Surrogate key Vs primary key

Surrogate Key is similar to Primary key interms of its characteristics like the value will be user generated or auto generated sequence having not null values. Surrogate Key is primary key for the Key columns defined in the Dimension tables in DWH. In OLTP system this will be achieved by introducing Composite Primary Keys. Suppose, if you want query a table with composite key, you have to define no of columns specified in the composite key in the where condition this will be overhead to database. Instead, we define a Surrogate key which is unique for the composite key in Dimension Table. Having a Surrogate Key will help the BI Team to fetch the dimension records faster than using Primary or composite primary key.