3221 lines
120 KiB
Plaintext
3221 lines
120 KiB
Plaintext
<!-- doc/src/sgml/charset.sgml -->
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<chapter id="charset">
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<title>Localization</title>
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<para>
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This chapter describes the available localization features from the
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point of view of the administrator.
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<productname>PostgreSQL</productname> supports two localization
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facilities:
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<itemizedlist>
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<listitem>
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<para>
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Using the locale features of the operating system to provide
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locale-specific collation order, number formatting, translated
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messages, and other aspects.
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This is covered in <xref linkend="locale"/> and
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<xref linkend="collation"/>.
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</para>
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</listitem>
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<listitem>
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<para>
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Providing a number of different character sets to support storing text
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in all kinds of languages, and providing character set translation
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between client and server.
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This is covered in <xref linkend="multibyte"/>.
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</para>
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</listitem>
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</itemizedlist>
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</para>
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<sect1 id="locale">
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<title>Locale Support</title>
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<indexterm zone="locale"><primary>locale</primary></indexterm>
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<para>
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<firstterm>Locale</firstterm> support refers to an application respecting
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cultural preferences regarding alphabets, sorting, number
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formatting, etc. <productname>PostgreSQL</productname> uses the standard ISO
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C and <acronym>POSIX</acronym> locale facilities provided by the server operating
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system. For additional information refer to the documentation of your
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system.
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</para>
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<sect2 id="locale-overview">
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<title>Overview</title>
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<para>
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Locale support is automatically initialized when a database
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cluster is created using <command>initdb</command>.
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<command>initdb</command> will initialize the database cluster
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with the locale setting of its execution environment by default,
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so if your system is already set to use the locale that you want
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in your database cluster then there is nothing else you need to
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do. If you want to use a different locale (or you are not sure
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which locale your system is set to), you can instruct
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<command>initdb</command> exactly which locale to use by
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specifying the <option>--locale</option> option. For example:
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<screen>
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initdb --locale=sv_SE
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</screen>
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</para>
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<para>
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This example for Unix systems sets the locale to Swedish
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(<literal>sv</literal>) as spoken
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in Sweden (<literal>SE</literal>). Other possibilities might include
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<literal>en_US</literal> (U.S. English) and <literal>fr_CA</literal> (French
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Canadian). If more than one character set can be used for a
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locale then the specifications can take the form
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<replaceable>language_territory.codeset</replaceable>. For example,
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<literal>fr_BE.UTF-8</literal> represents the French language (fr) as
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spoken in Belgium (BE), with a <acronym>UTF-8</acronym> character set
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encoding.
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</para>
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<para>
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What locales are available on your
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system under what names depends on what was provided by the operating
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system vendor and what was installed. On most Unix systems, the command
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<literal>locale -a</literal> will provide a list of available locales.
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Windows uses more verbose locale names, such as <literal>German_Germany</literal>
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or <literal>Swedish_Sweden.1252</literal>, but the principles are the same.
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</para>
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<para>
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Occasionally it is useful to mix rules from several locales, e.g.,
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use English collation rules but Spanish messages. To support that, a
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set of locale subcategories exist that control only certain
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aspects of the localization rules:
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<informaltable>
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<tgroup cols="2">
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<colspec colname="col1" colwidth="1*"/>
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<colspec colname="col2" colwidth="3*"/>
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<tbody>
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<row>
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<entry><envar>LC_COLLATE</envar></entry>
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<entry>String sort order</entry>
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</row>
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<row>
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<entry><envar>LC_CTYPE</envar></entry>
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<entry>Character classification (What is a letter? Its upper-case equivalent?)</entry>
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</row>
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<row>
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<entry><envar>LC_MESSAGES</envar></entry>
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<entry>Language of messages</entry>
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</row>
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<row>
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<entry><envar>LC_MONETARY</envar></entry>
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<entry>Formatting of currency amounts</entry>
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</row>
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<row>
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<entry><envar>LC_NUMERIC</envar></entry>
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<entry>Formatting of numbers</entry>
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</row>
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<row>
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<entry><envar>LC_TIME</envar></entry>
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<entry>Formatting of dates and times</entry>
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</row>
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</tbody>
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</tgroup>
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</informaltable>
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The category names translate into names of
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<command>initdb</command> options to override the locale choice
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for a specific category. For instance, to set the locale to
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French Canadian, but use U.S. rules for formatting currency, use
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<literal>initdb --locale=fr_CA --lc-monetary=en_US</literal>.
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</para>
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<para>
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If you want the system to behave as if it had no locale support,
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use the special locale name <literal>C</literal>, or equivalently
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<literal>POSIX</literal>.
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</para>
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<para>
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Some locale categories must have their values
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fixed when the database is created. You can use different settings
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for different databases, but once a database is created, you cannot
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change them for that database anymore. <literal>LC_COLLATE</literal>
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and <literal>LC_CTYPE</literal> are these categories. They affect
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the sort order of indexes, so they must be kept fixed, or indexes on
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text columns would become corrupt.
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(But you can alleviate this restriction using collations, as discussed
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in <xref linkend="collation"/>.)
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The default values for these
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categories are determined when <command>initdb</command> is run, and
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those values are used when new databases are created, unless
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specified otherwise in the <command>CREATE DATABASE</command> command.
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</para>
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<para>
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The other locale categories can be changed whenever desired
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by setting the server configuration parameters
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that have the same name as the locale categories (see <xref
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linkend="runtime-config-client-format"/> for details). The values
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that are chosen by <command>initdb</command> are actually only written
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into the configuration file <filename>postgresql.conf</filename> to
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serve as defaults when the server is started. If you remove these
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assignments from <filename>postgresql.conf</filename> then the
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server will inherit the settings from its execution environment.
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</para>
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<para>
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Note that the locale behavior of the server is determined by the
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environment variables seen by the server, not by the environment
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of any client. Therefore, be careful to configure the correct locale settings
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before starting the server. A consequence of this is that if
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client and server are set up in different locales, messages might
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appear in different languages depending on where they originated.
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</para>
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<note>
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<para>
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When we speak of inheriting the locale from the execution
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environment, this means the following on most operating systems:
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For a given locale category, say the collation, the following
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environment variables are consulted in this order until one is
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found to be set: <envar>LC_ALL</envar>, <envar>LC_COLLATE</envar>
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(or the variable corresponding to the respective category),
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<envar>LANG</envar>. If none of these environment variables are
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set then the locale defaults to <literal>C</literal>.
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</para>
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<para>
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Some message localization libraries also look at the environment
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variable <envar>LANGUAGE</envar> which overrides all other locale
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settings for the purpose of setting the language of messages. If
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in doubt, please refer to the documentation of your operating
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system, in particular the documentation about
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<application>gettext</application>.
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</para>
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</note>
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<para>
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To enable messages to be translated to the user's preferred language,
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<acronym>NLS</acronym> must have been selected at build time
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(<literal>configure --enable-nls</literal>). All other locale support is
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built in automatically.
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</para>
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</sect2>
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<sect2 id="locale-behavior">
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<title>Behavior</title>
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<para>
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The locale settings influence the following SQL features:
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<itemizedlist>
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<listitem>
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<para>
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Sort order in queries using <literal>ORDER BY</literal> or the standard
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comparison operators on textual data
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<indexterm><primary>ORDER BY</primary><secondary>and locales</secondary></indexterm>
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</para>
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</listitem>
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<listitem>
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<para>
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The <function>upper</function>, <function>lower</function>, and <function>initcap</function>
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functions
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<indexterm><primary>upper</primary><secondary>and locales</secondary></indexterm>
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<indexterm><primary>lower</primary><secondary>and locales</secondary></indexterm>
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</para>
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</listitem>
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<listitem>
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<para>
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Pattern matching operators (<literal>LIKE</literal>, <literal>SIMILAR TO</literal>,
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and POSIX-style regular expressions); locales affect both case
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insensitive matching and the classification of characters by
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character-class regular expressions
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<indexterm><primary>LIKE</primary><secondary>and locales</secondary></indexterm>
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<indexterm><primary>regular expressions</primary><secondary>and locales</secondary></indexterm>
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</para>
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</listitem>
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<listitem>
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<para>
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The <function>to_char</function> family of functions
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<indexterm><primary>to_char</primary><secondary>and locales</secondary></indexterm>
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</para>
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</listitem>
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<listitem>
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<para>
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The ability to use indexes with <literal>LIKE</literal> clauses
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</para>
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</listitem>
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</itemizedlist>
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</para>
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<para>
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The drawback of using locales other than <literal>C</literal> or
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<literal>POSIX</literal> in <productname>PostgreSQL</productname> is its performance
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impact. It slows character handling and prevents ordinary indexes
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from being used by <literal>LIKE</literal>. For this reason use locales
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only if you actually need them.
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</para>
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<para>
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As a workaround to allow <productname>PostgreSQL</productname> to use indexes
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with <literal>LIKE</literal> clauses under a non-C locale, several custom
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operator classes exist. These allow the creation of an index that
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performs a strict character-by-character comparison, ignoring
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locale comparison rules. Refer to <xref linkend="indexes-opclass"/>
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for more information. Another approach is to create indexes using
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the <literal>C</literal> collation, as discussed in
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<xref linkend="collation"/>.
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</para>
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</sect2>
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<sect2 id="locale-selecting-locales">
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<title>Selecting Locales</title>
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<para>
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Locales can be selected in different scopes depending on requirements.
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The above overview showed how locales are specified using
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<command>initdb</command> to set the defaults for the entire cluster. The
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following list shows where locales can be selected. Each item provides
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the defaults for the subsequent items, and each lower item allows
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overriding the defaults on a finer granularity.
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</para>
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<orderedlist>
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<listitem>
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<para>
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As explained above, the environment of the operating system provides the
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defaults for the locales of a newly initialized database cluster. In
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many cases, this is enough: If the operating system is configured for
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the desired language/territory, then
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<productname>PostgreSQL</productname> will by default also behave
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according to that locale.
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</para>
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</listitem>
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<listitem>
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<para>
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As shown above, command-line options for <command>initdb</command>
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specify the locale settings for a newly initialized database cluster.
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Use this if the operating system does not have the locale configuration
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you want for your database system.
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</para>
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</listitem>
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<listitem>
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<para>
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A locale can be selected separately for each database. The SQL command
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<command>CREATE DATABASE</command> and its command-line equivalent
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<command>createdb</command> have options for that. Use this for example
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if a database cluster houses databases for multiple tenants with
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different requirements.
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</para>
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</listitem>
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<listitem>
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<para>
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Locale settings can be made for individual table columns. This uses an
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SQL object called <firstterm>collation</firstterm> and is explained in
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<xref linkend="collation"/>. Use this for example to sort data in
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different languages or customize the sort order of a particular table.
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</para>
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</listitem>
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<listitem>
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<para>
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Finally, locales can be selected for an individual query. Again, this
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uses SQL collation objects. This could be used to change the sort order
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based on run-time choices or for ad-hoc experimentation.
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</para>
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</listitem>
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</orderedlist>
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</sect2>
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<sect2 id="locale-providers">
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<title>Locale Providers</title>
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<para>
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<productname>PostgreSQL</productname> supports multiple <firstterm>locale
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providers</firstterm>. This specifies which library supplies the locale
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data. One standard provider name is <literal>libc</literal>, which uses
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the locales provided by the operating system C library. These are the
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locales used by most tools provided by the operating system. Another
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provider is <literal>icu</literal>, which uses the external
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ICU<indexterm><primary>ICU</primary></indexterm> library. ICU locales can
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only be used if support for ICU was configured when PostgreSQL was built.
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</para>
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<para>
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The commands and tools that select the locale settings, as described
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above, each have an option to select the locale provider. The examples
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shown earlier all use the <literal>libc</literal> provider, which is the
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default. Here is an example to initialize a database cluster using the
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ICU provider:
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<programlisting>
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initdb --locale-provider=icu --icu-locale=en
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</programlisting>
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See the description of the respective commands and programs for
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details. Note that you can mix locale providers at different
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granularities, for example use <literal>libc</literal> by default for the
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cluster but have one database that uses the <literal>icu</literal>
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provider, and then have collation objects using either provider within
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those databases.
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</para>
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<para>
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Which locale provider to use depends on individual requirements. For most
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basic uses, either provider will give adequate results. For the libc
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provider, it depends on what the operating system offers; some operating
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systems are better than others. For advanced uses, ICU offers more locale
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variants and customization options.
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</para>
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</sect2>
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<sect2 id="icu-locales">
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<title>ICU Locales</title>
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<sect3 id="icu-locale-names">
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<title>ICU Locale Names</title>
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<para>
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The ICU format for the locale name is a <link
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linkend="icu-language-tag">Language Tag</link>.
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<programlisting>
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CREATE COLLATION mycollation1 (PROVIDER = icu, LOCALE = 'ja-JP');
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CREATE COLLATION mycollation2 (PROVIDER = icu, LOCALE = 'fr');
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</programlisting>
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</para>
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</sect3>
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<sect3 id="icu-canonicalization">
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<title>Locale Canonicalization and Validation</title>
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<para>
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When defining a new ICU collation object or database with ICU as the
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provider, the given locale name is transformed ("canonicalized") into a
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language tag if not already in that form. For instance,
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<screen>
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CREATE COLLATION mycollation3 (PROVIDER = icu, LOCALE = 'en-US-u-kn-true');
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NOTICE: using standard form "en-US-u-kn" for locale "en-US-u-kn-true"
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CREATE COLLATION mycollation4 (PROVIDER = icu, LOCALE = 'de_DE.utf8');
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NOTICE: using standard form "de-DE" for locale "de_DE.utf8"
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</screen>
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If you see this notice, ensure that the <symbol>PROVIDER</symbol> and
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<symbol>LOCALE</symbol> are the expected result. For consistent results
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when using the ICU provider, specify the canonical <link
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linkend="icu-language-tag">language tag</link> instead of relying on the
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transformation.
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</para>
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<para>
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A locale with no language name, or the special language name
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<literal>root</literal>, is transformed to have the language
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<literal>und</literal> ("undefined").
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</para>
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<para>
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ICU can transform most libc locale names, as well as some other formats,
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into language tags for easier transition to ICU. If a libc locale name is
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used in ICU, it may not have precisely the same behavior as in libc.
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</para>
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<para>
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If there is a problem interpreting the locale name, or if the locale name
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represents a language or region that ICU does not recognize, you will see
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the following warning:
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<screen>
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CREATE COLLATION nonsense (PROVIDER = icu, LOCALE = 'nonsense');
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WARNING: ICU locale "nonsense" has unknown language "nonsense"
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HINT: To disable ICU locale validation, set parameter icu_validation_level to DISABLED.
