my %session;

tie %session,'Apache::Session::MySQL', undef, { 
    DataSource => 'dbi:mysql:sessions',
   UserName => 'login',
    Password => 'pass',
    LockDataSource => 'dbi:mysql:sessions',
    LockUserName   => 'login',
    LockPassword   => 'pass' };

my $id = $session{_session_id};
$session{TIMESTAMP} =time;
$session{tree} = $treeP; ## $treeP is a N-ary Tree

$session{uname} = $uname;
untie(%session) || die " Cant untie! \n";

##-- in another code
my %session1;

tie %session1,'Apache::Session::MySQL', undef, {
    DataSource => 'dbi:mysql:sessions',
   UserName => 'login',
    Password => 'pass',
    LockDataSource => 'dbi:mysql:sessions',
    LockUserName   => 'login',
    LockPassword   => 'pass' };


my $u = $session1{uname}; ## this value is undef if I try to store the tree as well in the above code

print STDERR "name $u \n"; 
untie(%session1) or die "CANT CLOSE!! \n";