When you are depending on the fields in the rows as part of your audit record, you need to ensure that the values reflect reality. We were able to make sure that the
last_changed_ * fields always contain the correct value, but how about the
created_at values? These can easily be changed in later updates, but they should never change. Even initially, they can be set to false values, since default values can be easily overridden by giving any other value in the
So, let's modify our
changestamp() trigger function into a
usagestamp() function, which makes sure that initial values are what they should be and that they stay like that:
CREATE OR REPLACE FUNCTION usagestamp() RETURNS TRIGGER AS $$ ...