.g. with {{ic|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:
  
Line 143: Line 126:
 
{{Note|this last step can create problems when upgrading via {{ic|pg_upgrade}}.}}
 
{{Note|this last step can create problems when upgrading via {{ic|pg_upgrade}}.}}
  
Now you can create a new database by running from regular shell:
+
Now you can create a new database:
  su -
+
  [postgres]$ createdb blog
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:
 
If you log in back to psql and check the databases, you should see the proper encoding of your new database:
Line 175: Line 156:
 
   su - postgres -c 'mv /var/lib/postgres/data /var/lib/postgres/data-9.2'
 
   su - postgres -c 'mv /var/lib/postgres/data /var/lib/postgres/data-9.2'
 
   su - postgres -c 'mkdir /var/lib/postgres/data'
 
   su - postgres -c 'mkdir /var/lib/postgres/data'
   su - postgres -c 'initdb --locale en_US.UTF-8 -E UTF8 -D '/var/lib/postgres/data''
+
   su - postgres -c 'initdb --locale en_US.UTF-8 -E UTF8 -D /var/lib/postgres/data'
  
 
If you had custom settings in configuration files like pg_hba.conf and postgresql.conf, merge them into the new ones. Then:
 
If you had custom settings in configuration files like pg_hba.conf and postgresql.conf, merge them into the new ones. Then:
Line 224: Line 205:
 
For those wishing to use {{ic|pg_upgrade}}, 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 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
 
  pacman -Syu postgresql postgresql-libs postgresql-old-upgrade
 
  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.
+
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, as described near the top of this page.
  
 
  # systemctl stop postgresql
 
  # systemctl stop postgresql
 
  # su - postgres -c 'mv /var/lib/postgres/data /var/lib/postgres/olddata'
 
  # su - postgres -c 'mv /var/lib/postgres/data /var/lib/postgres/olddata'
  # systemctl start postgresql
+
  # su - postgres -c 'initdb --locale en_US.UTF-8 -E UTF8 -D /var/lib/postgres/data'
# systemctl stop postgresql
+
  
 
Reference the [http://www.postgresql.org/docs/current/static/pgupgrade.html upstream pg_upgrade documentation] for details.
 
Reference the [http://www.postgresql.org/docs/current/static/pgupgrade.html upstream pg_upgrade documentation] for details.
Line 237: Line 217:
 
  # 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 - postgres -c 'pg_upgrade -d /var/lib/postgres/olddata/ -D /var/lib/postgres/data/ -b /opt/pgsql-8.4/bin/ -B /usr/bin/'
  
You could also do something like this (after the upgrade and install of postgresql-old-upgrade)
+
==== Manual dump and reload ====
 +
 
 +
You could also do something like this (after the upgrade and install of postgresql-old-upgrade) (NB: below is command for postgres8.4 update, you can find similar command in /opt/ for postgres 9.2 update. )
  
 
  # systemctl stop postgresql
 
  # systemctl stop postgresql
 
  # /opt/pgsql-8.4/bin/pg_ctl -D /var/lib/postgres/olddata/ start
 
  # /opt/pgsql-8.4/bin/pg_ctl -D /var/lib/postgres/olddata/ start
  # pg_dumpall >> old_backup.sql
+
  # /opt/pgsql-8.4/bin/pg_dumpall >> old_backup.sql
 
  # /opt/pgsql-8.4/bin/pg_ctl -D /var/lib/postgres/olddata/ stop
 
  # /opt/pgsql-8.4/bin/pg_ctl -D /var/lib/postgres/olddata/ stop
 
  # systemctl start postgresql
 
  # systemctl start postgresql
Line 259: Line 241:
  
 
  stats_temp_directory = '/run/postgresql'
 
  stats_temp_directory = '/run/postgresql'
 
== See also ==
 
 
* [http://www.postgresql.org/ Official PostgreSQL Homepage]
 

Revision as of 10:37, 7 March 2014

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. 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.

Before you start

Several sections have instructions stating "become the postgres user". Commands that should be run as the postgres user are prefixed by [postgres]$ in this article.

Execute the following as root to get a shell as the postgres user:

# su - postgres

If you use sudo, you can use the following:

$ sudo -i -u postgres

The postgres user will automatically be created by installing PostgreSQL.

Installing PostgreSQL

Install postgresql from the official repositories.

