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Mention configurations early in text search documentation to table/index

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section makes a little more sense.
This commit is contained in:
Bruce Momjian 2007-08-28 03:10:45 +00:00
parent 56cbd29328
commit baf3a134d9
1 changed files with 24 additions and 8 deletions
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doc/src/sgml/textsearch.sgml
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@ -329,8 +329,27 @@ The form <type>text</type> <literal>@@</literal> <type>tsquery</type>
is equivalent to <literal>to_tsvector(x) @@ y</literal>. is equivalent to <literal>to_tsvector(x) @@ y</literal>.
The form <type>text</type> <literal>@@</literal> <type>text</type> The form <type>text</type> <literal>@@</literal> <type>text</type>
is equivalent to <literal>to_tsvector(x) @@ plainto_tsquery(y)</literal>. 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 </para>
linkend="guc-default-text-search-config">.
<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> </para>
</sect2> </sect2>
@ -2646,15 +2665,12 @@ database you must be careful to reference the proper text search
configuration. This can be done by either setting configuration. This can be done by either setting
<varname>default_text_search_config</> in each session or supplying the <varname>default_text_search_config</> in each session or supplying the
configuration name in every function call, e.g. to_tsquery('french', configuration name in every function call, e.g. to_tsquery('french',
'friend'), to_tsvector('english', col). If you are using an expression index, 'friend'), to_tsvector('english', col). If you are using an expression
you must also be sure to use the proper text search configuration every index you must embed the configuration name into the expression index, e.g.:
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.:
<programlisting> <programlisting>
CREATE INDEX pgweb_idx ON pgweb USING gin(to_tsvector('french', title || body)); CREATE INDEX pgweb_idx ON pgweb USING gin(to_tsvector('french', title || body));
</programlisting> </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. <literal>WHERE</> clause as well so the expression index will be used.
</para> </para>