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Convert more charset/locale documentation to DocBook

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Peter Eisentraut
2000-09-30 16:58:20 +00:00
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4
doc/src/sgml/admin.sgml
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<!--
$Header: /cvsroot/pgsql/doc/src/sgml/Attic/admin.sgml,v 1.26 2000/09/12 05:37:07 thomas Exp $
$Header: /cvsroot/pgsql/doc/src/sgml/Attic/admin.sgml,v 1.27 2000/09/30 16:58:20 petere Exp $
Postgres Administrator's Guide.
Derived from postgres.sgml.
@ -98,9 +98,9 @@ Derived from postgres.sgml.
&intro-ag;
&installation;
&installw;
&charset;
&runtime;
&client-auth;
&charset;
&manage-ag;
&user-manag;
&backup;

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doc/src/sgml/charset.sgml
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@ -1,44 +1,235 @@
<chapter id="charset">
<title>Character Sets</title>
<!-- $Header: /cvsroot/pgsql/doc/src/sgml/charset.sgml,v 2.3 2000/09/30 16:58:20 petere Exp $ -->
<abstract>
<para>
Describes the available language and character set support in
<productname>Postgres</productname>.
</para>
</abstract>
<chapter id="charset">
<title>Localization</>
<abstract>
<para>
Describes the available localization features from the point of
view of the administrator.
</para>
</abstract>
<para>
<productname>Postgres</productname> supports non-ASCII character
sets with two approaches:
<productname>Postgres</productname> supports localization with
three approaches:
<itemizedlist>
<listitem>
<para>
Using locale features in underlying
system libraries. This allows single-byte character sets to be
configured with a locale-specific collation order, provided that
the underlying system supports the required locale. This
technique supports only one character set per server, and can
not support multi-byte character sets.
Using the locale features of the operating system to provide
locale-specific collation order, number formatting, and other
aspects.
</para>
</listitem>
<listitem>
<para>
Using explicit multiple-byte character sets defined in the
<productname>Postgres</productname> server. These character sets
are also known to some client libraries. The number of character
sets is fixed at the time the server is compiled, and internal
operations such as string comparisons require expansion of each
character into a 32-bit word.
<productname>Postgres</productname> server to support languages
that require more characters than will fit into a single byte,
and to provide character set recoding between client and server.
The number of supported character sets is fixed at the time the
server is compiled, and internal operations such as string
comparisons require expansion of each character into a 32-bit
word.
</para>
</listitem>
<listitem>
<para>
Single byte character recoding provides a more light-weight
solution for users of multiple, yet single-byte character sets.
</para>
</listitem>
</itemizedlist>
</para>
<sect1 id="locale">
<title>Locale Support</title>
<para>
<firstterm>Locale</> support refers to an application respecting
cultural preferences regarding alphabets, sorting, number
formatting, etc. <productname>PostgreSQL</> uses the standard ISO
C and POSIX-like locale facilities provided by the server operating
system. For additional information refer the documentation of your
system.
</para>
<sect2>
<title>Overview</>
<para>
Locale support is not build into <productname>PostgreSQL</> by
default; to enable it, supply the <option>--enable-locale</> option
to the <filename>configure</> script:
<informalexample>
<screen>
<prompt>$ </><userinput>./configure --enable-locale</>
</screen>
</informalexample>
Locale support only affects the server; all clients are compatible
with servers with or without locale support.
</para>
<para>
The information about which particular cultural rules to use is
determined by standard environment variables. If you are getting
localized behavior from other programs you probably have them set
up already. The simplest way to set the localization information
is the <envar>LANG</> variable, for example:
<programlisting>
export LANG=sv_SE
</programlisting>
This sets the locale to Swedish (<literal>sv</>) as spoken in
Sweden (<literal>SE</>). Other possibilities might be
<literal>en_US</> (U.S. English) and <literal>fr_CA</> (Canada,
French). If more than one character set can be useful for a locale
then the specifications look like this:
<literal>cs_CZ.ISO8859-2</>. What locales are available under what
names on your system depends on what was provided by the operating
system vendor and what was installed.
