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1<?xml version="1.0" encoding="UTF-8" standalone="no"?>2<!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>9.19. Array Functions and Operators</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="functions-conditional.html" title="9.18. Conditional Expressions" /><link rel="next" href="functions-range.html" title="9.20. Range/Multirange Functions and Operators" /></head><body id="docContent" class="container-fluid col-10"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="5" align="center">9.19. Array Functions and Operators</th></tr><tr><td width="10%" align="left"><a accesskey="p" href="functions-conditional.html" title="9.18. Conditional Expressions">Prev</a> </td><td width="10%" align="left"><a accesskey="u" href="functions.html" title="Chapter 9. Functions and Operators">Up</a></td><th width="60%" align="center">Chapter 9. Functions and Operators</th><td width="10%" align="right"><a accesskey="h" href="index.html" title="PostgreSQL 16.3 Documentation">Home</a></td><td width="10%" align="right"> <a accesskey="n" href="functions-range.html" title="9.20. Range/Multirange Functions and Operators">Next</a></td></tr></table><hr /></div><div class="sect1" id="FUNCTIONS-ARRAY"><div class="titlepage"><div><div><h2 class="title" style="clear: both">9.19. Array Functions and Operators <a href="#FUNCTIONS-ARRAY" class="id_link">#</a></h2></div></div></div><p>3   <a class="xref" href="functions-array.html#ARRAY-OPERATORS-TABLE" title="Table 9.53. Array Operators">Table 9.53</a> shows the specialized operators4   available for array types.5   In addition to those, the usual comparison operators shown in <a class="xref" href="functions-comparison.html#FUNCTIONS-COMPARISON-OP-TABLE" title="Table 9.1. Comparison Operators">Table 9.1</a> are available for6   arrays.  The comparison operators compare the array contents7   element-by-element, using the default B-tree comparison function for8   the element data type, and sort based on the first difference.9   In multidimensional arrays the elements are visited in row-major order10   (last subscript varies most rapidly).11   If the contents of two arrays are equal but the dimensionality is12   different, the first difference in the dimensionality information13   determines the sort order.14  </p><div class="table" id="ARRAY-OPERATORS-TABLE"><p class="title"><strong>Table 9.53. Array Operators</strong></p><div class="table-contents"><table class="table" summary="Array Operators" border="1"><colgroup><col /></colgroup><thead><tr><th class="func_table_entry"><p class="func_signature">15        Operator16       </p>17       <p>18        Description19       </p>20       <p>21        Example(s)22       </p></th></tr></thead><tbody><tr><td class="func_table_entry"><p class="func_signature">23        <code class="type">anyarray</code> <code class="literal">@&gt;</code> <code class="type">anyarray</code>24        → <code class="returnvalue">boolean</code>25       </p>26       <p>27        Does the first array contain the second, that is, does each element28        appearing in the second array equal some element of the first array?29        (Duplicates are not treated specially,30        thus <code class="literal">ARRAY[1]</code> and <code class="literal">ARRAY[1,1]</code> are31        each considered to contain the other.)32       </p>33       <p>34        <code class="literal">ARRAY[1,4,3] @&gt; ARRAY[3,1,3]</code>35        → <code class="returnvalue">t</code>36       </p></td></tr><tr><td class="func_table_entry"><p class="func_signature">37        <code class="type">anyarray</code> <code class="literal">&lt;@</code> <code class="type">anyarray</code>38        → <code class="returnvalue">boolean</code>39       </p>40       <p>41        Is the first array contained by the second?42       </p>43       <p>44        <code class="literal">ARRAY[2,2,7] &lt;@ ARRAY[1,7,4,2,6]</code>45        → <code class="returnvalue">t</code>46       </p></td></tr><tr><td class="func_table_entry"><p class="func_signature">47        <code class="type">anyarray</code> <code class="literal">&amp;&amp;</code> <code class="type">anyarray</code>48        → <code class="returnvalue">boolean</code>49       </p>50       <p>51        Do the arrays overlap, that is, have any elements in common?52       </p>53       <p>54        <code class="literal">ARRAY[1,4,3] &amp;&amp; ARRAY[2,1]</code>55        → <code class="returnvalue">t</code>56       </p></td></tr><tr><td class="func_table_entry"><p class="func_signature">57        <code class="type">anycompatiblearray</code> <code class="literal">||</code> <code class="type">anycompatiblearray</code>58        → <code class="returnvalue">anycompatiblearray</code>59       </p>60       <p>61        Concatenates the two arrays.  