set @@sql_mode=strict_trans_tables; create table t1(a text not null) row_format=dynamic engine=innodb; create index idx1 on t1(a(3073)); Warnings: Note 1071 Specified key was too long; max key length is 3072 bytes show create table t1; Table Create Table t1 CREATE TABLE `t1` ( `a` text NOT NULL, KEY `idx1` (`a`(3072)) ) ENGINE=InnoDB DEFAULT CHARSET=latin1 ROW_FORMAT=DYNAMIC drop table t1; set @@sql_mode=default;