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   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>52.13. 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="52.12. pg_collation" /><link rel="next" href="catalog-pg-conversion.html" title="52.14. 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">52.13. <code class="structname">pg_constraint</code></th></tr><tr><td width="10%" align="left"><a accesskey="p" href="catalog-pg-collation.html" title="52.12. pg_collation">Prev</a> </td><td width="10%" align="left"><a accesskey="u" href="catalogs.html" title="Chapter 52. System Catalogs">Up</a></td><th width="60%" align="center">Chapter 52. System Catalogs</th><td width="10%" align="right"><a accesskey="h" href="index.html" title="PostgreSQL 18.0 Documentation">Home</a></td><td width="10%" align="right"> <a accesskey="n" href="catalog-pg-conversion.html" title="52.14. 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">52.13. <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, not-null,
   4    primary key, unique, foreign key, and exclusion constraints on tables.
   5    (Column constraints are not treated specially.  Every column constraint is
   6    equivalent to some table constraint.)
   7   </p><p>
   8    User-defined constraint triggers (created with <a class="link" href="sql-createtrigger.html" title="CREATE TRIGGER">
   9    <code class="command">CREATE CONSTRAINT TRIGGER</code></a>) also give rise to an entry in this table.
  10   </p><p>
  11    Check constraints on domains are stored here, too.
  12   </p><div class="table" id="id-1.10.4.15.6"><p class="title"><strong>Table 52.13. <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">
  13        Column Type
  14       </p>
  15       <p>
  16        Description
  17       </p></th></tr></thead><tbody><tr><td class="catalog_table_entry"><p class="column_definition">
  18        <code class="structfield">oid</code> <code class="type">oid</code>
  19       </p>
  20       <p>
  21        Row identifier
  22       </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">
  23        <code class="structfield">conname</code> <code class="type">name</code>
  24       </p>
  25       <p>
  26        Constraint name (not necessarily unique!)
  27       </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">
  28        <code class="structfield">connamespace</code> <code class="type">oid</code>
  29        (references <a class="link" href="catalog-pg-namespace.html" title="52.32. pg_namespace"><code class="structname">pg_namespace</code></a>.<code class="structfield">oid</code>)
  30       </p>
  31       <p>
  32        The OID of the namespace that contains this constraint
  33       </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">
  34        <code class="structfield">contype</code> <code class="type">char</code>
  35       </p>
  36       <p>
  37        <code class="literal">c</code> = check constraint,
  38        <code class="literal">f</code> = foreign key constraint,
  39        <code class="literal">n</code> = not-null constraint,
  40        <code class="literal">p</code> = primary key constraint,
  41        <code class="literal">u</code> = unique constraint,
  42        <code class="literal">t</code> = constraint trigger,
  43        <code class="literal">x</code> = exclusion constraint
  44       </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">
  45        <code class="structfield">condeferrable</code> <code class="type">bool</code>
  46       </p>
  47       <p>
  48        Is the constraint deferrable?
  49       </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">
  50        <code class="structfield">condeferred</code> <code class="type">bool</code>
  51       </p>
  52       <p>
  53        Is the constraint deferred by default?
  54       </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">
  55        <code class="structfield">conenforced</code> <code class="type">bool</code>
  56       </p>
  57       <p>
  58        Is the constraint enforced?
  59       </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">
  60        <code class="structfield">convalidated</code> <code class="type">bool</code>
