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<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>F.9. btree_gist</title><link rel="stylesheet" type="text/css" href="stylesheet.css" /><link rev="made" href="pgsql-docs@lists.postgresql.org" /><meta name="generator" content="DocBook XSL Stylesheets Vsnapshot" /><link rel="prev" href="btree-gin.html" title="F.8. btree_gin" /><link rel="next" href="citext.html" title="F.10. citext" /></head><body id="docContent" class="container-fluid col-10"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="5" align="center">F.9. btree_gist</th></tr><tr><td width="10%" align="left"><a accesskey="p" href="btree-gin.html" title="F.8. btree_gin">Prev</a> </td><td width="10%" align="left"><a accesskey="u" href="contrib.html" title="Appendix F. Additional Supplied Modules">Up</a></td><th width="60%" align="center">Appendix F. Additional Supplied Modules</th><td width="10%" align="right"><a accesskey="h" href="index.html" title="PostgreSQL 15.5 Documentation">Home</a></td><td width="10%" align="right"> <a accesskey="n" href="citext.html" title="F.10. citext">Next</a></td></tr></table><hr /></div><div class="sect1" id="BTREE-GIST"><div class="titlepage"><div><div><h2 class="title" style="clear: both">F.9. btree_gist</h2></div></div></div><div class="toc"><dl class="toc"><dt><span class="sect2"><a href="btree-gist.html#id-1.11.7.18.8">F.9.1. Example Usage</a></span></dt><dt><span class="sect2"><a href="btree-gist.html#id-1.11.7.18.9">F.9.2. Authors</a></span></dt></dl></div><a id="id-1.11.7.18.2" class="indexterm"></a><p>
<code class="filename">btree_gist</code> provides GiST index operator classes that
implement B-tree equivalent behavior for the data types
<code class="type">int2</code>, <code class="type">int4</code>, <code class="type">int8</code>, <code class="type">float4</code>,
<code class="type">float8</code>, <code class="type">numeric</code>, <code class="type">timestamp with time zone</code>,
<code class="type">timestamp without time zone</code>, <code class="type">time with time zone</code>,
<code class="type">time without time zone</code>, <code class="type">date</code>, <code class="type">interval</code>,
<code class="type">oid</code>, <code class="type">money</code>, <code class="type">char</code>,
<code class="type">varchar</code>, <code class="type">text</code>, <code class="type">bytea</code>, <code class="type">bit</code>,
<code class="type">varbit</code>, <code class="type">macaddr</code>, <code class="type">macaddr8</code>, <code class="type">inet</code>,
<code class="type">cidr</code>, <code class="type">uuid</code>, <code class="type">bool</code> and all <code class="type">enum</code> types.
</p><p>
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 provide some other features that are not available with a B-tree
index, as described below. Also, these operator classes are useful
when a multicolumn GiST index is needed, wherein some of the columns
are of data types that are only indexable with GiST but other columns
are just simple data types. Lastly, these operator classes are useful for
GiST testing and as a base for developing other GiST operator classes.
</p><p>
In addition to the typical B-tree search operators, <code class="filename">btree_gist</code>
also provides index support for <code class="literal"><></code> (<span class="quote">“<span class="quote">not
equals</span>”</span>). This may be useful in combination with an
<a class="link" href="sql-createtable.html#SQL-CREATETABLE-EXCLUDE">exclusion constraint</a>,
as described below.
</p><p>
Also, for data types for which there is a natural distance metric,
<code class="filename">btree_gist</code> defines a distance operator <code class="literal"><-></code>,
and provides GiST index support for nearest-neighbor searches using
this operator. Distance operators are provided for
<code class="type">int2</code>, <code class="type">int4</code>, <code class="type">int8</code>, <code class="type">float4</code>,
<code class="type">float8</code>, <code class="type">timestamp with time zone</code>,
<code class="type">timestamp without time zone</code>,
<code class="type">time without time zone</code>, <code class="type">date</code>, <code class="type">interval</code>,
<code class="type">oid</code>, and <code class="type">money</code>.
</p><p>
This module is considered <span class="quote">“<span class="quote">trusted</span>”</span>, that is, it can be
installed by non-superusers who have <code class="literal">CREATE</code> privilege
on the current database.
</p><div class="sect2" id="id-1.11.7.18.8"><div class="titlepage"><div><div><h3 class="title">F.9.1. Example Usage</h3></div></div></div><p>
Simple example using <code class="literal">btree_gist</code> instead of <code class="literal">btree</code>:
</p><pre class="programlisting">
CREATE TABLE test (a int4);
-- create index
CREATE INDEX testidx ON test USING GIST (a);
-- query
SELECT * FROM test WHERE a < 10;
-- nearest-neighbor search: find the ten entries closest to "42"
SELECT *, a <-> 42 AS dist FROM test ORDER BY a <-> 42 LIMIT 10;
</pre><p>
Use an <a class="link" href="sql-createtable.html#SQL-CREATETABLE-EXCLUDE">exclusion
constraint</a> to enforce the rule that a cage at a zoo
can contain only one kind of animal:
</p><pre class="programlisting">
=> CREATE TABLE zoo (
cage INTEGER,
animal TEXT,
EXCLUDE USING GIST (cage WITH =, animal WITH <>)
);
=> INSERT INTO zoo VALUES(123, 'zebra');
INSERT 0 1
=> INSERT INTO zoo VALUES(123, 'zebra');
INSERT 0 1
=> INSERT INTO zoo VALUES(123, 'lion');
ERROR: conflicting key value violates exclusion constraint "zoo_cage_animal_excl"
DETAIL: Key (cage, animal)=(123, lion) conflicts with existing key (cage, animal)=(123, zebra).
=> INSERT INTO zoo VALUES(124, 'lion');
INSERT 0 1
</pre></div><div class="sect2" id="id-1.11.7.18.9"><div class="titlepage"><div><div><h3 class="title">F.9.2. Authors</h3></div></div></div><p>
Teodor Sigaev (<code class="email"><<a class="email" href="mailto:teodor@stack.net">teodor@stack.net</a>></code>),
Oleg Bartunov (<code class="email"><<a class="email" href="mailto:oleg@sai.msu.su">oleg@sai.msu.su</a>></code>),
Janko Richter (<code class="email"><<a class="email" href="mailto:jankorichter@yahoo.de">jankorichter@yahoo.de</a>></code>), and
Paul Jungwirth (<code class="email"><<a class="email" href="mailto:pj@illuminatedcomputing.com">pj@illuminatedcomputing.com</a>></code>). See
<a class="ulink" href="http://www.sai.msu.su/~megera/postgres/gist/" target="_top">http://www.sai.msu.su/~megera/postgres/gist/</a>
for additional information.
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