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CREATE COLLATION
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</screen>
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<xref linkend="guc-icu-validation-level"/> controls how the message is
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reported. Unless set to <literal>ERROR</literal>, the collation will
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still be created, but the behavior may not be what the user intended.
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</para>
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</sect3>
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<sect3 id="icu-language-tag">
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<title>Language Tag</title>
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<para>
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A language tag, defined in BCP 47, is a standardized identifier used to
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identify languages, regions, and other information about a locale.
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</para>
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<para>
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Basic language tags are simply
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<replaceable>language</replaceable><literal>-</literal><replaceable>region</replaceable>;
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or even just <replaceable>language</replaceable>. The
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<replaceable>language</replaceable> is a language code
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(e.g. <literal>fr</literal> for French), and
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<replaceable>region</replaceable> is a region code
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(e.g. <literal>CA</literal> for Canada). Examples:
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<literal>ja-JP</literal>, <literal>de</literal>, or
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<literal>fr-CA</literal>.
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</para>
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<para>
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Collation settings may be included in the language tag to customize
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collation behavior. ICU allows extensive customization, such as
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sensitivity (or insensitivity) to accents, case, and punctuation;
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treatment of digits within text; and many other options to satisfy a
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variety of uses.
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</para>
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<para>
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To include this additional collation information in a language tag,
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append <literal>-u</literal>, which indicates there are additional
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collation settings, followed by one or more
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<literal>-</literal><replaceable>key</replaceable><literal>-</literal><replaceable>value</replaceable>
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pairs. The <replaceable>key</replaceable> is the key for a <link
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linkend="icu-collation-settings">collation setting</link> and
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<replaceable>value</replaceable> is a valid value for that setting. For
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boolean settings, the <literal>-</literal><replaceable>key</replaceable>
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may be specified without a corresponding
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<literal>-</literal><replaceable>value</replaceable>, which implies a
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value of <literal>true</literal>.
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</para>
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<para>
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For example, the language tag <literal>en-US-u-kn-ks-level2</literal>
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means the locale with the English language in the US region, with
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collation settings <literal>kn</literal> set to <literal>true</literal>
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and <literal>ks</literal> set to <literal>level2</literal>. Those
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settings mean the collation will be case-insensitive and treat a sequence
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of digits as a single number:
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<screen>
|
|
CREATE COLLATION mycollation5 (PROVIDER = icu, DETERMINISTIC = false, LOCALE = 'en-US-u-kn-ks-level2');
|
|
SELECT 'aB' = 'Ab' COLLATE mycollation5 as result;
|
|
result
|
|
--------
|
|
t
|
|
(1 row)
|
|
|
|
SELECT 'N-45' < 'N-123' COLLATE mycollation5 as result;
|
|
result
|
|
--------
|
|
t
|
|
(1 row)
|
|
</screen>
|
|
</para>
|
|
<para>
|
|
See <xref linkend="icu-custom-collations"/> for details and additional
|
|
examples of using language tags with custom collation information for the
|
|
locale.
|
|
</para>
|
|
</sect3>
|
|
</sect2>
|
|
<sect2 id="locale-problems">
|
|
<title>Problems</title>
|
|
|
|
<para>
|
|
If locale support doesn't work according to 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 can use the command <literal>locale -a</literal> if
|
|
your operating system provides it.
|
|
</para>
|
|
|
|
<para>
|
|
Check that <productname>PostgreSQL</productname> is actually using the locale
|
|
that you think it is. The <envar>LC_COLLATE</envar> and <envar>LC_CTYPE</envar>
|
|
settings are determined when a database is created, and cannot be
|
|
changed except by creating a new database. Other locale
|
|
settings including <envar>LC_MESSAGES</envar> and <envar>LC_MONETARY</envar>
|
|
are initially determined by the environment the server is started
|
|
in, but can be changed on-the-fly. You can check the active locale
|
|
settings using the <command>SHOW</command> command.
|
|
</para>
|
|
|
|
<para>
|
|
The directory <filename>src/test/locale</filename> in the source
|
|
distribution contains a test suite for
|
|
<productname>PostgreSQL</productname>'s locale support.
|
|
</para>
|
|
|
|
<para>
|
|
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.
|
|
</para>
|
|
|
|
<para>
|
|
Maintaining catalogs of message translations requires the on-going
|
|
efforts of many volunteers that want to see
|
|
<productname>PostgreSQL</productname> speak their preferred language well.
|
|
If messages in your language are currently not available or not fully
|
|
translated, your assistance would be appreciated. If you want to
|
|
help, refer to <xref linkend="nls"/> or write to the developers'
|
|
mailing list.
|
|
</para>
|
|
</sect2>
|
|
</sect1>
|
|
|
|
|
|
<sect1 id="collation">
|
|
<title>Collation Support</title>
|
|
|
|
<indexterm zone="collation"><primary>collation</primary></indexterm>
|
|
|
|
<para>
|
|
The collation feature allows specifying the sort order and character
|
|
classification behavior of data per-column, or even per-operation.
|
|
This alleviates the restriction that the
|
|
<symbol>LC_COLLATE</symbol> and <symbol>LC_CTYPE</symbol> settings
|
|
of a database cannot be changed after its creation.
|
|
</para>
|
|
|
|
<sect2 id="collation-concepts">
|
|
<title>Concepts</title>
|
|
|
|
<para>
|
|
Conceptually, every expression of a collatable data type has a
|
|
collation. (The built-in collatable data types are
|
|
<type>text</type>, <type>varchar</type>, and <type>char</type>.
|
|
User-defined base types can also be marked collatable, and of course
|
|
a <glossterm linkend="glossary-domain">domain</glossterm> over a
|
|
collatable data type is collatable.) If the
|
|
expression is a column reference, the collation of the expression is the
|
|
defined collation of the column. If the expression is a constant, the
|
|
collation is the default collation of the data type of the
|
|
constant. The collation of a more complex expression is derived
|
|
from the collations of its inputs, as described below.
|
|
</para>
|
|
|
|
<para>
|
|
The collation of an expression can be the <quote>default</quote>
|
|
collation, which means the locale settings defined for the
|
|
database. It is also possible for an expression's collation to be
|
|
indeterminate. In such cases, ordering operations and other
|
|
operations that need to know the collation will fail.
|
|
</para>
|
|
|
|
<para>
|
|
When the database system has to perform an ordering or a character
|
|
classification, it uses the collation of the input expression. This
|
|
happens, for example, with <literal>ORDER BY</literal> clauses
|
|
and function or operator calls such as <literal><</literal>.
|
|
The collation to apply for an <literal>ORDER BY</literal> clause
|
|
is simply the collation of the sort key. The collation to apply for a
|
|
function or operator call is derived from the arguments, as described
|
|
below. In addition to comparison operators, collations are taken into
|
|
account by functions that convert between lower and upper case
|
|
letters, such as <function>lower</function>, <function>upper</function>, and
|
|
<function>initcap</function>; by pattern matching operators; and by
|
|
<function>to_char</function> and related functions.
|
|
</para>
|
|
|
|
<para>
|
|
For a function or operator call, the collation that is derived by
|
|
examining the argument collations is used at run time for performing
|
|
the specified operation. If the result of the function or operator
|
|
call is of a collatable data type, the collation is also used at parse
|
|
time as the defined collation of the function or operator expression,
|
|
in case there is a surrounding expression that requires knowledge of
|
|
its collation.
|
|
</para>
|
|
|
|
<para>
|
|
The <firstterm>collation derivation</firstterm> of an expression can be
|
|
implicit or explicit. This distinction affects how collations are
|
|
combined when multiple different collations appear in an
|
|
expression. An explicit collation derivation occurs when a
|
|
<literal>COLLATE</literal> clause is used; all other collation
|
|
derivations are implicit. When multiple collations need to be
|
|
combined, for example in a function call, the following rules are
|
|
used:
|
|
|
|
<orderedlist>
|
|
<listitem>
|
|
<para>
|
|
If any input expression has an explicit collation derivation, then
|
|
all explicitly derived collations among the input expressions must be
|
|
the same, otherwise an error is raised. If any explicitly
|
|
derived collation is present, that is the result of the
|
|
collation combination.
|
|
</para>
|
|
</listitem>
|
|
|
|
<listitem>
|
|
<para>
|
|
Otherwise, all input expressions must have the same implicit
|
|
collation derivation or the default collation. If any non-default
|
|
collation is present, that is the result of the collation combination.
|
|
Otherwise, the result is the default collation.
|
|
</para>
|
|
</listitem>
|
|
|
|
<listitem>
|
|
<para>
|
|
If there are conflicting non-default implicit collations among the
|
|
input expressions, then the combination is deemed to have indeterminate
|
|
collation. This is not an error condition unless the particular
|
|
function being invoked requires knowledge of the collation it should
|
|
apply. If it does, an error will be raised at run-time.
|
|
</para>
|
|
</listitem>
|
|
</orderedlist>
|
|
|
|
For example, consider this table definition:
|
|
<programlisting>
|
|
CREATE TABLE test1 (
|
|
a text COLLATE "de_DE",
|
|
b text COLLATE "es_ES",
|
|
...
|
|
);
|
|
</programlisting>
|
|
|
|
Then in
|
|
<programlisting>
|
|
SELECT a < 'foo' FROM test1;
|
|
</programlisting>
|
|
the <literal><</literal> comparison is performed according to
|
|
<literal>de_DE</literal> rules, because the expression combines an
|
|
implicitly derived collation with the default collation. But in
|
|
<programlisting>
|
|
SELECT a < ('foo' COLLATE "fr_FR") FROM test1;
|
|
</programlisting>
|
|
the comparison is performed using <literal>fr_FR</literal> rules,
|
|
because the explicit collation derivation overrides the implicit one.
|
|
Furthermore, given
|
|
<programlisting>
|
|
SELECT a < b FROM test1;
|
|
</programlisting>
|
|
the parser cannot determine which collation to apply, since the
|
|
<structfield>a</structfield> and <structfield>b</structfield> columns have conflicting
|
|
implicit collations. Since the <literal><</literal> operator
|
|
does need to know which collation to use, this will result in an
|
|
error. The error can be resolved by attaching an explicit collation
|
|
specifier to either input expression, thus:
|
|
<programlisting>
|
|
SELECT a < b COLLATE "de_DE" FROM test1;
|
|
</programlisting>
|
|
or equivalently
|
|
<programlisting>
|
|
SELECT a COLLATE "de_DE" < b FROM test1;
|
|
</programlisting>
|
|
On the other hand, the structurally similar case
|
|
<programlisting>
|
|
SELECT a || b FROM test1;
|
|
</programlisting>
|
|
does not result in an error, because the <literal>||</literal> operator
|
|
does not care about collations: its result is the same regardless
|
|
of the collation.
|
|
</para>
|
|
|
|
<para>
|
|
The collation assigned to a function or operator's combined input
|
|
expressions is also considered to apply to the function or operator's
|
|
result, if the function or operator delivers a result of a collatable
|
|
data type. So, in
|
|
<programlisting>
|
|
SELECT * FROM test1 ORDER BY a || 'foo';
|
|
</programlisting>
|
|
the ordering will be done according to <literal>de_DE</literal> rules.
|
|
But this query:
|
|
<programlisting>
|
|
SELECT * FROM test1 ORDER BY a || b;
|
|
</programlisting>
|
|
results in an error, because even though the <literal>||</literal> operator
|
|
doesn't need to know a collation, the <literal>ORDER BY</literal> clause does.
|
|
As before, the conflict can be resolved with an explicit collation
|
|
specifier:
|
|
<programlisting>
|
|
SELECT * FROM test1 ORDER BY a || b COLLATE "fr_FR";
|
|
</programlisting>
|
|
</para>
|
|
</sect2>
|
|
|
|
<sect2 id="collation-managing">
|
|
<title>Managing Collations</title>
|
|
|
|
<para>
|
|
A collation is an SQL schema object that maps an SQL name to locales
|
|
provided by libraries installed in the operating system. A collation
|
|
definition has a <firstterm>provider</firstterm> that specifies which
|
|
library supplies the locale data. One standard provider name
|
|
is <literal>libc</literal>, which uses the locales provided by the
|
|
operating system C library. These are the locales used by most tools
|
|
provided by the operating system. Another provider
|
|
is <literal>icu</literal>, which uses the external
|
|
ICU<indexterm><primary>ICU</primary></indexterm> library. ICU locales can only be
|
|
used if support for ICU was configured when PostgreSQL was built.
|
|
</para>
|
|
|
|
<para>
|
|
A collation object provided by <literal>libc</literal> maps to a
|
|
combination of <symbol>LC_COLLATE</symbol> and <symbol>LC_CTYPE</symbol>
|
|
settings, as accepted by the <literal>setlocale()</literal> system library call. (As
|
|
the name would suggest, the main purpose of a collation is to set
|
|
<symbol>LC_COLLATE</symbol>, which controls the sort order. But
|
|
it is rarely necessary in practice to have an
|
|
<symbol>LC_CTYPE</symbol> setting that is different from
|
|
<symbol>LC_COLLATE</symbol>, so it is more convenient to collect
|
|
these under one concept than to create another infrastructure for
|
|
setting <symbol>LC_CTYPE</symbol> per expression.) Also,
|
|
a <literal>libc</literal> collation
|
|
is tied to a character set encoding (see <xref linkend="multibyte"/>).
|
|
The same collation name may exist for different encodings.
|
|
</para>
|
|
|
|
<para>
|
|
A collation object provided by <literal>icu</literal> maps to a named
|
|
collator provided by the ICU library. ICU does not support
|
|
separate <quote>collate</quote> and <quote>ctype</quote> settings, so
|
|
they are always the same. Also, ICU collations are independent of the
|
|
encoding, so there is always only one ICU collation of a given name in
|
|
a database.
|
|
</para>
|
|
|
|
<sect3 id="collation-managing-standard">
|
|
<title>Standard Collations</title>
|
|
|
|
<para>
|
|
On all platforms, the collations named <literal>default</literal>,
|
|
<literal>C</literal>, and <literal>POSIX</literal> are available. Additional
|
|
collations may be available depending on operating system support.
|
|
The <literal>default</literal> collation selects the <symbol>LC_COLLATE</symbol>
|
|
and <symbol>LC_CTYPE</symbol> values specified at database creation time.
|
|
The <literal>C</literal> and <literal>POSIX</literal> collations both specify
|
|
<quote>traditional C</quote> behavior, in which only the ASCII letters
|
|
<quote><literal>A</literal></quote> through <quote><literal>Z</literal></quote>
|
|
are treated as letters, and sorting is done strictly by character
|
|
code byte values.
|
|
</para>
|
|
|
|
<note>
|
|
<para>
|
|
The <literal>C</literal> and <literal>POSIX</literal> locales may behave
|
|
differently depending on the database encoding.
|
|
</para>
|
|
</note>
|
|
|
|
<para>
|
|
Additionally, two SQL standard collation names are available:
|
|
|
|
<variablelist>
|
|
<varlistentry>
|
|
<term><literal>unicode</literal></term>
|
|
<listitem>
|
|
<para>
|
|
This collation sorts using the Unicode Collation Algorithm with the
|
|
Default Unicode Collation Element Table. It is available in all
|
|
encodings. ICU support is required to use this collation. (This
|
|
collation has the same behavior as the ICU root locale; see <xref
|
|
linkend="collation-managing-predefined-icu-und-x-icu"/>.)
