how to create odata service using sql server for big size data using .net

Not entirely sure this is the correct community for that, you would probably have more luck on a TechNet developer forum, but here is a link to get you started:

http://www.asp.net/web-api/overview/odata-support-in-aspnet-web-api

Hi,

Why don't you want simply to use a 3rd party solution, like Skyvia Connect, to expose your SQL Server data as OData REST API, and use it in real time? Skyvia has OData connectors for cloud applications and relational databases, including SQL Server.