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Improve headeline generation. Now headline can contain

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several fragments a-la Google.

Sushant Sinha <sushant354@gmail.com>
This commit is contained in:
Teodor Sigaev
2008-10-17 18:05:19 +00:00
parent 906b7e5f6c
commit 2a0083ede8
6 changed files with 518 additions and 63 deletions
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27
doc/src/sgml/textsearch.sgml
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@ -1,4 +1,4 @@
<!-- $PostgreSQL: pgsql/doc/src/sgml/textsearch.sgml,v 1.45 2008/09/23 09:20:34 heikki Exp $ -->
<!-- $PostgreSQL: pgsql/doc/src/sgml/textsearch.sgml,v 1.46 2008/10/17 18:05:19 teodor Exp $ -->
<chapter id="textsearch">
<title id="textsearch-title">Full Text Search</title>
@ -1098,6 +1098,29 @@ ORDER BY rank DESC LIMIT 10;
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.
</para>
</listitem>
<listitem>
<para>
<literal>HighlightAll</literal>: Boolean flag; if
@ -1109,7 +1132,7 @@ ORDER BY rank DESC LIMIT 10;
Any unspecified options receive these defaults:
<programlisting>
StartSel=&lt;b&gt;, StopSel=&lt;/b&gt;, MaxWords=35, MinWords=15, ShortWord=3, HighlightAll=FALSE
StartSel=&lt;b&gt;, StopSel=&lt;/b&gt;, MaxFragments=0, FragmentDelimiter=" ... ", MaxWords=35, MinWords=15, ShortWord=3, HighlightAll=FALSE
</programlisting>
</para>