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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.20. 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.19. intagg" /><link rel="next" href="isn.html" title="F.21. isn" /></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.20. intarray</th></tr><tr><td width="10%" align="left"><a accesskey="p" href="intagg.html" title="F.19. 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 15.7 Documentation">Home</a></td><td width="10%" align="right"> <a accesskey="n" href="isn.html" title="F.21. isn">Next</a></td></tr></table><hr /></div><div class="sect1" id="INTARRAY"><div class="titlepage"><div><div><h2 class="title" style="clear: both">F.20. intarray</h2></div></div></div><div class="toc"><dl class="toc"><dt><span class="sect2"><a href="intarray.html#id-1.11.7.29.7">F.20.1. <code class="filename">intarray</code> Functions and Operators</a></span></dt><dt><span class="sect2"><a href="intarray.html#id-1.11.7.29.8">F.20.2. Index Support</a></span></dt><dt><span class="sect2"><a href="intarray.html#id-1.11.7.29.9">F.20.3. Example</a></span></dt><dt><span class="sect2"><a href="intarray.html#id-1.11.7.29.10">F.20.4. Benchmark</a></span></dt><dt><span class="sect2"><a href="intarray.html#id-1.11.7.29.11">F.20.5. Authors</a></span></dt></dl></div><a id="id-1.11.7.29.2" 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><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-1.11.7.29.7"><div class="titlepage"><div><div><h3 class="title">F.20.1. <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 /></colgroup><thead><tr><th class="func_table_entry"><p class="func_signature">
Function
</p>
<p>
Description
</p>
<p>
Example(s)
</p></th></tr></thead><tbody><tr><td class="func_table_entry"><p class="func_signature">
<a id="id-1.11.7.29.7.3.2.2.1.1.1.1" class="indexterm"></a>
<code class="function">icount</code> ( <code class="type">integer[]</code> )
→ <code class="returnvalue">integer</code>
</p>
<p>
Returns the number of elements in the array.
</p>
<p>
<code class="literal">icount('{1,2,3}'::integer[])</code>
→ <code class="returnvalue">3</code>
</p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
<a id="id-1.11.7.29.7.3.2.2.2.1.1.1" class="indexterm"></a>
<code class="function">sort</code> ( <code class="type">integer[]</code>, <em class="parameter"><code>dir</code></em> <code class="type">text</code> )
→ <code class="returnvalue">integer[]</code>
</p>
<p>
Sorts the array in either ascending or descending order.
<em class="parameter"><code>dir</code></em> must be <code class="literal">asc</code>
or <code class="literal">desc</code>.
</p>
<p>
<code class="literal">sort('{1,3,2}'::integer[], 'desc')</code>
→ <code class="returnvalue">{3,2,1}</code>
</p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
<code class="function">sort</code> ( <code class="type">integer[]</code> )
→ <code class="returnvalue">integer[]</code>
</p>
<p class="func_signature">
<a id="id-1.11.7.29.7.3.2.2.3.1.2.1" class="indexterm"></a>
<code class="function">sort_asc</code> ( <code class="type">integer[]</code> )
→ <code class="returnvalue">integer[]</code>
</p>
<p>
Sorts in ascending order.
</p>
<p>
<code class="literal">sort(array[11,77,44])</code>
→ <code class="returnvalue">{11,44,77}</code>
</p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
<a id="id-1.11.7.29.7.3.2.2.4.1.1.1" class="indexterm"></a>
<code class="function">sort_desc</code> ( <code class="type">integer[]</code> )
→ <code class="returnvalue">integer[]</code>
</p>
<p>
Sorts in descending order.
</p>
<p>
<code class="literal">sort_desc(array[11,77,44])</code>
→ <code class="returnvalue">{77,44,11}</code>
</p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
<a id="id-1.11.7.29.7.3.2.2.5.1.1.1" class="indexterm"></a>
<code class="function">uniq</code> ( <code class="type">integer[]</code> )
→ <code class="returnvalue">integer[]</code>
</p>
<p>
Removes adjacent duplicates.
