ETL - what is scd dimensions? explain the types in brief?

ETL - what is scd dimensions? explain the types in brief?

Postby kiruthika » Fri May 04, 2012 1:21 am

what is SCD dimensions? what are the types in SCD?
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Re: ETL - what is scd dimensions? explain the types in brief

Postby deepthi12 » Wed Mar 12, 2014 5:41 pm

Dimensions types :
1)SCD's(Type 1,Type 2,Type 3)
2) Confirmed dimensions
3)Junk dimensions
4) Time dimensions
So, SCD's are one of the types of dimension tables .
In this they are categorized into 3 types :
1) SCD type 1: Only current data ( Inserts are inserts and updates are updates )
If there is a new record in the source then this record gets inserted in the target
If any record got updated in the source and this updated record should be updated in the target too.)
2) SCD type 2: current data + Historical data ( this is the mostly used dimension in Dataware house ) As the DW stores historical data too..
Inserts are inserts
updates are inserts
If there is a new record in the source it gets inserted in the target too.
If there is any updated record in the source it shouls get inserted as a new row in the target so now target contains(old + new record)
In more detail about scd2 it tracks historical data with a separate SK concept or effetctive data or flag or versioning)
3)SCD type 33:
Currentdata + most recent data


Inserts are inserts
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