Reply To: raised table top board, 5 inches from edge.

Nails might not be your best bet they will come out eventually , especially out side.
The picture is hard to see but I think what you are saying is the joint moved.
You could epoxy it and clamp it flat , 1 mm isn’t a lot to flex. And epoxy might hold. Especially in cedar. It’s kinda oily and the joint is contaminated from old glue