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- <!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.7. 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 V1.79.1" /><link rel="prev" href="btree-gin.html" title="F.6. btree_gin" /><link rel="next" href="citext.html" title="F.8. citext" /></head><body><div xmlns="http://www.w3.org/TR/xhtml1/transitional" class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="5" align="center">F.7. btree_gist</th></tr><tr><td width="10%" align="left"><a accesskey="p" href="btree-gin.html" title="F.6. 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 12.4 Documentation">Home</a></td><td width="10%" align="right"> <a accesskey="n" href="citext.html" title="F.8. citext">Next</a></td></tr></table><hr></hr></div><div class="sect1" id="BTREE-GIST"><div class="titlepage"><div><div><h2 class="title" style="clear: both">F.7. btree_gist</h2></div></div></div><div class="toc"><dl class="toc"><dt><span class="sect2"><a href="btree-gist.html#id-1.11.7.16.7">F.7.1. Example Usage</a></span></dt><dt><span class="sect2"><a href="btree-gist.html#id-1.11.7.16.8">F.7.2. Authors</a></span></dt></dl></div><a id="id-1.11.7.16.2" 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>, 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><div class="sect2" id="id-1.11.7.16.7"><div class="titlepage"><div><div><h3 class="title">F.7.1. 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-1.11.7.16.8"><div class="titlepage"><div><div><h3 class="title">F.7.2. 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.
- </p></div></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="btree-gin.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="contrib.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="citext.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">F.6. btree_gin </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> F.8. citext</td></tr></table></div></body></html>
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