<!-- $Header: /cvsroot/pgsql/doc/src/sgml/backup.sgml,v 2.12 2001/08/25 18:52:41 tgl Exp $ -->

<!-- $Header: /cvsroot/pgsql/doc/src/sgml/backup.sgml,v 2.13 2001/09/09 23:52:12 petere Exp $ -->

<chapter id="backup">

<title>Backup and Restore</title>

<formalpara>

<title>Use the custom dump format (V7.1).</title>

<para>

If PostgreSQL was built on a system with the zlib compression library

If PostgreSQL was built on a system with the<application>zlib</> compression library

installed, the custom dump format will compress data as it writes it

to the output file. For large databases, this will produce similar dump

sizes to using gzip, but has the added advantage that the tables can be

sizes to using<command>gzip</command>, but has the added advantage that the tables can be

restored selectively. The following command dumps a database using the

custom dump format:

<!-- $Header: /cvsroot/pgsql/doc/src/sgml/charset.sgml,v 2.8 2001/05/03 21:38:44 momjian Exp $ -->

<!-- $Header: /cvsroot/pgsql/doc/src/sgml/charset.sgml,v 2.9 2001/09/09 23:52:12 petere Exp $ -->

<chapter id="charset">

<title>Localization</>

<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

C and<acronym>POSIX</acronym>-like locale facilities provided by the server operating

system. For additional information refer to the documentation of your

system.

</para>

<tgroup cols="2">

<tbody>

<row>

<entry>LC_COLLATE</>

<entry><envar>LC_COLLATE</></>

<entry>String sort order</>

</row>

<row>

<entry>LC_CTYPE</>

<entry><envar>LC_CTYPE</></>

<entry>Character classification (What is a letter? The upper-case equivalent?)</>

</row>

<row>

<entry>LC_MESSAGES</>

<entry><envar>LC_MESSAGES</></>

<entry>Language of messages</>

</row>

<row>

<entry>LC_MONETARY</>

<entry><envar>LC_MONETARY</></>

<entry>Formatting of currency amounts</>

</row>

<row>

<entry>LC_NUMERIC</>

<entry><envar>LC_NUMERIC</></>

<entry>Formatting of numbers</>

</row>

<row>

<entry>LC_TIME</>

<entry><envar>LC_TIME</></>

<entry>Formatting of dates and times</>

</row>

</tbody>

<para>

If locale support doesn't work in spite of the explanation above,

check that the locale support in your operating system isokay.

check that the locale support in your operating system iscorrectly configured.

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

<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

locations include: <filename>/usr/lib/locale</filename> (<systemitem class="osname">Linux</>,

<systemitem class="osname">Solaris</>), <filename>/usr/share/locale</filename> (<systemitem class="osname">Linux</>),

<filename>/usr/lib/nls/loc</filename> (<systemitem class="osname">DUX 4.0</>). Check the locale

man page of your system if you are not sure.

</para>

<para>

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 usemulti-byte

multiple-byte character sets such as<acronym>EUC</> (Extended Unix Code), Unicode and