  61       </p>
  62       <p>
  63        Has the constraint been validated?
  64       </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">
  65        <code class="structfield">conrelid</code> <code class="type">oid</code>
  66        (references <a class="link" href="catalog-pg-class.html" title="52.11. pg_class"><code class="structname">pg_class</code></a>.<code class="structfield">oid</code>)
  67       </p>
  68       <p>
  69        The table this constraint is on; zero if not a table constraint
  70       </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">
  71        <code class="structfield">contypid</code> <code class="type">oid</code>
  72        (references <a class="link" href="catalog-pg-type.html" title="52.64. pg_type"><code class="structname">pg_type</code></a>.<code class="structfield">oid</code>)
  73       </p>
  74       <p>
  75        The domain this constraint is on; zero if not a domain constraint
  76       </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">
  77        <code class="structfield">conindid</code> <code class="type">oid</code>
  78        (references <a class="link" href="catalog-pg-class.html" title="52.11. pg_class"><code class="structname">pg_class</code></a>.<code class="structfield">oid</code>)
  79       </p>
  80       <p>
  81        The index supporting this constraint, if it's a unique, primary
  82        key, foreign key, or exclusion constraint; else zero
  83       </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">
  84        <code class="structfield">conparentid</code> <code class="type">oid</code>
  85        (references <a class="link" href="catalog-pg-constraint.html" title="52.13. pg_constraint"><code class="structname">pg_constraint</code></a>.<code class="structfield">oid</code>)
  86       </p>
  87       <p>
  88        The corresponding constraint of the parent partitioned table,
  89        if this is a constraint on a partition; else zero
  90       </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">
  91        <code class="structfield">confrelid</code> <code class="type">oid</code>
  92        (references <a class="link" href="catalog-pg-class.html" title="52.11. pg_class"><code class="structname">pg_class</code></a>.<code class="structfield">oid</code>)
  93       </p>
  94       <p>
  95        If a foreign key, the referenced table; else zero
  96       </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">
  97        <code class="structfield">confupdtype</code> <code class="type">char</code>
  98       </p>
  99       <p>
 100        Foreign key update action code:
 101        <code class="literal">a</code> = no action,
 102        <code class="literal">r</code> = restrict,
 103        <code class="literal">c</code> = cascade,
 104        <code class="literal">n</code> = set null,
 105        <code class="literal">d</code> = set default
 106       </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">
 107        <code class="structfield">confdeltype</code> <code class="type">char</code>
 108       </p>
 109       <p>
 110        Foreign key deletion action code:
 111        <code class="literal">a</code> = no action,
 112        <code class="literal">r</code> = restrict,
 113        <code class="literal">c</code> = cascade,
 114        <code class="literal">n</code> = set null,
 115        <code class="literal">d</code> = set default
 116       </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">
 117        <code class="structfield">confmatchtype</code> <code class="type">char</code>
 118       </p>
 119       <p>
 120        Foreign key match type:
 121        <code class="literal">f</code> = full,
 122        <code class="literal">p</code> = partial,
 123        <code class="literal">s</code> = simple
 124       </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">
 125        <code class="structfield">conislocal</code> <code class="type">bool</code>
 126       </p>
 127       <p>
 128        This constraint is defined locally for the relation.  Note that a
 129        constraint can be locally defined and inherited simultaneously.
 130       </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">
 131        <code class="structfield">coninhcount</code> <code class="type">int2</code>
 132       </p>
 133       <p>
 134        The number of direct inheritance ancestors this constraint has.
 135        A constraint with
 136        a nonzero number of ancestors cannot be dropped nor renamed.
 137       </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">
 138        <code class="structfield">connoinherit</code> <code class="type">bool</code>
 139       </p>
 140       <p>
 141        This constraint is defined locally for the relation.  It is a
 142        non-inheritable constraint.
 143       </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">
 144        <code class="structfield">conperiod</code> <code class="type">bool</code>
 145       </p>
 146       <p>
 147        This constraint is defined with <code class="literal">WITHOUT OVERLAPS</code>
 148        (for primary keys and unique constraints) or <code class="literal">PERIOD</code>
 149        (for foreign keys).
