Encoding-related problems are some of the most frequent problems that occur when people start with a fresh PostgreSQL setup. In PostgreSQL, every database in your instance has a specific encoding. One database might be en_US@UTF-8, while some other database might have been created as de_AT@UTF-8 (which denotes German as it is used in Austria).

To figure out which encodings your database system is using, try to run psql -l from your Unix shell. What you will get is a list of all databases in the instance that include those encodings.

So where can we actually expect trouble? Once a database has been created, many people would want to load data into the system. Let's assume that you are loading data into the aUTF-8 database. However, the data you are loading contains some ASCII characters such as ä, ö, and so on. The ASCII code for ö is 148. Binary 148 is not a valid Unicode character. In Unicode, U+00F6 is needed. Boom! Your import will fail and PostgreSQL will error out.

If you are planning to load data into a new database, ensure that the encoding or character set of the data is the same as that of the database. Otherwise, you may face ugly surprises.

To create a database using the correct locale, check out the syntax of CREATE DATABASE:

test=# \h CREATE DATABASE
Command:     CREATE DATABASE
Description: create a new database
Syntax:
CREATE DATABASE name
    [ [ WITH ] [ OWNER [=] user_name ]
           [ TEMPLATE [=] template ]
           [ ENCODING [=] encoding ]
           [ LC_COLLATE [=] lc_collate ]
           [ LC_CTYPE [=] lc_ctype ]
           [ TABLESPACE [=] tablespace_name ]
           [ CONNECTION LIMIT [=] connlimit ] ]

ENCODING and the LC* settings are used here to define the proper encoding for your new database.