Hi Asish,
There is no limit theoretically. It completely depends on how many columns a table at Postgres can handle which I know is very large.
Question is what is your use case.
To have 200-250 fields in a resource doesn't sound valid if this is the number if fields you are trying to achieve.
The resources should adhere to database normalization and you should define resources to respect 3rd Normal form of RDBMS
Hope this helps.
Regards,
Vipul