These rules are the same in Oracle and postgres. Why the split?

BTW, all the stuff in `$(ENV_DIR)` being managed in `data/common` is confusing. Targets in a specific  should be managed, to the extent it's practical, from makefiles in the directory they're in. Not saying this has to be improved in this PR, but probably some refactoring is due on the next change. As it stands it's confusing.