Concatenating a null or empty array is a62        no-op; otherwise the arrays must have the same number of dimensions63        (as illustrated by the first example) or differ in number of64        dimensions by one (as illustrated by the second).65        If the arrays are not of identical element types, they will be coerced66        to a common type (see <a class="xref" href="typeconv-union-case.html" title="10.5. UNION, CASE, and Related Constructs">Section 10.5</a>).67       </p>68       <p>69        <code class="literal">ARRAY[1,2,3] || ARRAY[4,5,6,7]</code>70        → <code class="returnvalue">{1,2,3,4,5,6,7}</code>71       </p>72       <p>73        <code class="literal">ARRAY[1,2,3] || ARRAY[[4,5,6],[7,8,9.9]]</code>74        → <code class="returnvalue">{{1,2,3},{4,5,6},{7,8,9.9}}</code>75       </p></td></tr><tr><td class="func_table_entry"><p class="func_signature">76        <code class="type">anycompatible</code> <code class="literal">||</code> <code class="type">anycompatiblearray</code>77        → <code class="returnvalue">anycompatiblearray</code>78       </p>79       <p>80        Concatenates an element onto the front of an array (which must be81        empty or one-dimensional).82       </p>83       <p>84        <code class="literal">3 || ARRAY[4,5,6]</code>85        → <code class="returnvalue">{3,4,5,6}</code>86       </p></td></tr><tr><td class="func_table_entry"><p class="func_signature">87        <code class="type">anycompatiblearray</code> <code class="literal">||</code> <code class="type">anycompatible</code>88        → <code class="returnvalue">anycompatiblearray</code>89       </p>90       <p>91        Concatenates an element onto the end of an array (which must be92        empty or one-dimensional).93       </p>94       <p>95        <code class="literal">ARRAY[4,5,6] || 7</code>96        → <code class="returnvalue">{4,5,6,7}</code>97       </p></td></tr></tbody></table></div></div><br class="table-break" /><p>98   See <a class="xref" href="arrays.html" title="8.15. Arrays">Section 8.15</a> for more details about array operator99   behavior.  See <a class="xref" href="indexes-types.html" title="11.2. Index Types">Section 11.2</a> for more details about100   which operators support indexed operations.101  </p><p>102   <a class="xref" href="functions-array.html#ARRAY-FUNCTIONS-TABLE" title="Table 9.54. Array Functions">Table 9.54</a> shows the functions103   available for use with array types. See <a class="xref" href="arrays.html" title="8.15. Arrays">Section 8.15</a>104   for more information  and examples of the use of these functions.105  </p><div class="table" id="ARRAY-FUNCTIONS-TABLE"><p class="title"><strong>Table 9.54. Array Functions</strong></p><div class="table-contents"><table class="table" summary="Array Functions" border="1"><colgroup><col /></colgroup><thead><tr><th class="func_table_entry"><p class="func_signature">106        Function107       </p>108       <p>109        Description110       </p>111       <p>112        Example(s)113       </p></th></tr></thead><tbody><tr><td class="func_table_entry"><p class="func_signature">114        <a id="id-1.5.8.25.6.2.2.1.1.1.1" class="indexterm"></a>115        <code class="function">array_append</code> ( <code class="type">anycompatiblearray</code>, <code class="type">anycompatible</code> )116        → <code class="returnvalue">anycompatiblearray</code>117       </p>118       <p>119        Appends an element to the end of an array (same as120        the <code class="type">anycompatiblearray</code> <code class="literal">||</code> <code class="type">anycompatible</code>121        operator).122       </p>123       <p>124        <code class="literal">array_append(ARRAY[1,2], 3)</code>125        → <code class="returnvalue">{1,2,3}</code>126       </p></td></tr><tr><td class="func_table_entry"><p class="func_signature">127        <a id="id-1.5.8.25.6.2.2.2.1.1.1" class="indexterm"></a>128        <code class="function">array_cat</code> ( <code class="type">anycompatiblearray</code>, <code class="type">anycompatiblearray</code> )129        → <code class="returnvalue">anycompatiblearray</code>130       </p>131       <p>132        Concatenates two arrays (same as133        the <code class="type">anycompatiblearray</code> <code class="literal">||</code> <code class="type">anycompatiblearray</code>134        operator).135       </p>136       <p>137        <code class="literal">array_cat(ARRAY[1,2,3], ARRAY[4,5])</code>138        → <code class="returnvalue">{1,2,3,4,5}</code>139       </p></td></tr><tr><td class="func_table_entry"><p class="func_signature">140        <a id="id-1.5.8.25.6.2.2.3.1.1.1" class="indexterm"></a>141        <code class="function">array_dims</code> ( <code class="type">anyarray</code> )142        → <code class="returnvalue">text</code>143       </p>144       <p>145        Returns a text representation of the array's dimensions.146       </p>147       <p>148        <code class="literal">array_dims(ARRAY[[1,2,3], [4,5,6]])</code>149        → <code class="returnvalue">[1:2][1:3]</code>150       </p></td></tr><tr><td class="func_table_entry"><p class="func_signature">151        <a id="id-1.5.8.25.6.2.2.4.1.1.1" class="indexterm"></a>152        <code class="function">array_fill</code> ( <code class="type">anyelement</code>, <code class="type">integer[]</code>153          [<span class="optional">, <code class="type">integer[]</code> </span>] )154        → <code class="returnvalue">anyarray</code>155       </p>156       <p>157        Returns an array filled with copies of the given value, having158        dimensions of the lengths specified by the second argument.159        The optional third argument supplies lower-bound values for each160        dimension (which default to all <code class="literal">1</code>).161       </p>162       <p>163        <code class="literal">array_fill(11, ARRAY[2,3])</code>164        → <code class="returnvalue">{{11,11,11},{11,11,11}}</code>165       </p>166       <p>167        <code class="literal">array_fill(7, ARRAY[3], ARRAY[2])</code>168        → <code class="returnvalue">[2:4]={7,7,7}</code>169       </p></td></tr><tr><td class="func_table_entry"><p class="func_signature">170        <a id="id-1.5.8.25.6.2.2.5.1.1.1" class="indexterm"></a>171        <code class="function">array_length</code> ( <code class="type">anyarray</code>, <code class="type">integer</code> )172        → <code class="returnvalue">integer</code>173       </p>174       <p>175        Returns the length of the requested array dimension.176        (Produces NULL instead of 0 for empty or missing array dimensions.)177       </p>178       <p>179        <code class="literal">array_length(array[1,2,3], 1)</code>180        → <code class="returnvalue">3</code>181       </p>182       <p>183        <code class="literal">array_length(array[]::int[], 1)</code>184        → <code class="returnvalue">NULL</code>185       </p>186       <p>187        <code class="literal">array_length(array['text'], 2)</code>188        → <code class="returnvalue">NULL</code>189       </p></td></tr><tr><td class="func_table_entry"><p class="func_signature">190        <a id="id-1.5.8.25.6.2.2.6.1.1.1" class="indexterm"></a>191        <code class="function">array_lower</code> ( <code class="type">anyarray</code>, <code class="type">integer</code> )192        → <code class="returnvalue">integer</code>193       </p>194       <p>195        Returns the lower bound of the requested array dimension.196       </p>197       <p>198        <code class="literal">array_lower('[0:2]={1,2,3}'::integer[], 1)</code>199        → <code class="returnvalue">0</code>200       </p></td></tr><tr><td class="func_table_entry"><p class="func_signature">201        <a id="id-1.5.8.25.6.2.2.7.1.1.1" class="indexterm"></a>202        <code class="function">array_ndims</code> ( <code class="type">anyarray</code> )203        → <code