Apex: Caveat PK column name length
It is highly encouraged in Apex to use system generated, single primary key columns whenever possible.
When choosing multi-column, composed primary keys, you quickly get in trouble when dealing with the standard MRU Processes. This is limited to handling tables with at most a 2 column primary key.
So, it is a good practice to work with auto-generated, sequence-based PK’s, on 1 column.
There is one caveat that you should be aware of.
Within Oracle, the maximum length of a column name is 30 characters.
However, when you plan to build tabular forms on your tables, the length of the primary key column name may not exceed 22 characters.