doc/src/sgml/btree-gin.sgml

   1 <!-- doc/src/sgml/btree-gin.sgml -->
   2
   3 <sect1 id="btree-gin" xreflabel="btree_gin">
   4  <title>btree_gin &mdash; GIN operator classes with B-tree behavior</title>
   5
   6  <indexterm zone="btree-gin">
   7   <primary>btree_gin</primary>
   8  </indexterm>
   9
  10  <para>
  11   <filename>btree_gin</filename> provides GIN operator classes that
  12   implement B-tree equivalent behavior for the data types
  13   <type>int2</type>, <type>int4</type>, <type>int8</type>, <type>float4</type>,
  14   <type>float8</type>, <type>timestamp with time zone</type>,
  15   <type>timestamp without time zone</type>, <type>time with time zone</type>,
  16   <type>time without time zone</type>, <type>date</type>, <type>interval</type>,
  17   <type>oid</type>, <type>money</type>, <type>"char"</type>,
  18   <type>varchar</type>, <type>text</type>, <type>bytea</type>, <type>bit</type>,
  19   <type>varbit</type>, <type>macaddr</type>, <type>macaddr8</type>, <type>inet</type>,
  20   <type>cidr</type>, <type>uuid</type>, <type>name</type>, <type>bool</type>,
  21   <type>bpchar</type>, and all <type>enum</type> types.
  22  </para>
  23
  24  <para>
  25   In general, these operator classes will not outperform the equivalent
  26   standard B-tree index methods, and they lack one major feature of the
  27   standard B-tree code: the ability to enforce uniqueness.  However,
  28   they are useful for GIN testing and as a base for developing other
  29   GIN operator classes.  Also, for queries that test both a GIN-indexable
  30   column and a B-tree-indexable column, it might be more efficient to create
  31   a multicolumn GIN index that uses one of these operator classes than to create
  32   two separate indexes that would have to be combined via bitmap ANDing.
  33  </para>
  34
  35  <para>
  36   This module is considered <quote>trusted</quote>, that is, it can be
  37   installed by non-superusers who have <literal>CREATE</literal> privilege
  38   on the current database.
  39  </para>
  40
  41  <sect2 id="btree-gin-example-usage">
  42   <title>Example Usage</title>
  43
  44 <programlisting>
  45 CREATE TABLE test (a int4);
  46 -- create index
  47 CREATE INDEX testidx ON test USING GIN (a);
  48 -- query
  49 SELECT * FROM test WHERE a &lt; 10;
  50 </programlisting>
  51
  52  </sect2>
  53
  54  <sect2 id="btree-gin-authors">
  55   <title>Authors</title>
  56
  57   <para>
  58    Teodor Sigaev (<email>teodor@stack.net</email>) and
  59    Oleg Bartunov (<email>oleg@sai.msu.su</email>).  See
  60    <ulink url="http://www.sai.msu.su/~megera/oddmuse/index.cgi/Gin"></ulink>
  61    for additional information.
  62   </para>
  63
  64  </sect2>
  65
  66 </sect1>