mysql中hash索引存在的奇怪的问题

create table t1(x char(10), y char(10), key hs using hash(x,y)) engine=myisam

insert into t1 values('fdsfd', 'gdfas'),('fds', 'gasd');

describe select * from t1 where x>'fd'

结果为


1 SIMPLE t1 index hs hs 62 2 Using where; Using index


请问hash索引这是怎么了, 支持范围查找了????????????????????????????