Page 46 - DCAP606_BUSINESS_INTELLIGENCE

Unit 3: Dimensional Data Warehouse

Fact Table: Fact table generally represent a process or reporting environment that is of value to Notes
the organization.
HOLAP: HOLAP (Hybrid Online Analytical Processing) is a combination of ROLAP (Relational
OLAP) and MOLAP (Multidimensional OLAP) which are other possible implementations of
OLAP.

Multidimensional Online Analytical Processing (MOLAP): This is the more traditional way of
OLAP analysis. In MOLAP, data is stored in a multidimensional cube. The storage is not in the
relational database, but in proprietary formats.
Result Table: A table that contains a set of rows that a database selects or generates, directly or
indirectly, from one or more base tables in response to an SQL statement is known as result
table.
ROLAP: This methodology relies on manipulating the data stored in the relational database to
give the appearance of traditional OLAP's slicing and dicing functionality.
Surrogate Key: A surrogate key in a database is a unique identifier for either an entity in the
modelled world or an object in the database.

Temporal Table: A temporal table is a table that records the period of time when a row is valid.
Transactional Table: The grain associated with a transactional fact table is usually specified as
one row per line in a transaction.

XML Table: It is a special table that holds only XML data.

3.8 Review Questions

1. What is dimension?
2. Explain the dimensional model.

3. “Dimensions define the axis of enquiry of a fact.” Elucidate.
4. Give examples of dimensional model.
5. What do you understand by fact table?
6. Explain the types of measure and fact table.
7. “Dimension tables consist of attributes that describe fact records in the fact table”. Discuss.

8. Define the concept of surrogate key. Also write down the advantages and disadvantages.
9. What do you understand by alternative tables used in data warehousing?
10. Briefly explain about multidimensional OLAP.

Answers: Self Assessment

1. Fact table 2. Dimensions

3. E-R model 4. Semi additive
5. Periodic snapshots 6. Accumulating snapshots
7. Fact records 8. Dimension tables
9. False 10. False

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