Mule internal code. With <acronym>MB</acronym> enabled you can usemultibyte

character sets in regular expressions (regexp), LIKE, and some

other functions. The default

encoding system is selected while initializing your

</thead>

<tbody>

<row>

<entry>SQL_ASCII</entry>

<entry>ASCII</entry>

<entry><literal>SQL_ASCII</literal></entry>

<entry><acronym>ASCII</acronym></entry>

</row>

<row>

<entry>EUC_JP</entry>

<entry>Japanese EUC</entry>

<entry><literal>EUC_JP</literal></entry>

<entry>Japanese<acronym>EUC</></entry>

</row>

<row>

<entry>EUC_CN</entry>

<entry>Chinese EUC</entry>

<entry><literal>EUC_CN</literal></entry>

<entry>Chinese<acronym>EUC</></entry>

</row>

<row>

<entry>EUC_KR</entry>

<entry>Korean EUC</entry>

<entry><literal>EUC_KR</literal></entry>

<entry>Korean<acronym>EUC</></entry>

</row>

<row>

<entry>EUC_TW</entry>

<entry>Taiwan EUC</entry>

<entry><literal>EUC_TW</literal></entry>

<entry>Taiwan<acronym>EUC</acronym></entry>

</row>

<row>

<entry>UNICODE</entry>

<entry>Unicode(UTF-8)</entry>

<entry><literal>UNICODE</literal></entry>

<entry>Unicode (<acronym>UTF</acronym>-8)</entry>

</row>

<row>

<entry>MULE_INTERNAL</entry>

<entry><literal>MULE_INTERNAL</literal></entry>

<entry>Mule internal</entry>

</row>

<row>

<entry>LATIN1</entry>

<entry><literal>LATIN1</literal></entry>

<entry>ISO 8859-1 English and some European languages</entry>

</row>

<row>

<entry>LATIN2</entry>

<entry><literal>LATIN2</literal></entry>

<entry>ISO 8859-2 English and some European languages</entry>

</row>

<row>

<entry>LATIN3</entry>

<entry><literal>LATIN3</literal></entry>

<entry>ISO 8859-3 English and some European languages</entry>

</row>

<row>

<entry>LATIN4</entry>

<entry><literal>LATIN4</literal></entry>

<entry>ISO 8859-4 English and some European languages</entry>

</row>

<row>

<entry>LATIN5</entry>

<entry><literal>LATIN5</literal></entry>

<entry>ISO 8859-5 English and some European languages</entry>

</row>

<row>

<entry>KOI8</entry>

<entry>KOI8-R(U)</entry>

<entry><literal>KOI8</literal></entry>

<entry><acronym>KOI</acronym>8-R(U)</entry>

</row>

<row>

<entry>WIN</entry>

<entry><literal>WIN</literal></entry>

<entry>Windows CP1251</entry>

</row>

<row>

<entry>ALT</entry>

<entry><literal>ALT</literal></entry>

<entry>Windows CP866</entry>

</row>

</tbody>

% initdb -E EUC_JP

</programlisting>

sets the default encoding to EUC_JP (Extended Unix Code for Japanese).

sets the default encoding to<literal>EUC_JP</literal> (Extended Unix Code for Japanese).

Note that you can use "--encoding" instead of "-E" if you prefer

to type longer option strings.

If no -E or --encoding option is given, the encoding

% createdb -E EUC_KR korean

</programlisting>

will create a database named"korean" with EUC_KR encoding.

will create a database named<database>korean</database> with<literal>EUC_KR</literal> encoding.

Another way to accomplish this is to use a SQL command:

<programlisting>

The encoding for a database is represented as an

<firstterm>encoding column</firstterm> in the

<literal>pg_database</literal> system catalog.

You can see that by using-l or\l of psql

You can see that by using<option>-l</option> or<command>\l</command> of<command>psql</command>

command.

<programlisting>

</thead>

<tbody>

<row>

<entry>EUC_JP</entry>

<entry>EUC_JP,SJIS</entry>

<entry><literal>EUC_JP</literal></entry>

<entry><literal>EUC_JP</literal>, <literal>SJIS</literal></entry>

</row>

<row>

<entry>EUC_TW</entry>

<entry>EUC_TW,BIG5</entry>

<entry><literal>EUC_TW</literal></entry>

<entry><literal>EUC_TW</literal>, <literal>BIG5</literal></entry>

</row>

<row>

<entry>LATIN2</entry>

<entry>LATIN2,WIN1250</entry>

<entry><literal>LATIN2</literal></entry>

<entry><literal>LATIN2</literal>, <literal>WIN1250</literal></entry>

</row>

<row>

<entry>LATIN5</entry>

<entry>LATIN5,WIN,ALT</entry>

<entry><literal>LATIN5</literal></entry>

<entry><literal>LATIN5</literal>, <literal>WIN</literal>, <literal>ALT</literal></entry>

</row>

<row>

<entry>MULE_INTERNAL</entry>

<entry>EUC_JP,SJIS,EUC_KR,EUC_CN,

EUC_TW,BIG5,LATIN1 to LATIN5,

WIN,ALT,WIN1250</entry>

<entry><literal>MULE_INTERNAL</literal></entry>

<entry><literal>EUC_JP</literal>, <literal>SJIS</literal>, <literal>EUC_KR</literal>, <literal>EUC_CN</literal>,

<literal>EUC_TW</literal>, <literal>BIG5</literal>, <literal>LATIN1</literal> to<literal>LATIN5</literal>,

<literal>WIN</literal>, <literal>ALT</literal>, <literal>WIN1250</literal></entry>

</row>

</tbody>

</tgroup>

<application>psql</application>.

