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Mention configurations early in text search documentation to table/index
section makes a little more sense.
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@ -329,8 +329,27 @@ The form <type>text</type> <literal>@@</literal> <type>tsquery</type>
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is equivalent to <literal>to_tsvector(x) @@ y</literal>.
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is equivalent to <literal>to_tsvector(x) @@ y</literal>.
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The form <type>text</type> <literal>@@</literal> <type>text</type>
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The form <type>text</type> <literal>@@</literal> <type>text</type>
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is equivalent to <literal>to_tsvector(x) @@ plainto_tsquery(y)</literal>.
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is equivalent to <literal>to_tsvector(x) @@ plainto_tsquery(y)</literal>.
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Note that the results of these forms will depend on the setting of <xref
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</para>
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linkend="guc-default-text-search-config">.
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<sect2 id="textsearch-configurations">
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<title>Configurations</title>
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<indexterm zone="textsearch-configurations">
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<primary>configurations</primary>
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</indexterm>
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<para>
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The above are all simple text search examples. As mentioned before, full
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text search functionality includes the ability to do many more things:
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skip indexing certain words (stop words), process synonyms, and use
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sophisticated parsing, e.g. parse based on more than just white space.
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This functionality is controlled by <emphasis>configurations</>.
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Fortunately, <productname>PostgreSQL</> comes with predefined
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configurations for many languages. (<application>psql</>'s <command>\dF</>
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shows all predefined configurations.) During installation an appropriate
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configuration was selected and <xref
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linkend="guc-default-text-search-config"> was set accordingly. If you
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need to change it, see <xref linkend="textsearch-tables-multiconfig">.
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</para>
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</para>
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</sect2>
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</sect2>
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@ -2646,15 +2665,12 @@ database you must be careful to reference the proper text search
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configuration. This can be done by either setting
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configuration. This can be done by either setting
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<varname>default_text_search_config</> in each session or supplying the
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<varname>default_text_search_config</> in each session or supplying the
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configuration name in every function call, e.g. to_tsquery('french',
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configuration name in every function call, e.g. to_tsquery('french',
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'friend'), to_tsvector('english', col). If you are using an expression index,
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'friend'), to_tsvector('english', col). If you are using an expression
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you must also be sure to use the proper text search configuration every
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index you must embed the configuration name into the expression index, e.g.:
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time an <command>INSERT</> or <command>UPDATE</> is executed because these
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will modify the index, or you can embed the configuration name into the
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expression index, e.g.:
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<programlisting>
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<programlisting>
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CREATE INDEX pgweb_idx ON pgweb USING gin(to_tsvector('french', title || body));
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CREATE INDEX pgweb_idx ON pgweb USING gin(to_tsvector('french', title || body));
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</programlisting>
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</programlisting>
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And if you do that, make sure you specify the configuration name in the
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And for an expression index, specify the configuration name in the
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<literal>WHERE</> clause as well so the expression index will be used.
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<literal>WHERE</> clause as well so the expression index will be used.
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</para>
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</para>
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