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><literal>ucs_basic</literal></term>
|
|
<listitem>
|
|
<para>
|
|
This collation sorts by Unicode code point. It is only available for
|
|
encoding <literal>UTF8</literal>. (This collation has the same
|
|
behavior as the libc locale specification <literal>C</literal> in
|
|
<literal>UTF8</literal> encoding.)
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
</variablelist>
|
|
</para>
|
|
</sect3>
|
|
|
|
<sect3 id="collation-managing-predefined">
|
|
<title>Predefined Collations</title>
|
|
|
|
<para>
|
|
If the operating system provides support for using multiple locales
|
|
within a single program (<function>newlocale</function> and related functions),
|
|
or if support for ICU is configured,
|
|
then when a database cluster is initialized, <command>initdb</command>
|
|
populates the system catalog <literal>pg_collation</literal> with
|
|
collations based on all the locales it finds in the operating
|
|
system at the time.
|
|
</para>
|
|
|
|
<para>
|
|
To inspect the currently available locales, use the query <literal>SELECT
|
|
* FROM pg_collation</literal>, or the command <command>\dOS+</command>
|
|
in <application>psql</application>.
|
|
</para>
|
|
|
|
<sect4 id="collation-managing-predefined-libc">
|
|
<title>libc Collations</title>
|
|
|
|
<para>
|
|
For example, the operating system might
|
|
provide a locale named <literal>de_DE.utf8</literal>.
|
|
<command>initdb</command> would then create a collation named
|
|
<literal>de_DE.utf8</literal> for encoding <literal>UTF8</literal>
|
|
that has both <symbol>LC_COLLATE</symbol> and
|
|
<symbol>LC_CTYPE</symbol> set to <literal>de_DE.utf8</literal>.
|
|
It will also create a collation with the <literal>.utf8</literal>
|
|
tag stripped off the name. So you could also use the collation
|
|
under the name <literal>de_DE</literal>, which is less cumbersome
|
|
to write and makes the name less encoding-dependent. Note that,
|
|
nevertheless, the initial set of collation names is
|
|
platform-dependent.
|
|
</para>
|
|
|
|
<para>
|
|
The default set of collations provided by <literal>libc</literal> map
|
|
directly to the locales installed in the operating system, which can be
|
|
listed using the command <literal>locale -a</literal>. In case
|
|
a <literal>libc</literal> collation is needed that has different values
|
|
for <symbol>LC_COLLATE</symbol> and <symbol>LC_CTYPE</symbol>, or if new
|
|
locales are installed in the operating system after the database system
|
|
was initialized, then a new collation may be created using
|
|
the <xref linkend="sql-createcollation"/> command.
|
|
New operating system locales can also be imported en masse using
|
|
the <link linkend="functions-admin-collation"><function>pg_import_system_collations()</function></link> function.
|
|
</para>
|
|
|
|
<para>
|
|
Within any particular database, only collations that use that
|
|
database's encoding are of interest. Other entries in
|
|
<literal>pg_collation</literal> are ignored. Thus, a stripped collation
|
|
name such as <literal>de_DE</literal> can be considered unique
|
|
within a given database even though it would not be unique globally.
|
|
Use of the stripped collation names is recommended, since it will
|
|
make one fewer thing you need to change if you decide to change to
|
|
another database encoding. Note however that the <literal>default</literal>,
|
|
<literal>C</literal>, and <literal>POSIX</literal> collations can be used regardless of
|
|
the database encoding.
|
|
</para>
|
|
|
|
<para>
|
|
<productname>PostgreSQL</productname> considers distinct collation
|
|
objects to be incompatible even when they have identical properties.
|
|
Thus for example,
|
|
<programlisting>
|
|
SELECT a COLLATE "C" < b COLLATE "POSIX" FROM test1;
|
|
</programlisting>
|
|
will draw an error even though the <literal>C</literal> and <literal>POSIX</literal>
|
|
collations have identical behaviors. Mixing stripped and non-stripped
|
|
collation names is therefore not recommended.
|
|
</para>
|
|
</sect4>
|
|
|
|
<sect4 id="collation-managing-predefined-icu">
|
|
<title>ICU Collations</title>
|
|
|
|
<para>
|
|
With ICU, it is not sensible to enumerate all possible locale names. ICU
|
|
uses a particular naming system for locales, but there are many more ways
|
|
to name a locale than there are actually distinct locales.
|
|
<command>initdb</command> uses the ICU APIs to extract a set of distinct
|
|
locales to populate the initial set of collations. Collations provided by
|
|
ICU are created in the SQL environment with names in BCP 47 language tag
|
|
format, with a <quote>private use</quote>
|
|
extension <literal>-x-icu</literal> appended, to distinguish them from
|
|
libc locales.
|
|
</para>
|
|
|
|
<para>
|
|
Here are some example collations that might be created:
|
|
|
|
<variablelist>
|
|
<varlistentry id="collation-managing-predefined-icu-de-x-icu">
|
|
<term><literal>de-x-icu</literal></term>
|
|
<listitem>
|
|
<para>German collation, default variant</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="collation-managing-predefined-icu-de-at-x-icu">
|
|
<term><literal>de-AT-x-icu</literal></term>
|
|
<listitem>
|
|
<para>German collation for Austria, default variant</para>
|
|
<para>
|
|
(There are also, say, <literal>de-DE-x-icu</literal>
|
|
or <literal>de-CH-x-icu</literal>, but as of this writing, they are
|
|
equivalent to <literal>de-x-icu</literal>.)
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="collation-managing-predefined-icu-und-x-icu">
|
|
<term><literal>und-x-icu</literal> (for <quote>undefined</quote>)</term>
|
|
<listitem>
|
|
<para>
|
|
ICU <quote>root</quote> collation. Use this to get a reasonable
|
|
language-agnostic sort order.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
</variablelist>
|
|
</para>
|
|
|
|
<para>
|
|
Some (less frequently used) encodings are not supported by ICU. When the
|
|
database encoding is one of these, ICU collation entries
|
|
in <literal>pg_collation</literal> are ignored. Attempting to use one
|
|
will draw an error along the lines of <quote>collation "de-x-icu" for
|
|
encoding "WIN874" does not exist</quote>.
|
|
</para>
|
|
</sect4>
|
|
</sect3>
|
|
|
|
<sect3 id="collation-create">
|
|
<title>Creating New Collation Objects</title>
|
|
|
|
<para>
|
|
If the standard and predefined collations are not sufficient, users can
|
|
create their own collation objects using the SQL
|
|
command <xref linkend="sql-createcollation"/>.
|
|
</para>
|
|
|
|
<para>
|
|
The standard and predefined collations are in the
|
|
schema <literal>pg_catalog</literal>, like all predefined objects.
|
|
User-defined collations should be created in user schemas. This also
|
|
ensures that they are saved by <command>pg_dump</command>.
|
|
</para>
|
|
|
|
<sect4 id="collation-managing-create-libc">
|
|
<title>libc Collations</title>
|
|
|
|
<para>
|
|
New libc collations can be created like this:
|
|
<programlisting>
|
|
CREATE COLLATION german (provider = libc, locale = 'de_DE');
|
|
</programlisting>
|
|
The exact values that are acceptable for the <literal>locale</literal>
|
|
clause in this command depend on the operating system. On Unix-like
|
|
systems, the command <literal>locale -a</literal> will show a list.
|
|
</para>
|
|
|
|
<para>
|
|
Since the predefined libc collations already include all collations
|
|
defined in the operating system when the database instance is
|
|
initialized, it is not often necessary to manually create new ones.
|
|
Reasons might be if a different naming system is desired (in which case
|
|
see also <xref linkend="collation-copy"/>) or if the operating system has
|
|
been upgraded to provide new locale definitions (in which case see
|
|
also <link linkend="functions-admin-collation"><function>pg_import_system_collations()</function></link>).
|
|
</para>
|
|
</sect4>
|
|
|
|
<sect4 id="collation-managing-create-icu">
|
|
<title>ICU Collations</title>
|
|
|
|
<para>
|
|
ICU collations can be created like:
|
|
|
|
<programlisting>
|
|
CREATE COLLATION german (provider = icu, locale = 'de-DE');
|
|
</programlisting>
|
|
|
|
ICU locales are specified as a BCP 47 <link
|
|
linkend="icu-language-tag">Language Tag</link>, but can also accept most
|
|
libc-style locale names. If possible, libc-style locale names are
|
|
transformed into language tags.
|
|
</para>
|
|
<para>
|
|
New ICU collations can customize collation behavior extensively by
|
|
including collation attributes in the language tag. See <xref
|
|
linkend="icu-custom-collations"/> for details and examples.
|
|
</para>
|
|
</sect4>
|
|
<sect4 id="collation-copy">
|
|
<title>Copying Collations</title>
|
|
|
|
<para>
|
|
The command <xref linkend="sql-createcollation"/> can also be used to
|
|
create a new collation from an existing collation, which can be useful to
|
|
be able to use operating-system-independent collation names in
|
|
applications, create compatibility names, or use an ICU-provided collation
|
|
under a more readable name. For example:
|
|
<programlisting>
|
|
CREATE COLLATION german FROM "de_DE";
|
|
CREATE COLLATION french FROM "fr-x-icu";
|
|
</programlisting>
|
|
</para>
|
|
</sect4>
|
|
</sect3>
|
|
|
|
<sect3 id="collation-nondeterministic">
|
|
<title>Nondeterministic Collations</title>
|
|
|
|
<para>
|
|
A collation is either <firstterm>deterministic</firstterm> or
|
|
<firstterm>nondeterministic</firstterm>. A deterministic collation uses
|
|
deterministic comparisons, which means that it considers strings to be
|
|
equal only if they consist of the same byte sequence. Nondeterministic
|
|
comparison may determine strings to be equal even if they consist of
|
|
different bytes. Typical situations include case-insensitive comparison,
|
|
accent-insensitive comparison, as well as comparison of strings in
|
|
different Unicode normal forms. It is up to the collation provider to
|
|
actually implement such insensitive comparisons; the deterministic flag
|
|
only determines whether ties are to be broken using bytewise comparison.
|
|
See also <ulink url="https://www.unicode.org/reports/tr10">Unicode Technical
|
|
Standard 10</ulink> for more information on the terminology.
|
|
</para>
|
|
|
|
<para>
|
|
To create a nondeterministic collation, specify the property
|
|
<literal>deterministic = false</literal> to <command>CREATE
|
|
COLLATION</command>, for example:
|
|
<programlisting>
|
|
CREATE COLLATION ndcoll (provider = icu, locale = 'und', deterministic = false);
|
|
</programlisting>
|
|
This example would use the standard Unicode collation in a
|
|
nondeterministic way. In particular, this would allow strings in
|
|
different normal forms to be compared correctly. More interesting
|
|
examples make use of the ICU customization facilities explained above.
|
|
For example:
|
|
<programlisting>
|
|
CREATE COLLATION case_insensitive (provider = icu, locale = 'und-u-ks-level2', deterministic = false);
|
|
CREATE COLLATION ignore_accents (provider = icu, locale = 'und-u-ks-level1-kc-true', deterministic = false);
|
|
</programlisting>
|
|
</para>
|
|
|
|
<para>
|
|
All standard and predefined collations are deterministic, all
|
|
user-defined collations are deterministic by default. While
|
|
nondeterministic collations give a more <quote>correct</quote> behavior,
|
|
especially when considering the full power of Unicode and its many
|
|
special cases, they also have some drawbacks. Foremost, their use leads
|
|
to a performance penalty. Note, in particular, that B-tree cannot use
|
|
deduplication with indexes that use a nondeterministic collation. Also,
|
|
certain operations are not possible with nondeterministic collations,
|
|
such as pattern matching operations. Therefore, they should be used
|
|
only in cases where they are specifically wanted.
|
|
</para>
|
|
|
|
<tip>
|
|
<para>
|
|
To deal with text in different Unicode normalization forms, it is also
|
|
an option to use the functions/expressions
|
|
<function>normalize</function> and <literal>is normalized</literal> to
|
|
preprocess or check the strings, instead of using nondeterministic
|
|
collations. There are different trade-offs for each approach.
|
|
</para>
|
|
</tip>
|
|
</sect3>
|
|
</sect2>
|
|
<sect2 id="icu-custom-collations">
|
|
<title>ICU Custom Collations</title>
|
|
|
|
<para>
|
|
ICU allows extensive control over collation behavior by defining new
|
|
collations with collation settings as a part of the language tag. These
|
|
settings can modify the collation order to suit a variety of needs. For
|
|
instance:
|
|
|
|
<programlisting>
|
|
-- ignore differences in accents and case
|
|
CREATE COLLATION ignore_accent_case (PROVIDER = icu, DETERMINISTIC = false, LOCALE = 'und-u-ks-level1');
|
|
SELECT 'Å' = 'A' COLLATE ignore_accent_case; -- true
|
|
SELECT 'z' = 'Z' COLLATE ignore_accent_case; -- true
|
|
|
|
-- upper case letters sort before lower case.
|
|
CREATE COLLATION upper_first (PROVIDER=icu, LOCALE = 'und-u-kf-upper');
|
|
SELECT 'B' < 'b' COLLATE upper_first; -- true
|
|
|
|
-- treat digits numerically and ignore punctuation
|
|
CREATE COLLATION num_ignore_punct (PROVIDER = icu, DETERMINISTIC = false, LOCALE = 'und-u-ka-shifted-kn');
|
|
SELECT 'id-45' < 'id-123' COLLATE num_ignore_punct; -- true
|
|
SELECT 'w;x*y-z' = 'wxyz' COLLATE num_ignore_punct; -- true
|
|
</programlisting>
|
|
|
|
Many of the available options are described in <xref
|
|
linkend="icu-collation-settings"/>, or see <xref
|
|
linkend="icu-external-references"/> for more details.
|
|
</para>
|
|
<sect3 id="icu-collation-comparison-levels">
|
|
<title>ICU Comparison Levels</title>
|
|
<para>
|
|
Comparison of two strings (collation) in ICU is determined by a
|
|
multi-level process, where textual features are grouped into
|
|
"levels". Treatment of each level is controlled by the <link
|
|
linkend="icu-collation-settings-table">collation settings</link>. Higher
|
|
levels correspond to finer textual features.
