<indexterm zone="catalog-pg-transform">
   <primary>pg_transform</primary>
  </indexterm>

  <para>
   The catalog <structname>pg_transform</structname> stores information about
   transforms, which are a mechanism to adapt data types to procedural
   languages.  See <xref linkend="sql-createtransform"/> for more information.
  </para>

  <table>
   <title><structname>pg_transform</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>trftype</structfield> <type>oid</type>
       (references <link linkend="catalog-pg-type"><structname>pg_type</structname></link>.<structfield>oid</structfield>)
      </para>
      <para>
       OID of the data type this transform is for
      </para></entry>
     </row>

     <row>
      <entry role="catalog_table_entry"><para role="column_definition">
       <structfield>trflang</structfield> <type>oid</type>
       (references <link linkend="catalog-pg-language"><structname>pg_language</structname></link>.<structfield>oid</structfield>)
      </para>
      <para>
       OID of the language this transform is for
      </para></entry>
     </row>

     <row>
      <entry role="catalog_table_entry"><para role="column_definition">
       <structfield>trffromsql</structfield> <type>regproc</type>
       (references <link linkend="catalog-pg-proc"><structname>pg_proc</structname></link>.<structfield>oid</structfield>)
      </para>
      <para>
       The OID of the function to use when converting the data type for input
       to the procedural language (e.g., function parameters).  Zero is stored
       if the default behavior should be used.
      </para></entry>
     </row>

     <row>
      <entry role="catalog_table_entry"><para role="column_definition">
       <structfield>trftosql</structfield> <type>regproc</type>
       (references <link linkend="catalog-pg-proc"><structname>pg_proc</structname></link>.<structfield>oid</structfield>)
      </para>
      <para>
       The OID of the function to use when converting output from the
       procedural language (e.g., return values) to the data type.  Zero is
       stored if the default behavior should be used.
      </para></entry>
     </row>
    </tbody>
   </tgroup>
  </table>
 </sect1>


 <sect1 id="catalog-pg-trigger">
  <title><structname>pg_trigger</structname></title>

  <indexterm zone="catalog-pg-trigger">
   <primary>pg_trigger</primary>
  </indexterm>

  <para>
   The catalog <structname>pg_trigger</structname> stores triggers on tables
   and views.
   See <xref linkend="sql-createtrigger"/>
   for more information.
  </para>

  <table>
   <title><structname>pg_trigger</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>tgrelid</structfield> <type>oid</type>
       (references <link linkend="catalog-pg-class"><structname>pg_class</structname></link>.<structfield>oid</structfield>)
      </para>
      <para>
       The table this trigger is on
      </para></entry>