From f767f737e4e1697f5f6840ae33b57de94ce955a8 Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Tue, 9 Dec 2008 20:52:03 +0000
Subject: [PATCH] Add a specific example of parenthesizing when extracting a
 field of a composite column.  Might help cut down on future questions...

---
 doc/src/sgml/syntax.sgml | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/doc/src/sgml/syntax.sgml b/doc/src/sgml/syntax.sgml
index 3ce5909d8c..ac4fd78362 100644
--- a/doc/src/sgml/syntax.sgml
+++ b/doc/src/sgml/syntax.sgml
@@ -1387,7 +1387,18 @@ $1.somecolumn
 </programlisting>
 
     (Thus, a qualified column reference is actually just a special case
-    of the field selection syntax.)
+    of the field selection syntax.)  An important special case is
+    extracting a field from a table column that is of a composite type:
+
+<programlisting>
+(compositecol).somefield
+(mytable.compositecol).somefield
+</programlisting>
+
+    The parentheses are required here to show that
+    <structfield>compositecol</> is a column name not a table name,
+    or that <structname>mytable</> is a table name not a schema name
+    in the second case.
    </para>
   </sect2>
 
-- 
2.39.5