Recalculate Aggregates

Question

Hi All,

I have a situation where I am suppose to calculate the Standard deviation on a fact table.

The question is :

How is it best to calculate this for any subsequent incremental loads?
Does it mean that I have to recompute the standard deviation evert time after inserting the data in the fact?

Sridhar

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Sridhar

Answer 1

First, you need to calculate the standard deviation of *what* exactly?  You can't simply calculate standard deviation across an arbitrary number of records - you need to have and understand what population of the data you will be using to calculate standard deviation.  At the moment, it doesn't sound like you have a firm understanding of the requirements.

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Phil Brammer | http://www.ssistalk.com | Twitter: http://twitter.com/PhilBrammer

Answer 2

Phil, I have all the understanding of the requisites ..

All my question states is, what is the best way to calculate Std dev for any incremental loads on table for a relevant set of data !

Say a table T has 5 columns and I want to calculate std dev grouping 3 columns.
Table T is then fed the next day.

Now is there an intelligent way I can avoid running the stddev function on the whole set of T+(delta)T.

I assumed , the question was comprehendible but nevertheless. hope it makes now !

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Sridhar