|
|
</para>
|
|
<para>
|
|
<table id="icu-collation-levels">
|
|
<title>ICU Collation Levels</title>
|
|
<tgroup cols="8">
|
|
<colspec colname="col1" colwidth="1*"/>
|
|
<colspec colname="col2" colwidth="1.25*"/>
|
|
<colspec colname="col3" colwidth="1*"/>
|
|
<colspec colname="col4" colwidth="1*"/>
|
|
<colspec colname="col5" colwidth="1*"/>
|
|
<colspec colname="col6" colwidth="1*"/>
|
|
<colspec colname="col7" colwidth="1*"/>
|
|
<colspec colname="col8" colwidth="1*"/>
|
|
<thead>
|
|
<row>
|
|
<entry>Level</entry>
|
|
<entry>Description</entry>
|
|
<entry><literal>'f' = 'f'</literal></entry>
|
|
<entry><literal>'ab' = U&'a\2063b'</literal></entry>
|
|
<entry><literal>'x-y' = 'x_y'</literal></entry>
|
|
<entry><literal>'g' = 'G'</literal></entry>
|
|
<entry><literal>'n' = 'ñ'</literal></entry>
|
|
<entry><literal>'y' = 'z'</literal></entry>
|
|
</row>
|
|
</thead>
|
|
<tbody>
|
|
<row>
|
|
<entry>level1</entry>
|
|
<entry>Base Character</entry>
|
|
<entry><literal>true</literal></entry>
|
|
<entry><literal>true</literal></entry>
|
|
<entry><literal>true</literal></entry>
|
|
<entry><literal>true</literal></entry>
|
|
<entry><literal>true</literal></entry>
|
|
<entry><literal>false</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry>level2</entry>
|
|
<entry>Accents</entry>
|
|
<entry><literal>true</literal></entry>
|
|
<entry><literal>true</literal></entry>
|
|
<entry><literal>true</literal></entry>
|
|
<entry><literal>true</literal></entry>
|
|
<entry><literal>false</literal></entry>
|
|
<entry><literal>false</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry>level3</entry>
|
|
<entry>Case/Variants</entry>
|
|
<entry><literal>true</literal></entry>
|
|
<entry><literal>true</literal></entry>
|
|
<entry><literal>true</literal></entry>
|
|
<entry><literal>false</literal></entry>
|
|
<entry><literal>false</literal></entry>
|
|
<entry><literal>false</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry>level4</entry>
|
|
<entry>Punctuation</entry>
|
|
<entry><literal>true</literal></entry>
|
|
<entry><literal>true</literal></entry>
|
|
<entry><literal>false</literal></entry>
|
|
<entry><literal>false</literal></entry>
|
|
<entry><literal>false</literal></entry>
|
|
<entry><literal>false</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry>identic</entry>
|
|
<entry>All</entry>
|
|
<entry><literal>true</literal></entry>
|
|
<entry><literal>false</literal></entry>
|
|
<entry><literal>false</literal></entry>
|
|
<entry><literal>false</literal></entry>
|
|
<entry><literal>false</literal></entry>
|
|
<entry><literal>false</literal></entry>
|
|
</row>
|
|
</tbody>
|
|
</tgroup>
|
|
</table>
|
|
|
|
The above table shows which textual feature differences are
|
|
considered significant when determining equality at the given level. The
|
|
unicode character <literal>U+2063</literal> is an invisible separator,
|
|
and as seen in the table, is ignored for at all levels of comparison less
|
|
than <literal>identic</literal>.
|
|
</para>
|
|
<para>
|
|
At every level, even with full normalization off, basic normalization is
|
|
performed. For example, <literal>'á'</literal> may be composed of the
|
|
code points <literal>U&'\0061\0301'</literal> or the single code
|
|
point <literal>U&'\00E1'</literal>, and those sequences will be
|
|
considered equal even at the <literal>identic</literal> level. To treat
|
|
any difference in code point representation as distinct, use a collation
|
|
created with <symbol>DETERMINISTIC</symbol> set to
|
|
<literal>true</literal>.
|
|
</para>
|
|
<sect4 id="icu-collation-level-examples">
|
|
<title>Collation Level Examples</title>
|
|
<para>
|
|
|
|
<programlisting>
|
|
CREATE COLLATION level3 (PROVIDER=icu, DETERMINISTIC=false, LOCALE='und-u-ka-shifted-ks-level3');
|
|
CREATE COLLATION level4 (PROVIDER=icu, DETERMINISTIC=false, LOCALE='und-u-ka-shifted-ks-level4');
|
|
CREATE COLLATION identic (PROVIDER=icu, DETERMINISTIC=false, LOCALE='und-u-ka-shifted-ks-identic');
|
|
|
|
-- invisible separator ignored at all levels except identic
|
|
SELECT 'ab' = U&'a\2063b' COLLATE level4; -- true
|
|
SELECT 'ab' = U&'a\2063b' COLLATE identic; -- false
|
|
|
|
-- punctuation ignored at level3 but not at level 4
|
|
SELECT 'x-y' = 'x_y' COLLATE level3; -- true
|
|
SELECT 'x-y' = 'x_y' COLLATE level4; -- false
|
|
</programlisting>
|
|
|
|
</para>
|
|
</sect4>
|
|
</sect3>
|
|
<sect3 id="icu-collation-settings">
|
|
<title>Collation Settings for an ICU Locale</title>
|
|
<para>
|
|
<table id="icu-collation-settings-table">
|
|
<title>ICU Collation Settings</title>
|
|
<tgroup cols="4">
|
|
<colspec colname="col1" colwidth="1*"/>
|
|
<colspec colname="col2" colwidth="2*"/>
|
|
<colspec colname="col3" colwidth="2*"/>
|
|
<colspec colname="col4" colwidth="5*"/>
|
|
<thead>
|
|
<row>
|
|
<entry>Key</entry>
|
|
<entry>Values</entry>
|
|
<entry>Default</entry>
|
|
<entry>Description</entry>
|
|
</row>
|
|
</thead>
|
|
<tbody>
|
|
<row>
|
|
<entry><literal>ks</literal></entry>
|
|
<entry><literal>level1</literal>, <literal>level2</literal>, <literal>level3</literal>, <literal>level4</literal>, <literal>identic</literal></entry>
|
|
<entry><literal>level3</literal></entry>
|
|
<entry>
|
|
Sensitivity (or "strength") when determining equality, with
|
|
<literal>level1</literal> the least sensitive to differences and
|
|
<literal>identic</literal> the most sensitive to differences. See
|
|
<xref linkend="icu-collation-levels"/> for details.
|
|
</entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>ka</literal></entry>
|
|
<entry><literal>noignore</literal>, <literal>shifted</literal></entry>
|
|
<entry><literal>noignore</literal></entry>
|
|
<entry>
|
|
If set to <literal>shifted</literal>, causes some characters
|
|
(e.g. punctuation or space) to be ignored in comparison. Key
|
|
<literal>ks</literal> must be set to <literal>level3</literal> or
|
|
lower to take effect. Set key <literal>kv</literal> to control which
|
|
character classes are ignored.
|
|
</entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>kb</literal></entry>
|
|
<entry><literal>true</literal>, <literal>false</literal></entry>
|
|
<entry><literal>false</literal></entry>
|
|
<entry>
|
|
Backwards comparison for the level 2 differences. For example,
|
|
locale <literal>und-u-kb</literal> sorts <literal>'àe'</literal>
|
|
before <literal>'aé'</literal>.
|
|
</entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>kk</literal></entry>
|
|
<entry><literal>true</literal>, <literal>false</literal></entry>
|
|
<entry><literal>false</literal></entry>
|
|
<entry>
|
|
<para>
|
|
Enable full normalization; may affect performance. Basic
|
|
normalization is performed even when set to
|
|
<literal>false</literal>. Locales for languages that require full
|
|
normalization typically enable it by default.
|
|
</para>
|
|
<para>
|
|
Full normalization is important in some cases, such as when
|
|
multiple accents are applied to a single character. For example,
|
|
the code point sequences <literal>U&'\0065\0323\0302'</literal>
|
|
and <literal>U&'\0065\0302\0323'</literal> represent
|
|
an <literal>e</literal> with circumflex and dot-below accents
|
|
applied in different orders. With full normalization
|
|
on, these code point sequences are treated as equal; otherwise they
|
|
are unequal.
|
|
</para>
|
|
</entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>kc</literal></entry>
|
|
<entry><literal>true</literal>, <literal>false</literal></entry>
|
|
<entry><literal>false</literal></entry>
|
|
<entry>
|
|
<para>
|
|
Separates case into a "level 2.5" that falls between accents and
|
|
other level 3 features.
|
|
</para>
|
|
<para>
|
|
If set to <literal>true</literal> and <literal>ks</literal> is set
|
|
to <literal>level1</literal>, will ignore accents but take case
|
|
into account.
|
|
</para>
|
|
</entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>kf</literal></entry>
|
|
<entry>
|
|
<literal>upper</literal>, <literal>lower</literal>,
|
|
<literal>false</literal>
|
|
</entry>
|
|
<entry><literal>false</literal></entry>
|
|
<entry>
|
|
If set to <literal>upper</literal>, upper case sorts before lower
|
|
case. If set to <literal>lower</literal>, lower case sorts before
|
|
upper case. If set to <literal>false</literal>, the sort depends on
|
|
the rules of the locale.
|
|
</entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>kn</literal></entry>
|
|
<entry><literal>true</literal>, <literal>false</literal></entry>
|
|
<entry><literal>false</literal></entry>
|
|
<entry>
|
|
If set to <literal>true</literal>, numbers within a string are
|
|
treated as a single numeric value rather than a sequence of
|
|
digits. For example, <literal>'id-45'</literal> sorts before
|
|
<literal>'id-123'</literal>.
|
|
</entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>kr</literal></entry>
|
|
<entry>
|
|
<literal>space</literal>, <literal>punct</literal>,
|
|
<literal>symbol</literal>, <literal>currency</literal>,
|
|
<literal>digit</literal>, <replaceable>script-id</replaceable>
|
|
</entry>
|
|
<entry></entry>
|
|
<entry>
|
|
<para>
|
|
Set to one or more of the valid values, or any BCP 47
|
|
<replaceable>script-id</replaceable>, e.g. <literal>latn</literal>
|
|
("Latin") or <literal>grek</literal> ("Greek"). Multiple values are
|
|
separated by "<literal>-</literal>".
|
|
</para>
|
|
<para>
|
|
Redefines the ordering of classes of characters; those characters
|
|
belonging to a class earlier in the list sort before characters
|
|
belonging to a class later in the list. For instance, the value
|
|
<literal>digit-currency-space</literal> (as part of a language tag
|
|
like <literal>und-u-kr-digit-currency-space</literal>) sorts
|
|
punctuation before digits and spaces.
|
|
</para>
|
|
</entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>kv</literal></entry>
|
|
<entry>
|
|
<literal>space</literal>, <literal>punct</literal>,
|
|
<literal>symbol</literal>, <literal>currency</literal>
|
|
</entry>
|
|
<entry><literal>punct</literal></entry>
|
|
<entry>
|
|
Classes of characters ignored during comparison at level 3. Setting
|
|
to a later value includes earlier values;
|
|
e.g. <literal>symbol</literal> also includes
|
|
<literal>punct</literal> and <literal>space</literal> in the
|
|
characters to be ignored. Key <literal>ka</literal> must be set to
|
|
<literal>shifted</literal> and key <literal>ks</literal> must be set
|
|
to <literal>level3</literal> or lower to take effect.
|
|
</entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>co</literal></entry>
|
|
<entry><literal>emoji</literal>, <literal>phonebk</literal>, <literal>standard</literal>, <replaceable>...</replaceable></entry>
|
|
<entry><literal>standard</literal></entry>
|
|
<entry>
|
|
Collation type. See <xref linkend="icu-external-references"/> for additional options and details.
|
|
</entry>
|
|
</row>
|
|
</tbody>
|
|
</tgroup>
|
|
</table>
|
|
Defaults may depend on locale. The above table is not meant to be
|
|
complete. See <xref linkend="icu-external-references"/> for additional
|
|
options and details.
|
|
</para>
|
|
<note>
|
|
<para>
|
|
For many collation settings, you must create the collation with
|
|
<option>DETERMINISTIC</option> set to <literal>false</literal> for the
|
|
setting to have the desired effect (see <xref
|
|
linkend="collation-nondeterministic"/>). Additionally, some settings
|
|
only take effect when the key <literal>ka</literal> is set to
|
|
<literal>shifted</literal> (see <xref
|
|
linkend="icu-collation-settings-table"/>).
|
|
</para>
|
|
</note>
|
|
</sect3>
|
|
<sect3 id="icu-locale-examples">
|
|
<title>Examples</title>
|
|
<para>
|
|
<variablelist>
|
|
<varlistentry id="collation-managing-create-icu-de-u-co-phonebk-x-icu">
|
|
<term><literal>CREATE COLLATION "de-u-co-phonebk-x-icu" (provider = icu, locale = 'de-u-co-phonebk');</literal></term>
|
|
<listitem>
|
|
<para>German collation with phone book collation type</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="collation-managing-create-icu-und-u-co-emoji-x-icu">
|
|
<term><literal>CREATE COLLATION "und-u-co-emoji-x-icu" (provider = icu, locale = 'und-u-co-emoji');</literal></term>
|
|
<listitem>
|
|
<para>
|
|
Root collation with Emoji collation type, per Unicode Technical Standard #51
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="collation-managing-create-icu-en-u-kr-grek-latn">
|
|
<term><literal>CREATE COLLATION latinlast (provider = icu, locale = 'en-u-kr-grek-latn');</literal></term>
|
|
<listitem>
|
|
<para>
|
|
Sort Greek letters before Latin ones. (The default is Latin before Greek.)
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="collation-managing-create-icu-en-u-kf-upper">
|
|
<term><literal>CREATE COLLATION upperfirst (provider = icu, locale = 'en-u-kf-upper');</literal></term>
|
|
<listitem>
|
|
<para>
|
|
Sort upper-case letters before lower-case letters. (The default is
|
|
lower-case letters first.)
