Question

In a data warehouse, a 3D cube initially has dimensions: Product type, Month, and Country. After visualization, the dimension Country is refined into State. Which OLAP operation is performed?

• A. Roll up
• B. Slicing
• C. Dicing
• D. Drill down

Hint:

Roll up = summarize to higher level. Drill down = go to more detailed level. Slicing = fix one dimension. Dicing = create a subcube using multiple filters.

Answer 1

The Correct Option is D

Step 1: Understanding the Topic
This question is about OLAP (Online Analytical Processing) operations, which are used to analyze multidimensional data in a data warehouse. A data cube is a common model for this, with dimensions representing categories of data (e.g., Geography, Time, Product).
Step 2: Key Approach - Defining OLAP Operations
We need to understand the meaning of the common OLAP operations to identify the one described in the scenario.

Drill-down: Navigating from less detailed data to more detailed data. It involves moving down a concept hierarchy. Example: moving from "Year" to "Quarter" or from "Country" to "State".
Roll-up: The opposite of drill-down. It involves aggregating data to a higher, more summarized level. Example: moving from "City" to "Country".
Slicing: Selecting a single value for one dimension to create a smaller, lower-dimensional cube (a "slice"). Example: viewing data for only the "USA".
Dicing: Selecting a sub-cube by specifying a range of values for multiple dimensions. Example: viewing data for "Laptops" sold in "Europe" during "Q3".
Step 3: Detailed Explanation
The scenario describes a change in the 'Geography' dimension. The initial level of detail is Country. The refined level of detail is State. Since a state is a more specific, detailed component of a country, the operation involves moving from a higher-level summary (Country) to a lower, more detailed level (State). This action of increasing the level of detail by moving down a concept hierarchy is the definition of a Drill-down operation.
Step 4: Final Answer
The OLAP operation performed is Drill-down. \[ \boxed{\text{Drill down}} \]