In our library we are using the partnumber a the primary key. This is just a 'dumb' number like '1004473'.
Every part in the library has, among others, the following properties to further identify the part;
Part Name : ELJPA220KF, The actual part number from the manuacturer
Manufacturer : Panasonic, The actual manufacturer of the part
It sometimes happens that a manufacturer went broke, or merges with an other manufacturer making
the above properties invalid.
This means that we have to update all the involved parts, or declare them obsolete and enter new parts as a replacement. In case of a
manufacturer for resistors this is a awful lot of work.
I am very interested how others are handling this issue.