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry id="collation-managing-create-icu-en-u-kf-upper-kr-grek-latn">
|
|
<term><literal>CREATE COLLATION special (provider = icu, locale = 'en-u-kf-upper-kr-grek-latn');</literal></term>
|
|
<listitem>
|
|
<para>
|
|
Combines both of the above options.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
</variablelist>
|
|
</para>
|
|
</sect3>
|
|
<sect3 id="icu-external-references">
|
|
<title>External References for ICU</title>
|
|
<para>
|
|
This section (<xref linkend="icu-custom-collations"/>) is only a brief
|
|
overview of ICU behavior and language tags. Refer to the following
|
|
documents for technical details, additional options, and new behavior:
|
|
</para>
|
|
<itemizedlist>
|
|
<listitem>
|
|
<para>
|
|
<ulink
|
|
url="https://www.unicode.org/reports/tr35/tr35-collation.html">Unicode
|
|
Technical Standard #35</ulink>
|
|
</para>
|
|
</listitem>
|
|
<listitem>
|
|
<para>
|
|
<ulink url="https://tools.ietf.org/html/bcp47">BCP 47</ulink>
|
|
</para>
|
|
</listitem>
|
|
<listitem>
|
|
<para>
|
|
<ulink url="https://github.com/unicode-org/cldr/blob/master/common/bcp47/collation.xml">CLDR
|
|
repository</ulink>
|
|
</para>
|
|
</listitem>
|
|
<listitem>
|
|
<para>
|
|
<ulink url="https://unicode-org.github.io/icu/userguide/locale/"></ulink>
|
|
</para>
|
|
</listitem>
|
|
<listitem>
|
|
<para>
|
|
<ulink url="https://unicode-org.github.io/icu/userguide/collation/api.html"></ulink>
|
|
</para>
|
|
</listitem>
|
|
</itemizedlist>
|
|
</sect3>
|
|
</sect2>
|
|
</sect1>
|
|
|
|
<sect1 id="multibyte">
|
|
<title>Character Set Support</title>
|
|
|
|
<indexterm zone="multibyte"><primary>character set</primary></indexterm>
|
|
|
|
<para>
|
|
The character set support in <productname>PostgreSQL</productname>
|
|
allows you to store text in a variety of character sets (also called
|
|
encodings), including
|
|
single-byte character sets such as the ISO 8859 series and
|
|
multiple-byte character sets such as <acronym>EUC</acronym> (Extended Unix
|
|
Code), UTF-8, and Mule internal code. All supported character sets
|
|
can be used transparently by clients, but a few are not supported
|
|
for use within the server (that is, as a server-side encoding).
|
|
The default character set is selected while
|
|
initializing your <productname>PostgreSQL</productname> database
|
|
cluster using <command>initdb</command>. It can be overridden when you
|
|
create a database, so you can have multiple
|
|
databases each with a different character set.
|
|
</para>
|
|
|
|
<para>
|
|
An important restriction, however, is that each database's character set
|
|
must be compatible with the database's <envar>LC_CTYPE</envar> (character
|
|
classification) and <envar>LC_COLLATE</envar> (string sort order) locale
|
|
settings. For <literal>C</literal> or
|
|
<literal>POSIX</literal> locale, any character set is allowed, but for other
|
|
libc-provided locales there is only one character set that will work
|
|
correctly.
|
|
(On Windows, however, UTF-8 encoding can be used with any locale.)
|
|
If you have ICU support configured, ICU-provided locales can be used
|
|
with most but not all server-side encodings.
|
|
</para>
|
|
|
|
<sect2 id="multibyte-charset-supported">
|
|
<title>Supported Character Sets</title>
|
|
|
|
<para>
|
|
<xref linkend="charset-table"/> shows the character sets available
|
|
for use in <productname>PostgreSQL</productname>.
|
|
</para>
|
|
|
|
<table id="charset-table">
|
|
<title><productname>PostgreSQL</productname> Character Sets</title>
|
|
<tgroup cols="7">
|
|
<colspec colname="col1" colwidth="3*"/>
|
|
<colspec colname="col2" colwidth="2*"/>
|
|
<colspec colname="col3" colwidth="2*"/>
|
|
<colspec colname="col4" colwidth="1.25*"/>
|
|
<colspec colname="col5" colwidth="1*"/>
|
|
<colspec colname="col6" colwidth="1*"/>
|
|
<colspec colname="col7" colwidth="2*"/>
|
|
<thead>
|
|
<row>
|
|
<entry>Name</entry>
|
|
<entry>Description</entry>
|
|
<entry>Language</entry>
|
|
<entry>Server?</entry>
|
|
<entry>ICU?</entry>
|
|
<!--
|
|
The Bytes/Char field is populated by looking at the values returned
|
|
by pg_wchar_table.mblen function for each encoding.
|
|
-->
|
|
<entry>Bytes/&zwsp;Char</entry>
|
|
<entry>Aliases</entry>
|
|
</row>
|
|
</thead>
|
|
<tbody>
|
|
<row>
|
|
<entry><literal>BIG5</literal></entry>
|
|
<entry>Big Five</entry>
|
|
<entry>Traditional Chinese</entry>
|
|
<entry>No</entry>
|
|
<entry>No</entry>
|
|
<entry>1–2</entry>
|
|
<entry><literal>WIN950</literal>, <literal>Windows950</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>EUC_CN</literal></entry>
|
|
<entry>Extended UNIX Code-CN</entry>
|
|
<entry>Simplified Chinese</entry>
|
|
<entry>Yes</entry>
|
|
<entry>Yes</entry>
|
|
<entry>1–3</entry>
|
|
<entry></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>EUC_JP</literal></entry>
|
|
<entry>Extended UNIX Code-JP</entry>
|
|
<entry>Japanese</entry>
|
|
<entry>Yes</entry>
|
|
<entry>Yes</entry>
|
|
<entry>1–3</entry>
|
|
<entry></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>EUC_JIS_2004</literal></entry>
|
|
<entry>Extended UNIX Code-JP, JIS X 0213</entry>
|
|
<entry>Japanese</entry>
|
|
<entry>Yes</entry>
|
|
<entry>No</entry>
|
|
<entry>1–3</entry>
|
|
<entry></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>EUC_KR</literal></entry>
|
|
<entry>Extended UNIX Code-KR</entry>
|
|
<entry>Korean</entry>
|
|
<entry>Yes</entry>
|
|
<entry>Yes</entry>
|
|
<entry>1–3</entry>
|
|
<entry></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>EUC_TW</literal></entry>
|
|
<entry>Extended UNIX Code-TW</entry>
|
|
<entry>Traditional Chinese, Taiwanese</entry>
|
|
<entry>Yes</entry>
|
|
<entry>Yes</entry>
|
|
<entry>1–3</entry>
|
|
<entry></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>GB18030</literal></entry>
|
|
<entry>National Standard</entry>
|
|
<entry>Chinese</entry>
|
|
<entry>No</entry>
|
|
<entry>No</entry>
|
|
<entry>1–4</entry>
|
|
<entry></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>GBK</literal></entry>
|
|
<entry>Extended National Standard</entry>
|
|
<entry>Simplified Chinese</entry>
|
|
<entry>No</entry>
|
|
<entry>No</entry>
|
|
<entry>1–2</entry>
|
|
<entry><literal>WIN936</literal>, <literal>Windows936</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>ISO_8859_5</literal></entry>
|
|
<entry>ISO 8859-5, <acronym>ECMA</acronym> 113</entry>
|
|
<entry>Latin/Cyrillic</entry>
|
|
<entry>Yes</entry>
|
|
<entry>Yes</entry>
|
|
<entry>1</entry>
|
|
<entry></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>ISO_8859_6</literal></entry>
|
|
<entry>ISO 8859-6, <acronym>ECMA</acronym> 114</entry>
|
|
<entry>Latin/Arabic</entry>
|
|
<entry>Yes</entry>
|
|
<entry>Yes</entry>
|
|
<entry>1</entry>
|
|
<entry></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>ISO_8859_7</literal></entry>
|
|
<entry>ISO 8859-7, <acronym>ECMA</acronym> 118</entry>
|
|
<entry>Latin/Greek</entry>
|
|
<entry>Yes</entry>
|
|
<entry>Yes</entry>
|
|
<entry>1</entry>
|
|
<entry></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>ISO_8859_8</literal></entry>
|
|
<entry>ISO 8859-8, <acronym>ECMA</acronym> 121</entry>
|
|
<entry>Latin/Hebrew</entry>
|
|
<entry>Yes</entry>
|
|
<entry>Yes</entry>
|
|
<entry>1</entry>
|
|
<entry></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>JOHAB</literal></entry>
|
|
<entry><acronym>JOHAB</acronym></entry>
|
|
<entry>Korean (Hangul)</entry>
|
|
<entry>No</entry>
|
|
<entry>No</entry>
|
|
<entry>1–3</entry>
|
|
<entry></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>KOI8R</literal></entry>
|
|
<entry><acronym>KOI</acronym>8-R</entry>
|
|
<entry>Cyrillic (Russian)</entry>
|
|
<entry>Yes</entry>
|
|
<entry>Yes</entry>
|
|
<entry>1</entry>
|
|
<entry><literal>KOI8</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>KOI8U</literal></entry>
|
|
<entry><acronym>KOI</acronym>8-U</entry>
|
|
<entry>Cyrillic (Ukrainian)</entry>
|
|
<entry>Yes</entry>
|
|
<entry>Yes</entry>
|
|
<entry>1</entry>
|
|
<entry></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>LATIN1</literal></entry>
|
|
<entry>ISO 8859-1, <acronym>ECMA</acronym> 94</entry>
|
|
<entry>Western European</entry>
|
|
<entry>Yes</entry>
|
|
<entry>Yes</entry>
|
|
<entry>1</entry>
|
|
<entry><literal>ISO88591</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>LATIN2</literal></entry>
|
|
<entry>ISO 8859-2, <acronym>ECMA</acronym> 94</entry>
|
|
<entry>Central European</entry>
|
|
<entry>Yes</entry>
|
|
<entry>Yes</entry>
|
|
<entry>1</entry>
|
|
<entry><literal>ISO88592</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>LATIN3</literal></entry>
|
|
<entry>ISO 8859-3, <acronym>ECMA</acronym> 94</entry>
|
|
<entry>South European</entry>
|
|
<entry>Yes</entry>
|
|
<entry>Yes</entry>
|
|
<entry>1</entry>
|
|
<entry><literal>ISO88593</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>LATIN4</literal></entry>
|
|
<entry>ISO 8859-4, <acronym>ECMA</acronym> 94</entry>
|
|
<entry>North European</entry>
|
|
<entry>Yes</entry>
|
|
<entry>Yes</entry>
|
|
<entry>1</entry>
|
|
<entry><literal>ISO88594</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>LATIN5</literal></entry>
|
|
<entry>ISO 8859-9, <acronym>ECMA</acronym> 128</entry>
|
|
<entry>Turkish</entry>
|
|
<entry>Yes</entry>
|
|
<entry>Yes</entry>
|
|
<entry>1</entry>
|
|
<entry><literal>ISO88599</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>LATIN6</literal></entry>
|
|
<entry>ISO 8859-10, <acronym>ECMA</acronym> 144</entry>
|
|
<entry>Nordic</entry>
|
|
<entry>Yes</entry>
|
|
<entry>Yes</entry>
|
|
<entry>1</entry>
|
|
<entry><literal>ISO885910</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>LATIN7</literal></entry>
|
|
<entry>ISO 8859-13</entry>
|
|
<entry>Baltic</entry>
|
|
<entry>Yes</entry>
|
|
<entry>Yes</entry>
|
|
<entry>1</entry>
|
|
<entry><literal>ISO885913</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>LATIN8</literal></entry>
|
|
<entry>ISO 8859-14</entry>
|
|
<entry>Celtic</entry>
|
|
<entry>Yes</entry>
|
|
<entry>Yes</entry>
|
|
<entry>1</entry>
|
|
<entry><literal>ISO885914</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>LATIN9</literal></entry>
|
|
<entry>ISO 8859-15</entry>
|
|
<entry>LATIN1 with Euro and accents</entry>
|
|
<entry>Yes</entry>
|
|
<entry>Yes</entry>
|
|
<entry>1</entry>
|
|
<entry><literal>ISO885915</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>LATIN10</literal></entry>
|
|
<entry>ISO 8859-16, <acronym>ASRO</acronym> SR 14111</entry>
|
|
<entry>Romanian</entry>
|
|
<entry>Yes</entry>
|
|
<entry>No</entry>
|
|
<entry>1</entry>
|
|
<entry><literal>ISO885916</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>MULE_INTERNAL</literal></entry>
|
|
<entry>Mule internal code</entry>
|
|
<entry>Multilingual Emacs</entry>
|
|
<entry>Yes</entry>
|
|
<entry>No</entry>
|
|
<entry>1–4</entry>
|
|
<entry></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>SJIS</literal></entry>
|
|
<entry>Shift JIS</entry>
|
|
<entry>Japanese</entry>
|
|
<entry>No</entry>
|
|
<entry>No</entry>
|
|
<entry>1–2</entry>
|
|
<entry><literal>Mskanji</literal>, <literal>ShiftJIS</literal>, <literal>WIN932</literal>, <literal>Windows932</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>SHIFT_JIS_2004</literal></entry>
|
|
<entry>Shift JIS, JIS X 0213</entry>
|
|
<entry>Japanese</entry>
|
|
<entry>No</entry>
|
|
<entry>No</entry>
|
|
<entry>1–2</entry>
|
|
<entry></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>SQL_ASCII</literal></entry>
|
|
<entry>unspecified (see text)</entry>
|
|
<entry><emphasis>any</emphasis></entry>
|
|
<entry>Yes</entry>
|
|
<entry>No</entry>
|
|
<entry>1</entry>
|
|
<entry></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>UHC</literal></entry>
|
|
<entry>Unified Hangul Code</entry>
|
|
<entry>Korean</entry>
|
|
<entry>No</entry>
|
|
<entry>No</entry>
|
|
<entry>1–2</entry>
|
|
<entry><literal>WIN949</literal>, <literal>Windows949</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>UTF8</literal></entry>
|
|
<entry>Unicode, 8-bit</entry>
|
|
<entry><emphasis>all</emphasis></entry>
|
|
<entry>Yes</entry>
|
|
<entry>Yes</entry>
|
|
<entry>1–4</entry>
|
|
<entry><literal>Unicode</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>WIN866</literal></entry>
|
|
<entry>Windows CP866</entry>
|
|
<entry>Cyrillic</entry>
|
|
<entry>Yes</entry>
|
|
<entry>Yes</entry>
|
|
<entry>1</entry>
|
|
<entry><literal>ALT</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>WIN874</literal></entry>
|
|
<entry>Windows CP874</entry>
|
|
<entry>Thai</entry>
|
|
<entry>Yes</entry>
|
|
<entry>No</entry>
|
|
<entry>1</entry>
|
|
<entry></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>WIN1250</literal></entry>
|
|
<entry>Windows CP1250</entry>
|
|
<entry>Central European</entry>
|
|
<entry>Yes</entry>
|
|
<entry>Yes</entry>
|
|
<entry>1</entry>
|
|
<entry></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>WIN1251</literal></entry>
|
|
<entry>Windows CP1251</entry>
|
|
<entry>Cyrillic</entry>
|
|
<entry>Yes</entry>
|
|
<entry>Yes</entry>
|
|
<entry>1</entry>
|
|
<entry><literal>WIN</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>WIN1252</literal></entry>
|
|
<entry>Windows CP1252</entry>
|
|
<entry>Western European</entry>
|
|
<entry>Yes</entry>
|
|
<entry>Yes</entry>
|
|
<entry>1</entry>
|
|
<entry></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>WIN1253</literal></entry>
|
|
<entry>Windows CP1253</entry>
|
|
<entry>Greek</entry>
|
|
<entry>Yes</entry>
|
|
<entry>Yes</entry>
|
|
<entry>1</entry>
|
|
<entry></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>WIN1254</literal></entry>
|
|
<entry>Windows CP1254</entry>
|
|
<entry>Turkish</entry>
|
|
<entry>Yes</entry>
|
|
<entry>Yes</entry>
|
|
<entry>1</entry>
|
|
<entry></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>WIN1255</literal></entry>
|
|
<entry>Windows CP1255</entry>
|
|
<entry>Hebrew</entry>
|
|
<entry>Yes</entry>
|
|
<entry>Yes</entry>
|
|
<entry>1</entry>
|
|
<entry></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>WIN1256</literal></entry>
|
|
<entry>Windows CP1256</entry>
|
|
<entry>Arabic</entry>
|
|
<entry>Yes</entry>
|
|
<entry>Yes</entry>
|
|
<entry>1</entry>
|
|
<entry></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>WIN1257</literal></entry>
|
|
<entry>Windows CP1257</entry>
|
|
<entry>Baltic</entry>
|
|
<entry>Yes</entry>
|
|
<entry>Yes</entry>
|
|
<entry>1</entry>
|
|
<entry></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>WIN1258</literal></entry>
|
|
<entry>Windows CP1258</entry>
|
|
<entry>Vietnamese</entry>
|
|
<entry>Yes</entry>
|
|
<entry>Yes</entry>
|
|
<entry>1</entry>
|
|
<entry><literal>ABC</literal>, <literal>TCVN</literal>, <literal>TCVN5712</literal>, <literal>VSCII</literal></entry>
|
|
</row>
|
|
</tbody>
|
|
</tgroup>
|
|
</table>
|
|
|
|
<para>
|
|
Not all client <acronym>API</acronym>s support all the listed character sets. For example, the
|
|
<productname>PostgreSQL</productname>
|
|
JDBC driver does not support <literal>MULE_INTERNAL</literal>, <literal>LATIN6</literal>,
|
|
<literal>LATIN8</literal>, and <literal>LATIN10</literal>.
