is equivalent to <literal>to_tsvector(x) @@ y</literal>.
The form <type>text</type> <literal>@@</literal> <type>text</type>
is equivalent to <literal>to_tsvector(x) @@ plainto_tsquery(y)</literal>.
-Note that the results of these forms will depend on the setting of <xref
-linkend="guc-default-text-search-config">.
+</para>
+
+<sect2 id="textsearch-configurations">
+<title>Configurations</title>
+
+<indexterm zone="textsearch-configurations">
+<primary>configurations</primary>
+</indexterm>
+
+<para>
+The above are all simple text search examples. As mentioned before, full
+text search functionality includes the ability to do many more things:
+skip indexing certain words (stop words), process synonyms, and use
+sophisticated parsing, e.g. parse based on more than just white space.
+This functionality is controlled by <emphasis>configurations</>.
+Fortunately, <productname>PostgreSQL</> comes with predefined
+configurations for many languages. (<application>psql</>'s <command>\dF</>
+shows all predefined configurations.) During installation an appropriate
+configuration was selected and <xref
+linkend="guc-default-text-search-config"> was set accordingly. If you
+need to change it, see <xref linkend="textsearch-tables-multiconfig">.
</para>
</sect2>
configuration. This can be done by either setting
<varname>default_text_search_config</> in each session or supplying the
configuration name in every function call, e.g. to_tsquery('french',
-'friend'), to_tsvector('english', col). If you are using an expression index,
-you must also be sure to use the proper text search configuration every
-time an <command>INSERT</> or <command>UPDATE</> is executed because these
-will modify the index, or you can embed the configuration name into the
-expression index, e.g.:
+'friend'), to_tsvector('english', col). If you are using an expression
+index you must embed the configuration name into the expression index, e.g.:
<programlisting>
CREATE INDEX pgweb_idx ON pgweb USING gin(to_tsvector('french', title || body));
</programlisting>
-And if you do that, make sure you specify the configuration name in the
+And for an expression index, specify the configuration name in the
<literal>WHERE</> clause as well so the expression index will be used.
</para>