[porridgeraisin]

Doesn't a view do that?

  create view active_cx as select * from customer join audit_events using(...) join ... where -- active condition

  -- use active_cx wherever

  select ... from orders join active_cx using(...) where ts > start_of_month() group by active_cx.id

[cryptonector]

It sounds like "semantic layer" == views/queries created automatically and on the fly.