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Values of Mini Dimension in SCD Type 4......!

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Values of Mini Dimension in SCD Type 4......! Empty Values of Mini Dimension in SCD Type 4......!

Post  sridharbabu Fri Oct 23, 2015 1:31 am

Hello techies,

As per kimball artical, in SCD Type 4 we maintain frequently changing attributes in a separate dimension called Mini dimension. Some where I read that the mini dimension is going to have combinations of all possible values and in fact table we maintain the history. Can someone help me to understand how combinations will be maintained in mini dimension?

Thanks,
Sridhar.

sridharbabu

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Join date : 2015-10-13

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Values of Mini Dimension in SCD Type 4......! Empty Values of Mini Dimension in SCD Type 4......!

Post  zoom Fri Oct 23, 2015 3:22 pm

The main purpose of Mini dim design technique is used to save memory space. Memory is cheap and time is money. I did not use Mini dim design technique even I had the opportunity to do so. The reason is the Fact table. A fact table would have far more rows in it then a mini dim. When a mini dim tie to a Fact table then it size increases too so concept of saving space is lost. Anyway this is my opinion and you are welcome to create mini dim.

Combinations of all possible values are kept in a junk dim. I think you are confusing yourself a junk dim with a mini dim. Kimball described them both in detail in his DW tool book. Please read about them there.

zoom

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Post  ngalemmo Fri Oct 23, 2015 3:55 pm

Unless the number of possible combinations is relatively small, I generally maintain junk dimensions based on the values encountered. Often there is significant correlation between values and the number of combinations encountered is usually significantly lower than all possible combinations.
ngalemmo
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