<literal>gist__intbig_ops</literal> uses a larger signature and is more
   suitable for indexing large data sets (i.e., columns containing
   a large number of distinct array values).
   The implementation uses an RD-tree data structure with
   built-in lossy compression.
  </para>

  <para>
   <literal>gist__int_ops</literal> approximates an integer set as an array of
   integer ranges.  Its optional integer parameter <literal>numranges</literal>
   determines the maximum number of ranges in
   one index key.  The default value of <literal>numranges</literal> is 100.
   Valid values are between 1 and 253.  Using larger arrays as GiST index
   keys leads to a more precise search (scanning a smaller fraction of the index and
   fewer heap pages), at the cost of a larger index.
  </para>

  <para>
   <literal>gist__intbig_ops</literal> approximates an integer set as a bitmap
   signature.  Its optional integer parameter <literal>siglen</literal>
   determines the signature length in bytes.
   The default signature length is 16 bytes.  Valid values of signature length
   are between 1 and 2024 bytes.  Longer signatures lead to a more precise
   search (scanning a smaller fraction of the index and fewer heap pages), at
   the cost of a larger index.
  </para>

  <para>
   There is also a non-default GIN operator class
   <literal>gin__int_ops</literal>, which supports these operators as well
   as <literal>&lt;@</literal>.
  </para>

  <para>
   The choice between GiST and GIN indexing depends on the relative
   performance characteristics of GiST and GIN, which are discussed elsewhere.
  </para>
 </sect2>

 <sect2 id="intarray-example">
  <title>Example</title>

<programlisting>
-- a message can be in one or more <quote>sections</quote>
CREATE TABLE message (mid INT PRIMARY KEY, sections INT[], ...);

-- create specialized index with signature length of 32 bytes
CREATE INDEX message_rdtree_idx ON message USING GIST (sections gist__intbig_ops (siglen = 32));

-- select messages in section 1 OR 2 - OVERLAP operator
SELECT message.mid FROM message WHERE message.sections &amp;&amp; '{1,2}';

-- select messages in sections 1 AND 2 - CONTAINS operator
SELECT message.mid FROM message WHERE message.sections @&gt; '{1,2}';

-- the same, using QUERY operator
SELECT message.mid FROM message WHERE message.sections @@ '1&amp;2'::query_int;
</programlisting>
 </sect2>

 <sect2 id="intarray-benchmark">
  <title>Benchmark</title>

  <para>
   The source directory <filename>contrib/intarray/bench</filename> contains a
   benchmark test suite, which can be run against an installed
   <productname>PostgreSQL</productname> server.  (It also requires <filename>DBD::Pg</filename>
   to be installed.)  To run:
  </para>

<programlisting>
cd .../contrib/intarray/bench
createdb TEST
psql -c "CREATE EXTENSION intarray" TEST
./create_test.pl | psql TEST
./bench.pl
</programlisting>

  <para>
   The <filename>bench.pl</filename> script has numerous options, which
   are displayed when it is run without any arguments.
  </para>
 </sect2>

 <sect2 id="intarray-Authors">
  <title>Authors</title>

  <para>
   All work was done by Teodor Sigaev (<email>teodor@sigaev.ru</email>) and
   Oleg Bartunov (<email>oleg@sai.msu.su</email>). See
   <ulink url="http://www.sai.msu.su/~megera/postgres/gist/"></ulink> for
   additional information. Andrey Oktyabrski did a great work on adding new
   functions and operations.
  </para>
 </sect2>

</sect1>