http://dev.mysql .com/doc/refman/5.0/hi/group-by-functions.html#function_group-concat
SET [GLOBAL | SESSION] group_concat_max_len = val;
http://dev.mysql .com/doc/refman/5.0/hi/group-by-functions.html#function_group-concat
SET [GLOBAL | SESSION] group_concat_max_len = val;