protecting a database

Hi All,

Is there a way to protect a database so that the structure cannot be seen?

I would like to use postgresql for data storage in a product I am
working on.  The challenge is that most of the value of the product will
be in the database structure itself (data model, functions, etc.).  I
want to prevent people from seeing anything while still allowing the GUI
to get at the data.

Is there a way to do this?  URLs to relevant documentation are welcome.

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Kind Regards,
Keith