10. Code convention

1. use nvarchar instead of varchar. Rationale. The size and performance impact is relatively small because betl only contains meta data. Microsoft uses nvarchar for it's own meta data repository, so theoretically strange characters could appear in the meta data. It's better to be prepared than to face a bug in this case.

2. Stored procedures and functions should perform only one atomic function. I.e. do do not execute refresh inside push because this complicates testing and this is bad for performance ( since refresh is executed too many times).

3. use nvarchar(max) to prevent truncation errors.