 150       </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">
 151        <code class="structfield">conkey</code> <code class="type">int2[]</code>
 152        (references <a class="link" href="catalog-pg-attribute.html" title="52.7. pg_attribute"><code class="structname">pg_attribute</code></a>.<code class="structfield">attnum</code>)
 153       </p>
 154       <p>
 155        If a table constraint (including foreign keys, but not constraint
 156        triggers), list of the constrained columns
 157       </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">
 158        <code class="structfield">confkey</code> <code class="type">int2[]</code>
 159        (references <a class="link" href="catalog-pg-attribute.html" title="52.7. pg_attribute"><code class="structname">pg_attribute</code></a>.<code class="structfield">attnum</code>)
 160       </p>
 161       <p>
 162        If a foreign key, list of the referenced columns
 163       </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">
 164        <code class="structfield">conpfeqop</code> <code class="type">oid[]</code>
 165        (references <a class="link" href="catalog-pg-operator.html" title="52.34. pg_operator"><code class="structname">pg_operator</code></a>.<code class="structfield">oid</code>)
 166       </p>
 167       <p>
 168        If a foreign key, list of the equality operators for PK = FK comparisons
 169       </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">
 170        <code class="structfield">conppeqop</code> <code class="type">oid[]</code>
 171        (references <a class="link" href="catalog-pg-operator.html" title="52.34. pg_operator"><code class="structname">pg_operator</code></a>.<code class="structfield">oid</code>)
 172       </p>
 173       <p>
 174        If a foreign key, list of the equality operators for PK = PK comparisons
 175       </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">
 176        <code class="structfield">conffeqop</code> <code class="type">oid[]</code>
 177        (references <a class="link" href="catalog-pg-operator.html" title="52.34. pg_operator"><code class="structname">pg_operator</code></a>.<code class="structfield">oid</code>)
 178       </p>
 179       <p>
 180        If a foreign key, list of the equality operators for FK = FK comparisons
 181       </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">
 182        <code class="structfield">confdelsetcols</code> <code class="type">int2[]</code>
 183        (references <a class="link" href="catalog-pg-attribute.html" title="52.7. pg_attribute"><code class="structname">pg_attribute</code></a>.<code class="structfield">attnum</code>)
 184       </p>
 185       <p>
 186        If a foreign key with a <code class="literal">SET NULL</code> or <code class="literal">SET
 187        DEFAULT</code> delete action, the columns that will be updated.
 188        If null, all of the referencing columns will be updated.
 189       </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">
 190        <code class="structfield">conexclop</code> <code class="type">oid[]</code>
 191        (references <a class="link" href="catalog-pg-operator.html" title="52.34. pg_operator"><code class="structname">pg_operator</code></a>.<code class="structfield">oid</code>)
 192       </p>
 193       <p>
 194        If an exclusion constraint or <code class="literal">WITHOUT OVERLAPS</code>
 195        primary key/unique constraint, list of the per-column exclusion operators.
 196       </p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">
 197        <code class="structfield">conbin</code> <code class="type">pg_node_tree</code>
 198       </p>
 199       <p>
 200        If a check constraint, an internal representation of the
 201        expression.  (It's recommended to use
 202        <code class="function">pg_get_constraintdef()</code> to extract the definition of
 203        a check constraint.)
 204       </p></td></tr></tbody></table></div></div><br class="table-break" /><p>
 205    In the case of an exclusion constraint, <code class="structfield">conkey</code>
 206    is only useful for constraint elements that are simple column references.
 207    For other cases, a zero appears in <code class="structfield">conkey</code>
 208    and the associated index must be consulted to discover the expression
 209    that is constrained.  (<code class="structfield">conkey</code> thus has the
 210    same contents as <a class="link" href="catalog-pg-index.html" title="52.26. pg_index"><code class="structname">pg_index</code></a>.<code class="structfield">indkey</code> for the
 211    index.)
 212   </p><div class="note"><h3 class="title">Note</h3><p>
 213     <code class="literal">pg_class.relchecks</code> needs to agree with the
 214     number of check-constraint entries found in this table for each
 215     relation.
 216    </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="52.12. pg_collation">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="catalogs.html" title="Chapter 52. System Catalogs">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="catalog-pg-conversion.html" title="52.14. pg_conversion">Next</a></td></tr><tr><td width="40%" align="left" valign="top">52.12. <code class="structname">pg_collation</code> </td><td width="20%" align="center"><a accesskey="h" href="index.html" title="PostgreSQL 18.0 Documentation">Home</a></td><td width="40%" align="right" valign="top"> 52.14. <code class="structname">pg_conversion</code></td></tr></table></div></body></html>