There’s no need for a separate start_date (and I can’t envision how you’d implement it, given that (a) you don’t want to refer to the log table’s contents in the trigger and (b) the start of the log table can be truncated at will to save space); all this can be done based solely on the log_date and the log_action column. What I meant is that it’s not *trivial* to fetch cross-table dependencies, because for every joined table you need to analyse both log_time and log_action. Still, this is preferable to storing ‘validity window’ start+end dates for rows in the main database.