What is the best way to store data in DB (in json format), full value or capital letters?

Question

Data archiving

Good afternoon.
Advise how it is better to store the data in a DB (while in plans to use FireBase). For example, the field "Kind" can have one of the values: "Job", "Notice", "Control", store them like this or just: "J", "N", "C"? Or the "State" field: "Work", "Done", "Break", etc.
In the first case, it is clear what's what, in the second, there is less space for storage and transmission.

Answer 1

The compact form of the record makes sense if the amount of json received is hundreds of KB or there are many records.
And if the data is received by a mobile client, then the size should be as compact as possible.