Surogate Keys

[ksk2]

Hi every one,

Can any one give info about the surogate keys.with example.

do we use this keys only for star schema?

Thanks for help ..

ksk2

 

[srinathmk]

Surrogate keys are system generated numeric fields which do not have any business meaning. They are used in data warehousing. These surrogate keys will be primary keys in dimension table which will be mapped as foreign keys in fact table.Ex: Say there is a Customer Dimension table. The Customer_Key may be called a surrogate key which uniquely represents his name, age etc.
The following are the advantages of surrogate keys:
1. They are independent of business meaning. Hence are also useful in slowly changing dimension senario.
2. Since they are numeric keys, the indexing on these keys will be optimal.

Warm Regards,
Srinath M.K Thanks and Warm Regards,
Srinath M.K

 

[padelg]

Other reason for using this surrogates keys.
If the operational changes its ids, the facts tables in the DWH is not affected. May be you only have to change in the dimension tables the id's traduction for the operational to the multdimensional. But you don't have to update the fact tables (normally with millions of records).

regards
Pablo