1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
|
<!-- $PostgreSQL: pgsql/doc/src/sgml/btree-gin.sgml,v 1.2 2010/08/17 04:37:20 petere Exp $ -->
<sect1 id="btree-gin">
<title>btree_gin</title>
<indexterm zone="btree-gin">
<primary>btree_gin</primary>
</indexterm>
<para>
<filename>btree_gin</> provides sample GIN operator classes that
implement B-tree equivalent behavior for the data types
<type>int2</>, <type>int4</>, <type>int8</>, <type>float4</>,
<type>float8</>, <type>timestamp with time zone</>,
<type>timestamp without time zone</>, <type>time with time zone</>,
<type>time without time zone</>, <type>date</>, <type>interval</>,
<type>oid</>, <type>money</>, <type>"char"</>,
<type>varchar</>, <type>text</>, <type>bytea</>, <type>bit</>,
<type>varbit</>, <type>macaddr</>, <type>inet</>, and <type>cidr</>.
</para>
<para>
In general, these operator classes will not outperform the equivalent
standard B-tree index methods, and they lack one major feature of the
standard B-tree code: the ability to enforce uniqueness. However,
they are useful for GIN testing and as a base for developing other
GIN operator classes. Also, for queries that test both a GIN-indexable
column and a B-tree-indexable column, it might be more efficient to create
a multicolumn GIN index that uses one of these operator classes than to create
two separate indexes that would have to be combined via bitmap ANDing.
</para>
<sect2>
<title>Example usage</title>
<programlisting>
CREATE TABLE test (a int4);
-- create index
CREATE INDEX testidx ON test USING gin (a);
-- query
SELECT * FROM test WHERE a < 10;
</programlisting>
</sect2>
<sect2>
<title>Authors</title>
<para>
Teodor Sigaev (<email>teodor@stack.net</email>) and
Oleg Bartunov (<email>oleg@sai.msu.su</email>). See
<ulink url="http://www.sai.msu.su/~megera/oddmuse/index.cgi/Gin"></ulink>
for additional information.
</para>
</sect2>
</sect1>
|