|
|
</para>
|
|
|
|
<para>
|
|
The <literal>SQL_ASCII</literal> setting behaves considerably differently
|
|
from the other settings. When the server character set is
|
|
<literal>SQL_ASCII</literal>, the server interprets byte values 0–127
|
|
according to the ASCII standard, while byte values 128–255 are taken
|
|
as uninterpreted characters. No encoding conversion will be done when
|
|
the setting is <literal>SQL_ASCII</literal>. Thus, this setting is not so
|
|
much a declaration that a specific encoding is in use, as a declaration
|
|
of ignorance about the encoding. In most cases, if you are
|
|
working with any non-ASCII data, it is unwise to use the
|
|
<literal>SQL_ASCII</literal> setting because
|
|
<productname>PostgreSQL</productname> will be unable to help you by
|
|
converting or validating non-ASCII characters.
|
|
</para>
|
|
</sect2>
|
|
|
|
<sect2 id="multibyte-setting">
|
|
<title>Setting the Character Set</title>
|
|
|
|
<para>
|
|
<command>initdb</command> defines the default character set (encoding)
|
|
for a <productname>PostgreSQL</productname> cluster. For example,
|
|
|
|
<screen>
|
|
initdb -E EUC_JP
|
|
</screen>
|
|
|
|
sets the default character set to
|
|
<literal>EUC_JP</literal> (Extended Unix Code for Japanese). You
|
|
can use <option>--encoding</option> instead of
|
|
<option>-E</option> if you prefer longer option strings.
|
|
If no <option>-E</option> or <option>--encoding</option> option is
|
|
given, <command>initdb</command> attempts to determine the appropriate
|
|
encoding to use based on the specified or default locale.
|
|
</para>
|
|
|
|
<para>
|
|
You can specify a non-default encoding at database creation time,
|
|
provided that the encoding is compatible with the selected locale:
|
|
|
|
<screen>
|
|
createdb -E EUC_KR -T template0 --lc-collate=ko_KR.euckr --lc-ctype=ko_KR.euckr korean
|
|
</screen>
|
|
|
|
This will create a database named <literal>korean</literal> that
|
|
uses the character set <literal>EUC_KR</literal>, and locale <literal>ko_KR</literal>.
|
|
Another way to accomplish this is to use this SQL command:
|
|
|
|
<programlisting>
|
|
CREATE DATABASE korean WITH ENCODING 'EUC_KR' LC_COLLATE='ko_KR.euckr' LC_CTYPE='ko_KR.euckr' TEMPLATE=template0;
|
|
</programlisting>
|
|
|
|
Notice that the above commands specify copying the <literal>template0</literal>
|
|
database. When copying any other database, the encoding and locale
|
|
settings cannot be changed from those of the source database, because
|
|
that might result in corrupt data. For more information see
|
|
<xref linkend="manage-ag-templatedbs"/>.
|
|
</para>
|
|
|
|
<para>
|
|
The encoding for a database is stored in the system catalog
|
|
<literal>pg_database</literal>. You can see it by using the
|
|
<command>psql</command> <option>-l</option> option or the
|
|
<command>\l</command> command.
|
|
|
|
<screen>
|
|
$ <userinput>psql -l</userinput>
|
|
List of databases
|
|
Name | Owner | Encoding | Collation | Ctype | Access Privileges
|
|
-----------+----------+-----------+-------------+-------------+-------------------------------------
|
|
clocaledb | hlinnaka | SQL_ASCII | C | C |
|
|
englishdb | hlinnaka | UTF8 | en_GB.UTF8 | en_GB.UTF8 |
|
|
japanese | hlinnaka | UTF8 | ja_JP.UTF8 | ja_JP.UTF8 |
|
|
korean | hlinnaka | EUC_KR | ko_KR.euckr | ko_KR.euckr |
|
|
postgres | hlinnaka | UTF8 | fi_FI.UTF8 | fi_FI.UTF8 |
|
|
template0 | hlinnaka | UTF8 | fi_FI.UTF8 | fi_FI.UTF8 | {=c/hlinnaka,hlinnaka=CTc/hlinnaka}
|
|
template1 | hlinnaka | UTF8 | fi_FI.UTF8 | fi_FI.UTF8 | {=c/hlinnaka,hlinnaka=CTc/hlinnaka}
|
|
(7 rows)
|
|
</screen>
|
|
</para>
|
|
|
|
<important>
|
|
<para>
|
|
On most modern operating systems, <productname>PostgreSQL</productname>
|
|
can determine which character set is implied by the <envar>LC_CTYPE</envar>
|
|
setting, and it will enforce that only the matching database encoding is
|
|
used. On older systems it is your responsibility to ensure that you use
|
|
the encoding expected by the locale you have selected. A mistake in
|
|
this area is likely to lead to strange behavior of locale-dependent
|
|
operations such as sorting.
|
|
</para>
|
|
|
|
<para>
|
|
<productname>PostgreSQL</productname> will allow superusers to create
|
|
databases with <literal>SQL_ASCII</literal> encoding even when
|
|
<envar>LC_CTYPE</envar> is not <literal>C</literal> or <literal>POSIX</literal>. As noted
|
|
above, <literal>SQL_ASCII</literal> does not enforce that the data stored in
|
|
the database has any particular encoding, and so this choice poses risks
|
|
of locale-dependent misbehavior. Using this combination of settings is
|
|
deprecated and may someday be forbidden altogether.
|
|
</para>
|
|
</important>
|
|
</sect2>
|
|
|
|
<sect2 id="multibyte-automatic-conversion">
|
|
<title>Automatic Character Set Conversion Between Server and Client</title>
|
|
|
|
<para>
|
|
<productname>PostgreSQL</productname> supports automatic character
|
|
set conversion between server and client for many combinations of
|
|
character sets (<xref linkend="multibyte-conversions-supported"/>
|
|
shows which ones).
|
|
</para>
|
|
|
|
<para>
|
|
To enable automatic character set conversion, you have to
|
|
tell <productname>PostgreSQL</productname> the character set
|
|
(encoding) you would like to use in the client. There are several
|
|
ways to accomplish this:
|
|
|
|
<itemizedlist>
|
|
<listitem>
|
|
<para>
|
|
Using the <command>\encoding</command> command in
|
|
<application>psql</application>.
|
|
<command>\encoding</command> allows you to change client
|
|
encoding on the fly. For
|
|
example, to change the encoding to <literal>SJIS</literal>, type:
|
|
|
|
<programlisting>
|
|
\encoding SJIS
|
|
</programlisting>
|
|
</para>
|
|
</listitem>
|
|
|
|
<listitem>
|
|
<para>
|
|
<application>libpq</application> (<xref linkend="libpq-control"/>) has functions to control the client encoding.
|
|
</para>
|
|
</listitem>
|
|
|
|
<listitem>
|
|
<para>
|
|
Using <command>SET client_encoding TO</command>.
|
|
|
|
Setting the client encoding can be done with this SQL command:
|
|
|
|
<programlisting>
|
|
SET CLIENT_ENCODING TO '<replaceable>value</replaceable>';
|
|
</programlisting>
|
|
|
|
Also you can use the standard SQL syntax <literal>SET NAMES</literal>
|
|
for this purpose:
|
|
|
|
<programlisting>
|
|
SET NAMES '<replaceable>value</replaceable>';
|
|
</programlisting>
|
|
|
|
To query the current client encoding:
|
|
|
|
<programlisting>
|
|
SHOW client_encoding;
|
|
</programlisting>
|
|
|
|
To return to the default encoding:
|
|
|
|
<programlisting>
|
|
RESET client_encoding;
|
|
</programlisting>
|
|
</para>
|
|
</listitem>
|
|
|
|
<listitem>
|
|
<para>
|
|
Using <envar>PGCLIENTENCODING</envar>. If the environment variable
|
|
<envar>PGCLIENTENCODING</envar> is defined in the client's
|
|
environment, that client encoding is automatically selected
|
|
when a connection to the server is made. (This can
|
|
subsequently be overridden using any of the other methods
|
|
mentioned above.)
|
|
</para>
|
|
</listitem>
|
|
|
|
<listitem>
|
|
<para>
|
|
Using the configuration variable <xref
|
|
linkend="guc-client-encoding"/>. If the
|
|
<varname>client_encoding</varname> variable is set, that client
|
|
encoding is automatically selected when a connection to the
|
|
server is made. (This can subsequently be overridden using any
|
|
of the other methods mentioned above.)
|
|
</para>
|
|
</listitem>
|
|
|
|
</itemizedlist>
|
|
</para>
|
|
|
|
<para>
|
|
If the conversion of a particular character is not possible
|
|
— suppose you chose <literal>EUC_JP</literal> for the
|
|
server and <literal>LATIN1</literal> for the client, and some
|
|
Japanese characters are returned that do not have a representation in
|
|
<literal>LATIN1</literal> — an error is reported.
|
|
</para>
|
|
|
|
<para>
|
|
If the client character set is defined as <literal>SQL_ASCII</literal>,
|
|
encoding conversion is disabled, regardless of the server's character
|
|
set. (However, if the server's character set is
|
|
not <literal>SQL_ASCII</literal>, the server will still check that
|
|
incoming data is valid for that encoding; so the net effect is as
|
|
though the client character set were the same as the server's.)
|
|
Just as for the server, use of <literal>SQL_ASCII</literal> is unwise
|
|
unless you are working with all-ASCII data.
|
|
</para>
|
|
</sect2>
|
|
|
|
<sect2 id="multibyte-conversions-supported">
|
|
<title>Available Character Set Conversions</title>
|
|
|
|
<para>
|
|
<productname>PostgreSQL</productname> allows conversion between any
|
|
two character sets for which a conversion function is listed in the
|
|
<link linkend="catalog-pg-conversion"><structname>pg_conversion</structname></link>
|
|
system catalog. <productname>PostgreSQL</productname> comes with
|
|
some predefined conversions, as summarized in
|
|
<xref linkend="multibyte-translation-table"/> and shown in more
|
|
detail in <xref linkend="builtin-conversions-table"/>. You can
|
|
create a new conversion using the SQL command
|
|
<xref linkend="sql-createconversion"/>. (To be used for automatic
|
|
client/server conversions, a conversion must be marked
|
|
as <quote>default</quote> for its character set pair.)
