no more than one <structname>pg_opclass</structname>
   row having <structfield>opcdefault</structfield> true for any given combination of
   <structfield>opcmethod</structfield> and <structfield>opcintype</structfield>.
  </para>

 </sect1>


 <sect1 id="catalog-pg-operator">
  <title><structname>pg_operator</structname></title>

  <indexterm zone="catalog-pg-operator">
   <primary>pg_operator</primary>
  </indexterm>

  <para>
   The catalog <structname>pg_operator</structname> stores information about operators.
   See <xref linkend="sql-createoperator"/>
   and <xref linkend="xoper"/> for more information.
  </para>

  <table>
   <title><structname>pg_operator</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>oprname</structfield> <type>name</type>
      </para>
      <para>
       Name of the operator
      </para></entry>
     </row>

     <row>
      <entry role="catalog_table_entry"><para role="column_definition">
       <structfield>oprnamespace</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 operator
      </para></entry>
     </row>

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

     <row>
      <entry role="catalog_table_entry"><para role="column_definition">
       <structfield>oprkind</structfield> <type>char</type>
      </para>
      <para>
       <literal>b</literal> = infix operator (<quote>both</quote>),
       or <literal>l</literal> = prefix operator (<quote>left</quote>)
      </para></entry>
     </row>

     <row>
      <entry role="catalog_table_entry"><para role="column_definition">
       <structfield>oprcanmerge</structfield> <type>bool</type>
      </para>
      <para>
       This operator supports merge joins
      </para></entry>
     </row>

     <row>
      <entry role="catalog_table_entry"><para role="column_definition">
       <structfield>oprcanhash</structfield> <type>bool</type>
      </para>
      <para>
       This operator supports hash joins
      </para></entry>
     </row>

     <row>
      <entry role="catalog_table_entry"><para role="column_definition">
       <structfield>oprleft</structfield> <type>oid</type>
       (references <link linkend="catalog-pg-type"><structname>pg_type</structname></link>.<structfield>oid</structfield>)
      </para>
      <para>
       Type of the left operand (zero for a prefix operator)
      </para></entry>
     </row>

     <row>
      <entry role="catalog_table_entry"><para role="column_definition">
       <structfield>oprright</structfield> <type>oid</type>
       (references <link linkend="catalog-pg-type"><structname>pg_type</structname></link>.<structfield>oid</structfield>)
      </para>
      <para>
       Type of the right operand
      </para></entry>
     </row>

     <row>
      <entry role="catalog_table_entry"><para role="column_definition">
       <structfield>oprresult</structfield> <type>oid</type>
       (references <link linkend="catalog-pg-type"><structname>pg_type</structname></link>.<structfield>oid</structfield>)