title: Using custom or different column other than rowtime column as timestamp column in KSQL while doing joins
body: <p>Hi i am trying out KSQL and found that most of the documentation provides example of direct joins with kstream or ktable. Lets say i have 2 streams already created by team X and i can't change it or recreate new streams and also want to use existing stream. Here by default rowtime is consider for timestamp column while joining. Is there any way to specify other than rowtime column as timestamp column in existing streams and consider its time windows for joining in KSQL.</p>