</para>
<para>
Occasionally it is useful to mix rules from several locales, e.g.,
use U.S. rules but Spanish messages. To do that a set of
environment variables exist that override the default of
<envar>LANG</> for a particular category:
<informaltable>
<tgroup cols="2">
<tbody>
<row>
<entry>LC_COLLATE</>
<entry>String sort order</>
</row>
<row>
<entry>LC_CTYPE</>
<entry>Character classification (What is a letter? What is the upper-case equivalent of this letter?)</>
</row>
<row>
<entry>LC_MESSAGES</>
<entry>Language of messages</>
</row>
<row>
<entry>LC_MONETARY</>
<entry>Formatting of currency amounts</>
</row>
<row>
<entry>LC_NUMERIC</>
<entry>Formatting of numbers</>
</row>
<row>
<entry>LC_TIME</>
<entry>Formatting of dates and times</>
</row>
</tbody>
</tgroup>
</informaltable>
<envar>LC_MESSAGES</> only affects the messages that come from the
operating system, not <productname>PostgreSQL</>.
</para>
<para>
If you want the system to behave as if it had no locale support,
use the special locale <literal>C</> or <literal>POSIX</>, or
simply unset all locale related variables.
</para>
<para>
Once you have chosen a set of localization rules this way you must
keep them fixed for any particular database cluster. That means
that the locales that were active when you ran <filename>initdb</>
must be kept the same when you start the postmaster. Otherwise,
the changed sort order can corrupt indexes or make your data
disappear mysteriously. It is currently not possible to change the
locales after database initialization or to use more than one set
of locales for a given database cluster.
</para>
</sect2>
<sect2>
<title>Benefits</>
<para>
Locale support influences in particular the following features:
<itemizedlist>
<listitem>
<para>
Sort order in <command>ORDER BY</> queries.
</para>
</listitem>
<listitem>
<para>
The <function>to_char</> family of functions
</para>
</listitem>
<listitem>
<para>
The <literal>LIKE</> and <literal>~</> operators for pattern
matching
</para>
</listitem>
</itemizedlist>
</para>
<para>
The only severe drawback of using the locale support in
<productname>PostgreSQL</> is its speed. So use locale only if you
actually need it.
</para>
</sect2>
<sect2>
<title>Problems</>
<para>
If locale support doesn't work in spite of the explanation above,
check that the locale support in your operating system is okay.
To check whether a given locale is installed and functional you
can use <application>Perl</>, for example. Perl has also support
for locales and if a locale is broken <command>perl -v</> will
complain something like this:
<screen>
<prompt>$</> <userinput>export LC_CTYPE='not_exist'</>
<prompt>$</> <userinput>perl -v</>
<computeroutput>
perl: warning: Setting locale failed.
perl: warning: Please check that your locale settings:
LC_ALL = (unset),
LC_CTYPE = "not_exist",
LANG = (unset)
are supported and installed on your system.
perl: warning: Falling back to the standard locale ("C").
</computeroutput>
</screen>
</para>
<para>
Check that your locale files are in the right location. Possible
locations include: <filename>/usr/lib/locale</filename> (Linux,
Solaris), <filename>/usr/share/locale</filename> (Linux),
<filename>/usr/lib/nls/loc</filename> (DUX 4.0). Check the locale
man page of your system if you are not sure.
</para>
<para>
The directory <filename>src/test/locale</> contains a test suite
for <productname>PostgreSQL</>'s locale support.
</para>
</sect2>
</sect1>
<sect1 id="multibyte">
<title>Multi-byte Support</title>
<title>Multibyte Support</title>
<note>
<title>Author</title>
@ -53,7 +244,7 @@
</note>
<para>
Multi-byte (<acronym>MB</acronym>) support is intended to allow
Multibyte (<acronym>MB</acronym>) support is intended to allow
<productname>Postgres</productname> to handle
multiple-byte character sets such as EUC (Extended Unix Code), Unicode and
Mule internal code. With <acronym>MB</acronym> enabled you can use multi-byte
@ -680,7 +871,78 @@ SET CLIENT_ENCODING = 'WIN1250';
</procedure>
</sect2>
</sect1>
</chapter>
<sect1 id="recode">
<title>Single-byte character set recoding</>
<!-- formerly in README.charsets, by Josef Balatka, <balatka@email.cz> -->
<para>
You can set up this feature with the <option>--enable-recode</> option
to <filename>configure</>. This option was formerly described as
<quote>Cyrillic recode support</> which doesn't express all its
power. It can be used for <emphasis>any</> single-byte character
set recoding.
