Using a notched post and beam connection will lock the beam in place, secure it from rotating and resist wind uplift. Notching a post does not weaken the structural integrity of the wood support post because the load for the deck is transferred down through the post to the footings. The upright notched section of the post acts stabilizes the beam. Most deck builders use a reciprocating saw to cut an L shaped seat in the top of the post large enough to hold the beam. Another building method to consider if you don’t have a reciprocating saw involves using circular saw to score the top of the post to remove the weakened sections with a chisel. A 2-2×10 beam will require a notch 3” wide by 9-1/4 inches tall. To hold the beam in place you will then need to predrill and run two ½” threaded carriage bolts through the beam and the top of the notch.