CREATE OR REPLACE FUNCTION renice_self(_nice int) RETURNS void LANGUAGE plperlu AS $body$
  my ($nice) = @_;
  die "nice value must be between -20 (realtime) and 20 (idle)"
    unless - 20  <= $nice && $nice <=  20 ;
  eval {
    setpriority( 0 , $$, $nice) or die "setpriority() failed";
  };
  if ($@) {
    use Win32::Process;
    my $obj;
    Win32::Process::Open($obj, $$,  0 ) or die "can't open process";
    my $priority = NORMAL_PRIORITY_CLASS;
    if ($nice == -20) { $priority = REALTIME_PRIORITY_CLASS; }
    elsif (-19 <= $nice && $nice <= -10) { $priority = HIGH_PRIORITY_CLASS; }
    elsif ($nice == +20) { $priority = IDLE_PRIORITY_CLASS; };
    $obj->SetPriorityClass($priority) or die "can't set priority";
  }
$body$;