nction must
    <SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>not</I
></SPAN
> alter the <TT
CLASS="STRUCTNAME"
>TriggerData</TT
>
    structure or any of the data it points to.
   </P
><P
>    <TT
CLASS="STRUCTNAME"
>struct TriggerData</TT
> is defined in
    <TT
CLASS="FILENAME"
>commands/trigger.h</TT
>:

</P><PRE
CLASS="PROGRAMLISTING"
>typedef struct TriggerData
{
    NodeTag       type;
    TriggerEvent  tg_event;
    Relation      tg_relation;
    HeapTuple     tg_trigtuple;
    HeapTuple     tg_newtu