>Hi, George.
>
>I think manufacturing in general is one of the more complex things. We have a Manufacturing Control application that was born in FoxBase+ and had a lot of reincarnations trough all this time.
>
>A few years ago the last version for DOS (FPD 2.6) was translated to the brand new VFP 5 and I was in charge of the redesign (I have had not participated much in the application since the first versions).
>
>I found a table that stored the machine used in a certain task within a product specification. The primary key was:
> Product code
>+ Route number (a product can have many)
>+ Revision number (a rout can have many)
>+ Profile type (within the same revision: normal, reprocess, etc)
>+ Step number (a first division of the production cycle)
>+ Process number (second one)
>+ Task number (third level)
>+ Machine (and order number related to another list)
>
>All this meant a primary key of 37 bytes! Of course this table was heavily accessed trought the control process (and this is the worst case I remember, but there where a lot more). Do I need to mention that one of the primary goals of the new version was to improve the sluggish performance?
>
>We changed everything to surrogate keys and at the first implementations, all users commented that it was incredible how faster was Windows than DOS! 8-)
>
>The speed improvements in almost any proceess averaged 400%.
>
>Another -apparently- unrelated case happened many years ago was when a quite big customer (local subsidiary of a multinational company), received the order from headquarters in Korea of use a totally new set of product codes.
>
>As the product code was our natural key everywhere, the conversion process was terrible! Thanks god we already had a data dicionary in which the program could be based. But it involved hundreds of tables with many thousands (sometimes millions) of records.
>
>Since then, one of the first things in our internal handbook is USE SURROGATE KEYS!
>
> Just my two argentine pesos to the PK debate.
>
This application (one of many) originally had its "birth" back in FoxBASE+. The example I mentioned is, admittedly the most complex, but even something as simple as the PKs for machine style data uses surrogate keys.