[erlang-questions] How do you efficiently do this kind of mnesia schema?

[ryeguy]

I'm trying to break free of the RDBMS thought process, but I can't
wrap my head around how to efficiently implement this kind of schema.

Say I have a User record, and he has many SubItemA records, which has
many SubItem B records, so:

User
-SubItem A
--SubItem B
...

I need to run queries on SubItem B. Is it efficient to do it when it's
this nested? Should I just normalize it so it will be quicker?

I have heard of some people using data duplication so the data is both
nested and separate, is this ridiculous or is this actually useful in
some cases?