1 files changed, 14 insertions, 1 deletions
diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index c753eb63007..17b0f3667da 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -1,5 +1,5 @@
 <!--
-$PostgreSQL: pgsql/doc/src/sgml/ref/alter_table.sgml,v 1.87 2006/07/04 18:07:24 tgl Exp $
+$PostgreSQL: pgsql/doc/src/sgml/ref/alter_table.sgml,v 1.88 2006/08/03 20:57:06 tgl Exp $
 PostgreSQL documentation
 -->
 
@@ -742,6 +742,19 @@ ALTER TABLE foo
   </para>
 
   <para>
+   The same, when the column has a default expression that won't automatically
+   cast to the new datatype:
+<programlisting>
+ALTER TABLE foo
+    ALTER COLUMN foo_timestamp DROP DEFAULT,
+    ALTER COLUMN foo_timestamp TYPE timestamp with time zone
+    USING
+        timestamp with time zone 'epoch' + foo_timestamp * interval '1 second',
+    ALTER COLUMN foo_timestamp SET DEFAULT now();
+</programlisting>
+  </para>
+
+  <para>
    To rename an existing column:
 <programlisting>
 ALTER TABLE distributors RENAME COLUMN address TO city;