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<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<!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>12.8. Testing and Debugging Text Search</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="textsearch-configuration.html" title="12.7. Configuration Example" /><link rel="next" href="textsearch-indexes.html" title="12.9. Preferred Index Types for Text Search" /></head><body id="docContent" class="container-fluid col-10"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="5" align="center">12.8. Testing and Debugging Text Search</th></tr><tr><td width="10%" align="left"><a accesskey="p" href="textsearch-configuration.html" title="12.7. Configuration Example">Prev</a> </td><td width="10%" align="left"><a accesskey="u" href="textsearch.html" title="Chapter 12. Full Text Search">Up</a></td><th width="60%" align="center">Chapter 12. Full Text Search</th><td width="10%" align="right"><a accesskey="h" href="index.html" title="PostgreSQL 15.4 Documentation">Home</a></td><td width="10%" align="right"> <a accesskey="n" href="textsearch-indexes.html" title="12.9. Preferred Index Types for Text Search">Next</a></td></tr></table><hr /></div><div class="sect1" id="TEXTSEARCH-DEBUGGING"><div class="titlepage"><div><div><h2 class="title" style="clear: both">12.8. Testing and Debugging Text Search</h2></div></div></div><div class="toc"><dl class="toc"><dt><span class="sect2"><a href="textsearch-debugging.html#TEXTSEARCH-CONFIGURATION-TESTING">12.8.1. Configuration Testing</a></span></dt><dt><span class="sect2"><a href="textsearch-debugging.html#TEXTSEARCH-PARSER-TESTING">12.8.2. Parser Testing</a></span></dt><dt><span class="sect2"><a href="textsearch-debugging.html#TEXTSEARCH-DICTIONARY-TESTING">12.8.3. Dictionary Testing</a></span></dt></dl></div><p>
The behavior of a custom text search configuration can easily become
confusing. The functions described
in this section are useful for testing text search objects. You can
test a complete configuration, or test parsers and dictionaries separately.
</p><div class="sect2" id="TEXTSEARCH-CONFIGURATION-TESTING"><div class="titlepage"><div><div><h3 class="title">12.8.1. Configuration Testing</h3></div></div></div><p>
The function <code class="function">ts_debug</code> allows easy testing of a
text search configuration.
</p><a id="id-1.5.11.11.3.3" class="indexterm"></a><pre class="synopsis">
ts_debug([<span class="optional"> <em class="replaceable"><code>config</code></em> <code class="type">regconfig</code>, </span>] <em class="replaceable"><code>document</code></em> <code class="type">text</code>,
OUT <em class="replaceable"><code>alias</code></em> <code class="type">text</code>,
OUT <em class="replaceable"><code>description</code></em> <code class="type">text</code>,
OUT <em class="replaceable"><code>token</code></em> <code class="type">text</code>,
OUT <em class="replaceable"><code>dictionaries</code></em> <code class="type">regdictionary[]</code>,
OUT <em class="replaceable"><code>dictionary</code></em> <code class="type">regdictionary</code>,
OUT <em class="replaceable"><code>lexemes</code></em> <code class="type">text[]</code>)
returns setof record
</pre><p>
<code class="function">ts_debug</code> displays information about every token of
<em class="replaceable"><code>document</code></em> as produced by the
parser and processed by the configured dictionaries. It uses the
configuration specified by <em class="replaceable"><code>config</code></em>,
or <code class="varname">default_text_search_config</code> if that argument is
omitted.