Often used with <code class="function">sort</code> to remove all duplicates.
</p>
<p>
<code class="literal">uniq('{1,2,2,3,1,1}'::integer[])</code>
→ <code class="returnvalue">{1,2,3,1}</code>
</p>
<p>
<code class="literal">uniq(sort('{1,2,3,2,1}'::integer[]))</code>
→ <code class="returnvalue">{1,2,3}</code>
</p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
<a id="id-1.11.7.29.7.3.2.2.6.1.1.1" class="indexterm"></a>
<code class="function">idx</code> ( <code class="type">integer[]</code>, <em class="parameter"><code>item</code></em> <code class="type">integer</code> )
→ <code class="returnvalue">integer</code>
</p>
<p>
Returns index of the first array element
matching <em class="parameter"><code>item</code></em>, or 0 if no match.
</p>
<p>
<code class="literal">idx(array[11,22,33,22,11], 22)</code>
→ <code class="returnvalue">2</code>
</p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
<a id="id-1.11.7.29.7.3.2.2.7.1.1.1" class="indexterm"></a>
<code class="function">subarray</code> ( <code class="type">integer[]</code>, <em class="parameter"><code>start</code></em> <code class="type">integer</code>, <em class="parameter"><code>len</code></em> <code class="type">integer</code> )
→ <code class="returnvalue">integer[]</code>
</p>
<p>
Extracts the portion of the array starting at
position <em class="parameter"><code>start</code></em>, with <em class="parameter"><code>len</code></em>
elements.
</p>
<p>
<code class="literal">subarray('{1,2,3,2,1}'::integer[], 2, 3)</code>
→ <code class="returnvalue">{2,3,2}</code>
</p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
<code class="function">subarray</code> ( <code class="type">integer[]</code>, <em class="parameter"><code>start</code></em> <code class="type">integer</code> )
→ <code class="returnvalue">integer[]</code>
</p>
<p>
Extracts the portion of the array starting at
position <em class="parameter"><code>start</code></em>.
</p>
<p>
<code class="literal">subarray('{1,2,3,2,1}'::integer[], 2)</code>
→ <code class="returnvalue">{2,3,2,1}</code>
</p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
<a id="id-1.11.7.29.7.3.2.2.9.1.1.1" class="indexterm"></a>
<code class="function">intset</code> ( <code class="type">integer</code> )
→ <code class="returnvalue">integer[]</code>
</p>
<p>
Makes a single-element array.
</p>
<p>
<code class="literal">intset(42)</code>
→ <code class="returnvalue">{42}</code>
</p></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 /></colgroup><thead><tr><th class="func_table_entry"><p class="func_signature">
Operator
</p>
<p>
Description
</p></th></tr></thead><tbody><tr><td class="func_table_entry"><p class="func_signature">
<code class="type">integer[]</code> <code class="literal">&&</code> <code class="type">integer[]</code>
→ <code class="returnvalue">boolean</code>
</p>
<p>
Do arrays overlap (have at least one element in common)?
</p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
<code class="type">integer[]</code> <code class="literal">@></code> <code class="type">integer[]</code>
→ <code class="returnvalue">boolean</code>
</p>
<p>
Does left array contain right array?
</p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
<code class="type">integer[]</code> <code class="literal"><@</code> <code class="type">integer[]</code>
→ <code class="returnvalue">boolean</code>
</p>
<p>
Is left array contained in right array?
</p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
<code class="type"></code> <code class="literal">#</code> <code class="type">integer[]</code>
→ <code class="returnvalue">integer</code>
</p>
<p>
Returns the number of elements in the array.
</p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
<code class="type">integer[]</code> <code class="literal">#</code> <code class="type">integer</code>
→ <code class="returnvalue">integer</code>
</p>
<p>
Returns index of the first array element
matching the right argument, or 0 if no match.
(Same as <code class="function">idx</code> function.)
</p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
<code class="type">integer[]</code> <code class="literal">+</code> <code class="type">integer</code>
→ <code class="returnvalue">integer[]</code>
</p>
<p>
Adds element to end of array.