class="returnvalue">integer</code>204       </p>205       <p>206        Returns the number of dimensions of the array.207       </p>208       <p>209        <code class="literal">array_ndims(ARRAY[[1,2,3], [4,5,6]])</code>210        → <code class="returnvalue">2</code>211       </p></td></tr><tr><td class="func_table_entry"><p class="func_signature">212        <a id="id-1.5.8.25.6.2.2.8.1.1.1" class="indexterm"></a>213        <code class="function">array_position</code> ( <code class="type">anycompatiblearray</code>, <code class="type">anycompatible</code> [<span class="optional">, <code class="type">integer</code> </span>] )214        → <code class="returnvalue">integer</code>215       </p>216       <p>217        Returns the subscript of the first occurrence of the second argument218        in the array, or <code class="literal">NULL</code> if it's not present.219        If the third argument is given, the search begins at that subscript.220        The array must be one-dimensional.221        Comparisons are done using <code class="literal">IS NOT DISTINCT FROM</code>222        semantics, so it is possible to search for <code class="literal">NULL</code>.223       </p>224       <p>225        <code class="literal">array_position(ARRAY['sun', 'mon', 'tue', 'wed', 'thu', 'fri', 'sat'], 'mon')</code>226        → <code class="returnvalue">2</code>227       </p></td></tr><tr><td class="func_table_entry"><p class="func_signature">228        <a id="id-1.5.8.25.6.2.2.9.1.1.1" class="indexterm"></a>229        <code class="function">array_positions</code> ( <code class="type">anycompatiblearray</code>, <code class="type">anycompatible</code> )230        → <code class="returnvalue">integer[]</code>231       </p>232       <p>233        Returns an array of the subscripts of all occurrences of the second234        argument in the array given as first argument.235        The array must be one-dimensional.236        Comparisons are done using <code class="literal">IS NOT DISTINCT FROM</code>237        semantics, so it is possible to search for <code class="literal">NULL</code>.238        <code class="literal">NULL</code> is returned only if the array239        is <code class="literal">NULL</code>; if the value is not found in the array, an240        empty array is returned.241       </p>242       <p>243        <code class="literal">array_positions(ARRAY['A','A','B','A'], 'A')</code>244        → <code class="returnvalue">{1,2,4}</code>245       </p></td></tr><tr><td class="func_table_entry"><p class="func_signature">246        <a id="id-1.5.8.25.6.2.2.10.1.1.1" class="indexterm"></a>247        <code class="function">array_prepend</code> ( <code class="type">anycompatible</code>, <code class="type">anycompatiblearray</code> )248        → <code class="returnvalue">anycompatiblearray</code>249       </p>250       <p>251        Prepends an element to the beginning of an array (same as252        the <code class="type">anycompatible</code> <code class="literal">||</code> <code class="type">anycompatiblearray</code>253        operator).254       </p>255       <p>256        <code class="literal">array_prepend(1, ARRAY[2,3])</code>257        → <code class="returnvalue">{1,2,3}</code>258       </p></td></tr><tr><td class="func_table_entry"><p class="func_signature">259        <a id="id-1.5.8.25.6.2.2.11.1.1.1" class="indexterm"></a>260        <code class="function">array_remove</code> ( <code class="type">anycompatiblearray</code>, <code class="type">anycompatible</code> )261        → <code class="returnvalue">anycompatiblearray</code>262       </p>263       <p>264        Removes all elements equal to the given value from the array.265        The array must be one-dimensional.266        Comparisons are done using <code class="literal">IS NOT DISTINCT FROM</code>267        semantics, so it is possible to remove <code class="literal">NULL</code>s.268       </p>269       <p>270        <code class="literal">array_remove(ARRAY[1,2,3,2], 2)</code>271        → <code class="returnvalue">{1,3}</code>272       </p></td></tr><tr><td class="func_table_entry"><p class="func_signature">273        <a id="id-1.5.8.25.6.2.2.12.1.1.1" class="indexterm"></a>274        <code class="function">array_replace</code> ( <code