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# Bug #20762798 FK DDL: CRASH IN DICT_FOREIGN_REMOVE_FROM_CACHE
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create table t1(a int, b int, key(a),key(b))engine=innodb;
create table t2(a int, b int, key(a),key(b))engine=innodb;
alter table t2 add constraint b foreign key (b) references t1(a);
alter table t1 add constraint b1 foreign key (b) references t2(a);
alter table t2 add constraint b1 foreign key (b) references t1(a);
ERROR HY000: Can't create table `test`.`t2` (errno: 121 "Duplicate key on write or update")
alter table t2 drop foreign key b;
alter table t1 drop foreign key b1;
drop table t2;
drop table t1;