1# 2# Bug #20762798 FK DDL: CRASH IN DICT_FOREIGN_REMOVE_FROM_CACHE 3# 4create table t1(a int, b int, key(a),key(b))engine=innodb; 5create table t2(a int, b int, key(a),key(b))engine=innodb; 6alter table t2 add constraint b foreign key (b) references t1(a); 7alter table t1 add constraint b1 foreign key (b) references t2(a); 8alter table t2 add constraint b1 foreign key (b) references t1(a); 9ERROR HY000: Can't create table `test`.`t2` (errno: 121 "Duplicate key on write or update") 10alter table t2 drop foreign key b; 11alter table t1 drop foreign key b1; 12drop table t2; 13drop table t1; 14