@@ -705,15 +705,6 @@ CREATE INDEX test1_lower_col1_idx ON test1 (lower(col1));
705705</programlisting>
706706 </para>
707707
708- <para>
709- Expression indexes also allow control over the scope of unique indexes.
710- For example, this unique index prevents duplicate integer values from
711- being stored in a <type>double precision</type>-typed column:
712- <programlisting>
713- CREATE UNIQUE INDEX test1_uniq_int ON tests ((floor(double_col)))
714- </programlisting>
715- </para>
716-
717708 <para>
718709 If we were to declare this index <literal>UNIQUE</literal>, it would prevent
719710 creation of rows whose <literal>col1</literal> values differ only in case,
@@ -953,18 +944,11 @@ CREATE UNIQUE INDEX tests_success_constraint ON tests (subject, target)
953944 WHERE success;
954945</programlisting>
955946 This is a particularly efficient approach when there are few
956- successful tests and many unsuccessful ones.
947+ successful tests and many unsuccessful ones. It is also possible to
948+ allow only one null in a column by creating a unique partial index
949+ with an <literal>IS NULL</literal> restriction.
957950 </para>
958951
959- <para>
960- This index allows only one null in the indexed column by using a
961- partial index clause to process only null column values, and using
962- an expression index clause to index <literal>true</literal> instead
963- of <literal>null</literal>:
964- <programlisting>
965- CREATE UNIQUE INDEX tests_target_one_null ON tests ((target IS NULL)) WHERE target IS NULL;
966- </programlisting>
967- </para>
968952 </example>
969953
970954 <para>