</p><p>
<code class="function">ts_debug</code> returns one row for each token identified in the text
by the parser. The columns returned are
</p><div class="itemizedlist"><ul class="itemizedlist compact" style="list-style-type: bullet; "><li class="listitem" style="list-style-type: disc"><p>
<em class="replaceable"><code>alias</code></em> <code class="type">text</code> — short name of the token type
</p></li><li class="listitem" style="list-style-type: disc"><p>
<em class="replaceable"><code>description</code></em> <code class="type">text</code> — description of the
token type
</p></li><li class="listitem" style="list-style-type: disc"><p>
<em class="replaceable"><code>token</code></em> <code class="type">text</code> — text of the token
</p></li><li class="listitem" style="list-style-type: disc"><p>
<em class="replaceable"><code>dictionaries</code></em> <code class="type">regdictionary[]</code> — the
dictionaries selected by the configuration for this token type
</p></li><li class="listitem" style="list-style-type: disc"><p>
<em class="replaceable"><code>dictionary</code></em> <code class="type">regdictionary</code> — the dictionary
that recognized the token, or <code class="literal">NULL</code> if none did
</p></li><li class="listitem" style="list-style-type: disc"><p>
<em class="replaceable"><code>lexemes</code></em> <code class="type">text[]</code> — the lexeme(s) produced
by the dictionary that recognized the token, or <code class="literal">NULL</code> if
none did; an empty array (<code class="literal">{}</code>) means it was recognized as a
stop word
</p></li></ul></div><p>
</p><p>
Here is a simple example:
</p><pre class="screen">
SELECT * FROM ts_debug('english', 'a fat cat sat on a mat - it ate a fat rats');
alias | description | token | dictionaries | dictionary | lexemes
-----------+-----------------+-------+----------------+--------------+---------
asciiword | Word, all ASCII | a | {english_stem} | english_stem | {}
blank | Space symbols | | {} | |
asciiword | Word, all ASCII | fat | {english_stem} | english_stem | {fat}
blank | Space symbols | | {} | |
asciiword | Word, all ASCII | cat | {english_stem} | english_stem | {cat}
blank | Space symbols | | {} | |
asciiword | Word, all ASCII | sat | {english_stem} | english_stem | {sat}
blank | Space symbols | | {} | |
asciiword | Word, all ASCII | on | {english_stem} | english_stem | {}
blank | Space symbols | | {} | |
asciiword | Word, all ASCII | a | {english_stem} | english_stem | {}
blank | Space symbols | | {} | |
asciiword | Word, all ASCII | mat | {english_stem} | english_stem | {mat}
blank | Space symbols | | {} | |
blank | Space symbols | - | {} | |
asciiword | Word, all ASCII | it | {english_stem} | english_stem | {}
blank | Space symbols | | {} | |
asciiword | Word, all ASCII | ate | {english_stem} | english_stem | {ate}
blank | Space symbols | | {} | |
asciiword | Word, all ASCII | a | {english_stem} | english_stem | {}
blank | Space symbols | | {} | |
asciiword | Word, all ASCII | fat | {english_stem} | english_stem | {fat}
blank | Space symbols | | {} | |
asciiword | Word, all ASCII | rats | {english_stem} | english_stem | {rat}
</pre><p>
</p><p>
For a more extensive demonstration, we
first create a <code class="literal">public.english</code> configuration and
Ispell dictionary for the English language:
</p><pre class="programlisting">
CREATE TEXT SEARCH CONFIGURATION public.english ( COPY = pg_catalog.english );
CREATE TEXT SEARCH DICTIONARY english_ispell (
TEMPLATE = ispell,
DictFile = english,
AffFile = english,
StopWords = english
);
ALTER TEXT SEARCH CONFIGURATION public.english
ALTER MAPPING FOR asciiword WITH english_ispell, english_stem;
</pre><pre class="screen">
SELECT * FROM ts_debug('public.english', 'The Brightest supernovaes');
alias | description | token | dictionaries | dictionary | lexemes
-----------+-----------------+-------------+-------------------------------+----------------+-------------
asciiword | Word, all ASCII | The | {english_ispell,english_stem} | english_ispell | {}
blank | Space symbols | | {} | |
asciiword | Word, all ASCII | Brightest | {english_ispell,english_stem} | english_ispell | {bright}
blank | Space symbols | | {} | |
asciiword | Word, all ASCII | supernovaes | {english_ispell,english_stem} | english_stem | {supernova}
</pre><p>
In this example, the word <code class="literal">Brightest</code> was recognized by the
parser as an <code class="literal">ASCII word</code> (alias <code class="literal">asciiword</code>).
