Question

Basically, I will need to combine product data from multiple vendors into a single database (it’s more complex than that, of course) which has several tables that will need to be joined together for most OLTP operations.

I was going to stick with the default and use an auto-incrementing integer as the primary key, but while one vendor supplies their own ‘ProductiD’ field, the rest do not and I would have to do a lot of manual mapping to the other tables then to load the data (as I would have to first load it into the Products table, then pull the ID out and add that along with the other information I need to the other tables).

Alternatively, I could use the product’s SKU as it’s primary key since the SKU is unique for a single product, and all of the vendors supply a SKU in their data feeds. If I use the SKU as the PK then I could easily load the data feeds as everything is based off of the SKU, which is how it works in the real world. However the SKU is alphanumeric and will probably be slightly less efficient than an integer-based key.

Any ideas on which I should look at?

Answer 1

This is a choice between surrogate and natural primary keys.

IMHO always favour surrogate primary keys. Primary keys shouldn’t have meaning because that meaning can change. Even country names can change and countries can come into existence and disappear, let alone products. Changing primary keys is definitely not advised, which can happen with natural keys.

More on surrogate vs primary keys:

So surrogate keys win right? Well, let’s review and see if any of the con’s of natural key’s apply to surrogate keys:

• Con 1: Primary key size – Surrogate keys generally don’t have problems with index size since they’re usually a single column of type int. That’s about as small as it gets.
• Con 2: Foreign key size – They don’t have foreign key or foreign index size problems either for the same reason as Con 1.
• Con 3: Asthetics – Well, it’s an eye of the beholder type thing, but they certainly don’t involve writing as much code as with compound natural keys.
• Con 4 & 5: Optionality & Applicability – Surrogate keys have no problems with people or things not wanting to or not being able to provide the data.
• Con 6: Uniqueness – They are 100% guaranteed to be unique. That’s a relief.
• Con 7: Privacy – They have no privacy concerns should an unscrupulous person obtain them.
• Con 8: Accidental Denormalization – You can’t accidentally denormalize non-business data.
• Con 9: Cascading Updates – Surrogate keys don’t change, so no worries about how to cascade them on update.
• Con 10: Varchar join speed – They’re generally int’s, so they’re generally as fast to join over as you can get.

And there’s also Surrogate Keys vs Natural Keys for Primary Key?