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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>53.13. pg_constraint</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="catalog-pg-collation.html" title="53.12. pg_collation" /><link rel="next" href="catalog-pg-conversion.html" title="53.14. pg_conversion" /></head><body id="docContent" class="container-fluid col-10"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="5" align="center">53.13. <code class="structname">pg_constraint</code></th></tr><tr><td width="10%" align="left"><a accesskey="p" href="catalog-pg-collation.html" title="53.12. pg_collation">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-conversion.html" title="53.14. pg_conversion">Next</a></td></tr></table><hr /></div><div class="sect1" id="CATALOG-PG-CONSTRAINT"><div class="titlepage"><div><div><h2 class="title" style="clear: both">53.13. <code class="structname">pg_constraint</code> <a href="#CATALOG-PG-CONSTRAINT" class="id_link">#</a></h2></div></div></div><a id="id-1.10.4.15.2" class="indexterm"></a><p>3 The catalog <code class="structname">pg_constraint</code> stores check, primary4 key, unique, foreign key, and exclusion constraints on tables.5 (Column constraints are not treated specially. Every column constraint is6 equivalent to some table constraint.)7 Not-null constraints are represented in the8 <a class="link" href="catalog-pg-attribute.html" title="53.7. pg_attribute"><code class="structname">pg_attribute</code></a>9 catalog, not here.10 </p><p>11 User-defined constraint triggers (created with <a class="link" href="sql-createtrigger.html" title="CREATE TRIGGER">12 <code class="command">CREATE CONSTRAINT TRIGGER</code></a>) also give rise to an entry in this table.13 </p><p>14 Check constraints on domains are stored here, too.15 </p><div class="table" id="id-1.10.4.15.6"><p class="title"><strong>Table 53.13. <code class="structname">pg_constraint</code> Columns</strong></p><div class="table-contents"><table class="table" summary="pg_constraint 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">oid</code> <code class="type">oid</code>22 </p>23 <p>24 Row identifier25 </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">26 <code class="structfield">conname</code> <code class="type">name</code>27 </p>28 <p>29 Constraint name (not necessarily unique!)30 </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">31 <code class="structfield">connamespace</code> <code class="type">oid</code>32 (references <a class="link" href="catalog-pg-namespace.html" title="53.32. pg_namespace"><code class="structname">pg_namespace</code></a>.<code class="structfield">oid</code>)33 </p>34 <p>35 The OID of the namespace that contains this constraint36 </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">37 <code class="structfield">contype</code> <code class="type">char</code>38 </p>39 <p>40 <code class="literal">c</code> = check constraint,41 <code class="literal">f</code> = foreign key constraint,42 <code class="literal">p</code> = primary key constraint,43 <code class="literal">u</code> = unique constraint,44 <code class="literal">t</code> = constraint trigger,45 <code class="literal">x</code> = exclusion constraint46 </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">47 <code class="structfield">condeferrable</code> <code class="type">bool</code>48 </p>49 <p>50 Is the constraint deferrable?51 </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">52 <code class="structfield">condeferred</code> <code class="type">bool</code>53 </p>54 <p>55 Is the constraint deferred by default?56 </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">57 <code class="structfield">convalidated</code> <code class="type">bool</code>58 </p>59 <p>60 Has the constraint been validated?61 Currently, can be false only for foreign keys and CHECK constraints62 </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">63 <code class="structfield">conrelid</code> <code class="type">oid</code>64 (references <a class="link" href="catalog-pg-class.html" title="53.11. pg_class"><code class="structname">pg_class</code></a>.<code class="structfield">oid</code>)65 </p>66 <p>67 The table this constraint is on; zero if not a table constraint68 </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">69 <code class="structfield">contypid</code> <code class="type">oid</code>70 (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>)71 </p>72 <p>73 The domain this constraint is on; zero if not a domain constraint74 </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">75 <code class="structfield">conindid</code> <code class="type">oid</code>76 (references <a class="link" href="catalog-pg-class.html" title="53.11. pg_class"><code class="structname">pg_class</code></a>.<code class="structfield">oid</code>)77 </p>78 <p>79 The index supporting this constraint, if it's a unique, primary80 key, foreign key, or exclusion constraint; else zero81 </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">82 <code class="structfield">conparentid</code> <code class="type">oid</code>83 (references <a class="link" href="catalog-pg-constraint.html" title="53.13. pg_constraint"><code class="structname">pg_constraint</code></a>.<code class="structfield">oid</code>)84 </p>85 <p>86 The corresponding constraint of the parent partitioned table,87 if this is a constraint on a partition; else zero88 </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">89 <code class="structfield">confrelid</code> <code class="type">oid</code>90 (references <a class="link" href="catalog-pg-class.html" title="53.11. pg_class"><code class="structname">pg_class</code></a>.