[keycloak-user] Migrating Users Database

Hi, I'm trying to replace my current authentication system with Keycloak, but I have one problem. I already have a database of users, populated with millions of records, and I wanted to make it work with Keycloak. What would be the best approach on this scenario? Should I migrate everything to the Keycloak tables, or try to make Keycloak understand my current database? Is there any recommendation on this matter? And if there is, some explanation or documentation? Thanks! -- Rodrigo Sasaki