Answered Questions

  • What is surrogate key ? Where we use it explain with examples?

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    Answered by: saravanan

    • Dec 2nd, 2005


    Surrogate key is a unique identification key, it is like an artificial or alternative key to production key, bz the production key may be alphanumeric or composite key but the surrogate key is always single numeric key. Assume the production key is an alphanumeric field if you create an index for this fields it will occupy more space, so it is not advisable to join/index, bz generally all the datawarehousing fact table are having historical data. These factable are linked with so many dimension table. if it's a numerical fields the performance is high

    P.Manideep

    • Oct 29th, 2017

    Surrogate key is system generated key. It is a column or set of columns declared as primary key instead of real of natural key.

    Anukul Thawarey

    • Aug 8th, 2017

    Just to add on to this point, we can also have date stamp as in the format (yyyymmdd) which is actually an 4 Byte unsigned integer to keep track of the historical data. This date stamp column can also be considered as an surrogate key.

  • What is meant by metadata in context of a Datawarehouse and how it is important?

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    kalpit

    • Mar 10th, 2009

    Metadata is the Information about the Data which is being stored in DWH , Why its imp : 1. To know the flow of source data into Data Warehouse, 2. In case if you have many star schema or many subjec...