<code class="structfield">oid</code>)91 </p>92 <p>93 If a foreign key, the referenced table; else zero94 </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">95 <code class="structfield">confupdtype</code> <code class="type">char</code>96 </p>97 <p>98 Foreign key update action code:99 <code class="literal">a</code> = no action,100 <code class="literal">r</code> = restrict,101 <code class="literal">c</code> = cascade,102 <code class="literal">n</code> = set null,103 <code class="literal">d</code> = set default104 </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">105 <code class="structfield">confdeltype</code> <code class="type">char</code>106 </p>107 <p>108 Foreign key deletion action code:109 <code class="literal">a</code> = no action,110 <code class="literal">r</code> = restrict,111 <code class="literal">c</code> = cascade,112 <code class="literal">n</code> = set null,113 <code class="literal">d</code> = set default114 </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">115 <code class="structfield">confmatchtype</code> <code class="type">char</code>116 </p>117 <p>118 Foreign key match type:119 <code class="literal">f</code> = full,120 <code class="literal">p</code> = partial,121 <code class="literal">s</code> = simple122 </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">123 <code class="structfield">conislocal</code> <code class="type">bool</code>124 </p>125 <p>126 This constraint is defined locally for the relation. Note that a127 constraint can be locally defined and inherited simultaneously.128 </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">129 <code class="structfield">coninhcount</code> <code class="type">int2</code>130 </p>131 <p>132 The number of direct inheritance ancestors this constraint has.133 A constraint with134 a nonzero number of ancestors cannot be dropped nor renamed.135 </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">136 <code class="structfield">connoinherit</code> <code class="type">bool</code>137 </p>138 <p>139 This constraint is defined locally for the relation. It is a140 non-inheritable constraint.141 </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">142 <code class="structfield">conkey</code> <code class="type">int2[]</code>143 (references <a class="link" href="catalog-pg-attribute.html" title="53.7. pg_attribute"><code class="structname">pg_attribute</code></a>.<code class="structfield">attnum</code>)144 </p>145 <p>146 If a table constraint (including foreign keys, but not constraint147 triggers), list of the constrained columns148 </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">149 <code class="structfield">confkey</code> <code class="type">int2[]</code>150 (references <a class="link" href="catalog-pg-attribute.html" title="53.7. pg_attribute"><code class="structname">pg_attribute</code></a>.<code class="structfield">attnum</code>)151 </p>152 <p>153 If a foreign key, list of the referenced columns154 </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">155 <code class="structfield">conpfeqop</code> <code class="type">oid[]</code>156 (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>)157 </p>158 <p>159 If a foreign key, list of the equality operators for PK = FK comparisons160 </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">161 <code class="structfield">conppeqop</code> <code class="type">oid[]</code>162 (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>)163 </p>164 <p>165 If a foreign key, list of the equality operators for PK = PK comparisons166 </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">167 <code class="structfield">conffeqop</code> <code class="type">oid[]</code>168 (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>)169 </p>170 <p>171 If a foreign key, list of the equality operators for FK = FK comparisons172 </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">173 <code class="structfield">confdelsetcols</code> <code class="type">int2[]</code>174 (references <a class="link" href="catalog-pg-attribute.html" title="53.7. pg_attribute"><code class="structname">pg_attribute</code></a>.<code class="structfield">attnum</code>)175 </p>176 <p>177 If a foreign key with a <code class="literal">SET NULL</code> or <code class="literal">SET178 DEFAULT</code> delete action, the columns that will be updated.179 If null, all of the referencing columns will be updated.180 </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">181 <code class="structfield">conexclop</code> <code class="type">oid[]</code>182 (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>)183 </p>184 <p>185 If an exclusion constraint, list of the per-column exclusion operators186 </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">187 <code class="structfield">conbin</code> <code class="type">pg_node_tree</code>188 </p>189 <p>190 If a check constraint, an internal representation of the191 expression. (It's recommended to use192 <code class="function">pg_get_constraintdef()</code> to extract the definition of193 a check constraint.)194 </p></td></tr></tbody></table></div></div><br class="table-break" /><p>195 In the case of an exclusion constraint, <code class="structfield">conkey</code>196 is only useful for constraint elements that are simple column references.197 For other cases, a zero appears in <code class="structfield">conkey</code>198 and the associated index must be consulted to discover the expression199 that is constrained. (<code class="structfield">conkey</code> thus has the200 same contents as <a class="link" href="catalog-pg-index.html" title="53.26. pg_index"><code class="structname">pg_index</code></a>.<code class="structfield">indkey</code> for the201 index.)202 </p><div class="note"><h3 class="title">Note</h3><p>203 <code class="literal">pg_class.relchecks</code> needs to agree with the204 number of check-constraint entries found in this table for each205 relation.206 </p></div></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="catalog-pg-collation.html" title="53.12. pg_collation">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="catalogs.html" title="Chapter 53. 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