</para>
<para>
This method uses a file <filename>charset.conf</> file located in
the database directory (<envar>PGDATA</>). It's a typical
configuration text file where spaces and newlines separate items
and records and # specifies comments. Three keywords with the
following syntax are recognized here:
<synopsis>
BaseCharset <replaceable>server_charset</>
RecodeTable <replaceable>from_charset</> <replaceable>to_charset</> <replaceable>file_name</>
HostCharset <replaceable>host_spec</> <replaceable>host_charset</>
</synopsis>
</para>
<para>
<token>BaseCharset</> defines the encoding of the database server.
All character set names are only used for mapping inside of
<filename>charset.conf</> so you can freely use typing-friendly
names.
</para>
<para>
<token>RecodeTable</> records specify translation tables between
server and client. The file name is relative to the
<envar>PGDATA</> directory. The table file format is very
simple. There are no keywords and characters are represented by a
pair of decimal or hexadecimal (0x prefixed) values on single
lines:
<synopsis>
<replaceable>char_value</> <replaceable>translated_char_value</>
</synopsis>
</para>
<para>
<token>HostCharset</> records define the client character set by IP
address. You can use a single IP address, an IP mask range starting
from the given address or an IP interval (e.g., 127.0.0.1,
192.168.1.100/24, 192.168.1.20-192.168.1.40).
</para>
<para>
The <filename>charset.conf</> file is always processed up to the
end, so you can easily specify exceptions from the previous
rules. In the src/data you will find charset.conf example and a few
recoding tables.
</para>
<para>
As this solution is based on the client's IP address and character
set mapping there are obviously some restrictions as well. You
cannot use different encodings on the same host at the same
time. It is also inconvenient when you boot your client hosts into
more operating systems. Nevertheless, when these restrictions are
not limiting and you do not need multi-byte characters than it is a
simple and effective solution.
</para>
</sect1>
</chapter>
<!-- Keep this comment at the end of the file
Local variables:

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doc/src/sgml/installation.sgml
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@ -1,4 +1,4 @@
<!-- $Header: /cvsroot/pgsql/doc/src/sgml/installation.sgml,v 1.21 2000/09/29 20:21:34 petere Exp $ -->
<!-- $Header: /cvsroot/pgsql/doc/src/sgml/installation.sgml,v 1.22 2000/09/30 16:58:20 petere Exp $ -->
<chapter id="installation">
<title><![%flattext-install-include[<productname>PostgreSQL</> ]]>Installation Instructions</title>
@ -447,8 +447,9 @@ su - postgres
<term>--enable-recode</term>
<listitem>
<para>
Enables character set recode support. See
<filename>doc/README.Charsets</> for details on this feature.
Enables single-byte character set recode support. See
<![%flattext-install-include[the <citetitle>Administrator's Guide</citetitle>]]>
<![%flattext-install-ignore[<xref linkend="recode">]]> about this feature.
</para>
</listitem>
</varlistentry>
@ -459,7 +460,10 @@ su - postgres
<para>
Allows the use of multibyte character encodings. This is
primarily for languages like Japanese, Korean, and Chinese.
Read <filename>doc/README.mb</> for details.
Read
<![%flattext-install-include[the <citetitle>Administrator's Guide</citetitle>]]>
<![%flattext-install-ignore[<xref linkend="multibyte">]]>
for details.
