I definitely agree that there may be some unexpected consequences of using the primary key in this way. It certainly won't behave like a timestamp and could di

I definitely agree that there may be some unexpected consequences of using the primary key in this way. It certainly won't behave like a timestamp and could distort the function outputs. Would it be possible to substitute the integer count of seconds since epoch (or some other arbitrary base timestamp) and use that instead? Then you'd still have an immutable function to satisfy the index, but also you'd preserve valuable information about the relative time intervals between posts.