</p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
<code class="type">integer[]</code> <code class="literal">+</code> <code class="type">integer[]</code>
→ <code class="returnvalue">integer[]</code>
</p>
<p>
Concatenates the arrays.
</p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
<code class="type">integer[]</code> <code class="literal">-</code> <code class="type">integer</code>
→ <code class="returnvalue">integer[]</code>
</p>
<p>
Removes entries matching the right argument from the array.
</p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
<code class="type">integer[]</code> <code class="literal">-</code> <code class="type">integer[]</code>
→ <code class="returnvalue">integer[]</code>
</p>
<p>
Removes elements of the right array from the left array.
</p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
<code class="type">integer[]</code> <code class="literal">|</code> <code class="type">integer</code>
→ <code class="returnvalue">integer[]</code>
</p>
<p>
Computes the union of the arguments.
</p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
<code class="type">integer[]</code> <code class="literal">|</code> <code class="type">integer[]</code>
→ <code class="returnvalue">integer[]</code>
</p>
<p>
Computes the union of the arguments.
</p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
<code class="type">integer[]</code> <code class="literal">&</code> <code class="type">integer[]</code>
→ <code class="returnvalue">integer[]</code>
</p>
<p>
Computes the intersection of the arguments.
</p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
<code class="type">integer[]</code> <code class="literal">@@</code> <code class="type">query_int</code>
→ <code class="returnvalue">boolean</code>
</p>
<p>
Does array satisfy query? (see below)
</p></td></tr><tr><td class="func_table_entry"><p class="func_signature">
<code class="type">query_int</code> <code class="literal">~~</code> <code class="type">integer[]</code>
→ <code class="returnvalue">boolean</code>
</p>
<p>
Does array satisfy query? (commutator of <code class="literal">@@</code>)
</p></td></tr></tbody></table></div></div><br class="table-break" /><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-1.11.7.29.8"><div class="titlepage"><div><div><h3 class="title">F.20.2. 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>,
and <code class="literal">@@</code> operators, as well as regular array equality.
</p><p>
Two parameterized 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>
<code class="literal">gist__int_ops</code> approximates an integer set as an array of
integer ranges. Its optional integer parameter <code class="literal">numranges</code>
determines the maximum number of ranges in
one index key. The default value of <code class="literal">numranges</code> is 100.
Valid values are between 1 and 253. Using larger arrays as GiST index
keys leads to a more precise search (scanning a smaller fraction of the index and
fewer heap pages), at the cost of a larger index.
</p><p>
<code class="literal">gist__intbig_ops</code> approximates an integer set as a bitmap
signature. Its optional integer parameter <code class="literal">siglen</code>
determines the signature length in bytes.
The default signature length is 16 bytes. Valid values of signature length
are between 1 and 2024 bytes. Longer signatures lead to a more precise
search (scanning a smaller fraction of the index and fewer heap pages), at
the cost of a larger index.
</p><p>
There is also a non-default GIN operator class
<code class="literal">gin__int_ops</code>, which supports these operators as well
as <code class="literal"><@</code>.
</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-1.11.7.29.9"><div class="titlepage"><div><div><h3 class="title">F.20.3. 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 with signature length of 32 bytes
CREATE INDEX message_rdtree_idx ON message USING GIST (sections gist__intbig_ops (siglen = 32));
-- 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-1.11.7.29.10"><div class="titlepage"><div><div><h3 class="title">F.20.4. 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-1.11.7.29.11"><div class="titlepage"><div><div><h3 class="title">F.20.5. 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.
</p></div></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="intagg.html" title="F.19. intagg">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="contrib.html" title="Appendix F. Additional Supplied Modules">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="isn.html" title="F.21. isn">Next</a></td></tr><tr><td width="40%" align="left" valign="top">F.19. intagg </td><td width="20%" align="center"><a accesskey="h" href="index.html" title="PostgreSQL 15.7 Documentation">Home</a></td><td width="40%" align="right" valign="top"> F.21. isn</td></tr></table></div></body></html>
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