Can i make new database column for entities ?

I want to make a web for event ,
i need:

city

state

date

 

I know i can save them using entity metadata like $entity->city , but it will be difficult to sort entities list . For example : list of events that will be held in New york , US, before 2 January 2017 .

I think it will be easier if i have some new  column in entities table like :  entities.city , entities.state . entities.date

 

can i do that safely ?