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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.18. intarray</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="intagg.html" title="F.17. intagg" /><link rel="next" href="isn.html" title="F.19. isn" /></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.18. intarray</th></tr><tr><td width="10%" align="left"><a accesskey="p" href="intagg.html" title="F.17. intagg">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 11.5 Documentation">Home</a></td><td width="10%" align="right"> <a accesskey="n" href="isn.html" title="F.19. isn">Next</a></td></tr></table><hr></hr></div><div class="sect1" id="INTARRAY"><div class="titlepage"><div><div><h2 class="title" style="clear: both">F.18. intarray</h2></div></div></div><div class="toc"><dl class="toc"><dt><span class="sect2"><a href="intarray.html#id-1.11.7.27.6">F.18.1. <code class="filename">intarray</code> Functions and Operators</a></span></dt><dt><span class="sect2"><a href="intarray.html#id-1.11.7.27.7">F.18.2. Index Support</a></span></dt><dt><span class="sect2"><a href="intarray.html#id-1.11.7.27.8">F.18.3. Example</a></span></dt><dt><span class="sect2"><a href="intarray.html#id-1.11.7.27.9">F.18.4. Benchmark</a></span></dt><dt><span class="sect2"><a href="intarray.html#id-1.11.7.27.10">F.18.5. Authors</a></span></dt></dl></div><a id="id-1.11.7.27.2" class="indexterm"></a><p>
The <code class="filename">intarray</code> module provides a number of useful functions
and operators for manipulating null-free arrays of integers.
There is also support for indexed searches using some of the operators.
</p><p>
All of these operations will throw an error if a supplied array contains any
NULL elements.
</p><p>
Many of these operations are only sensible for one-dimensional arrays.
Although they will accept input arrays of more dimensions, the data is
treated as though it were a linear array in storage order.
</p><div class="sect2" id="id-1.11.7.27.6"><div class="titlepage"><div><div><h3 class="title">F.18.1. <code class="filename">intarray</code> Functions and Operators</h3></div></div></div><p>
The functions provided by the <code class="filename">intarray</code> module
are shown in <a class="xref" href="intarray.html#INTARRAY-FUNC-TABLE" title="Table F.9. intarray Functions">Table F.9</a>, the operators
in <a class="xref" href="intarray.html#INTARRAY-OP-TABLE" title="Table F.10. intarray Operators">Table F.10</a>.
</p><div class="table" id="INTARRAY-FUNC-TABLE"><p class="title"><strong>Table F.9. <code class="filename">intarray</code> Functions</strong></p><div class="table-contents"><table class="table" summary="intarray Functions" border="1"><colgroup><col /><col /><col /><col /><col /></colgroup><thead><tr><th>Function</th><th>Return Type</th><th>Description</th><th>Example</th><th>Result</th></tr></thead><tbody><tr><td><code class="function">icount(int[])</code><a id="id-1.11.7.27.6.3.2.2.1.1.2" class="indexterm"></a></td><td><code class="type">int</code></td><td>number of elements in array</td><td><code class="literal">icount('{1,2,3}'::int[])</code></td><td><code class="literal">3</code></td></tr><tr><td><code class="function">sort(int[], text dir)</code><a id="id-1.11.7.27.6.3.2.2.2.1.2" class="indexterm"></a></td><td><code class="type">int[]</code></td><td>sort array — <em class="parameter"><code>dir</code></em> must be <code class="literal">asc</code> or <code class="literal">desc</code></td><td><code class="literal">sort('{1,2,3}'::int[], 'desc')</code></td><td><code class="literal">{3,2,1}</code></td></tr><tr><td><code class="function">sort(int[])</code></td><td><code class="type">int[]</code></td><td>sort in ascending order</td><td><code class="literal">sort(array[11,77,44])</code></td><td><code class="literal">{11,44,77}</code></td></tr><tr><td><code class="function">sort_asc(int[])</code><a id="id-1.11.7.27.6.3.2.2.4.1.2" class="indexterm"></a></td><td><code class="type">int[]</code></td><td>sort in ascending order</td><td><code class="literal"></code></td><td><code class="literal"></code></td></tr><tr><td><code class="function">sort_desc(int[])</code><a id="id-1.11.7.27.6.3.2.2.5.1.2" class="indexterm"></a></td><td><code class="type">int[]</code></td><td>sort in descending order</td><td><code class="literal"></code></td><td><code class="literal"></code></td></tr><tr><td><code class="function">uniq(int[])</code><a id="id-1.11.7.27.6.3.2.2.6.1.2" class="indexterm"></a></td><td><code class="type">int[]</code></td><td>remove adjacent