DB Foreign Key in diffrente Schemas (Constraint not created)

Hi all,

We develop an applications (web and mobile) and because we do not want our applicational data mixed up with infrastructure related data we decided to separate it by creating a new schema for each  new application, lets say for example Schema EMP

For auditing purposes the tables have same audit fields such as CreatedBy, UpdatedBy etc. However this fields are foreign keys refering to the Users table which happened to be in a different schema, HUBADMIN.

Even though the foreign key is sucessfully created Oustsystems cannot guarantee the integrity between tables in different schemas, this is clear whenever I move my application from one environment to the other and Lifetime outputs the following warning: 

Constraint for 'EMPLOYEE.CreatedBy' was not created because it references a entity from an module in a different database schema. The delete rule should be changed to ignore.

My question is the following. In terms of performance what are the implication of having this set up with relationships between different schemas, especially taking in consideration that: 

  1.  - the constraints are not being created and;
  2.  - almost all queries will have joins between tables in diferent schemas

Thanks in advance for your assistance.

Just to clarify, are you talking about creating schemas in an external database? Per the documentation here?