one or more Entity models for one database for entity framework?

When use entity framework f开发者_C百科or DAL tier, VS 2010 can create edmx for each database.

Question: If I have a database with many tables, should I create only one edmx for all tables or mutiple edmx files? for example, maybe all security tables for one edmx file, other tables for another edmx file. If there is more than one, then in other tiers, there will have more then on ObjectContext in code for business logic.

Which one it the best solution for this case?

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I've done this before when experimenting with AdventureWorks. If you have a large database with lots of tables, and the tables are segmented into separate schemas (like the Purchasing, Sales, HumanResources schemas in AdventureWorks) then it may work well to create multiple models. They don't have to be separate schemas- any two groups of related tables where there are no relations between the groups would work.

You'd want to make sure that you include all related tables in each model so that you don't have to try to join entities across models.