How to change the locale of a PostgreSQL cluster

There may be reasons to change the locale of your Postgres cluster. A popular one is your development system's locale being used by default (which may be annoying). Here is how to do that.

Beware: By following the steps below, you will drop and recreate your cluster. You will lose all data (including roles). Instructions below include a procedure for dumping and restoring all cluster data (including roles). While it worked at the time of writing, you should have extra backup strategies for a production database.

1. Find the cluster you want to change.

   Copypg_lsclusters
   

   Output looks like this:

   CopyVer Cluster Port Status Owner    Data directory               Log file
   9.3 main    5433 online postgres /var/lib/postgresql/9.3/main /var/log/postgresql/postgresql-9.3-main.log
   9.4 main    5434 online postgres /var/lib/postgresql/9.4/main /var/log/postgresql/postgresql-9.4-main.log
   9.5 main    5435 online postgres /var/lib/postgresql/9.5/main /var/log/postgresql/postgresql-9.5-main.log
   

   Take note of the cluster version and name, and port. You will need them below.

   As an example, we will be modifying 9.5 main (running on port 5435) below.

2. Become a PostgreSQL superuser

   Copysudo su postgres
   

3. Backup entire database

   Copypg_dumpall -p 5435 > 5435.sql
   

   Make sure to pass the correct port! (default is 5432)

4. Drop your cluster (its data will be lost!):

   Copypg_dropcluster --stop 9.5 main
   

5. Create the cluster anew (we create it with the en_US.UTF-8 locale here):

   Copypg_createcluster --locale en_US.UTF-8 --start 9.5 main
   

6. Confirm cluster locale settings:

   Copypsql -p 5435
   

   ^

   Copypostgres=# SHOW LC_COLLATE;
    lc_collate  
   -------------
    en_US.UTF-8
   (1 row)
   
   postgres=# SHOW LC_CTYPE;
    lc_ctype  
   -------------
    en_US.UTF-8
   (1 row)
   

   You may also list all tables via \l and check their locales.

7. Load your backup

   Copypsql -p 5435 -f 5435.sql postgres