Doc: remove obsolete example.

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: 

diff --git a/doc/src/sgml/textsearch.sgml b/doc/src/sgml/textsearch.sgml
index 5a70d7db8025046664811eec0446c25fd625e739..2da75955d0b5557e82d8783697346c204c60a52e 100644 (file)
--- a/doc/src/sgml/textsearch.sgml
+++ b/doc/src/sgml/textsearch.sgml
@@ -1290,19 +1290,7 @@ query.',
    
     ts_headline uses the original document, not a
     tsvector summary, so it can be slow and should be used with
-    care.  A typical mistake is to call ts_headline for
-    every matching document when only ten documents are
-    to be shown. SQL subqueries can help; here is an
-    example:
-
-
-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;
-
+    care.