Basic Data Wrehousing and Architectures

Question 1

-a central goal you are trying to achieve

Answer 1

theme

Question 2

-a group of data elements tat are central to achieving that goal

Answer 2

critical success factor

Question 3

• a specific question that can be tied to data to identifyif the critical success factoe is being met ot not.

Answer 3

business questions

Question 4

1. Select the business process to model
2. Declare the grain of the business process
3. Choose the dimensions that apply to each fact table row.
   4.Identify the facts
   –is part science, part art

Answer 4

Dimensional Modeling Process

Answer 5

select business process to model

Question 6

-specify exactly what an individual fact table row represents-
-conveys the level of detail associated with fact table measurements.
-it is highly recommended to choose the most granular or atomic information captured by the business process.

Answer 6

declare the grain of the business process

Question 7

-determine the ways the data will be aggregated or filtered.
-identify the level of hierarchy associated with each part of the grain

Answer 7

choose the dimensions

Question 8

-determine the measurements that are available at the chosen grain
-identify any consolidations, calculations or conversions to be done.

Answer 8

identify the facts

Question 9

-all measurements must be at the sam grain
-contains two or more foreign keys to dimension tables
-expresses the many-to-many relationships between dimensions in dimensional models.
-primary table which stores the performance measurements of the business.
-each measurement is taken at the intersection of all relevant dimensions

Answer 9

fact table

Question 10

-look at the OLTP schema (or availbale extracts) to determine identify possible measures.
-determine the lowest grain possible

Answer 10

design guidelines

Question 11

-contain the textual dscriptors of the business
-usually low in cardinality, but very wide
-dimensionattributes used as queart constraints, groupings, and report labels.
-the more descriptice the dimension attributes, the better
-often contain hierarchical relationships

Answer 11

dimension tables

Question 12

(benefits of dimensional model)
-easy for business users to understand.
-improved query performance

Answer 12

simplicity

Question 13

(benefits of dimensional model)
-easily accommodates change

Answer 13

extensibility

Question 14

gross profit/salesdollar amount

Answer 14

gross margin

Question 15

sales dollar amount-cost dollar amount

Answer 15

gross profit

Question 16

a fact is …if we can sum the fact across all dimensions and obtain a valid and correct number

Answer 16

additive

Question 17

a fat is … if the summation of the fact across any dimension results in a meaningless, nonsensical number

Answer 17

nonadditive

Question 18

-a fact is…if it is additive across some dimensions and nonadditivie across other dimensions

Answer 18

semiadditive

Question 19

-it is highly recommended to use this for dimension table keys.
-are simply integers assigned sequentially to a particular dimension row.

Answer 19

surrogate keys

Question 20

-are frequently source natural keys and used to determine the surrogate key to use.
-are also retained for analysis purposes

Answer 20

operational codes

Question 21

buffer the data warehouse from changes in operational codes,
-can save space due to their small size comapared to operational codes.
-allow recording of conditions which do not have an operational code
-allow handling of changes to diemnsion table attributes

Answer 21

benefits of surrogate keys

Question 22

-that extracts data from legacy systems and external sources, consolidates and summarizes them, and loads them into the data warehouse.

Answer 22

data acquisition (back-end) software

Question 23

-that allows users to access and analyze data from the warehouse

Answer 23

client (front-end) software