Question

I know EF checks the EdmMetadata table to determine if the version of model classes is same as database tables.

I want to know exactly how EF can find if the version of a model has changed. In other words, I want to know what does EF compare to the modelhash in the database?

Answer 1

Have a look at this blog post about the EdmMetadata table.

For your question, this is the relevant parts:

The EdmMetadata table is a simple way for Code First to tell if the
model used to create a database is the same model that is now being
used to access the database. As of EF 4.1 the only thing stored in the
table is a single row containing a hash of the SSDL part of the model
used to create the database.

(Geek details: when you look in an EDMX file, the SSDL is the part of
that file that represents the database (store) schema. This means that
the EdmMetadata model hash only changes if the database schema that
would be generated changes; changes to the conceptual model (CSDL) or
the mapping between the conceptual model and the database (MSL) will
not affect the hash.)