Hi @JOHN1, welcome to the forum 
I see you have cross-posted this at https://or.stackexchange.com/questions/13239/solving-a-large-scale-milp-problem-with-cplex-takes-long-time.
If you post the same question in multiple places, please leave links so that we donât repeat work answering a question twice. Also note that this forum is for Julia-related questions. The or.stackexchange is probably a more relevant forum for discussing MIP formulations.