</para>
</listitem>
</varlistentry>

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doc/src/sgml/postgres.sgml
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<!--
$Header: /cvsroot/pgsql/doc/src/sgml/postgres.sgml,v 1.41 2000/09/12 05:37:09 thomas Exp $
$Header: /cvsroot/pgsql/doc/src/sgml/postgres.sgml,v 1.42 2000/09/30 16:58:20 petere Exp $
-->
<!doctype set PUBLIC "-//OASIS//DTD DocBook V3.1//EN" [
@ -173,9 +173,9 @@ $Header: /cvsroot/pgsql/doc/src/sgml/postgres.sgml,v 1.41 2000/09/12 05:37:09 th
-->
&installation;
&installw;
&charset;
&runtime;
&client-auth;
&charset;
&manage-ag;
&user-manag;
&backup;

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doc/src/sgml/runtime.sgml
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<!--
$Header: /cvsroot/pgsql/doc/src/sgml/runtime.sgml,v 1.25 2000/09/29 20:21:34 petere Exp $
$Header: /cvsroot/pgsql/doc/src/sgml/runtime.sgml,v 1.26 2000/09/30 16:58:20 petere Exp $
-->
<Chapter Id="runtime">
@ -1553,126 +1553,6 @@ set semsys:seminfo_semmsl=32
</sect1>
<sect1 id="locale">
<title>Locale Support</title>
<note>
<title>Acknowledgement</title>
<para>
Written by Oleg Bartunov. See <ulink
url="http://www.sai.msu.su/~megera/postgres/">Oleg's web
page</ulink> for additional information on locale and Russian
language support.
</para>
</note>
<para>
While doing a project for a company in Moscow, Russia, I
encountered the problem that <productname>Postgres</> had no
support of national alphabets. After looking for possible
workarounds I decided to develop support of locale myself. I'm not
a C programmer but already had some experience with locale
programming when I work with <productname>Perl</> (debugging) and
<productname>Glimpse</>. After several days of digging through the
<productname>Postgres</> source tree I made very minor corections
to <filename>src/backend/utils/adt/varlena.c</> and
<filename>src/backend/main/main.c</> and got what I needed! I did
support only for <envar>LC_CTYPE</envar> and
<envar>LC_COLLATE</envar>, but later <envar>LC_MONETARY</envar> was
added by others. I got many messages from people about this patch
so I decided to send it to developers and (to my surprise) it was
incorporated into the <productname>Postgres</> distribution.
</para>
<para>
People often complain that locale doesn't work for them. There are
several common mistakes:
<itemizedlist>
<listitem>
<para>
Didn't properly configure <productname>Postgres</> before
compilation. You must run <filename>configure</> with the
<option>--enable-locale</> option to enable locale support.
</para>
</listitem>
<listitem>
<para>
Didn't setup environment correctly when starting postmaster. You
must define environment variables <envar>LC_CTYPE</envar> and
<envar>LC_COLLATE</envar> before running postmaster because
backend gets information about locale from environment. I use
following shell script:
<programlisting>
#!/bin/sh
export LC_CTYPE=koi8-r
export LC_COLLATE=koi8-r
postmaster -B 1024 -S -D/usr/local/pgsql/data/ -o '-Fe'
</programlisting>
</para>
</listitem>
<listitem>
<para>
Broken locale support in the operating system (for example,
locale support in libc under Linux several times has changed and
this caused a lot of problems). Perl has also support of locale
and if locale is broken <command>perl -v</> will complain
something like:
<screen>
<prompt>$</> <userinput>export LC_CTYPE='not_exist'</>
<prompt>$</> <userinput>perl -v</>
<computeroutput>
perl: warning: Setting locale failed.
perl: warning: Please check that your locale settings:
LC_ALL = (unset),
LC_CTYPE = "not_exist",
LANG = (unset)
are supported and installed on your system.
perl: warning: Falling back to the standard locale ("C").
</computeroutput>
</screen>
</para>
</listitem>
<listitem>
<para>
Wrong location of locale files. Possible locations include:
<filename>/usr/lib/locale</filename> (Linux, Solaris),
<filename>/usr/share/locale</filename> (Linux),
<filename>/usr/lib/nls/loc</filename> (DUX 4.0).
Check <command>man locale</command> to find the correct
location. Under Linux I made a symbolic link between
<filename>/usr/lib/locale</filename> and
<filename>/usr/share/locale</filename> to be sure that the next
libc will not break my locale.
</para>
</listitem>
</itemizedlist>
</para>
<formalpara>
<title>What are the Benefits?</title>
<para>
You can use ~* and order by operators for strings contain
characters from national alphabets. Non-english users definitely
need that.
</para>
</formalpara>
<formalpara>
<title>What are the Drawbacks?</title>
<para>
There is one evident drawback of using locale - its speed! So, use
locale only if you really need it.
</para>
</formalpara>
</sect1>
<sect1 id="postmaster-shutdown">
<title>Shutting down the server</title>