<command>\encoding</command> allows you to change frontend

encoding on the fly. For

example, to change the encoding to SJIS, type:

example, to change the encoding to<literal>SJIS</literal>, type:

<programlisting>

\encoding SJIS

<listitem>

<para>

Using libpq functions.

Using<application>libpq</> functions.

<command>\encoding</command> actually calls

PQsetClientEncoding() for its purpose.

<function>PQsetClientEncoding()</function> for its purpose.

<programlisting>

int PQsetClientEncoding(PGconn *<replaceable>conn</replaceable>, const char *<replaceable>encoding</replaceable>)

</programlisting>

Note that it returns the "encoding id," not the encoding symbol string

such as"EUC_JP." To convert an encoding id to an encoding symbol, you

such as<literal>EUC_JP</literal>. To convert an encoding id to an encoding symbol, you

can use:

<programlisting>

encodings has been supported since PostgreSQL 7.1.

Because this requires huge conversion tables, it's not enabled by default.

To enable this feature, run configure with the

--enable-unicode-conversion option. Note that this requires

the --enable-multibyte option also.

<option>--enable-unicode-conversion</option> option. Note that this requires

the<option>--enable-multibyte</option> option also.

</para>

</sect2>

<sect2>

<title>What happens if the translation is not possible?</title>

<para>

Suppose you choose EUC_JP for the backend, LATIN1 for the frontend,

then some Japanese characters could not be translated into LATIN1. In

this case, a letter that cannot be represented in the LATIN1 character set

Suppose you choose<literal>EUC_JP</literal> for the backend,<literal>LATIN1</literal> for the frontend,

then some Japanese characters could not be translated into<literal>LATIN1</literal>. In

this case, a letter that cannot be represented in the<literal>LATIN1</literal> character set

would be transformed as:

<programlisting>

<para>

<ulink url="ftp://ftp.ora.com/pub/examples/nutshell/ujip/doc/cjk.inf">

ftp://ftp.ora.com/pub/examples/nutshell/ujip/doc/cjk.inf</ulink>

Detailed explanations of EUC_JP,EUC_CN,EUC_KR,EUC_TW

Detailed explanations of<literal>EUC_JP</literal>, <literal>EUC_CN</literal>, <literal>EUC_KR</literal>, <literal>EUC_TW</literal>

appear in section 3.2.

</para>

</listitem>

<listitem>

<para>

Unicode: <ulink url="http://www.unicode.org/">http://www.unicode.org/</ulink>

The homepage ofUNICODE.

The homepage ofUnicode.

</para>

</listitem>

<listitem>

<para>

<literal>RFC 2044</literal>

UTF-8 is defined here.

<literal>UTF</literal>-8 is defined here.

</para>

</listitem>

</itemizedlist>

<listitem>

<para>

Success depends on proper system locales. This has been tested

with RH6.0 and Slackware 3.6, with cs_CZ.iso8859-2 locale.

with <systemitem class="osname">Red Hat 6.0</> and <systemitem

class="osname">Slackware 3.6</>, with <literal>cs_CZ.iso8859-2</literal> locale.

</para>

</listitem>

<listitem>

<para>

WIN1250 encoding isuseable only forM$W ODBC clients. The

WIN1250 encoding isusable only forWindows ODBC clients. The

characters are recoded on the fly, to be displayed and stored

back properly.

</para>

<step>

<para>

Install ODBC driver forPgSQL on your M$ Windows machine.

Install ODBC driver for<productname>PostgreSQL</productname> on your Windows machine.

</para>

</step>

cannot use different encodings on the same host at the same

time. It is also inconvenient when you boot your client hosts into

multiple operating systems. Nevertheless, when these restrictions are

not limiting and you do not needmulti-byte characters than it is a

not limiting and you do not needmultibyte characters than it is a

simple and effective solution.

</para>

</sect1>