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Do some copy-editing on description of ts_headline().

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Tom Lane 2009-04-14 00:49:56 +00:00
parent 14a4f6f374
commit bda9dc7e19
1 changed files with 39 additions and 33 deletions
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72
doc/src/sgml/textsearch.sgml
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@ -1,4 +1,4 @@
<!-- $PostgreSQL: pgsql/doc/src/sgml/textsearch.sgml,v 1.48 2009/03/24 20:17:08 tgl Exp $ -->
<!-- $PostgreSQL: pgsql/doc/src/sgml/textsearch.sgml,v 1.49 2009/04/14 00:49:56 tgl Exp $ -->
<chapter id="textsearch">
<title id="textsearch-title">Full Text Search</title>
@ -1082,7 +1082,8 @@ ORDER BY rank DESC LIMIT 10;
<para>
<literal>StartSel</>, <literal>StopSel</literal>: the strings with which
query words appearing in the document should be delimited to distinguish
them from other excerpted words.
them from other excerpted words. You must double-quote these strings
if they contain spaces or commas.
</para>
</listitem>
<listitem >
@ -1095,36 +1096,36 @@ ORDER BY rank DESC LIMIT 10;
<para>
<literal>ShortWord</literal>: words of this length or less will be
dropped at the start and end of a headline. The default
value of three eliminates the English articles.
</para>
</listitem>
<listitem>
<para>
<literal>MaxFragments</literal>: maximum number of text excerpts
or fragments that matches the query words. It also triggers a
different headline generation function than the default one. This
function finds text fragments with as many query words as possible and
stretches those fragments around the query words. As a result
query words are close to the middle of each fragment and have words on
each side. Each fragment will be of at most MaxWords and will not
have words of size less than or equal to ShortWord at the start or
end of a fragment. If all query words are not found in the document,
then a single fragment of MinWords will be displayed.
</para>
</listitem>
<listitem>
<para>
<literal>FragmentDelimiter</literal>: When more than one fragments are
displayed, then the fragments will be separated by this delimiter. This
option is effective only if MaxFragments is greater than 1 and there are
more than one fragments to be diplayed. This option has no effect on the
default headline generation function.
value of three eliminates common English articles.
</para>
</listitem>
<listitem>
<para>
<literal>HighlightAll</literal>: Boolean flag; if
<literal>true</literal> the whole document will be highlighted.
<literal>true</literal> the whole document will be used as the
headline, ignoring the preceding three parameters.
</para>
</listitem>
<listitem>
<para>
<literal>MaxFragments</literal>: maximum number of text excerpts
or fragments to display. The default value of zero selects a
non-fragment-oriented headline generation method. A value greater than
zero selects fragment-based headline generation. This method
finds text fragments with as many query words as possible and
stretches those fragments around the query words. As a result
query words are close to the middle of each fragment and have words on
each side. Each fragment will be of at most <literal>MaxWords</> and
words of length <literal>ShortWord</> or less are dropped at the start
and end of each fragment. If not all query words are found in the
document, then a single fragment of the first <literal>MinWords</>
in the document will be displayed.
</para>
</listitem>
<listitem>
<para>
<literal>FragmentDelimiter</literal>: When more than one fragment is
displayed, the fragments will be separated by this string.
</para>
</listitem>
</itemizedlist>
@ -1132,7 +1133,9 @@ ORDER BY rank DESC LIMIT 10;
Any unspecified options receive these defaults:
<programlisting>
StartSel=&lt;b&gt;, StopSel=&lt;/b&gt;, MaxFragments=0, FragmentDelimiter=" ... ", MaxWords=35, MinWords=15, ShortWord=3, HighlightAll=FALSE
StartSel=&lt;b&gt;, StopSel=&lt;/b&gt;,
MaxWords=35, MinWords=15, ShortWord=3, HighlightAll=FALSE,
MaxFragments=0, FragmentDelimiter=" ... "
</programlisting>
</para>
@ -1140,17 +1143,20 @@ StartSel=&lt;b&gt;, StopSel=&lt;/b&gt;, MaxFragments=0, FragmentDelimiter=" ...
For example:
<programlisting>
SELECT ts_headline('english', 'The most common type of search
SELECT ts_headline('english',
'The most common type of search
is to find all documents containing given query terms
and return them in order of their similarity to the
query.', to_tsquery('query &amp; similarity'));
query.',
to_tsquery('query &amp; similarity'));
ts_headline
------------------------------------------------------------
given &lt;b&gt;query&lt;/b&gt; terms
containing given &lt;b&gt;query&lt;/b&gt; terms
and return them in order of their &lt;b&gt;similarity&lt;/b&gt; to the
&lt;b&gt;query&lt;/b&gt;.
SELECT ts_headline('english', 'The most common type of search
SELECT ts_headline('english',
'The most common type of search
is to find all documents containing given query terms
and return them in order of their similarity to the
query.',
@ -1158,7 +1164,7 @@ query.',
'StartSel = &lt;, StopSel = &gt;');
ts_headline
-------------------------------------------------------
given &lt;query&gt; terms
containing given &lt;query&gt; terms
and return them in order of their &lt;similarity&gt; to the
&lt;query&gt;.
</programlisting>