Manual:User creation

User creation occurs in one of four ways. In an "autocreate" log event, the user is automatically created, e.g. by Extension:CentralAuth. In a "byemail" log event, the created user receives its password by email. In a "create" log event, an anonymous user creates an account for himself. In a "create2" log event, a logged in user creates an account for someone else.

Database
contains a "4::userid" field with the of the created account.

API
API:Logevents puts the user ID of the created account in the "userid" property and does not reveal the user ID of the user creating the account.