>>So, I used the integer because of several facts.
>>1. Since, we don't capture seconds it's waste(processing, storage and data transfer) to store >>data on that. Initially I used LocalTime(in Java) and Time(Mysql) for duration. When using >>SMALLINT instead of TIME it improves performance by around(33%) at the mysql database.
>>2. Data manipulation over integer is faster than using TIME format in java.
>>Ex:- when using validations it uses lower overhead to data conversion and processing

Great job thinking this through in such detail @diunuge :+1: 

I have a different opinion here (who doesn't? :) ) and have a thing against premature optimization.....  I would have preferred using time if we needed to add a new column (do we?)  as it becomes obvious for somebody writing a report to manipulate the data etc) 

Also, the API returning start time as a number dosen't seem right.

Since we already have a start_date in the calendar (of type date) I would have probably changed it to dateTime (so we could persist time in the same field)

The API could also return startDate as dateTime (We are breaking the existing API, but the API is still intuitive..)