PostgreSQL

• Migrate Database
• Backup Database

Migrate Database

Find Settings of existing Database

sudo -u postgres psql --cluster <version>/main

-- Database-level info
\l+ your_database

-- Server-wide settings
SHOW SERVER_ENCODING;
SHOW LC_COLLATE;
SHOW LC_CTYPE;

-- Installed extensions
\dx

-- Example Output
Name     |  Owner   | Encoding |  Collate   |   Ctype    |   Access privileges
----------+----------+----------+------------+------------+--------------------
your_database | appuser | UTF8 | en_US.utf8 | en_US.utf8 |

Export existing Database

sudo -u postgres pg_dump -h <server> -p <port> -U <user> -W -Fc -f <output file> <database>

-h  = Hostname
-p  = Port
-U  = Username
-W  = Prompt for Password
-Fc = pg_dump non-Text-Format (required for pg_restore)
-f  = Output File

• Command needs to be run with sudo -u postgres as the postgres User has (as default) only local Access and only direct Login without any Password.

(Optional) Copy to new Server

scp <path-to-dump> <user>@<server>:/tmp/<filename.dump>

Create User on new Database

sudo -u postgres psql --cluster <version>/main -c "CREATE USER <username> WITH PASSWORD '<password>';"

Create (empty) Database

Restore Database

sudo -u postgres pg_restore -h <server> -p <port> -U <user> -d <database> -c <input_file>

-h  = Hostname
-p  = Port
-U  = Username
-W  = Prompt for Password
-d  = (New) Database Name
-c  = Input File

Backup Database

Find Database to Backup

1. List all Postgres Instances:

pg_lsclusters

root@SRV-PSQL-PRD-01:~# pg_lsclusters
perl: warning: Setting locale failed.
perl: warning: Please check that your locale settings:
        LANGUAGE = (unset),
        LC_ALL = (unset),
        LANG = "de_DE.UTF-8"
    are supported and installed on your system.
perl: warning: Falling back to the standard locale ("C").
Ver Cluster Port Status Owner    Data directory              Log file
13  main    5432 online postgres /var/lib/postgresql/13/main /var/log/postgresql/postgresql-13-main.log
15  main    5433 online postgres /var/lib/postgresql/15/main /var/log/postgresql/postgresql-15-main.log

2. Connect to Cluster

sudo -u postgres psql --cluster <version>/<release>

root@SRV-PSQL-PRD-01:~# sudo -u postgres psql --cluster 15/main
perl: warning: Setting locale failed.
perl: warning: Please check that your locale settings:
        LANGUAGE = (unset),
        LC_ALL = (unset),
        LANG = "de_DE.UTF-8"
    are supported and installed on your system.
perl: warning: Falling back to the standard locale ("C").
could not change directory to "/root": Permission denied
psql (15.14 (Debian 15.14-1.pgdg12+1))
Type "help" for help.

3. List Databases

\du

postgres=# \du
                                   List of roles
 Role name |                         Attributes                         | Member of
-----------+------------------------------------------------------------+-----------
 forgejo   | Create DB                                                  | {}
 postgres  | Superuser, Create role, Create DB, Replication, Bypass RLS | {}
 zabbix    |

4. Disconnect

\q

Create Backup of Database