|
|
</para>
|
|
|
|
<table id="multibyte-translation-table">
|
|
<title>Built-in Client/Server Character Set Conversions</title>
|
|
<tgroup cols="2">
|
|
<colspec colname="col1" colwidth="1*"/>
|
|
<colspec colname="col2" colwidth="3*"/>
|
|
<thead>
|
|
<row>
|
|
<entry>Server Character Set</entry>
|
|
<entry>Available Client Character Sets</entry>
|
|
</row>
|
|
</thead>
|
|
<tbody>
|
|
<row>
|
|
<entry><literal>BIG5</literal></entry>
|
|
<entry><emphasis>not supported as a server encoding</emphasis>
|
|
</entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>EUC_CN</literal></entry>
|
|
<entry><emphasis>EUC_CN</emphasis>,
|
|
<literal>MULE_INTERNAL</literal>,
|
|
<literal>UTF8</literal>
|
|
</entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>EUC_JP</literal></entry>
|
|
<entry><emphasis>EUC_JP</emphasis>,
|
|
<literal>MULE_INTERNAL</literal>,
|
|
<literal>SJIS</literal>,
|
|
<literal>UTF8</literal>
|
|
</entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>EUC_JIS_2004</literal></entry>
|
|
<entry><emphasis>EUC_JIS_2004</emphasis>,
|
|
<literal>SHIFT_JIS_2004</literal>,
|
|
<literal>UTF8</literal>
|
|
</entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>EUC_KR</literal></entry>
|
|
<entry><emphasis>EUC_KR</emphasis>,
|
|
<literal>MULE_INTERNAL</literal>,
|
|
<literal>UTF8</literal>
|
|
</entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>EUC_TW</literal></entry>
|
|
<entry><emphasis>EUC_TW</emphasis>,
|
|
<literal>BIG5</literal>,
|
|
<literal>MULE_INTERNAL</literal>,
|
|
<literal>UTF8</literal>
|
|
</entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>GB18030</literal></entry>
|
|
<entry><emphasis>not supported as a server encoding</emphasis>
|
|
</entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>GBK</literal></entry>
|
|
<entry><emphasis>not supported as a server encoding</emphasis>
|
|
</entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>ISO_8859_5</literal></entry>
|
|
<entry><emphasis>ISO_8859_5</emphasis>,
|
|
<literal>KOI8R</literal>,
|
|
<literal>MULE_INTERNAL</literal>,
|
|
<literal>UTF8</literal>,
|
|
<literal>WIN866</literal>,
|
|
<literal>WIN1251</literal>
|
|
</entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>ISO_8859_6</literal></entry>
|
|
<entry><emphasis>ISO_8859_6</emphasis>,
|
|
<literal>UTF8</literal>
|
|
</entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>ISO_8859_7</literal></entry>
|
|
<entry><emphasis>ISO_8859_7</emphasis>,
|
|
<literal>UTF8</literal>
|
|
</entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>ISO_8859_8</literal></entry>
|
|
<entry><emphasis>ISO_8859_8</emphasis>,
|
|
<literal>UTF8</literal>
|
|
</entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>JOHAB</literal></entry>
|
|
<entry><emphasis>not supported as a server encoding</emphasis>
|
|
</entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>KOI8R</literal></entry>
|
|
<entry><emphasis>KOI8R</emphasis>,
|
|
<literal>ISO_8859_5</literal>,
|
|
<literal>MULE_INTERNAL</literal>,
|
|
<literal>UTF8</literal>,
|
|
<literal>WIN866</literal>,
|
|
<literal>WIN1251</literal>
|
|
</entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>KOI8U</literal></entry>
|
|
<entry><emphasis>KOI8U</emphasis>,
|
|
<literal>UTF8</literal>
|
|
</entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>LATIN1</literal></entry>
|
|
<entry><emphasis>LATIN1</emphasis>,
|
|
<literal>MULE_INTERNAL</literal>,
|
|
<literal>UTF8</literal>
|
|
</entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>LATIN2</literal></entry>
|
|
<entry><emphasis>LATIN2</emphasis>,
|
|
<literal>MULE_INTERNAL</literal>,
|
|
<literal>UTF8</literal>,
|
|
<literal>WIN1250</literal>
|
|
</entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>LATIN3</literal></entry>
|
|
<entry><emphasis>LATIN3</emphasis>,
|
|
<literal>MULE_INTERNAL</literal>,
|
|
<literal>UTF8</literal>
|
|
</entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>LATIN4</literal></entry>
|
|
<entry><emphasis>LATIN4</emphasis>,
|
|
<literal>MULE_INTERNAL</literal>,
|
|
<literal>UTF8</literal>
|
|
</entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>LATIN5</literal></entry>
|
|
<entry><emphasis>LATIN5</emphasis>,
|
|
<literal>UTF8</literal>
|
|
</entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>LATIN6</literal></entry>
|
|
<entry><emphasis>LATIN6</emphasis>,
|
|
<literal>UTF8</literal>
|
|
</entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>LATIN7</literal></entry>
|
|
<entry><emphasis>LATIN7</emphasis>,
|
|
<literal>UTF8</literal>
|
|
</entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>LATIN8</literal></entry>
|
|
<entry><emphasis>LATIN8</emphasis>,
|
|
<literal>UTF8</literal>
|
|
</entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>LATIN9</literal></entry>
|
|
<entry><emphasis>LATIN9</emphasis>,
|
|
<literal>UTF8</literal>
|
|
</entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>LATIN10</literal></entry>
|
|
<entry><emphasis>LATIN10</emphasis>,
|
|
<literal>UTF8</literal>
|
|
</entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>MULE_INTERNAL</literal></entry>
|
|
<entry><emphasis>MULE_INTERNAL</emphasis>,
|
|
<literal>BIG5</literal>,
|
|
<literal>EUC_CN</literal>,
|
|
<literal>EUC_JP</literal>,
|
|
<literal>EUC_KR</literal>,
|
|
<literal>EUC_TW</literal>,
|
|
<literal>ISO_8859_5</literal>,
|
|
<literal>KOI8R</literal>,
|
|
<literal>LATIN1</literal> to <literal>LATIN4</literal>,
|
|
<literal>SJIS</literal>,
|
|
<literal>WIN866</literal>,
|
|
<literal>WIN1250</literal>,
|
|
<literal>WIN1251</literal>
|
|
</entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>SJIS</literal></entry>
|
|
<entry><emphasis>not supported as a server encoding</emphasis>
|
|
</entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>SHIFT_JIS_2004</literal></entry>
|
|
<entry><emphasis>not supported as a server encoding</emphasis>
|
|
</entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>SQL_ASCII</literal></entry>
|
|
<entry><emphasis>any (no conversion will be performed)</emphasis>
|
|
</entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>UHC</literal></entry>
|
|
<entry><emphasis>not supported as a server encoding</emphasis>
|
|
</entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>UTF8</literal></entry>
|
|
<entry><emphasis>all supported encodings</emphasis>
|
|
</entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>WIN866</literal></entry>
|
|
<entry><emphasis>WIN866</emphasis>,
|
|
<literal>ISO_8859_5</literal>,
|
|
<literal>KOI8R</literal>,
|
|
<literal>MULE_INTERNAL</literal>,
|
|
<literal>UTF8</literal>,
|
|
<literal>WIN1251</literal>
|
|
</entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>WIN874</literal></entry>
|
|
<entry><emphasis>WIN874</emphasis>,
|
|
<literal>UTF8</literal>
|
|
</entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>WIN1250</literal></entry>
|
|
<entry><emphasis>WIN1250</emphasis>,
|
|
<literal>LATIN2</literal>,
|
|
<literal>MULE_INTERNAL</literal>,
|
|
<literal>UTF8</literal>
|
|
</entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>WIN1251</literal></entry>
|
|
<entry><emphasis>WIN1251</emphasis>,
|
|
<literal>ISO_8859_5</literal>,
|
|
<literal>KOI8R</literal>,
|
|
<literal>MULE_INTERNAL</literal>,
|
|
<literal>UTF8</literal>,
|
|
<literal>WIN866</literal>
|
|
</entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>WIN1252</literal></entry>
|
|
<entry><emphasis>WIN1252</emphasis>,
|
|
<literal>UTF8</literal>
|
|
</entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>WIN1253</literal></entry>
|
|
<entry><emphasis>WIN1253</emphasis>,
|
|
<literal>UTF8</literal>
|
|
</entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>WIN1254</literal></entry>
|
|
<entry><emphasis>WIN1254</emphasis>,
|
|
<literal>UTF8</literal>
|
|
</entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>WIN1255</literal></entry>
|
|
<entry><emphasis>WIN1255</emphasis>,
|
|
<literal>UTF8</literal>
|
|
</entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>WIN1256</literal></entry>
|
|
<entry><emphasis>WIN1256</emphasis>,
|
|
<literal>UTF8</literal>
|
|
</entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>WIN1257</literal></entry>
|
|
<entry><emphasis>WIN1257</emphasis>,
|
|
<literal>UTF8</literal>
|
|
</entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>WIN1258</literal></entry>
|
|
<entry><emphasis>WIN1258</emphasis>,
|
|
<literal>UTF8</literal>
|
|
</entry>
|
|
</row>
|
|
</tbody>
|
|
</tgroup>
|
|
</table>
|
|
|
|
<table id="builtin-conversions-table">
|
|
<title>All Built-in Character Set Conversions</title>
|
|
<tgroup cols="3">
|
|
<colspec colname="col1" colwidth="2*"/>
|
|
<colspec colname="col2" colwidth="1*"/>
|
|
<colspec colname="col3" colwidth="1*"/>
|
|
<thead>
|
|
<row>
|
|
<entry>Conversion Name
|
|
<footnote>
|
|
<para>
|
|
The conversion names follow a standard naming scheme: The
|
|
official name of the source encoding with all
|
|
non-alphanumeric characters replaced by underscores, followed
|
|
by <literal>_to_</literal>, followed by the similarly processed
|
|
destination encoding name. Therefore, these names sometimes
|
|
deviate from the customary encoding names shown in
|
|
<xref linkend="charset-table"/>.
|
|
</para>
|
|
</footnote>
|
|
</entry>
|
|
<entry>Source Encoding</entry>
|
|
<entry>Destination Encoding</entry>
|
|
</row>
|
|
</thead>
|
|
|
|
<tbody>
|
|
<row>
|
|
<entry><literal>big5_to_euc_tw</literal></entry>
|
|
<entry><literal>BIG5</literal></entry>
|
|
<entry><literal>EUC_TW</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>big5_to_mic</literal></entry>
|
|
<entry><literal>BIG5</literal></entry>
|
|
<entry><literal>MULE_INTERNAL</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>big5_to_utf8</literal></entry>
|
|
<entry><literal>BIG5</literal></entry>
|
|
<entry><literal>UTF8</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>euc_cn_to_mic</literal></entry>
|
|
<entry><literal>EUC_CN</literal></entry>
|
|
<entry><literal>MULE_INTERNAL</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>euc_cn_to_utf8</literal></entry>
|
|
<entry><literal>EUC_CN</literal></entry>
|
|
<entry><literal>UTF8</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>euc_jp_to_mic</literal></entry>
|
|
<entry><literal>EUC_JP</literal></entry>
|
|
<entry><literal>MULE_INTERNAL</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>euc_jp_to_sjis</literal></entry>
|
|
<entry><literal>EUC_JP</literal></entry>
|
|
<entry><literal>SJIS</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>euc_jp_to_utf8</literal></entry>
|
|
<entry><literal>EUC_JP</literal></entry>
|
|
<entry><literal>UTF8</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>euc_kr_to_mic</literal></entry>
|
|
<entry><literal>EUC_KR</literal></entry>
|
|
<entry><literal>MULE_INTERNAL</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>euc_kr_to_utf8</literal></entry>
|
|
<entry><literal>EUC_KR</literal></entry>
|
|
<entry><literal>UTF8</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>euc_tw_to_big5</literal></entry>
|
|
<entry><literal>EUC_TW</literal></entry>
|
|
<entry><literal>BIG5</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>euc_tw_to_mic</literal></entry>
|
|
<entry><literal>EUC_TW</literal></entry>
|
|
<entry><literal>MULE_INTERNAL</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>euc_tw_to_utf8</literal></entry>
|
|
<entry><literal>EUC_TW</literal></entry>
|
|
<entry><literal>UTF8</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>gb18030_to_utf8</literal></entry>
|
|
<entry><literal>GB18030</literal></entry>
|
|
<entry><literal>UTF8</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>gbk_to_utf8</literal></entry>
|
|
<entry><literal>GBK</literal></entry>
|
|
<entry><literal>UTF8</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>iso_8859_10_to_utf8</literal></entry>
|
|
<entry><literal>LATIN6</literal></entry>
|
|
<entry><literal>UTF8</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>iso_8859_13_to_utf8</literal></entry>
|
|
<entry><literal>LATIN7</literal></entry>
|
|
<entry><literal>UTF8</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>iso_8859_14_to_utf8</literal></entry>
|
|
<entry><literal>LATIN8</literal></entry>
|
|
<entry><literal>UTF8</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>iso_8859_15_to_utf8</literal></entry>
|
|
<entry><literal>LATIN9</literal></entry>
|
|
<entry><literal>UTF8</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>iso_8859_16_to_utf8</literal></entry>
|
|
<entry><literal>LATIN10</literal></entry>
|
|
<entry><literal>UTF8</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>iso_8859_1_to_mic</literal></entry>
|
|
<entry><literal>LATIN1</literal></entry>
|
|
<entry><literal>MULE_INTERNAL</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>iso_8859_1_to_utf8</literal></entry>
|
|
<entry><literal>LATIN1</literal></entry>
|
|
<entry><literal>UTF8</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>iso_8859_2_to_mic</literal></entry>
|
|
<entry><literal>LATIN2</literal></entry>
|
|
<entry><literal>MULE_INTERNAL</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>iso_8859_2_to_utf8</literal></entry>
|
|
<entry><literal>LATIN2</literal></entry>
|
|
<entry><literal>UTF8</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>iso_8859_2_to_windows_1250</literal></entry>
|
|
<entry><literal>LATIN2</literal></entry>
|
|
<entry><literal>WIN1250</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>iso_8859_3_to_mic</literal></entry>
|
|
<entry><literal>LATIN3</literal></entry>
|
|
<entry><literal>MULE_INTERNAL</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>iso_8859_3_to_utf8</literal></entry>
|
|
<entry><literal>LATIN3</literal></entry>
|
|
<entry><literal>UTF8</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>iso_8859_4_to_mic</literal></entry>
|
|
<entry><literal>LATIN4</literal></entry>
|
|
<entry><literal>MULE_INTERNAL</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>iso_8859_4_to_utf8</literal></entry>
|
|
<entry><literal>LATIN4</literal></entry>
|
|
<entry><literal>UTF8</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>iso_8859_5_to_koi8_r</literal></entry>
|
|
<entry><literal>ISO_8859_5</literal></entry>
|
|
<entry><literal>KOI8R</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>iso_8859_5_to_mic</literal></entry>
|
|
<entry><literal>ISO_8859_5</literal></entry>
|
|
<entry><literal>MULE_INTERNAL</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>iso_8859_5_to_utf8</literal></entry>
|
|
<entry><literal>ISO_8859_5</literal></entry>
|
|
<entry><literal>UTF8</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>iso_8859_5_to_windows_1251</literal></entry>
|
|
<entry><literal>ISO_8859_5</literal></entry>
|
|
<entry><literal>WIN1251</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>iso_8859_5_to_windows_866</literal></entry>
|
|
<entry><literal>ISO_8859_5</literal></entry>
|
|
<entry><literal>WIN866</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>iso_8859_6_to_utf8</literal></entry>
|
|
<entry><literal>ISO_8859_6</literal></entry>
|
|
<entry><literal>UTF8</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>iso_8859_7_to_utf8</literal></entry>
|
|
<entry><literal>ISO_8859_7</literal></entry>
|
|
<entry><literal>UTF8</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>iso_8859_8_to_utf8</literal></entry>
|
|
<entry><literal>ISO_8859_8</literal></entry>
|
|
<entry><literal>UTF8</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>iso_8859_9_to_utf8</literal></entry>
