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Doc: remove obsolete example.

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The documentation for ts_headline() recommends using a sub-select to
avoid extra evaluations of ts_headline() in a query with ORDER BY+LIMIT.
Since commit 9118d03a8 this contortionism is unnecessary, so remove the
recommendation.  Noted by Oleg Bartunov.

Discussion: <CAF4Au4w6rrH_j1bvVhzpOsRiHCog7sGJ3LSX0tY8ZdwhHT88LQ@mail.gmail.com>
This commit is contained in:
Tom Lane 2016-11-13 13:12:35 -05:00
parent b7292a8670
commit d5d8a0b7e5
1 changed files with 1 additions and 13 deletions
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14
doc/src/sgml/textsearch.sgml
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@ -1290,19 +1290,7 @@ query.',
<para> <para>
<function>ts_headline</> uses the original document, not a <function>ts_headline</> uses the original document, not a
<type>tsvector</type> summary, so it can be slow and should be used with <type>tsvector</type> summary, so it can be slow and should be used with
care. A typical mistake is to call <function>ts_headline</function> for care.
<emphasis>every</emphasis> matching document when only ten documents are
to be shown. <acronym>SQL</acronym> subqueries can help; here is an
example:
<programlisting>
SELECT id, ts_headline(body, q), rank
FROM (SELECT id, body, q, ts_rank_cd(ti, q) AS rank
FROM apod, to_tsquery('stars') q
WHERE ti @@ q
ORDER BY rank DESC
LIMIT 10) AS foo;
</programlisting>
</para> </para>
</sect2> </sect2>