Database Reference
In-Depth Information
Time
Sales
Product
Date
DayNbWeek
DayNameWeek
DayNbMonth
DayNbYear
WeekNbYear
Quantity
UnitPrice: Avg +!
Discount: Avg +!
SalesAmount
Freight
/NetAmount
ProductNo
ProductName
QuantityPerUnit
UnitPrice
Discontinued
City
State
Country
CityName
Population
Altitude
StateName
EnglishStateName
StateType
StateCode
StateCapital
CountryName
CountryCode
CountryCapital
Population
Subdivision
Fig. 4.18 Multiple granularities for the Sales fact
Client
ClientId
ClientName
ClientAddress
...
Time
Account
Agency
Date
Event
WeekdayFlag
WeekendFlag
...
AccountNo
Type
Description
OpeningDate
...
AgencyName
Address
Area
NoEmployees
...
Balance
Amount
Fig. 4.19 Multidimensional schema for the analysis of bank accounts
account can be jointly owned by several clients, aggregation of the balance
according to the clients will count this balance as many times as the number
of account holders. For example, as shown in Fig. 4.20 , suppose that at
some point in time T1 there are two accounts A1 and A2 with balances
of, respectively, 100 and 500. Suppose further that both accounts are shared
between several clients: account A1 is shared by C1 , C2 ,and C3 and account
A2 by C1 and C2 . The total balance of the two accounts is equal to 600;
however, aggregation (e.g., according to the Time or the Client dimension)
gives a value equal to 1,300.
The problem of double counting introduced above can be analyzed
through the concept of multidimensional normal forms (MNFs). MNFs
determine the conditions that ensure correct measure aggregation in the
 
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