How do you store Historical data in a DWH ?

1.How do you store Historical data in a DWH?
2.What is the primary purpose of using surrogate key? Will those be used in fact tables?If not then what is the purpose in using it?
3. How do you update Information in Update strategy Transformation?
4. How do you validate data after you have transferred it into target table from flat files?

Questions by Prajwal Jaladanki

Showing Answers 1 - 2 of 2 Answers

vizaik

  • Mar 15th, 2007
 

By using scd2, we can store historical data.

Surrogate key is used for indexing purpose.  i.e. as a primary key for a table.  You can say that why can't we use primary key.  But the problem with pk is it may take more or less memory i.e. it may contain characters but sk contains only number.  So comparision of numbers is eary when comparing with characters. 
Yes sk will be used in fact tables to establish a relationship between demensions.

By keeping dd_update command or 1 in specified box in properties of upd transfor.

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vizaik

  • Mar 15th, 2007
 

By using scd2, we can store historical data.

Surrogate key is used for indexing purpose.  i.e. as a primary key for a table.  You can say that why can't we use primary key.  But the problem with pk is it may take more or less memory i.e. it may contain characters but sk contains only number.  So comparision of numbers is eary when comparing with characters. 
Yes sk will be used in fact tables to establish a relationship between demensions.

By keeping dd_update command or 1 in specified box in properties of upd transfor.

  Was this answer useful?  Yes

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