|
|
<entry><literal>LATIN5</literal></entry>
|
|
<entry><literal>UTF8</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>johab_to_utf8</literal></entry>
|
|
<entry><literal>JOHAB</literal></entry>
|
|
<entry><literal>UTF8</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>koi8_r_to_iso_8859_5</literal></entry>
|
|
<entry><literal>KOI8R</literal></entry>
|
|
<entry><literal>ISO_8859_5</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>koi8_r_to_mic</literal></entry>
|
|
<entry><literal>KOI8R</literal></entry>
|
|
<entry><literal>MULE_INTERNAL</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>koi8_r_to_utf8</literal></entry>
|
|
<entry><literal>KOI8R</literal></entry>
|
|
<entry><literal>UTF8</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>koi8_r_to_windows_1251</literal></entry>
|
|
<entry><literal>KOI8R</literal></entry>
|
|
<entry><literal>WIN1251</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>koi8_r_to_windows_866</literal></entry>
|
|
<entry><literal>KOI8R</literal></entry>
|
|
<entry><literal>WIN866</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>koi8_u_to_utf8</literal></entry>
|
|
<entry><literal>KOI8U</literal></entry>
|
|
<entry><literal>UTF8</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>mic_to_big5</literal></entry>
|
|
<entry><literal>MULE_INTERNAL</literal></entry>
|
|
<entry><literal>BIG5</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>mic_to_euc_cn</literal></entry>
|
|
<entry><literal>MULE_INTERNAL</literal></entry>
|
|
<entry><literal>EUC_CN</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>mic_to_euc_jp</literal></entry>
|
|
<entry><literal>MULE_INTERNAL</literal></entry>
|
|
<entry><literal>EUC_JP</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>mic_to_euc_kr</literal></entry>
|
|
<entry><literal>MULE_INTERNAL</literal></entry>
|
|
<entry><literal>EUC_KR</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>mic_to_euc_tw</literal></entry>
|
|
<entry><literal>MULE_INTERNAL</literal></entry>
|
|
<entry><literal>EUC_TW</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>mic_to_iso_8859_1</literal></entry>
|
|
<entry><literal>MULE_INTERNAL</literal></entry>
|
|
<entry><literal>LATIN1</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>mic_to_iso_8859_2</literal></entry>
|
|
<entry><literal>MULE_INTERNAL</literal></entry>
|
|
<entry><literal>LATIN2</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>mic_to_iso_8859_3</literal></entry>
|
|
<entry><literal>MULE_INTERNAL</literal></entry>
|
|
<entry><literal>LATIN3</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>mic_to_iso_8859_4</literal></entry>
|
|
<entry><literal>MULE_INTERNAL</literal></entry>
|
|
<entry><literal>LATIN4</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>mic_to_iso_8859_5</literal></entry>
|
|
<entry><literal>MULE_INTERNAL</literal></entry>
|
|
<entry><literal>ISO_8859_5</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>mic_to_koi8_r</literal></entry>
|
|
<entry><literal>MULE_INTERNAL</literal></entry>
|
|
<entry><literal>KOI8R</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>mic_to_sjis</literal></entry>
|
|
<entry><literal>MULE_INTERNAL</literal></entry>
|
|
<entry><literal>SJIS</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>mic_to_windows_1250</literal></entry>
|
|
<entry><literal>MULE_INTERNAL</literal></entry>
|
|
<entry><literal>WIN1250</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>mic_to_windows_1251</literal></entry>
|
|
<entry><literal>MULE_INTERNAL</literal></entry>
|
|
<entry><literal>WIN1251</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>mic_to_windows_866</literal></entry>
|
|
<entry><literal>MULE_INTERNAL</literal></entry>
|
|
<entry><literal>WIN866</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>sjis_to_euc_jp</literal></entry>
|
|
<entry><literal>SJIS</literal></entry>
|
|
<entry><literal>EUC_JP</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>sjis_to_mic</literal></entry>
|
|
<entry><literal>SJIS</literal></entry>
|
|
<entry><literal>MULE_INTERNAL</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>sjis_to_utf8</literal></entry>
|
|
<entry><literal>SJIS</literal></entry>
|
|
<entry><literal>UTF8</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>windows_1258_to_utf8</literal></entry>
|
|
<entry><literal>WIN1258</literal></entry>
|
|
<entry><literal>UTF8</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>uhc_to_utf8</literal></entry>
|
|
<entry><literal>UHC</literal></entry>
|
|
<entry><literal>UTF8</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>utf8_to_big5</literal></entry>
|
|
<entry><literal>UTF8</literal></entry>
|
|
<entry><literal>BIG5</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>utf8_to_euc_cn</literal></entry>
|
|
<entry><literal>UTF8</literal></entry>
|
|
<entry><literal>EUC_CN</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>utf8_to_euc_jp</literal></entry>
|
|
<entry><literal>UTF8</literal></entry>
|
|
<entry><literal>EUC_JP</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>utf8_to_euc_kr</literal></entry>
|
|
<entry><literal>UTF8</literal></entry>
|
|
<entry><literal>EUC_KR</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>utf8_to_euc_tw</literal></entry>
|
|
<entry><literal>UTF8</literal></entry>
|
|
<entry><literal>EUC_TW</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>utf8_to_gb18030</literal></entry>
|
|
<entry><literal>UTF8</literal></entry>
|
|
<entry><literal>GB18030</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>utf8_to_gbk</literal></entry>
|
|
<entry><literal>UTF8</literal></entry>
|
|
<entry><literal>GBK</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>utf8_to_iso_8859_1</literal></entry>
|
|
<entry><literal>UTF8</literal></entry>
|
|
<entry><literal>LATIN1</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>utf8_to_iso_8859_10</literal></entry>
|
|
<entry><literal>UTF8</literal></entry>
|
|
<entry><literal>LATIN6</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>utf8_to_iso_8859_13</literal></entry>
|
|
<entry><literal>UTF8</literal></entry>
|
|
<entry><literal>LATIN7</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>utf8_to_iso_8859_14</literal></entry>
|
|
<entry><literal>UTF8</literal></entry>
|
|
<entry><literal>LATIN8</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>utf8_to_iso_8859_15</literal></entry>
|
|
<entry><literal>UTF8</literal></entry>
|
|
<entry><literal>LATIN9</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>utf8_to_iso_8859_16</literal></entry>
|
|
<entry><literal>UTF8</literal></entry>
|
|
<entry><literal>LATIN10</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>utf8_to_iso_8859_2</literal></entry>
|
|
<entry><literal>UTF8</literal></entry>
|
|
<entry><literal>LATIN2</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>utf8_to_iso_8859_3</literal></entry>
|
|
<entry><literal>UTF8</literal></entry>
|
|
<entry><literal>LATIN3</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>utf8_to_iso_8859_4</literal></entry>
|
|
<entry><literal>UTF8</literal></entry>
|
|
<entry><literal>LATIN4</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>utf8_to_iso_8859_5</literal></entry>
|
|
<entry><literal>UTF8</literal></entry>
|
|
<entry><literal>ISO_8859_5</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>utf8_to_iso_8859_6</literal></entry>
|
|
<entry><literal>UTF8</literal></entry>
|
|
<entry><literal>ISO_8859_6</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>utf8_to_iso_8859_7</literal></entry>
|
|
<entry><literal>UTF8</literal></entry>
|
|
<entry><literal>ISO_8859_7</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>utf8_to_iso_8859_8</literal></entry>
|
|
<entry><literal>UTF8</literal></entry>
|
|
<entry><literal>ISO_8859_8</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>utf8_to_iso_8859_9</literal></entry>
|
|
<entry><literal>UTF8</literal></entry>
|
|
<entry><literal>LATIN5</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>utf8_to_johab</literal></entry>
|
|
<entry><literal>UTF8</literal></entry>
|
|
<entry><literal>JOHAB</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>utf8_to_koi8_r</literal></entry>
|
|
<entry><literal>UTF8</literal></entry>
|
|
<entry><literal>KOI8R</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>utf8_to_koi8_u</literal></entry>
|
|
<entry><literal>UTF8</literal></entry>
|
|
<entry><literal>KOI8U</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>utf8_to_sjis</literal></entry>
|
|
<entry><literal>UTF8</literal></entry>
|
|
<entry><literal>SJIS</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>utf8_to_windows_1258</literal></entry>
|
|
<entry><literal>UTF8</literal></entry>
|
|
<entry><literal>WIN1258</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>utf8_to_uhc</literal></entry>
|
|
<entry><literal>UTF8</literal></entry>
|
|
<entry><literal>UHC</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>utf8_to_windows_1250</literal></entry>
|
|
<entry><literal>UTF8</literal></entry>
|
|
<entry><literal>WIN1250</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>utf8_to_windows_1251</literal></entry>
|
|
<entry><literal>UTF8</literal></entry>
|
|
<entry><literal>WIN1251</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>utf8_to_windows_1252</literal></entry>
|
|
<entry><literal>UTF8</literal></entry>
|
|
<entry><literal>WIN1252</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>utf8_to_windows_1253</literal></entry>
|
|
<entry><literal>UTF8</literal></entry>
|
|
<entry><literal>WIN1253</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>utf8_to_windows_1254</literal></entry>
|
|
<entry><literal>UTF8</literal></entry>
|
|
<entry><literal>WIN1254</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>utf8_to_windows_1255</literal></entry>
|
|
<entry><literal>UTF8</literal></entry>
|
|
<entry><literal>WIN1255</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>utf8_to_windows_1256</literal></entry>
|
|
<entry><literal>UTF8</literal></entry>
|
|
<entry><literal>WIN1256</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>utf8_to_windows_1257</literal></entry>
|
|
<entry><literal>UTF8</literal></entry>
|
|
<entry><literal>WIN1257</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>utf8_to_windows_866</literal></entry>
|
|
<entry><literal>UTF8</literal></entry>
|
|
<entry><literal>WIN866</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>utf8_to_windows_874</literal></entry>
|
|
<entry><literal>UTF8</literal></entry>
|
|
<entry><literal>WIN874</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>windows_1250_to_iso_8859_2</literal></entry>
|
|
<entry><literal>WIN1250</literal></entry>
|
|
<entry><literal>LATIN2</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>windows_1250_to_mic</literal></entry>
|
|
<entry><literal>WIN1250</literal></entry>
|
|
<entry><literal>MULE_INTERNAL</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>windows_1250_to_utf8</literal></entry>
|
|
<entry><literal>WIN1250</literal></entry>
|
|
<entry><literal>UTF8</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>windows_1251_to_iso_8859_5</literal></entry>
|
|
<entry><literal>WIN1251</literal></entry>
|
|
<entry><literal>ISO_8859_5</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>windows_1251_to_koi8_r</literal></entry>
|
|
<entry><literal>WIN1251</literal></entry>
|
|
<entry><literal>KOI8R</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>windows_1251_to_mic</literal></entry>
|
|
<entry><literal>WIN1251</literal></entry>
|
|
<entry><literal>MULE_INTERNAL</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>windows_1251_to_utf8</literal></entry>
|
|
<entry><literal>WIN1251</literal></entry>
|
|
<entry><literal>UTF8</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>windows_1251_to_windows_866</literal></entry>
|
|
<entry><literal>WIN1251</literal></entry>
|
|
<entry><literal>WIN866</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>windows_1252_to_utf8</literal></entry>
|
|
<entry><literal>WIN1252</literal></entry>
|
|
<entry><literal>UTF8</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>windows_1256_to_utf8</literal></entry>
|
|
<entry><literal>WIN1256</literal></entry>
|
|
<entry><literal>UTF8</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>windows_866_to_iso_8859_5</literal></entry>
|
|
<entry><literal>WIN866</literal></entry>
|
|
<entry><literal>ISO_8859_5</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>windows_866_to_koi8_r</literal></entry>
|
|
<entry><literal>WIN866</literal></entry>
|
|
<entry><literal>KOI8R</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>windows_866_to_mic</literal></entry>
|
|
<entry><literal>WIN866</literal></entry>
|
|
<entry><literal>MULE_INTERNAL</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>windows_866_to_utf8</literal></entry>
|
|
<entry><literal>WIN866</literal></entry>
|
|
<entry><literal>UTF8</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>windows_866_to_windows_1251</literal></entry>
|
|
<entry><literal>WIN866</literal></entry>
|
|
<entry><literal>WIN</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>windows_874_to_utf8</literal></entry>
|
|
<entry><literal>WIN874</literal></entry>
|
|
<entry><literal>UTF8</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>euc_jis_2004_to_utf8</literal></entry>
|
|
<entry><literal>EUC_JIS_2004</literal></entry>
|
|
<entry><literal>UTF8</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>utf8_to_euc_jis_2004</literal></entry>
|
|
<entry><literal>UTF8</literal></entry>
|
|
<entry><literal>EUC_JIS_2004</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>shift_jis_2004_to_utf8</literal></entry>
|
|
<entry><literal>SHIFT_JIS_2004</literal></entry>
|
|
<entry><literal>UTF8</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>utf8_to_shift_jis_2004</literal></entry>
|
|
<entry><literal>UTF8</literal></entry>
|
|
<entry><literal>SHIFT_JIS_2004</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>euc_jis_2004_to_shift_jis_2004</literal></entry>
|
|
<entry><literal>EUC_JIS_2004</literal></entry>
|
|
<entry><literal>SHIFT_JIS_2004</literal></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>shift_jis_2004_to_euc_jis_2004</literal></entry>
|
|
<entry><literal>SHIFT_JIS_2004</literal></entry>
|
|
<entry><literal>EUC_JIS_2004</literal></entry>
|
|
</row>
|
|
</tbody>
|
|
</tgroup>
|
|
</table>
|
|
</sect2>
|
|
|
|
<sect2 id="multibyte-further-reading">
|
|
<title>Further Reading</title>
|
|
|
|
<para>
|
|
These are good sources to start learning about various kinds of encoding
|
|
systems.
|
|
|
|
<variablelist>
|
|
<varlistentry>
|
|
<term><citetitle>CJKV Information Processing: Chinese, Japanese, Korean & Vietnamese Computing</citetitle></term>
|
|
|
|
<listitem>
|
|
<para>
|
|
Contains detailed explanations of <literal>EUC_JP</literal>,
|
|
<literal>EUC_CN</literal>, <literal>EUC_KR</literal>,
|
|
<literal>EUC_TW</literal>.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><ulink url="https://www.unicode.org/"></ulink></term>
|
|
|
|
<listitem>
|
|
<para>
|
|
The web site of the Unicode Consortium.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><ulink url="https://tools.ietf.org/html/rfc3629">RFC 3629</ulink></term>
|
|
|
|
<listitem>
|
|
<para>
|
|
<acronym>UTF</acronym>-8 (8-bit UCS/Unicode Transformation
|
|
Format) is defined here.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
</variablelist>
|
|
</para>
|
|
</sect2>
|
|
|
|
</sect1>
|
|
|
|
</chapter>
|