duplicates</td><td><code class="literal">uniq(sort('{1,2,3,2,1}'::int[]))</code></td><td><code class="literal">{1,2,3}</code></td></tr><tr><td><code class="function">idx(int[], int item)</code><a id="id-1.11.7.27.6.3.2.2.7.1.2" class="indexterm"></a></td><td><code class="type">int</code></td><td>index of first element matching <em class="parameter"><code>item</code></em> (0 if none)</td><td><code class="literal">idx(array[11,22,33,22,11], 22)</code></td><td><code class="literal">2</code></td></tr><tr><td><code class="function">subarray(int[], int start, int len)</code><a id="id-1.11.7.27.6.3.2.2.8.1.2" class="indexterm"></a></td><td><code class="type">int[]</code></td><td>portion of array starting at position <em class="parameter"><code>start</code></em>, <em class="parameter"><code>len</code></em> elements</td><td><code class="literal">subarray('{1,2,3,2,1}'::int[], 2, 3)</code></td><td><code class="literal">{2,3,2}</code></td></tr><tr><td><code class="function">subarray(int[], int start)</code></td><td><code class="type">int[]</code></td><td>portion of array starting at position <em class="parameter"><code>start</code></em></td><td><code class="literal">subarray('{1,2,3,2,1}'::int[], 2)</code></td><td><code class="literal">{2,3,2,1}</code></td></tr><tr><td><code class="function">intset(int)</code><a id="id-1.11.7.27.6.3.2.2.10.1.2" class="indexterm"></a></td><td><code class="type">int[]</code></td><td>make single-element array</td><td><code class="literal">intset(42)</code></td><td><code class="literal">{42}</code></td></tr></tbody></table></div></div><br class="table-break" /><div class="table" id="INTARRAY-OP-TABLE"><p class="title"><strong>Table F.10. <code class="filename">intarray</code> Operators</strong></p><div class="table-contents"><table class="table" summary="intarray Operators" border="1"><colgroup><col /><col /><col /></colgroup><thead><tr><th>Operator</th><th>Returns</th><th>Description</th></tr></thead><tbody><tr><td><code class="literal">int[] && int[]</code></td><td><code class="type">boolean</code></td><td>overlap — <code class="literal">true</code> if arrays have at least one common element</td></tr><tr><td><code class="literal">int[] @> int[]</code></td><td><code class="type">boolean</code></td><td>contains — <code class="literal">true</code> if left array contains right array</td></tr><tr><td><code class="literal">int[] <@ int[]</code></td><td><code class="type">boolean</code></td><td>contained — <code class="literal">true</code> if left array is contained in right array</td></tr><tr><td><code class="literal"># int[]</code></td><td><code class="type">int</code></td><td>number of elements in array</td></tr><tr><td><code class="literal">int[] # int</code></td><td><code class="type">int</code></td><td>index (same as <code class="function">idx</code> function)</td></tr><tr><td><code class="literal">int[] + int</code></td><td><code class="type">int[]</code></td><td>push element onto array (add it to end of array)</td></tr><tr><td><code class="literal">int[] + int[] </code></td><td><code class="type">int[]</code></td><td>array concatenation (right array added to the end of left one)</td></tr><tr><td><code class="literal">int[] - int</code></td><td><code class="type">int[]</code></td><td>remove entries matching right argument from array</td></tr><tr><td><code class="literal">int[] - int[]</code></td><td><code class="type">int[]</code></td><td>remove elements of right array from left</td></tr><tr><td><code class="literal">int[] | int</code></td><td><code class="type">int[]</code></td><td>union of arguments</td></tr><tr><td><code class="literal">int[] | int[]</code></td><td><code class="type">int[]</code></td><td>union of arrays</td></tr><tr><td><code class="literal">int[] & int[]</code></td><td><code class="type">int[]</code></td><td>intersection of arrays</td></tr><tr><td><code class="literal">int[] @@ query_int</code></td><td><code class="type">boolean</code></td><td><code class="literal">true</code> if array satisfies query (see below)</td></tr><tr><td><code class="literal">query_int ~~ int[]</code></td><td><code class="type">boolean</code></td><td><code class="literal">true</code> if array satisfies query (commutator of <code class="literal">@@</code>)</td></tr></tbody></table></div></div><br class="table-break" /><p>
(Before PostgreSQL 8.2, the containment operators <code class="literal">@></code> and
<code class="literal"><@</code> were respectively called <code class="literal">@</code> and <code class="literal">~</code>.
