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8.1.1 Overview
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 for Unix systems 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 used for a
locale then the specifications can take the form
language_territory.codeset. For example,
fr_BE.UTF-8 represents the French language (fr) as
spoken in Belgium (BE), with a UTF-8 character set
encoding.
What locales are available on your
system under what names depends on what was provided by the operating
system vendor and what was installed. On most Unix systems, the command
locale -a will provide a list of available locales.
Windows uses more verbose locale names, such as German_Germany
or Swedish_Sweden.1252, but the principles are the same.
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 certain aspects of the localization rules:
LC_COLLATE | String sort order
|
LC_CTYPE | Character classification (What is a letter? Its upper-case equivalent?)
|
LC_MESSAGES | Language of messages
|
LC_MONETARY | Formatting of currency amounts
|
LC_NUMERIC | Formatting of numbers
|
LC_TIME | Formatting of dates and times |
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.
Some locale categories must have their values
fixed when the database is created. You can use different settings
for different databases, but once a database is created, you cannot
change them for that database anymore. LC_COLLATE
and LC_CTYPE are these type of categories. They affect
the sort order of indexes, so they must be kept fixed, or indexes on
text columns would become corrupt. The default values for these
categories are determined when initdb is run, and
those values are used when new databases are created, unless
specified otherwise in the CREATE DATABASE command.
The other locale categories can be changed whenever desired
by setting the server configuration parameters
that have the same name as the locale categories (see section 4.10.2 Locale and Formatting for details). The values
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 disable these
assignments from ‘postgresql.conf’ then the
server will inherit the settings from its 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 in different locales, messages might
appear in different languages depending on where they originated.
To enable messages to be translated to the user's preferred language, NLS must have been selected at build time (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(or the variable corresponding to the respective category),LANG. If none of these environment variables are set then the locale defaults toC.Some message localization libraries also look at the environment variable
LANGUAGEwhich 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.
configure --enable-nls). All other locale support is
built in automatically.
| ISBN 9781906966072 | The PostgreSQL 9.0 Reference Manual - Volume 3 - Server Administration Guide | See the print edition |