Description:
------------
Simple program:

// remember used memory
$start = memory_get_usage();
$dbh = new PDO('mysql:...','...','...');
// create empty table
$dbh->query('DROP TABLE IF EXISTS ttt;');
$dbh->query("CREATE TABLE ttt ( id integer, args longtext);");
// simple code
function doQuery($id)
{
	static $sth;
	if( !$sth )
		$sth = $GLOBALS['dbh']->prepare("SELECT * FROM ttt WHERE id = ?");
	$sth->execute(array($id));
	return $sth->fetchAll();
}
var_dump(doQuery('5'));
echo memory_get_usage()-$start;
// eats 1 megabyte of memory.
// if I duplicate doQuery()->doQuery2()
// and call doQuery2() - it eats 2(!!) Mb of memory
// if I remove LONGTEXT, everything is OK.

Reproduce code:
---------------
see above.

Expected result:
----------------
Please, not so much memory!