These names are still available, but are deprecated and will eventually be
retired. Notice that the old names are reversed from the convention
formerly followed by the core geometric data types!)
</p><p>
The operators <code class="literal">&&</code>, <code class="literal">@></code> and
<code class="literal"><@</code> are equivalent to <span class="productname">PostgreSQL</span>'s built-in
operators of the same names, except that they work only on integer arrays
that do not contain nulls, while the built-in operators work for any array
type. This restriction makes them faster than the built-in operators
in many cases.
</p><p>
The <code class="literal">@@</code> and <code class="literal">~~</code> operators test whether an array
satisfies a <em class="firstterm">query</em>, which is expressed as a value of a
specialized data type <code class="type">query_int</code>. A <em class="firstterm">query</em>
consists of integer values that are checked against the elements of
the array, possibly combined using the operators <code class="literal">&</code>
(AND), <code class="literal">|</code> (OR), and <code class="literal">!</code> (NOT). Parentheses
can be used as needed. For example,
the query <code class="literal">1&(2|3)</code> matches arrays that contain 1
and also contain either 2 or 3.
</p></div><div class="sect2" id="id-1.11.7.27.7"><div class="titlepage"><div><div><h3 class="title">F.18.2. Index Support</h3></div></div></div><p>
<code class="filename">intarray</code> provides index support for the
<code class="literal">&&</code>, <code class="literal">@></code>, <code class="literal"><@</code>,
and <code class="literal">@@</code> operators, as well as regular array equality.
</p><p>
Two GiST index operator classes are provided:
<code class="literal">gist__int_ops</code> (used by default) is suitable for
small- to medium-size data sets, while
<code class="literal">gist__intbig_ops</code> uses a larger signature and is more
suitable for indexing large data sets (i.e., columns containing
a large number of distinct array values).
The implementation uses an RD-tree data structure with
built-in lossy compression.
</p><p>
There is also a non-default GIN operator class
<code class="literal">gin__int_ops</code> supporting the same operators.
</p><p>
The choice between GiST and GIN indexing depends on the relative
performance characteristics of GiST and GIN, which are discussed elsewhere.
</p></div><div class="sect2" id="id-1.11.7.27.8"><div class="titlepage"><div><div><h3 class="title">F.18.3. Example</h3></div></div></div><pre class="programlisting">
-- a message can be in one or more <span class="quote">“<span class="quote">sections</span>”</span>
CREATE TABLE message (mid INT PRIMARY KEY, sections INT[], ...);
-- create specialized index
CREATE INDEX message_rdtree_idx ON message USING GIST (sections gist__int_ops);
-- select messages in section 1 OR 2 - OVERLAP operator
SELECT message.mid FROM message WHERE message.sections && '{1,2}';
-- select messages in sections 1 AND 2 - CONTAINS operator
SELECT message.mid FROM message WHERE message.sections @> '{1,2}';
-- the same, using QUERY operator
SELECT message.mid FROM message WHERE message.sections @@ '1&2'::query_int;
</pre></div><div class="sect2" id="id-1.11.7.27.9"><div class="titlepage"><div><div><h3 class="title">F.18.4. Benchmark</h3></div></div></div><p>
The source directory <code class="filename">contrib/intarray/bench</code> contains a
benchmark test suite, which can be run against an installed
<span class="productname">PostgreSQL</span> server. (It also requires <code class="filename">DBD::Pg</code>
to be installed.) To run:
</p><pre class="programlisting">
cd .../contrib/intarray/bench
createdb TEST
psql -c "CREATE EXTENSION intarray" TEST
./create_test.pl | psql TEST
./bench.pl
</pre><p>
The <code class="filename">bench.pl</code> script has numerous options, which
are displayed when it is run without any arguments.
</p></div><div class="sect2" id="id-1.11.7.27.10"><div class="titlepage"><div><div><h3 class="title">F.18.5. Authors</h3></div></div></div><p>
All work was done by Teodor Sigaev (<code class="email"><<a class="email" href="mailto:teodor@sigaev.ru">teodor@sigaev.ru</a>></code>) and
Oleg Bartunov (<code class="email"><<a class="email" href="mailto:oleg@sai.msu.su">oleg@sai.msu.su</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. Andrey Oktyabrski did a great work on adding new
functions and operations.
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