class="type">anycompatiblearray</code>, <code class="type">anycompatible</code>, <code class="type">anycompatible</code> )275        → <code class="returnvalue">anycompatiblearray</code>276       </p>277       <p>278        Replaces each array element equal to the second argument with the279        third argument.280       </p>281       <p>282        <code class="literal">array_replace(ARRAY[1,2,5,4], 5, 3)</code>283        → <code class="returnvalue">{1,2,3,4}</code>284       </p></td></tr><tr><td class="func_table_entry"><p class="func_signature">285        <a id="id-1.5.8.25.6.2.2.13.1.1.1" class="indexterm"></a>286        <code class="function">array_sample</code> ( <em class="parameter"><code>array</code></em> <code class="type">anyarray</code>, <em class="parameter"><code>n</code></em> <code class="type">integer</code> )287        → <code class="returnvalue">anyarray</code>288       </p>289       <p>290        Returns an array of <em class="parameter"><code>n</code></em> items randomly selected291        from <em class="parameter"><code>array</code></em>.  <em class="parameter"><code>n</code></em> may not292        exceed the length of <em class="parameter"><code>array</code></em>'s first dimension.293        If <em class="parameter"><code>array</code></em> is multi-dimensional,294        an <span class="quote">“<span class="quote">item</span>”</span> is a slice having a given first subscript.295       </p>296       <p>297        <code class="literal">array_sample(ARRAY[1,2,3,4,5,6], 3)</code>298        → <code class="returnvalue">{2,6,1}</code>299       </p>300       <p>301        <code class="literal">array_sample(ARRAY[[1,2],[3,4],[5,6]], 2)</code>302        → <code class="returnvalue">{{5,6},{1,2}}</code>303       </p></td></tr><tr><td class="func_table_entry"><p class="func_signature">304        <a id="id-1.5.8.25.6.2.2.14.1.1.1" class="indexterm"></a>305        <code class="function">array_shuffle</code> ( <code class="type">anyarray</code> )306        → <code class="returnvalue">anyarray</code>307       </p>308       <p>309        Randomly shuffles the first dimension of the array.310       </p>311       <p>312        <code class="literal">array_shuffle(ARRAY[[1,2],[3,4],[5,6]])</code>313        → <code class="returnvalue">{{5,6},{1,2},{3,4}}</code>314       </p></td></tr><tr><td class="func_table_entry"><p class="func_signature">315        <a id="FUNCTION-ARRAY-TO-STRING" class="indexterm"></a>316        <code class="function">array_to_string</code> ( <em class="parameter"><code>array</code></em> <code class="type">anyarray</code>, <em class="parameter"><code>delimiter</code></em> <code class="type">text</code> [<span class="optional">, <em class="parameter"><code>null_string</code></em> <code class="type">text</code> </span>] )317        → <code class="returnvalue">text</code>318       </p>319       <p>320        Converts each array element to its text representation, and321        concatenates those separated by322        the <em class="parameter"><code>delimiter</code></em> string.323        If <em class="parameter"><code>null_string</code></em> is given and is324        not <code class="literal">NULL</code>, then <code class="literal">NULL</code> array325        entries are represented by that string; otherwise, they are omitted.326        See also <a class="link" href="functions-string.html#FUNCTION-STRING-TO-ARRAY"><code class="function">string_to_array</code></a>.327       </p>328       <p>329        <code class="literal">array_to_string(ARRAY[1, 2, 3, NULL, 5], ',', '*')</code>330        → <code class="returnvalue">1,2,3,*,5</code>331       </p></td></tr><tr><td class="func_table_entry"><p class="func_signature">332        <a id="id-1.5.8.25.6.2.2.16.1.1.1" class="indexterm"></a>333        <code class="function">array_upper</code> ( <code class="type">anyarray</code>, <code class="type">integer</code> )334        → <code class="returnvalue">integer</code>335       </p>336       <p>337        Returns the upper bound of the requested array dimension.338       </p>339       <p>340        <code class="literal">array_upper(ARRAY[1,8,3,7], 1)</code>341        → <code class="returnvalue">4</code>342       </p></td></tr><tr><td