alter table partition error

[jason zhang]

I created two tables to reproduce this problem:

test:
id int(11) primary key
region_id int(11)

region:
id int(11) mul index
name char(32)

then create a constraint:
alter table test add constraint foreign key (region_id) references region (id);

Up to now, both two tables are empty, I executed below sql to create partition:

alter table test partition by hash(region_id) partitions 2;

I got below error info:

ERROR 1217 (23000): Cannot delete or update a parent row: a foreign key constraint fails

I can not understand why this operation raise an constraint error. There is no record been deleted or updated at all.


The real case is I already has a table include millions record and I want to partion on it now.