linkend="sql-createtype"/> for more information about creating
   range types.
  </para>
 </sect2>

 <sect2 id="rangetypes-indexing">
  <title>Indexing</title>

  <indexterm>
    <primary>range type</primary>
    <secondary>indexes on</secondary>
  </indexterm>

  <para>
   GiST and SP-GiST indexes can be created for table columns of range types.
   GiST indexes can be also created for table columns of multirange types.
   For instance, to create a GiST index:
<programlisting>
CREATE INDEX reservation_idx ON reservation USING GIST (during);
</programlisting>
   A GiST or SP-GiST index on ranges can accelerate queries involving these
   range operators:
   <literal>=</literal>,
   <literal>&amp;&amp;</literal>,
   <literal>&lt;@</literal>,
   <literal>@&gt;</literal>,
   <literal>&lt;&lt;</literal>,
   <literal>&gt;&gt;</literal>,
   <literal>-|-</literal>,
   <literal>&amp;&lt;</literal>, and
   <literal>&amp;&gt;</literal>.
   A GiST index on multiranges can accelerate queries involving the same
   set of multirange operators.
   A GiST index on ranges and GiST index on multiranges can also accelerate
   queries involving these cross-type range to multirange and multirange to
   range operators correspondingly:
   <literal>&amp;&amp;</literal>,
   <literal>&lt;@</literal>,
   <literal>@&gt;</literal>,
   <literal>&lt;&lt;</literal>,
   <literal>&gt;&gt;</literal>,
   <literal>-|-</literal>,
   <literal>&amp;&lt;</literal>, and
   <literal>&amp;&gt;</literal>.
   See <xref linkend="range-operators-table"/> for more information.
  </para>

  <para>
   In addition, B-tree and hash indexes can be created for table columns of
   range types.  For these index types, basically the only useful range
   operation is equality.  There is a B-tree sort ordering defined for range
   values, with corresponding <literal>&lt;</literal> and <literal>&gt;</literal> operators,
   but the ordering is rather arbitrary and not usually useful in the real
   world.  Range types' B-tree and hash support is primarily meant to
   allow sorting and hashing internally in queries, rather than creation of
   actual indexes.
  </para>
 </sect2>

 <sect2 id="rangetypes-constraint">
  <title>Constraints on Ranges</title>

  <indexterm>
    <primary>range type</primary>
    <secondary>exclude</secondary>
  </indexterm>

  <para>