class="func_table_entry"><p class="func_signature">343        <a id="id-1.5.8.25.6.2.2.17.1.1.1" class="indexterm"></a>344        <code class="function">cardinality</code> ( <code class="type">anyarray</code> )345        → <code class="returnvalue">integer</code>346       </p>347       <p>348        Returns the total number of elements in the array, or 0 if the array349        is empty.350       </p>351       <p>352        <code class="literal">cardinality(ARRAY[[1,2],[3,4]])</code>353        → <code class="returnvalue">4</code>354       </p></td></tr><tr><td class="func_table_entry"><p class="func_signature">355        <a id="id-1.5.8.25.6.2.2.18.1.1.1" class="indexterm"></a>356        <code class="function">trim_array</code> ( <em class="parameter"><code>array</code></em> <code class="type">anyarray</code>, <em class="parameter"><code>n</code></em> <code class="type">integer</code> )357        → <code class="returnvalue">anyarray</code>358       </p>359       <p>360        Trims an array by removing the last <em class="parameter"><code>n</code></em> elements.361        If the array is multidimensional, only the first dimension is trimmed.362       </p>363       <p>364        <code class="literal">trim_array(ARRAY[1,2,3,4,5,6], 2)</code>365        → <code class="returnvalue">{1,2,3,4}</code>366       </p></td></tr><tr><td class="func_table_entry"><p class="func_signature">367        <a id="id-1.5.8.25.6.2.2.19.1.1.1" class="indexterm"></a>368        <code class="function">unnest</code> ( <code class="type">anyarray</code> )369        → <code class="returnvalue">setof anyelement</code>370       </p>371       <p>372        Expands an array into a set of rows.373        The array's elements are read out in storage order.374       </p>375       <p>376        <code class="literal">unnest(ARRAY[1,2])</code>377        → <code class="returnvalue"></code>378</p><pre class="programlisting">379 1380 2381</pre><p>382       </p>383       <p>384        <code class="literal">unnest(ARRAY[['foo','bar'],['baz','quux']])</code>385        → <code class="returnvalue"></code>386</p><pre class="programlisting">387 foo388 bar389 baz390 quux391</pre><p>392       </p></td></tr><tr><td class="func_table_entry"><p class="func_signature">393        <code class="function">unnest</code> ( <code class="type">anyarray</code>, <code class="type">anyarray</code> [<span class="optional">, ... </span>] )394        → <code class="returnvalue">setof anyelement, anyelement [, ... ]</code>395       </p>396       <p>397        Expands multiple arrays (possibly of different data types) into a set of398        rows.  If the arrays are not all the same length then the shorter ones399        are padded with <code class="literal">NULL</code>s.  This form is only allowed400        in a query's FROM clause; see <a class="xref" href="queries-table-expressions.html#QUERIES-TABLEFUNCTIONS" title="7.2.1.4. Table Functions">Section 7.2.1.4</a>.401       </p>402       <p>403        <code class="literal">select * from unnest(ARRAY[1,2], ARRAY['foo','bar','baz']) as x(a,b)</code>404        → <code class="returnvalue"></code>405</p><pre class="programlisting">406 a |  b407---+-----408 1 | foo409 2 | bar410   | baz411</pre><p>412       </p></td></tr></tbody></table></div></div><br class="table-break" /><p>413    See also <a class="xref" href="functions-aggregate.html" title="9.21. Aggregate Functions">Section 9.21</a> about the aggregate414    function <code class="function">array_agg</code> for use with arrays.415   </p></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="functions-conditional.html" title="9.18. Conditional Expressions">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="functions.html" title="Chapter 9. Functions and Operators">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="functions-range.html" title="9.20. Range/Multirange Functions and Operators">Next</a></td></tr><tr><td width="40%" align="left" valign="top">9.18. Conditional Expressions </td><td width="20%" align="center"><a accesskey="h" href="index.html" title="PostgreSQL 16.3 Documentation">Home</a></td><td width="40%" align="right" valign="top"> 9.20. Range/Multirange Functions and Operators</td></tr></table></div></body></html>