Primary Key Mangling
or surrogate keys as they are called.
| Component | Component Version |
1 | Base | 1.0 | 2006-01-07 |
3 | Base | 1.1 | ~NULL~ |
|0000ff|Component, Component Version| was the original primary key and still identifies each record uniquely.
A (combination of) key(s) that identify a record uniquely is called a *candidate key*.
One of the candidate keys can be defined as the primary key (|ff0000|ID| in the example above).
|ff0000|ID| is an artificial key (surrogate key).
A surrogate key is not always required, but can increase performance while joining or selecting.