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diff --git a/doc/src/sgml/html/btree-gist.html b/doc/src/sgml/html/btree-gist.html new file mode 100644 index 0000000..56aa8db --- /dev/null +++ b/doc/src/sgml/html/btree-gist.html @@ -0,0 +1,80 @@ +<?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. + </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" title="F.8. btree_gin">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="contrib.html" title="Appendix F. 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