<title><structname>pg_collation</structname></title>

  <indexterm zone="catalog-pg-collation">
   <primary>pg_collation</primary>
  </indexterm>

  <para>
   The catalog <structname>pg_collation</structname> describes the
   available collations, which are essentially mappings from an SQL
   name to operating system locale categories.
   See <xref linkend="collation"/> for more information.
  </para>

  <table>
   <title><structname>pg_collation</structname> Columns</title>
   <tgroup cols="1">
    <thead>
     <row>
      <entry role="catalog_table_entry"><para role="column_definition">
       Column Type
      </para>
      <para>
       Description
      </para></entry>
     </row>
    </thead>

    <tbody>
     <row>
      <entry role="catalog_table_entry"><para role="column_definition">
       <structfield>oid</structfield> <type>oid</type>
      </para>
      <para>
       Row identifier
      </para></entry>
     </row>

     <row>
      <entry role="catalog_table_entry"><para role="column_definition">
       <structfield>collname</structfield> <type>name</type>
      </para>
      <para>
       Collation name (unique per namespace and encoding)
      </para></entry>
     </row>

     <row>
      <entry role="catalog_table_entry"><para role="column_definition">
       <structfield>collnamespace</structfield> <type>oid</type>
       (references <link linkend="catalog-pg-namespace"><structname>pg_namespace</structname></link>.<structfield>oid</structfield>)
      </para>
      <para>
       The OID of the namespace that contains this collation
      </para></entry>
     </row>

     <row>
      <entry role="catalog_table_entry"><para role="column_definition">
       <structfield>collowner</structfield> <type>oid</type>
       (references <link linkend="catalog-pg-authid"><structname>pg_authid</structname></link>.<structfield>oid</structfield>)
      </para>
      <para>
       Owner of the collation
      </para></entry>
     </row>

     <row>
      <entry role="catalog_table_entry"><para role="column_definition">
       <structfield>collprovider</structfield> <type>char</type>
      </para>
      <para>
       Provider of the collation: <literal>d</literal> = database default,
       <literal>b</literal> = builtin, <literal>c</literal> = libc,
       <literal>i</literal> = icu </para></entry>
     </row>

     <row>
      <entry role="catalog_table_entry"><para role="column_definition">
       <structfield>collisdeterministic</structfield> <type>bool</type>
      </para>
      <para>
       Is the collation deterministic?
      </para></entry>
     </row>

     <row>
      <entry role="catalog_table_entry"><para role="column_definition">
       <structfield>collencoding</structfield> <type>int4</type>
      </para>
      <para>
       Encoding in which the collation is applicable, or -1 if it
       works for any encoding
      </para></entry>
     </row>

     <row>
      <entry role="catalog_table_entry"><para role="column_definition">
       <structfield>collcollate</structfield> <type>text</type>
      </para>
      <para>
       <symbol>LC_COLLATE</symbol> for this collation object. If the provider is
       not <literal>libc</literal>, <structfield>collcollate</structfield> is
       <literal>NULL</literal> and <structfield>colllocale</structfield> is
       used instead.
      </para></entry>
     </row>

     <row>
      <entry role="catalog_table_entry"><para role="column_definition">
       <structfield>collctype</structfield> <type>text</type>
      </para>
      <para>
       <symbol>LC_CTYPE</symbol> for this collation object. If the provider is
       not <literal>libc</literal>, <structfield>collctype</structfield> is
       <literal>NULL</literal> and <structfield>colllocale</structfield> is
       used instead.
      </para></entry>
     </row>

     <row>
      <entry role="catalog_table_entry"><para role="column_definition">
       <structfield>colllocale</structfield> <type>text</type>
      </para>