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Designing a Data Warehouse: Supporting Customer Relationship Management by Chris Todman

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PERFORMANCE CONSIDERATIONS

This book is primarily concerned with accuracy of information and not with performance. However, it is recognized that performance considerations have to be made at some point and that performance may be considered to be more important than accuracy when design decisions are taken. For this reason we will briefly explore the subject of performance.

A query involving the fact table such as “The sum of sales for the year 2000 grouped by Sales Area” using a Type 2 approach, with surrogate keys, would be expressed as follows:

Select SalesAreaCode, sum(s.value)
       From sales s, customer c, time t
       Where s.CustomerSurrogate = c.CustomerSurrogate
       And s.timecode = t.timecode
       And t.year = 2000
       Group by SalesAreaCode

Using our ...

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