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<chapter id="datatype">
<title id="datatype-title">Data Types</title>
processed in UTF-8, computations will be most efficient if the
server encoding is also UTF-8.
</para>
-
- <para>
- <acronym>XML</> (Extensible Markup Language) support is not
- just the existance of an <type>xml</type> data type, but a
- variety of features supported by a database system. These
- capabilities include import/export, indexing, searching,
- transforming, and <acronym>XML</> to <acronym>SQL</> mapping.
- <productname>PostgreSQL</> supports some but not all of these
- <acronym>XML</> capabilities. For an overview of <acronym>XML</>
- use in databases, see <ulink
- url="http://www.rpbourret.com/xml/XMLAndDatabases.htm"></>.
- </para>
-
- <variablelist>
- <varlistentry>
- <term>Import/Export</term>
- <listitem>
-
- <para>
- There is no facility for mapping <acronym>XML</> to relational
- tables. An external tool must be used for this. One simple way to
- export <acronym>XML</> is to use <application>psql</> in
- <acronym>HTML</> mode (<literal>\pset format html</>), and convert
- the <acronym>XHTML</> output to XML using an external tool.
- </para>
- </listitem>
- </varlistentry>
-
- <varlistentry>
- <term>Indexing</term>
- <listitem>
-
- <para>
- <filename>/contrib/xml2</> functions can be used in expression
- indexes to index specific <acronym>XML</> fields. To index the
- full contents of <acronym>XML</> documents, the full-text indexing
- tool <filename>/contrib/tsearch2</> can be used. Of course,
- Tsearch2 indexes have no <acronym>XML</> awareness so additional
- <filename>/contrib/xml2</> checks should be added to queries.
- </para>
- </listitem>
- </varlistentry>
-
- <varlistentry>
- <term>Searching</term>
- <listitem>
-
- <para>
- XPath searches are implemented using <filename>/contrib/xml2</>.
- It processes <acronym>XML</> text documents and returns results
- based on the requested query.
- </para>
- </listitem>
- </varlistentry>
-
- <varlistentry>
- <term>Transforming</term>
- <listitem>
-
- <para>
- <filename>/contrib/xml2</> supports <acronym>XSLT</> (Extensible
- Stylesheet Language Transformation).
- </para>
- </listitem>
- </varlistentry>
-
- <varlistentry>
- <term>XML to SQL Mapping</term>
- <listitem>
-
- <para>
- This involves converting <acronym>XML</> data to and from
- relational structures. <productname>PostgreSQL</> has no internal
- support for such mapping, and relies on external tools to do such
- conversions.
- </para>
- </listitem>
- </varlistentry>
- </variablelist>
-
</sect1>
</chapter>