For this token type the dictionary list is
<code class="literal">english_ispell</code> and
<code class="literal">english_stem</code>. The word was recognized by
<code class="literal">english_ispell</code>, which reduced it to the noun
<code class="literal">bright</code>. The word <code class="literal">supernovaes</code> is
unknown to the <code class="literal">english_ispell</code> dictionary so it
was passed to the next dictionary, and, fortunately, was recognized (in
fact, <code class="literal">english_stem</code> is a Snowball dictionary which
recognizes everything; that is why it was placed at the end of the
dictionary list).
</p><p>
The word <code class="literal">The</code> was recognized by the
<code class="literal">english_ispell</code> dictionary as a stop word (<a class="xref" href="textsearch-dictionaries.html#TEXTSEARCH-STOPWORDS" title="12.6.1. Stop Words">Section 12.6.1</a>) and will not be indexed.
The spaces are discarded too, since the configuration provides no
dictionaries at all for them.
</p><p>
You can reduce the width of the output by explicitly specifying which columns
you want to see:
</p><pre class="screen">
SELECT alias, token, dictionary, lexemes
FROM ts_debug('public.english', 'The Brightest supernovaes');
alias | token | dictionary | lexemes
-----------+-------------+----------------+-------------
asciiword | The | english_ispell | {}
blank | | |
asciiword | Brightest | english_ispell | {bright}
blank | | |
asciiword | supernovaes | english_stem | {supernova}
</pre><p>
</p></div><div class="sect2" id="TEXTSEARCH-PARSER-TESTING"><div class="titlepage"><div><div><h3 class="title">12.8.2. Parser Testing</h3></div></div></div><p>
The following functions allow direct testing of a text search parser.
</p><a id="id-1.5.11.11.4.3" class="indexterm"></a><pre class="synopsis">
ts_parse(<em class="replaceable"><code>parser_name</code></em> <code class="type">text</code>, <em class="replaceable"><code>document</code></em> <code class="type">text</code>,
OUT <em class="replaceable"><code>tokid</code></em> <code class="type">integer</code>, OUT <em class="replaceable"><code>token</code></em> <code class="type">text</code>) returns <code class="type">setof record</code>
ts_parse(<em class="replaceable"><code>parser_oid</code></em> <code class="type">oid</code>, <em class="replaceable"><code>document</code></em> <code class="type">text</code>,
OUT <em class="replaceable"><code>tokid</code></em> <code class="type">integer</code>, OUT <em class="replaceable"><code>token</code></em> <code class="type">text</code>) returns <code class="type">setof record</code>
</pre><p>
<code class="function">ts_parse</code> parses the given <em class="replaceable"><code>document</code></em>
and returns a series of records, one for each token produced by
parsing. Each record includes a <code class="varname">tokid</code> showing the
assigned token type and a <code class="varname">token</code> which is the text of the
token. For example:
</p><pre class="screen">
SELECT * FROM ts_parse('default', '123 - a number');
tokid | token
-------+--------
22 | 123
12 |
12 | -
1 | a
12 |
1 | number
</pre><p>
</p><a id="id-1.5.11.11.4.6" class="indexterm"></a><pre class="synopsis">
ts_token_type(<em class="replaceable"><code>parser_name</code></em> <code class="type">text</code>, OUT <em class="replaceable"><code>tokid</code></em> <code class="type">integer</code>,
OUT <em class="replaceable"><code>alias</code></em> <code class="type">text</code>, OUT <em class="replaceable"><code>description</code></em> <code class="type">text</code>) returns <code class="type">setof record</code>
ts_token_type(<em class="replaceable"><code>parser_oid</code></em> <code class="type">oid</code>, OUT <em class="replaceable"><code>tokid</code></em> <code class="type">integer</code>,
OUT <em class="replaceable"><code>alias</code></em> <code class="type">text</code>, OUT <em class="replaceable"><code>description</code></em> <code class="type">text</code>) returns <code class="type">setof record</code>
</pre><p>
