Locale support is automatically initialized when a database
cluster is created using initdb.
initdb will initialize the database cluster
with the locale setting of its execution environment by default,
so if your system is already set to use the locale that you want
in your database cluster then there is nothing else you need to
do. If you want to use a different locale (or you are not sure
which locale your system is set to), you can instruct
initdb exactly which locale to use by
specifying the --locale option. For example:
initdb --locale=sv_SE
This example sets the locale to Swedish (sv) as spoken
in Sweden (SE). Other possibilities might be
en_US (U.S. English) and fr_CA (French
Canadian). If more than one character set can be useful for a
locale then the specifications look like this:
cs_CZ.ISO8859-2. What locales are available under what
names on your system depends on what was provided by the operating
system vendor and what was installed.
Occasionally it is useful to mix rules from several locales, e.g.,
use English collation rules but Spanish messages. To support that, a
set of locale subcategories exist that control only a certain
aspect of the localization rules.
The category names translate into names of
initdb options to override the locale choice
for a specific category. For instance, to set the locale to
French Canadian, but use U.S. rules for formatting currency, use
initdb --locale=fr_CA --lc-monetary=en_US.
If you want the system to behave as if it had no locale support,
use the special locale C or POSIX.
The nature of some locale categories is that their value has to be
fixed for the lifetime of a database cluster. That is, once
initdb has run, you cannot change them anymore.
LC_COLLATE and LC_CTYPE are
those categories. They affect the sort order of indexes, so they
must be kept fixed, or indexes on text columns will become corrupt.
EnterpriseDB enforces this by recording
the values of LC_COLLATE and LC_CTYPE that are
seen by initdb. The server automatically adopts
those two values when it is started.
The other locale categories can be changed as desired whenever the
server is running by setting the run-time configuration variables
that have the same name as the locale categories (see Section 30.4.11.2 for details). The defaults that are
chosen by initdb are actually only written into
the configuration file postgresql.conf to
serve as defaults when the server is started. If you delete the
assignments from postgresql.conf then the
server will inherit the settings from the execution environment.
Note that the locale behavior of the server is determined by the
environment variables seen by the server, not by the environment
of any client. Therefore, be careful to configure the correct locale settings
before starting the server. A consequence of this is that if
client and server are set up to different locales, messages may
appear in different languages depending on where they originated.
Note: When we speak of inheriting the locale from the execution
environment, this means the following on most operating systems:
For a given locale category, say the collation, the following
environment variables are consulted in this order until one is
found to be set: LC_ALL, LC_COLLATE
(the variable corresponding to the respective category),
LANG. If none of these environment variables are
set then the locale defaults to C.
Some message localization libraries also look at the environment
variable LANGUAGE which overrides all other locale
settings for the purpose of setting the language of messages. If
in doubt, please refer to the documentation of your operating
system, in particular the documentation about
gettext, for more information.
To enable messages translated to the user's preferred language,
NLS must have been enabled at build time. This
choice is independent of the other locale support.
If locale support doesn't work in spite of the explanation above,
check that the locale support in your operating system is
correctly configured. To check what locales are installed on your
system, you may use the command locale -a if
your operating system provides it.
Check that EnterpriseDB is actually using the locale
that you think it is. LC_COLLATE and LC_CTYPE
settings are determined at initdb time and cannot be
changed without repeating initdb. Other locale
settings including LC_MESSAGES and LC_MONETARY
are initially determined by the environment the server is started
in. You can check the LC_COLLATE and LC_CTYPE
settings of a database using the SHOW command.
The directory src/test/locale in the source
distribution contains a test suite for
EnterpriseDB's locale support.
Client applications that handle server-side errors by parsing the
text of the error message will obviously have problems when the
server's messages are in a different language. Authors of such
applications are advised to make use of the error code scheme
instead.