Foreign Key Different Database

[Ray Garrison]

I don't know if I am trying to do something that is not supported, or if I'm just making an error.

Does InnoDB support a foreign key relationship between databases?

Can I do this?

USE database1;
CREATE TABLE sometable ( id INT NOT NULL, somevalue TEXT, PRIMARY KEY (id) ) TYPE=InnoDB;

USE database2;
CREATE TABLE anotherone ( id INT NOT NULL, sometable_id INT, anothervalue TEXT, PRIMARY KEY (id), KEY (sometable_id), FOREIGN KEY (sometable_id) REFERENCES database1.sometable (id) ) TYPE=InnoDB;


When I try this, I get the standard "a foreign key constraint fails" error, but I don't know whether that's because the key migration across different databases isn't supported, or because I have a missing key value in the reference table, or some other problem.

Why would I want to do this? I am using a CRM system that creates it's own database, I have a different application that has it's own database, I am anticipating that for performance reasons I might want these databases on separate CPU's in a MySQL cluster, and besides I don't want to co-mingle the different databases because of support issues.