<code class="function">ts_token_type</code> returns a table which describes each type of
token the specified parser can recognize. For each token type, the table
gives the integer <code class="varname">tokid</code> that the parser uses to label a
token of that type, the <code class="varname">alias</code> that names the token type
in configuration commands, and a short <code class="varname">description</code>. For
example:
</p><pre class="screen">
SELECT * FROM ts_token_type('default');
tokid | alias | description
-------+-----------------+------------------------------------------
1 | asciiword | Word, all ASCII
2 | word | Word, all letters
3 | numword | Word, letters and digits
4 | email | Email address
5 | url | URL
6 | host | Host
7 | sfloat | Scientific notation
8 | version | Version number
9 | hword_numpart | Hyphenated word part, letters and digits
10 | hword_part | Hyphenated word part, all letters
11 | hword_asciipart | Hyphenated word part, all ASCII
12 | blank | Space symbols
13 | tag | XML tag
14 | protocol | Protocol head
15 | numhword | Hyphenated word, letters and digits
16 | asciihword | Hyphenated word, all ASCII
17 | hword | Hyphenated word, all letters
18 | url_path | URL path
19 | file | File or path name
20 | float | Decimal notation
21 | int | Signed integer
22 | uint | Unsigned integer
23 | entity | XML entity
</pre><p>
</p></div><div class="sect2" id="TEXTSEARCH-DICTIONARY-TESTING"><div class="titlepage"><div><div><h3 class="title">12.8.3. Dictionary Testing</h3></div></div></div><p>
The <code class="function">ts_lexize</code> function facilitates dictionary testing.
</p><a id="id-1.5.11.11.5.3" class="indexterm"></a><pre class="synopsis">
ts_lexize(<em class="replaceable"><code>dict</code></em> <code class="type">regdictionary</code>, <em class="replaceable"><code>token</code></em> <code class="type">text</code>) returns <code class="type">text[]</code>
</pre><p>
<code class="function">ts_lexize</code> returns an array of lexemes if the input
<em class="replaceable"><code>token</code></em> is known to the dictionary,
or an empty array if the token
is known to the dictionary but it is a stop word, or
<code class="literal">NULL</code> if it is an unknown word.
</p><p>
Examples:
</p><pre class="screen">
SELECT ts_lexize('english_stem', 'stars');
ts_lexize
-----------
{star}
SELECT ts_lexize('english_stem', 'a');
ts_lexize
-----------
{}
</pre><p>
</p><div class="note"><h3 class="title">Note</h3><p>
The <code class="function">ts_lexize</code> function expects a single
<span class="emphasis"><em>token</em></span>, not text. Here is a case
where this can be confusing:
</p><pre class="screen">
SELECT ts_lexize('thesaurus_astro', 'supernovae stars') is null;
?column?
----------
t
</pre><p>
The thesaurus dictionary <code class="literal">thesaurus_astro</code> does know the
phrase <code class="literal">supernovae stars</code>, but <code class="function">ts_lexize</code>
fails since it does not parse the input text but treats it as a single
token. Use <code class="function">plainto_tsquery</code> or <code class="function">to_tsvector</code> to
test thesaurus dictionaries, for example:
</p><pre class="screen">
SELECT plainto_tsquery('supernovae stars');
plainto_tsquery
-----------------
'sn'
</pre><p>
</p></div></div></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="textsearch-configuration.html" title="12.7. Configuration Example">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="textsearch.html" title="Chapter 12. Full Text Search">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="textsearch-indexes.html" title="12.9. Preferred Index Types for Text Search">Next</a></td></tr><tr><td width="40%" align="left" valign="top">12.7. Configuration Example </td><td width="20%" align="center"><a accesskey="h" href="index.html" title="PostgreSQL 15.4 Documentation">Home</a></td><td width="40%" align="right" valign="top"> 12.9. Preferred Index Types for Text Search</td></tr></table></div></body></html>
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