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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>53.2. pg_aggregate</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="catalogs-overview.html" title="53.1. Overview" /><link rel="next" href="catalog-pg-am.html" title="53.3. pg_am" /></head><body id="docContent" class="container-fluid col-10"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="5" align="center">53.2. <code class="structname">pg_aggregate</code></th></tr><tr><td width="10%" align="left"><a accesskey="p" href="catalogs-overview.html" title="53.1. Overview">Prev</a> </td><td width="10%" align="left"><a accesskey="u" href="catalogs.html" title="Chapter 53. System Catalogs">Up</a></td><th width="60%" align="center">Chapter 53. System Catalogs</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="catalog-pg-am.html" title="53.3. pg_am">Next</a></td></tr></table><hr /></div><div class="sect1" id="CATALOG-PG-AGGREGATE"><div class="titlepage"><div><div><h2 class="title" style="clear: both">53.2. <code class="structname">pg_aggregate</code> <a href="#CATALOG-PG-AGGREGATE" class="id_link">#</a></h2></div></div></div><a id="id-1.10.4.4.2" class="indexterm"></a><p>3 The catalog <code class="structname">pg_aggregate</code> stores information about4 aggregate functions. An aggregate function is a function that5 operates on a set of values (typically one column from each row6 that matches a query condition) and returns a single value computed7 from all these values. Typical aggregate functions are8 <code class="function">sum</code>, <code class="function">count</code>, and9 <code class="function">max</code>. Each entry in10 <code class="structname">pg_aggregate</code> is an extension of an entry11 in <a class="link" href="catalog-pg-proc.html" title="53.39. pg_proc"><code class="structname">pg_proc</code></a>.12 The <code class="structname">pg_proc</code> entry carries the aggregate's name,13 input and output data types, and other information that is similar to14 ordinary functions.15 </p><div class="table" id="id-1.10.4.4.4"><p class="title"><strong>Table 53.2. <code class="structname">pg_aggregate</code> Columns</strong></p><div class="table-contents"><table class="table" summary="pg_aggregate Columns" border="1"><colgroup><col /></colgroup><thead><tr><th class="catalog_table_entry"><p class="column_definition">16 Column Type17 </p>18 <p>19 Description20 </p></th></tr></thead><tbody><tr><td class="catalog_table_entry"><p class="column_definition">21 <code class="structfield">aggfnoid</code> <code class="type">regproc</code>22 (references <a class="link" href="catalog-pg-proc.html" title="53.39. pg_proc"><code class="structname">pg_proc</code></a>.<code class="structfield">oid</code>)23 </p>24 <p>25 <code class="structname">pg_proc</code> OID of the aggregate function26 </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">27 <code class="structfield">aggkind</code> <code class="type">char</code>28 </p>29 <p>30 Aggregate kind:31 <code class="literal">n</code> for <span class="quote">“<span class="quote">normal</span>”</span> aggregates,32 <code class="literal">o</code> for <span class="quote">“<span class="quote">ordered-set</span>”</span> aggregates, or33 <code class="literal">h</code> for <span class="quote">“<span class="quote">hypothetical-set</span>”</span> aggregates34 </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">35 <code class="structfield">aggnumdirectargs</code> <code class="type">int2</code>36 </p>37 <p>38 Number of direct (non-aggregated) arguments of an ordered-set or39 hypothetical-set aggregate, counting a variadic array as one argument.40 If equal to <code class="structfield">pronargs</code>, the aggregate must be variadic41 and the variadic array describes the aggregated arguments as well as42 the final direct arguments.43 Always zero for normal aggregates.44 </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">45 <code class="structfield">aggtransfn</code> <code class="type">regproc</code>46 (references <a class="link" href="catalog-pg-proc.html" title="53.39. pg_proc"><code class="structname">pg_proc</code></a>.<code class="structfield">oid</code>)47 </p>48 <p>49 Transition function50 </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">51 <code class="structfield">aggfinalfn</code> <code class="type">regproc</code>52 (references <a class="link" href="catalog-pg-proc.html" title="53.39. pg_proc"><code class="structname">pg_proc</code></a>.<code class="structfield">oid</code>)53 </p>54 <p>55 Final function (zero if none)56 </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">57 <code class="structfield">aggcombinefn</code> <code class="type">regproc</code>58 (references <a class="link" href="catalog-pg-proc.html" title="53.39. pg_proc"><code class="structname">pg_proc</code></a>.<code class="structfield">oid</code>)59 </p>60 <p>61 Combine function (zero if none)62 </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">63 <code class="structfield">aggserialfn</code> <code class="type">regproc</code>64 (references <a class="link" href="catalog-pg-proc.html" title="53.39. pg_proc"><code class="structname">pg_proc</code></a>.<code class="structfield">oid</code>)65 </p>66 <p>67 Serialization function (zero if none)68 </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">69 <code class="structfield">aggdeserialfn</code> <code class="type">regproc</code>70 (references <a class="link" href="catalog-pg-proc.html" title="53.39. pg_proc"><code class="structname">pg_proc</code></a>.<code class="structfield">oid</code>)71 </p>72 <p>73 Deserialization function (zero if none)74 </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">75 <code class="structfield">aggmtransfn</code> <code class="type">regproc</code>76 (references <a class="link" href="catalog-pg-proc.html" title="53.39. pg_proc"><code class="structname">pg_proc</code></a>.