Hi, I've been trying to solve an issue with my Federator for a few days now when I import users that don't exist in Keycloak (but they do exist in my Federator DB). I'm getting a duplicated value constraint violation error on email_constraint attribute from user_entity table. So I looked into the source code and found that the emailConstraint attribute is being set to the email value when I'm calling UserEntity.setEmail(String email). public void setEmail(String email) { this.email = email; this.emailConstraint = email != null ? email : KeycloakModelUtils.generateId(); } Also I saw this comment in UserEntity.java:64: // Hack just to workaround the fact that on MS-SQL you can't have unique constraint with multiple NULL values TODO: Find better solution (like unique index with 'where' but that's proprietary) @Column(name = "EMAIL_CONSTRAINT") protected String emailConstraint = KeycloakModelUtils.generateId(); My system allows duplicated email addresses and that cannot change. Is there any way to allow duplicated email addresses on Keycloak? Are you planning on an improvement to add support for a configurable unique key for users? What would be the best way to get rid of that constraint? As a reference, I'm using Keycloak 1.7.0 and Informix as a DB. Any help would be appreciated. Thanks in advance. Regards, Fab -- *Fabricio Milone* Developer *Shine Consulting * 30/600 Bourke Street Melbourne VIC 3000 T: 03 8488 9939 M: 04 3200 4006 www.shinetech.com *a* passion for excellence