CH6 - Data warehousing and OLAP

Question 1

• OLAP

Answer 1

(online analytical processing) is a term used to describe the analysis of complex data from the data warehouse.

Question 2

• DSS

Answer 2

(decision support systems) also known as EIS (executive information systems) supports organization’s leading decision makers for making complex and important decisions

Question 3

• Data mining

Answer 3

used for knowledge discovery, the process of searching data for unanticipated new knowledge

Question 4

 ODS

Answer 4

operational data store : this term is commonly used for intermediate form of databases before they are cleansed, aggregated and transformed into a warehouse

Question 5

 ADS

Answer 5

analytical data store : these are databases built for analysis. Typically, ODSs are reconfigured and repurposed into ADSs

Question 6

• Pivot (or rotation)

Answer 6

cross tabulation is performed.

Question 7

• Roll-up (or drill-up)

Answer 7

data is summarized with increasing generalization

Question 8

• Drill-down

Answer 8

increasing levels of detail are revealed

Question 9

• Slice and dice

Answer 9

projection operations are performed on the dimensions

Question 10

• Sorting

Answer 10

data is sorted by ordinal value

Question 11

• Selection

Answer 11

data is filtered by value or range

Question 12

• Derived (computed) attributes

Answer 12

attributes are computed by operations on stored and derived values.

Question 13

• Dimension table

Answer 13

it consists of tuples of attributes of the dimension

Question 14

• Fact table

Answer 14

each tuple is a recorded fact. This fact contains some measured or observed variable and identifies it with pointers to dimension tables. The fact table contains the data, and the dimensions to identify each tuple in the data. A fact table is an agglomerated view of transaction data whereas each dimension table represents “master data” that those transactions belonged to.

Question 15

• Star schema

Answer 15

consists of a fact table with a single table for each dimension

Question 16

• Snowflake schema

Answer 16

variation of star schema, in which the dimensional tables from a star schema are organized into a hierarchy by normalizing them.

Question 17

• Fact constellation

Answer 17

set of tables that share some dimension tables. However, fact constellation limit the possible queries for the warehouse

Question 18

 Indexing

Answer 18

data warehouse also utilizes indexing to support high performance access. A technique called bitmap indexing constructs a bit vector for each value in the domain being indexed. Indexing works very well for domains of low cardinality