If the enrolments table is too large, the database enrolment plugin may delay too much time to make all enrolments.

We can minimize this time if we use two tables. One original table, in which the enrolment is stored when the user logs in to Moodle, and another table, smaller than the original one, to do the synchronization with all changed enrolments only.

In that case, we recommend to disable unenrolaction to avoid the accidental massive unenrolment.