Before PostgreSQL can function correctly the database cluster must be initialized by the postgres user. Become the postgres user and run the following commmand:

[postgres]$ initdb --locale en_US.UTF-8 -E UTF8 -D '/var/lib/postgres/data'

Start PostgreSQL and, optionally, add it to the list of daemons that start on system startup:

# systemctl start postgresql
# systemctl enable postgresql
Warning: If the database resides on a Btrfs file system, you should consider disabling Copy-on-Write for the directory 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 db 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

Shows 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.

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 config files, including the pg_hba.conf.

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.

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_remote_ip_address'

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_ip_address/32   md5

where your_desired_ip_address is the IP address of the client.

See the documentation for pg_hba.conf.

After this you should restart the daemon process for the changes to take effect with:

# systemctl restart postgresql
Note: Postgresql uses port 5432 by default for remote connections. So make sure this port is open and able to receive incoming connections.

For troubleshooting take a look in the server log file

$ tail /var/log/postgresql.log

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

If enabled, disable postgres.service. Copy /usr/lib/systemd/system/postgresql.service to /etc/systemd/system/postgresql.service and edit it to change the default PGROOT and PIDFile paths.

Environment=PGROOT=/pathto/pgroot/
...
PIDFile=/pathto/pgroot/data/postmaster.pid

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 new database, one of the options is to change on-site template1. To do this, log into PostgresSQL 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';

(OPTIONAL) 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 in back to psql and check the databases, you should see the proper encoding of your new database:

\l

returns

                              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

Upgrading PostgreSQL

Quick guide

This is for upgrading from 9.2 to 9.3.

 pacman -S --needed postgresql-old-upgrade
 su -
 su - postgres -c 'mv /var/lib/postgres/data /var/lib/postgres/data-9.2'
 su - postgres -c 'mkdir /var/lib/postgres/data'
 su - postgres -c 'initdb --locale en_US.UTF-8 -E UTF8 -D /var/lib/postgres/data'

If you had custom settings in configuration files like pg_hba.conf and postgresql.conf, merge them into the new ones. Then:

 su - postgres -c 'pg_upgrade -b /opt/pgsql-9.2/bin/ -B /usr/bin/ -d /var/lib/postgres/data-9.2 -D /var/lib/postgres/data'

If the "pg_upgrade" step fails with:

  • cannot write to log file pg_upgrade_internal.log
    Failure, exiting

    Make sure you're in a directory that the "postgres" user has enough rights to write the log file to (/tmp for example). Or use "su - postgres" instead of "sudo -u postgres".
  • LC_COLLATE error that says that old and new values are different
    Figure out what the old locale was, C or en_US.UTF-8 for example, and force it when calling initdb.
 sudo -u postgres LC_ALL=C initdb -D /var/lib/postgres/data
  • There seems to be a postmaster servicing the old cluster.
    Please shutdown that postmaster and try again.

    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-9.2
   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-9.2/postmaster.pid /tmp
  • ERROR: could not access file "$libdir/postgis-2.0": No such file or directory
    Retrieve postgis-2.0.so from postgis package for version postgresql 9.2 () and copy it to /opt/pgsql-9.2/lib (make sure the privileges are right)

Detailed instructions

Note: Official PostgreSQL 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 /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 (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 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 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

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, as described near the top of this page.

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

Reference the upstream pg_upgrade documentation for details.

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!

# su - postgres -c 'pg_upgrade -d /var/lib/postgres/olddata/ -D /var/lib/postgres/data/ -b /opt/pgsql-8.4/bin/ -B /usr/bin/'

Manual dump and reload

You could also do something like this (after the upgrade and install of postgresql-old-upgrade) (NB: below is command for postgres8.4 update, you can find similar command in /opt/ for postgres 9.2 update. )

# systemctl stop postgresql
# /opt/pgsql-8.4/bin/pg_ctl -D /var/lib/postgres/olddata/ start
# /opt/pgsql-8.4/bin/pg_dumpall >> old_backup.sql
# /opt/pgsql-8.4/bin/pg_ctl -D /var/lib/postgres/olddata/ stop
# systemctl start postgresql
# 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 (/var/lib/postgres/data/postgresql.conf). Beware of the caveats, however.

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 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:

stats_temp_directory = '/run/postgresql'