our %h;
tie %h, "BerkeleyDB::Btree",
                -Filename 	=> '/tmp/ads_export.bdb',
                -Flags    	=> DB_CREATE,
				-Cachesize 	=> 250 * 1024 * 1024
        or die "$! $BerkeleyDB::Error\n" ;

$h{aaa} = $somevalue
untie %h;