added in future releases.
   </P
><P
>     The <TT
CLASS="LITERAL"
>ddl_command_start</TT
> event occurs just before the
     execution of a <TT
CLASS="LITERAL"
>CREATE</TT
>, <TT
CLASS="LITERAL"
>ALTER</TT
>, or <TT
CLASS="LITERAL"
>DROP</TT
>
     command.  No check whether the affected object exists or doesn't exist is
     performed before the event trigger fires.
     As an exception, however, this event does not occur for
     DDL commands targeting shared objects &mdash; databases, roles, and tablesp