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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>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 15.7 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></h2></div></div></div><a id="id-1.10.4.15.2" class="indexterm"></a><p>
The catalog <code class="structname">pg_constraint</code> stores check, primary
key, unique, foreign key, and exclusion constraints on tables.
(Column constraints are not treated specially. Every column constraint is
equivalent to some table constraint.)
Not-null constraints are represented in the
<a class="link" href="catalog-pg-attribute.html" title="53.7. pg_attribute"><code class="structname">pg_attribute</code></a>
catalog, not here.
</p><p>
User-defined constraint triggers (created with <a class="link" href="sql-createtrigger.html" title="CREATE TRIGGER">
<code class="command">CREATE CONSTRAINT TRIGGER</code></a>) also give rise to an entry in this table.
</p><p>
Check constraints on domains are stored here, too.
</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">
Column Type
</p>
<p>
Description
</p></th></tr></thead><tbody><tr><td class="catalog_table_entry"><p class="column_definition">
<code class="structfield">oid</code> <code class="type">oid</code>
</p>
<p>
Row identifier
</p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">
<code class="structfield">conname</code> <code class="type">name</code>
</p>
<p>
Constraint name (not necessarily unique!)
</p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">
<code class="structfield">connamespace</code> <code class="type">oid</code>
(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>)
</p>
<p>
The OID of the namespace that contains this constraint
</p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">
<code class="structfield">contype</code> <code class="type">char</code>
</p>
<p>
<code class="literal">c</code> = check constraint,
<code class="literal">f</code> = foreign key constraint,
<code class="literal">p</code> = primary key constraint,
<code class="literal">u</code> = unique constraint,
<code class="literal">t</code> = constraint trigger,
<code class="literal">x</code> = exclusion constraint
</p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">
<code class="structfield">condeferrable</code> <code class="type">bool</code>
</p>
<p>
Is the constraint deferrable?
</p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">
<code class="structfield">condeferred</code> <code class="type">bool</code>
</p>
<p>
Is the constraint deferred by default?
</p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">
<code class="structfield">convalidated</code> <code class="type">bool</code>
</p>
<p>
Has the constraint been validated?
Currently, can be false only for foreign keys and CHECK constraints
</p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">
<code class="structfield">conrelid</code> <code class="type">oid</code>
(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>)
</p>
<p>
The table this constraint is on; zero if not a table constraint
</p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">
<code class="structfield">contypid</code> <code class="type">oid</code>
(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>)
</p>
<p>
The domain this constraint is on; zero if not a domain constraint
</p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">
<code class="structfield">conindid</code> <code class="type">oid</code>
(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>)
</p>
<p>
The index supporting this constraint, if it's a unique, primary
key, foreign key, or exclusion constraint; else zero
</p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">
<code class="structfield">conparentid</code> <code class="type">oid</code>
(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>)
</p>
<p>
The corresponding constraint of the parent partitioned table,
if this is a constraint on a partition; else zero
</p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">
<code class="structfield">confrelid</code> <code class="type">oid</code>
(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>)
</p>
<p>
If a foreign key, the referenced table; else zero
</p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">
<code class="structfield">confupdtype</code> <code class="type">char</code>
</p>
<p>
Foreign key update action code:
<code class="literal">a</code> = no action,
<code class="literal">r</code> = restrict,
<code class="literal">c</code> = cascade,
<code class="literal">n</code> = set null,
<code class="literal">d</code> = set default
</p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">
<code class="structfield">confdeltype</code> <code class="type">char</code>
</p>
<p>
Foreign key deletion action code:
<code class="literal">a</code> = no action,
<code class="literal">r</code> = restrict,
<code class="literal">c</code> = cascade,
<code class="literal">n</code> = set null,
<code class="literal">d</code> = set default
</p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">
<code class="structfield">confmatchtype</code> <code class="type">char</code>
</p>
<p>
Foreign key match type:
<code class="literal">f</code> = full,
<code class="literal">p</code> = partial,
<code class="literal">s</code> = simple
</p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">
<code class="structfield">conislocal</code> <code class="type">bool</code>
</p>
<p>
This constraint is defined locally for the relation. Note that a
constraint can be locally defined and inherited simultaneously.
</p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">
<code class="structfield">coninhcount</code> <code class="type">int4</code>
</p>
<p>
The number of direct inheritance ancestors this constraint has.
A constraint with
a nonzero number of ancestors cannot be dropped nor renamed.
</p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">
<code class="structfield">connoinherit</code> <code class="type">bool</code>
</p>
<p>
This constraint is defined locally for the relation. It is a
non-inheritable constraint.
</p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">
<code class="structfield">conkey</code> <code class="type">int2[]</code>
(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>)
</p>
<p>
If a table constraint (including foreign keys, but not constraint
triggers), list of the constrained columns
</p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">
<code class="structfield">confkey</code> <code class="type">int2[]</code>
(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>)
</p>
<p>
If a foreign key, list of the referenced columns
</p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">
<code class="structfield">conpfeqop</code> <code class="type">oid[]</code>
(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>)
</p>
<p>
If a foreign key, list of the equality operators for PK = FK comparisons
</p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">
<code class="structfield">conppeqop</code> <code class="type">oid[]</code>
(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>)
</p>
<p>
If a foreign key, list of the equality operators for PK = PK comparisons
</p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">
<code class="structfield">conffeqop</code> <code class="type">oid[]</code>
(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>)
</p>
<p>
If a foreign key, list of the equality operators for FK = FK comparisons
</p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">
<code class="structfield">confdelsetcols</code> <code class="type">int2[]</code>
(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>)
</p>
<p>
If a foreign key with a <code class="literal">SET NULL</code> or <code class="literal">SET
DEFAULT</code> delete action, the columns that will be updated.
If null, all of the referencing columns will be updated.
</p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">
<code class="structfield">conexclop</code> <code class="type">oid[]</code>
(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>)
</p>
<p>
If an exclusion constraint, list of the per-column exclusion operators
</p></td></tr><tr><td class="catalog_table_entry"><p class="column_definition">
<code class="structfield">conbin</code> <code class="type">pg_node_tree</code>
</p>
<p>
If a check constraint, an internal representation of the
expression. (It's recommended to use
<code class="function">pg_get_constraintdef()</code> to extract the definition of
a check constraint.)
</p></td></tr></tbody></table></div></div><br class="table-break" /><p>
In the case of an exclusion constraint, <code class="structfield">conkey</code>
is only useful for constraint elements that are simple column references.
For other cases, a zero appears in <code class="structfield">conkey</code>
and the associated index must be consulted to discover the expression
that is constrained. (<code class="structfield">conkey</code> thus has the
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 the
index.)
</p><div class="note"><h3 class="title">Note</h3><p>
<code class="literal">pg_class.relchecks</code> needs to agree with the
number of check-constraint entries found in this table for each
relation.
</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. System Catalogs">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="catalog-pg-conversion.html" title="53.14. pg_conversion">Next</a></td></tr><tr><td width="40%" align="left" valign="top">53.12. <code class="structname">pg_collation</code> </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"> 53.14. <code class="structname">pg_conversion</code></td></tr></table></div></body></html>
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