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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>F.12. dict_xsyn</title><link rel="stylesheet" type="text/css" href="stylesheet.css" /><link rev="made" href="pgsql-docs@lists.postgresql.org" /><meta name="generator" content="DocBook XSL Stylesheets Vsnapshot" /><link rel="prev" href="dict-int.html" title="F.11. dict_int" /><link rel="next" href="earthdistance.html" title="F.13. earthdistance" /></head><body><div xmlns="http://www.w3.org/TR/xhtml1/transitional" class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="5" align="center">F.12. dict_xsyn</th></tr><tr><td width="10%" align="left"><a accesskey="p" href="dict-int.html" title="F.11. dict_int">Prev</a> </td><td width="10%" align="left"><a accesskey="u" href="contrib.html" title="Appendix F. Additional Supplied Modules">Up</a></td><th width="60%" align="center">Appendix F. Additional Supplied Modules</th><td width="10%" align="right"><a accesskey="h" href="index.html" title="PostgreSQL 11.5 Documentation">Home</a></td><td width="10%" align="right"> <a accesskey="n" href="earthdistance.html" title="F.13. earthdistance">Next</a></td></tr></table><hr></hr></div><div class="sect1" id="DICT-XSYN"><div class="titlepage"><div><div><h2 class="title" style="clear: both">F.12. dict_xsyn</h2></div></div></div><div class="toc"><dl class="toc"><dt><span class="sect2"><a href="dict-xsyn.html#id-1.11.7.21.4">F.12.1. Configuration</a></span></dt><dt><span class="sect2"><a href="dict-xsyn.html#id-1.11.7.21.5">F.12.2. Usage</a></span></dt></dl></div><a id="id-1.11.7.21.2" class="indexterm"></a><p>
<code class="filename">dict_xsyn</code> (Extended Synonym Dictionary) is an example of an
add-on dictionary template for full-text search. This dictionary type
replaces words with groups of their synonyms, and so makes it possible to
search for a word using any of its synonyms.
</p><div class="sect2" id="id-1.11.7.21.4"><div class="titlepage"><div><div><h3 class="title">F.12.1. Configuration</h3></div></div></div><p>
A <code class="literal">dict_xsyn</code> dictionary accepts the following options:
</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><p>
<code class="literal">matchorig</code> controls whether the original word is accepted by
the dictionary. Default is <code class="literal">true</code>.
</p></li><li class="listitem"><p>
<code class="literal">matchsynonyms</code> controls whether the synonyms are
accepted by the dictionary. Default is <code class="literal">false</code>.
</p></li><li class="listitem"><p>
<code class="literal">keeporig</code> controls whether the original word is included in
the dictionary's output. Default is <code class="literal">true</code>.
</p></li><li class="listitem"><p>
<code class="literal">keepsynonyms</code> controls whether the synonyms are included in
the dictionary's output. Default is <code class="literal">true</code>.
</p></li><li class="listitem"><p>
<code class="literal">rules</code> is the base name of the file containing the list of
synonyms. This file must be stored in
<code class="filename">$SHAREDIR/tsearch_data/</code> (where <code class="literal">$SHAREDIR</code> means
the <span class="productname">PostgreSQL</span> installation's shared-data directory).
Its name must end in <code class="literal">.rules</code> (which is not to be included in
the <code class="literal">rules</code> parameter).
</p></li></ul></div><p>
The rules file has the following format:
</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><p>
Each line represents a group of synonyms for a single word, which is
given first on the line. Synonyms are separated by whitespace, thus:
</p><pre class="programlisting">
word syn1 syn2 syn3
</pre><p>
</p></li><li class="listitem"><p>
The sharp (<code class="literal">#</code>) sign is a comment delimiter. It may appear at
any position in a line. The rest of the line will be skipped.
</p></li></ul></div><p>
Look at <code class="filename">xsyn_sample.rules</code>, which is installed in
<code class="filename">$SHAREDIR/tsearch_data/</code>, for an example.
</p></div><div class="sect2" id="id-1.11.7.21.5"><div class="titlepage"><div><div><h3 class="title">F.12.2. Usage</h3></div></div></div><p>
Installing the <code class="literal">dict_xsyn</code> extension creates a text search
template <code class="literal">xsyn_template</code> and a dictionary <code class="literal">xsyn</code>
based on it, with default parameters. You can alter the
parameters, for example
</p><pre class="programlisting">
mydb# ALTER TEXT SEARCH DICTIONARY xsyn (RULES='my_rules', KEEPORIG=false);
ALTER TEXT SEARCH DICTIONARY
</pre><p>
or create new dictionaries based on the template.
</p><p>
To test the dictionary, you can try
</p><pre class="programlisting">
mydb=# SELECT ts_lexize('xsyn', 'word');
ts_lexize
-----------------------
{syn1,syn2,syn3}
mydb# ALTER TEXT SEARCH DICTIONARY xsyn (RULES='my_rules', KEEPORIG=true);
ALTER TEXT SEARCH DICTIONARY
mydb=# SELECT ts_lexize('xsyn', 'word');
ts_lexize
-----------------------
{word,syn1,syn2,syn3}
mydb# ALTER TEXT SEARCH DICTIONARY xsyn (RULES='my_rules', KEEPORIG=false, MATCHSYNONYMS=true);
ALTER TEXT SEARCH DICTIONARY
mydb=# SELECT ts_lexize('xsyn', 'syn1');
ts_lexize
-----------------------
{syn1,syn2,syn3}
mydb# ALTER TEXT SEARCH DICTIONARY xsyn (RULES='my_rules', KEEPORIG=true, MATCHORIG=false, KEEPSYNONYMS=false);
ALTER TEXT SEARCH DICTIONARY
mydb=# SELECT ts_lexize('xsyn', 'syn1');
ts_lexize
-----------------------
{word}
</pre><p>
Real-world usage will involve including it in a text search
configuration as described in <a class="xref" href="textsearch.html" title="Chapter 12. Full Text Search">Chapter 12</a>.
That might look like this:
</p><pre class="programlisting">
ALTER TEXT SEARCH CONFIGURATION english
ALTER MAPPING FOR word, asciiword WITH xsyn, english_stem;
</pre><p>
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