barcode vb.net 2010 Factless Fact Tables 295 in Software

Creation QR Code 2d barcode in Software Factless Fact Tables 295

12 Factless Fact Tables 295
Decode QR Code In None
Using Barcode Control SDK for Software Control to generate, create, read, scan barcode image in Software applications.
Drawing QR Code In None
Using Barcode printer for Software Control to generate, create QR-Code image in Software applications.
Earlier in this book, you encountered another example of a factless fact table. The star in Figure 8-2 was used to track the history of changes to an insurance policy dimension. The grain of the fact table was defined as one row per change to a policy. Foreign keys referred to the policy dimension, the effective date, and the expiration date. Like contact_ facts, the fact table contained no facts but could be used for various kinds of analysis. While the policy_change_facts design was easily converted into a time-stamped dimension, this is not an option for contact_facts.
QR Code 2d Barcode Decoder In None
Using Barcode scanner for Software Control to read, scan read, scan image in Software applications.
Encode QR Code In C#.NET
Using Barcode creator for .NET framework Control to generate, create QR Code image in .NET applications.
Adding a Fact
Creating QR Code In VS .NET
Using Barcode creation for ASP.NET Control to generate, create QR Code 2d barcode image in ASP.NET applications.
Print QR Code In .NET
Using Barcode maker for .NET framework Control to generate, create QR Code ISO/IEC18004 image in VS .NET applications.
When a factless fact table tracks events, it is possible to make it resemble a standard fact table by adding a special fact. This fact will always contain the value 1. Although superfluous, the addition of this column makes it easier to read and write the SQL to analyze the process. In the case of contact_facts, this is achieved by adding a fact called contact, as depicted in Figure 12-2. The new fact, contact, will always contain the value 1, as shown in the instance grid beneath the schema diagram.
QR Code ISO/IEC18004 Generation In VB.NET
Using Barcode printer for Visual Studio .NET Control to generate, create Quick Response Code image in .NET framework applications.
UPC-A Supplement 5 Drawer In None
Using Barcode drawer for Software Control to generate, create UPC Symbol image in Software applications.
CONTACT_FACTS day_key time_key customer_key contact_type_key contact CONTACT_TYPE
Drawing EAN13 In None
Using Barcode generation for Software Control to generate, create GS1 - 13 image in Software applications.
Code 128C Drawer In None
Using Barcode maker for Software Control to generate, create Code 128 image in Software applications.
TIME
Encode Code 3/9 In None
Using Barcode generator for Software Control to generate, create Code 39 image in Software applications.
Bar Code Creation In None
Using Barcode encoder for Software Control to generate, create bar code image in Software applications.
CUSTOMER
Leitcode Generator In None
Using Barcode drawer for Software Control to generate, create Leitcode image in Software applications.
Make Bar Code In Java
Using Barcode encoder for BIRT Control to generate, create bar code image in BIRT applications.
(Always 1)
2D Barcode Generator In .NET Framework
Using Barcode printer for .NET framework Control to generate, create 2D Barcode image in Visual Studio .NET applications.
GS1-128 Decoder In Visual C#
Using Barcode recognizer for .NET framework Control to read, scan read, scan image in .NET framework applications.
CONTACT_FACTS day_key 27221 27221 27221 27221 27221 27221 27221 time_key 121 121 121 123 123 123 124 customer_ key 4622 3722 2828 1911 3922 3811 8201 contact_ type_key 101 101 102 102 103 101 101 contact 1 1 1 1 1 1 1
Code39 Drawer In Java
Using Barcode creator for Eclipse BIRT Control to generate, create Code 39 Extended image in Eclipse BIRT applications.
Create EAN-13 In None
Using Barcode encoder for Font Control to generate, create EAN13 image in Font applications.
Figure 12-2
Encode ANSI/AIM Code 128 In VB.NET
Using Barcode creator for Visual Studio .NET Control to generate, create Code 128C image in .NET applications.
Making EAN13 In VS .NET
Using Barcode maker for ASP.NET Control to generate, create GTIN - 13 image in ASP.NET applications.
Adding a fact to the factless fact table
Part IV
PART IV
Fact Table Design
With this fact in place, the fact table is no longer factless. It is not necessary to count an arbitrary column when querying this table. Instead, the new contact fact can be summed. This works in exactly the same way that any other fully additive fact is summed. A query that determines how many times each customer was contacted, for example, would begin as follows:
SELECT customer_name, SUM( contact_facts.contact ) FROM . . .
The presence of a column containing a single constant value may look like a kludge or a workaround. From a dimensional perspective, however, this column is a legitimate fact. It represents a quantity. While it will always contain the value 1 at a granular level, it will take on other values when aggregated to other levels. The results of the preceding query, for example, might look like this:
CUSTOMER_ NAME ============ Smith, M.E. Burns, K Smith, B Rogers, S Scanlon, C SUM (CONTACT) ========= 4 10 6 1 12
Here, it is clear the number of contacts is a meaningful and fully additive fact. Aggregation does not occur solely at query time. As you will learn in 15, Aggregates, aggregate tables are sometimes used to improve query performance. An aggregate table partially summarizes data from the original fact table. In the case of contact_facts, an aggregate might summarize contacts by month. In this aggregate, the contact fact will take on a variety of values. In the same way, a monthly contacts cube constructed using data from contact_facts will also contain values other than 1 for the contact fact. It is often possible to find a fact if you look for it carefully. Designs that start out factless often become the home for measurements of duration or cost. A factless fact table that tracks phone calls, for example, might track the duration of each call. Cost-oriented facts may also emerge from other business areas. The finance department may have a standard average cost metric that can be assigned to each call. Don t try to make up a measurement like this on your own; make sure it comes from the business. Also, don t go out of your way to accommodate a fact if it doesn t quite fit. In the contacts example, e-mail messages do not have a duration. That fact is only relevant for telephone contacts.
Copyright © OnBarcode.com . All rights reserved.