<code class="structfield">oid</code>)77 </p>78 <p>79 Forward transition function for moving-aggregate mode (zero if none)80 </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">81 <code class="structfield">aggminvtransfn</code> <code class="type">regproc</code>82 (references <a class="link" href="catalog-pg-proc.html" title="53.39. pg_proc"><code class="structname">pg_proc</code></a>.<code class="structfield">oid</code>)83 </p>84 <p>85 Inverse transition function for moving-aggregate mode (zero if none)86 </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">87 <code class="structfield">aggmfinalfn</code> <code class="type">regproc</code>88 (references <a class="link" href="catalog-pg-proc.html" title="53.39. pg_proc"><code class="structname">pg_proc</code></a>.<code class="structfield">oid</code>)89 </p>90 <p>91 Final function for moving-aggregate mode (zero if none)92 </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">93 <code class="structfield">aggfinalextra</code> <code class="type">bool</code>94 </p>95 <p>96 True to pass extra dummy arguments to <code class="structfield">aggfinalfn</code>97 </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">98 <code class="structfield">aggmfinalextra</code> <code class="type">bool</code>99 </p>100 <p>101 True to pass extra dummy arguments to <code class="structfield">aggmfinalfn</code>102 </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">103 <code class="structfield">aggfinalmodify</code> <code class="type">char</code>104 </p>105 <p>106 Whether <code class="structfield">aggfinalfn</code> modifies the107 transition state value:108 <code class="literal">r</code> if it is read-only,109 <code class="literal">s</code> if the <code class="structfield">aggtransfn</code>110 cannot be applied after the <code class="structfield">aggfinalfn</code>, or111 <code class="literal">w</code> if it writes on the value112 </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">113 <code class="structfield">aggmfinalmodify</code> <code class="type">char</code>114 </p>115 <p>116 Like <code class="structfield">aggfinalmodify</code>, but for117 the <code class="structfield">aggmfinalfn</code>118 </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">119 <code class="structfield">aggsortop</code> <code class="type">oid</code>120 (references <a class="link" href="catalog-pg-operator.html" title="53.34. pg_operator"><code class="structname">pg_operator</code></a>.<code class="structfield">oid</code>)121 </p>122 <p>123 Associated sort operator (zero if none)124 </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">125 <code class="structfield">aggtranstype</code> <code class="type">oid</code>126 (references <a class="link" href="catalog-pg-type.html" title="53.64. pg_type"><code class="structname">pg_type</code></a>.<code class="structfield">oid</code>)127 </p>128 <p>129 Data type of the aggregate function's internal transition (state) data130 </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">131 <code class="structfield">aggtransspace</code> <code class="type">int4</code>132 </p>133 <p>134 Approximate average size (in bytes) of the transition state135 data, or zero to use a default estimate136 </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">137 <code class="structfield">aggmtranstype</code> <code class="type">oid</code>138 (references <a class="link" href="catalog-pg-type.html" title="53.64. pg_type"><code class="structname">pg_type</code></a>.<code class="structfield">oid</code>)139 </p>140 <p>141 Data type of the aggregate function's internal transition (state)142 data for moving-aggregate mode (zero if none)143 </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">144 <code class="structfield">aggmtransspace</code> <code class="type">int4</code>145 </p>146 <p>147 Approximate average size (in bytes) of the transition state data148 for moving-aggregate mode, or zero to use a default estimate149 </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">150 <code class="structfield">agginitval</code> <code class="type">text</code>151 </p>152 <p>153 The initial value of the transition state. This is a text154 field containing the initial value in its external string155 representation. If this field is null, the transition state156 value starts out null.157 </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">158 <code class="structfield">aggminitval</code> <code class="type">text</code>159 </p>160 <p>161 The initial value of the transition state for moving-aggregate mode.162 This is a text field containing the initial value in its external163 string representation. If this field is null, the transition state164 value starts out null.165 </p></td></tr></tbody></table></div></div><br class="table-break" /><p>166 New aggregate functions are registered with the <a class="link" href="sql-createaggregate.html" title="CREATE AGGREGATE"><code class="command">CREATE AGGREGATE</code></a>167 command. See <a class="xref" href="xaggr.html" title="38.12. User-Defined Aggregates">Section 38.12</a> for more information about168 writing aggregate functions and the meaning of the transition169 functions, etc.170 </p></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="catalogs-overview.html" title="53.1. Overview">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="catalogs.html" title="Chapter 53. System Catalogs">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="catalog-pg-am.html" title="53.3. pg_am">Next</a></td></tr><tr><td width="40%" align="left" valign="top">53.1. Overview </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"> 53.3. <code class="structname">pg_am</code></td></tr></table></div></body></html>