Does the timestamp data type represent an instant-in-time or a year-month-date-hour-minute-second value? An instant in time is a moment, like the moment you started reading this, and it can be described with many different y-m-d-h-m-s+timezone values. Without timezone, it's ambiguous, the same moment can be 17:25 for me and 13:25 for someone else.
Here's what I think I get. The
current_timestamp function returns the current time in the current timezone, so this is an unambiguous instant, the real now. Inside a table, it is stored as UTC, so with this assumed timezone, it should also be unambiguous.
Now here's what I don't get: it's the existence of the
utc_timestamp function. I stored a
current_timestamp and an
utc_timestamp inside the same column, and they were different. This function shouldn't even exist, I don't understand why it represents a different instant in time.