sarogate key

[sairaochowdary]

Hi anybody
i would like to know about sarogate key

Thanks
Sairaochowdary

 

[DoubleD]

Surrogate Keys don't really have anything to do with Cognos, it is a database term.

Here is the definition from the Computing-Dictionary website.

(database) surrogate key - A unique primary key generated by the RDBMS that is not derived from any data in the database and whose only significance is to act as the primary key.

A surrogate key is frequently a sequential number (e.g. a Sybase "identity column") but doesn't have to be. Having the key independent of all other columns insulates the database relationships from changes in data values or database design and guarantees uniqueness.

Some database designers use surrogate keys religiously regardless of the suitability of other candidate keys. However, if a good key already exists, the addition of a surrogate key will merely slow down access, particularly if it is indexed.

Surrogate keys are most often used for performance considerations.

Pain is stress leaving the body.

DoubleD

 

[monsky]

One application of surrogate keys is in dimensional modeling of a data mart/data warehouse specifically in preserving history through the use of slowly changing dimensions.