General Ledger Account Number as Dimension Key

I am adding a General Ledger Account dimension to my DW. It will be populated from the chart of accounts table in our ERP system. Now, all the dimensions (product, customer, etc.) that I have previously designed have a proper surrogate key (SK), and I have never before been inclined to use a business/natural key as a DW dimension key.

However, for the General Ledger Account dimension I am sorely tempted to use the 5-digit account number (which can be stored as a 4-byte integer) as the key. The accounting folks assure me that account numbers never change, and there are no SCD2 attributes for an account number.

Should I use the account number as my dimension key? Is there a benefit to creating a proper SK for a Type1 dimension if the business key is truly unique and immutable?

I would definitely implement a surrogate key because you'll never know when it'll come back and bite you. Another reason is if your company acquires another company, chances are they will have a whole different set of GL account numbers.

Why risk it? Create a surrogate key and move on.

VHF wrote:The accounting folks assure me that account numbers never change, and there are no SCD2 attributes for an account number.

Should I use the account number as my dimension key? Is there a benefit to creating a proper SK for a Type1 dimension if the business key is truly unique and immutable?

If I could have a dollar every time a business user said 'always' or 'never' which really meant 'usually' or 'rarely'....

Always use surrogate keys... don't be seduced by the dark side...

In the past when business users have told me that something will "never" happen I have often replied that "'never' is a very long time"!

But in this case I was letting myself be tempted by those nice shinny, red, delicious, unique (at least for now) 4-byte integer business keys!

Don't worry, I'll create proper SKs... thanks everybody for keeping me on the straight and narrow!

Oh, and by the way, most accounting systems allow alphanumerics for account segments. They may be using numbers now, but it won't be long until they start using letters for things like memo accounts. Always store business keys in character fields in the data warehouse, no matter what the business tells you.